- Email: [email protected]
Global eradication of Guinea worm
Reviews Fran~ais de Recherche Scientifique pour le D6veloppement en Cooperation, ed.), p. 308 (in French) 17 Remme, J.H.F., Alley, E.S. and Plaisier, A.P. (19951in Estimation and Prediction in Tropical Disease Control (Mollison, D., ed.), pp 377-399, Cambridge University Press 18 Agoua, H. et al. (1995) Eludes entomologiques de posttraitement dans ie programme de lut~e contre I'onchocercose en Afriqne de l'Ouest. Parasite2, 281-288 (in French) 19 WHO (1991)Planof Operationsfor the FourtiiPl~se(1992-~.~97),WHO 20 Boatin, B. et al. (1997) Patterns of epidemiology and control of onchocerciasis in West Africa. J. HelminthaL71, 91-101 21 Awedoba, A.K. (1996) S~cio-demographicStudy of Oncho-endemic Communities in the l~asins of the Louwr Black Volta and $o~thwest Ghana,412/7/96/PET, WHO/OnchocerciasisControl Frogramme 22 Boussinesq, ..'~l., Prod'hon, J. and Chippaux, J-P. (1997) Onchocerca volvulns: striking decrease in transmission in the Vina valley (Cameroon) after eight annual large scale ivermectin treatments. Trans. R. Sac. Trap. Med. Hyg. 91, 82-86 23 Dadzie, K.Y. (1997) Onchocer¢iasis control: the APOC strategy. Africa Health,13--15 24 Cheke, R.A. and Garms, R. (1983) Reinfestation of lhe southern flank of the Osichocerciasis Control Programme area by windborne vectors. Philos.T~ns. R. Sac. London ~er. B 302, 471--484 25 Walsh, J.F, Philippon, B., Henderickx, J.E.E. and Kurtak, D.C. (1987) Entomological aspects and results of the Onchoeerciasis Control Programme. Trap. Med. ParasitoL38, 57-60 26 S~.k~t~li,A. et aL (1993) Equipes nationales entomologiques de la zone d'extension c.uest du programme de lutte contre l°onchocer¢ose en Afrique de l'Ouest (OCP) de 1986 -'1 1990. Pattie I, Structures op~rationnelles, fonctionnement et avenir. Bull. WHO 71,737-753 (in French) 27 Bake:, R.H.A. et al. (19e0) Progress in controlling the reinvasion of wind-borne veclors into the weslern area of the Onchocerciasis Control Programme in West Africa. Phi!as. "1tans. R. Sac. LondonSet. B 728, 731-750 28 Remme, J. et al. (1989) A community trial of ivermectin in the onchocerciasis focus in Asaben~e. I. Effect on the microfllarial re~rvo|r and the transmission of Onchoeerea volvulus. Trap. Med. Parasitet.Ser B. 40, 367-374 29 Guillet, P. ct al. (i-ca)5)Impact of combined la~e-scale ivermectin dietribution and vector control on transmission of Onehocerca voivulus in the Niger basin, Guinea. Bull. WHO 73,199-205 3,q Wilson, M.D., Post, R.J. and Comulski, LM. (1993) Multivariate morphotaxonomy in the identification of adult females of the Simulium d a m n o s u m Theobald complex (Diptera: Simuliidae)
in the Onchocerciasis Control Programme area of West Africa. Am1. Trap. Med. Parasitoi.87, 65-82 31 Crosskey, R.W. (1987) A taxa summarj for the Simulium damnosum complex, with special reference to distribution outs.;de the control areas of West Africa. Ann. Trap. IVied. Parasitol.81,181-192 ?? Zimrnerman, P.A., To~, L. and Unnasch, T.R. (1'~,3) Design of Onchocerca DNA probes based upon analysis of a repeated sequence family. MoL Biachem.ParesitoL58, 259-268 33 Tang, J. et aL (1995) The $inralium danmosura species complex: phylo~enetlc analysis ~ d nmlccular identification based ~p-an mitochondriallyencoded ~ e sequences. InsectMol. Biol.4, 34 To~, L. et m. (1997) Veclor-parasite t~ran~mission complexes for onchocerctasis in West Africa. Lancet349,163.-166 35 Quill~v~r~,D. et aL (1978)Etudedu c0mplexe$im~iium damnasum en Afrique de l'Ou¢~ ~lIL Etude de 1,1bi~.cotogie et du pouvok vectettr des femelles de savane. Comparaison avec lea femelles de for~t. Cab.ORSTOM ~'. Ent. Md'd.Parasitd,16,151-164(in French) 36 Meredith, S.E.C'., Cheke, R.A. and Garms, R. (1983) Variation and distributim~ o~ forms of $imulium damnoanm ¢emplex from West A~ica. Ann. Trap. Med. Paresitol.77, 627--640 37 Herder, S. (1996) Vaxlabillt~ g&m_tL~qued'Onchvcerca volvu|us (Leuckari, 18(~:.1.Relations ave¢ le faci~ &pid6mioingique de I'onchocercose. Th&~eset Dacumcnts Microfichds no. !45 (institut Fran~ais de Recherche Scientifique pour le D~veloppement en Cool, ration, ed.), p. 115 (in French) 33~9WHO (1996)Planof Or~ratlonsfor t;w FifthPlul~ (1998-2002),WHO Hougard, J-M. el aL (1994) De la n~.¢~it~ de n~ner ~ terme lea activit~s de iutte antivectorielle du programme de intie contre I'onchocetcose en A~rique de I'Ouest: rappel des enjeux et proposition d'un bud~,t a minima pmsr la p&,'iode 1998-206Z Parasite1,295-303 (in French) 40 Plaister, A.P. et aL (1997) The required duration of combined annual iverme~n treatment and v,',ctor control in ).he Onchocerciasis Control Pmsramme in West Africa. Bull. WHO 75, 237-245 4! Katholi, C.R. ct aL (1995) Determininfl the prevalence of Onchocerca volvulus infection in vector populations by polymerase chain reaction screening of pool~ of b l ~ k flies. I. Infect. Dis. 172,1414-1417 42 WHC (1996) Mt~thlg on OperationalResearchand Strategies.Report of ;he Experl AdvisoryCamminee, OCP/EAC 17.2, WHO 43 Hougard, J-M. et al. La lulte c o n ~ la nuisance simnlidienne, une consequence de i'm'r~ des activit@s de lutte contre le vecleur de i'onchoeercese en Afrique de I'Ouest. Faram Mo~:dialde la Sant~(in French) (in press)
Global Eradication of Guinea W o r m H. Peri(~s and S. Cairncross Little more than a decade ago, it was estimated that over three millio, cases a[ dracunciiliasis occurred worldwide, Since then, the tmmbers have falle:t dramatically, thanks to the water supply initiatives of the 1980s and, more recently, the national guinea zoorm era3ication programmes implemented in a score of endemic couh~ries. Hervd Perils and Sandy Cairncross discnss how eradicat;o, will require the containment of cases in the remaining endemic areas, together with the simultaneous strengthening of surveillance to permit the certification of eradication. This aim requires existing strategies to be adapted to maintain thei, efficacy and also to improve their sustainability and costeffectiveness. Sudan with its civil u~r, and more than a Herv~ Perils is at the UNICEF RegionalO~ce for We_--tand Cenb~l Africa,04 E~P443, Abidjan 04, Ivory Coast.West Africa. Sandy Ch!ri~r3es is at the London School of Hygieneand Tropical Medione, Kc.pF,=lSu'cet, London. LIK ~A:CIE%iT. Tel: +44 ITI 9'17 221 I, Fax: +44 171 636 7343,
e-mall: sc~rm:r~shtm.ac.uk Pora.~il.ology Toduy, vol. 13, no, I I, 1997
hlmdred thousand reported cases, remains a major obstacle to rapid achievement of the goal. D r a c u n c u l i a s i s , o r g u i n e a w o r m d i s e a s e , is a p a i n f u l and debilitating human condition, caused when an adLqt f e m a l e of t h e n e m a t o d e Dracunculus medine,lsis e m e r g e s ~~radually f r o m the s u b c u t a n e o u s tissue, u s u a l l y o n the legs. T h e d i s e a s e is e n d e m i c in r u r a l , p o o r a n d u s u a l l y w a t e r - s h o r t c o m m u n i t i e s of s u b - S a h a r a n Africa ( m o s t l y in t h e S a h e l Belt a n d G u l f of G u i n e a ) , a n d vestigial fact r e m a i n in p e r t s of t h e A r a b i a n p e n i n s u l a a n d t h e I n d i a n s u b c o n ~ n e n t . It is t h e o n l y d i s e a s e t h a t is t r a n s m i t t e d e x c l u s i v e l y in d r i n k i n g w a t e r . A l t h o u g h d r a c u n c u l i a s i s kills f e w p e o p l e , it c a u s e s f r e q u e n t c o m p l i c a t i o n s a n d l o n g - l a s t i n g disabilities, a n d a l s o h a s f a r - r e a c h i n g socio--economic effects in affected c o m m u n i t i e s . T h i s ancient, s c o u r g e h a s c a u g h t m a n y p e o p l e ' s i m a g i n a t i o n b e c a u s e of its s t r i k i n g clinical m a n i f e s tation, the a g e - o l d t r e a t m e n t o f w i n d i n g the w o r m 431
Reviews of the cyclopoid family (cyclops), which then become infected. The larvae require a development ~'~ period of about two weeks to ~~ become infective. The disease can Infec(ed ~ individ~ ~; then be transmRted to a new host through the inadvertent swallowing of infected cyclops (0.8 mm long) in drinking water. When _ they are ingested, cyclops (which are not themselves dangerous to drink) are killed by stomach acid, but the infective larvae pass through the gut wall of the duodenum, and begin to mature in the ~ ~ connective tissue of the abdominal or thoracic cavity. The worms mature sexually and meet and mate in the subcutaneous tissue, , .~..~ - infected I ~k approximately a hundred days t' I cyclops/ %. after infection. After mating, the male worms become encapsulated ! ovozo,p..~ 7 / and die. The female moves down the muscle planes and, after 10-14 months, the mature worm begins to release a fluid full of newly formed larvae. This around a stick (possibly the inspiration for the symsets off an allergic reaction causing a blister, through bol of the meclical profession), and its Power to parawhich the worm will emerge, repeating the life lyse entire villages during severe disease outbreaks. cyde 4's (Fig. 1). In the early 1980s, dro :m~culiasis was identified as a The painful ulcers and ab~cesses (usually on the suitable candidate for eradication because of ks vulfeet or legs) can cause a long period of disability, nerability to simple preventive measures. Thanks to a depending on the site of emergence and any complihigh level of mobilization L-f the international comcations. The degree of disability ranges from mild munity, a successful global programme of eradication (causing pain or a limp, but allowing the sufferer to is under way 1-3. work) to severe, when the victim is unable to leave the village and even the house to work or to attend The disease school. It can last from a few days to several months The first description of the life cycle of D. mediuensis if there are complications, if joints are attacked or if was made by the Russiar~ r~ahi~alist A.P. Fedchenko there are multiple infections6. Some complications in 1871. It was an important milestone in tropical medresulting in long-term disability are caused by nonicine as it was the first record of an arthropod intermeemergent worms. For instance, many cases of arthritis diate host of a human pathogen4, a few years before have been reported after irruption of a worm in a Manson's famous description of the role of Culex mosjoimL However, secondary infection is the principal quitoes in the transmission of bancroftian filafiasis. complication, affecting roughly half of the cases8, The female D. mcdineasis is one of the longest including lethal complications such as tetanus. One nematodes known, r,:,~suring 550-800 mm long by study found that 15 out of 211 cases of tetanus seen in 1.7-2.0 mm in diameter. The male is only about Ouagadougou Central Hospital, Burkina Faso (7.1%) 40 mm long. This great disparity in the length of the had contracted the infection from a wound caused by sexes Ls one of the features ~parating the dracunan emerging guittea worm 9. culids from the fllarial nematodes, with which they were formerly included. Feasibility of eradication With a silent incubati~r, period of 10-14 months, Following the success of the smallpox eradication the disease is characterized by the e~ergence c~! the campaign ~°, guinea worm disease is the next target mature female, causing a painful blister. ~ occurs for a future eradication, although poliomyelitis has most frequently on the lower limb at or lx~ow the knee, with a preference for the foot and ankle joint, also been su~ce.~-~,d as a competitor u. Table 1 combut sometimes in other locations such as the genitals, pares deacunculiasis and poliomyelitis as candidates for eradication with their predecessors, smallpox back, breasL tongue or eye. When the affected part of the patienVs body is immersed in water (for instance, (successful) and malaria (failed). Dracunculiasis seems to be a less likely candidate during household water collection or work in the fields, and when the patient wets it to relieve the for eradication than smallpox and poliomyelitis, not burning pain), water contact stimulates the female only because of the lack of immunity and of vaccines, worm to emerge further through the ruphtred blister chemovrovhvlaxis or treatment, but also because the and to release hundreds of thousands of microscopic principal c¢;r/~l measures require a change in behavlarvae into the "water. tour. Guinea worm does not Pose a threat of epiWhen the worm's larvae rare washed into a pond or demics outside its traditional endemic areas, so that shallow well, they are ingested by small crustaceans potential partners and donors have no direct national 432
Dro~nculos
Fig I. Life cycle of medin~a. (Hateria! kindly provided by CDC. Adanta, USA.)
individual
~.~
~
infected individual (I year I later) /
Non-infected t ~',.?~"~',.
~
/~~
Parosi~e."~gy Today.vol.13,rao,I I. 1997
Reviews
1 Table I. Characteristics o f past and p r e s e n t eradication candidates ~
Malaria b
Smallpox
Poliomyelitis
Dracunculiasis
+ -
+ +
+ +
+ +
-
+ +
+ -
+ +
L i m i t e d e n d e m i c area
+
+
Seasonal transmission
+
+
+
+
+/+
++ + -
~-
+ +
+ +
+ -
Agent N o animal r e s e r v o i r No mobile vector
Host L i m i t e d c a r r i e r state Easy diagnosis
Distribution
T h r e a t t o w e s t e r n c o u n t r i e s and visitors Intervention
Effective drugs exist P r e v e n t i o n cheap and c o m p l e t e P r e v e n t i o n needs n o b e h a v i o u r change Adapted from Ref. I. b Characteristics favouring eradica¢ion are marked ' + ' .
interest in its eradication, except for h u m m i t a r i a n motives. However, this seems not to have impeded the first phase of eradication, thanks to the personal involvement of former US President Jimmy Carter, the support of James Grant of the United Nations Children's Fund (UNICEF) and the strong commitment of governments and ti:eir funding partners. Several aspects of guinea v~orm disease favour its eradication prospects 2. First, no animal reservoirs have been identified. That people are the sole reservoir seems to be confirmed by the failure of the disease to reappear in former endemic countries such as lran, the ex-Soviet Union, Gambia and Egypt ~2. The parasite seems not to survive beyond its one-year transmission cycle, a n d there are no long-term c.arriers to be feared. The disease is easily diagnosed a~,d is well k n o w n in the endemic areas. Transmission can easily be prevented (i:}ox l), not only by the relati~.ely costly measure of installing safe water supplies, but also by simple a n d affordable alternative measures, such as filtering water through a cloth. The intermediate host is susceptible to chq.~mical treatment, and lives in stagnant water so that it cannot transmit infection over a long distance. However, infected .people cannot be identified during tbp one-year incubation period before emergence of the worm, and are therefore the m e a n s by which the disease is disseminated. Socio-economic impact o~ dracunculiasis Most cases of dracunculiasis go unreported: it is only very rarely ~. fatal disease, it occurs in poor remote rural areas, the disease itself m a k e s travel to a health iacility difficult, and it is usually followed by spontaneous recovery even in the absence of a n y treatment -~. The n u m b e r of dra.:unculiasis cases has therefore always been dramatically underestimated, and the disease has often been considered as an exotic olriosit3,', of minor public hea]th importance. As late as 1993, its very inclusion in the World Development Report 23 was hotly debated by the editorial team. However, in endemic areas, its social, nutritional, educational a n d economic consequences and the costs incurred by individuals, households and communities have bee~i well documented 6. In most endemic regions, the peak incidence of the disease coincides with the planting or harvesting Parasitology Today, vol. "13, no. I I,
•997
period of seasonal crop production, so that, .;n hyperendemic areas, agricultural losses directly attributable to disability from dracunculiasis can be substan:;o;~,~-=~. i~L South Kordofan, Sudan, a s t u d y of the impact of dracunculiasis in adults on the nutritional status of their children found that, in affected families, 16.6% of children aged 0-6 years were affected by wasting (ie. were two or more standard deviations below the reference median of weight for their height), compared with only 6% in other households 26. In the forest zone to the south, where the peak incidence is in the dry season, school absenteeism is more often mentioned as a consequence. Not only do the children themselves suffer from the diseas,% but they also miss school w h e n they are obliged to stand in for their disabled parents in the fields In Anambra State, Nigeria, before the eradication effort began, the absentee rate was found to treble during the guinea worm season 27.
Box I. P r e v e n t i v e Strategies
Despit.e the lack of available treatmel~t, chemoprophylaxis or vaccine1~14,dramatic reduc~ons in the incidence of guinea worra disease have been made possible by the combination of several complementary preventive interventions'5,16 in endemic or at-risk communities, mainly: (l) the provision of a safe water supplylT.la; (2) health education, combined with the provision of cloth fillers to prevent the consumption of unsafe drinking waterl'~.2°; (3) early case containment, including simple treatment and bandaging of cases, an~ raising community awareness to ensure that sufferers ~void contact with water-supply sourcest~; and (4) vector-control measures, through the treatment of ponds with insecticide non-toxic to humans, to kill the cyclops intermediate host2122. Interventions (2) and (3) can be implemented at village level by trained community volunteers. Eradication programmes initially gave priori .ty to direct implementation of activities by water agencies and health services, but there has been an increasing awareness of the effectiveness of involving village volunteers in surveillance, prevention and early case containment, and a progressive shift towards a more communi~-based and participatory approach2. 433
Reviews
~ f
°~':
D •
I D
Dracunculiasis-endemic 3racunculiasis-endemic countries Dracunculiasis-endemic villages Other countries
Fi~. 2. Geographical distribution of guinea worm in Africa. 1996. The shaded areas are the endemic countries, and individual endemic villages are shown by dots A few cases have also been found in Yemen (not shown). The data from Ghana refer to 1994, and those from Nigeria to 1993. [Hate~ai kindly provided by the joint WHO-UNICEF Programme on Mapping and Geographic Infor~.ation Systemsfor DracunculiasisEradication (HealthMap). WHO/CTD, Geneva.]
Currel:t ep|fiemio!ogical status Dracuncul~asis is still endemic in 19 countries, all but ~'wo of which (India and Yemen) ~rc in Africa (Fig. 2). It has disappeared spontaneously from the hi.~torical loci of infection in the Americas, where it was imported by the slave trade, and from the ancient loci in the Middle East and Central Asia. Pakistan is the only country so far to have demonstrably .eliminated the disease in the current eradication effort, but preliminary data indicate that India may also have eliminatecl it; the last known case there was in July 1996. It is difficult to estimate the total number of cases that occurred annually worldwide before the establishment of national guinea worm eradication prosrammes with ~ctive surveiliance, because of the very low rate reporting of guinea worm cases in health facilities3. Studies in Nigeria and in Togo in the 1970s27~ f,und ~.hat only 5% and <4% of cases studied, respec~.ively, had been reported to the he~lth system. Another study of 985 sufferers in Rajasthan, India in 1978-1979 showed that none bad visited a health facility'. 'Guesstimates' of the global incidence of dracunculiasis over the years have fallen gradually from Stoll's original estimate of 48 million cases in 1947 (Ref. 30) ~.o 10 million in 1976 (Ref. 31) and 3.3 million in 1986 (Ref. 32); the last figure referred to Africa alone, but k by 1986, there were fewer thau 30000 cases elsewhere. As each country conducted a national search (or cases, most in ,the early 1990s, it was found that there 454
J
were many times more cases than had been suggested by routine passive reporting, but fewer than the previous estimates; adding together the maximum number of cases ever reported by each endemic country gives a total of 1.3 million, of which half is the ~gure from Nigeria in 1988 (Ref. 33). To some extent, the progreasi~e decline in the estimates probably reflects a genuine fall in the number of cases; anecdotal evidence abounds of villages where the disease was endemic until hand pumps were installed. Rural water-supply programmes, particularly those implemented in a number of endemic countries after the Sahel drought of the early 1980s, probably contributed to this. However, it is also likely to reflect the increasing precision of the estimates, possibly inflated for advocacy purposes. Beginning in a few endemic countries in the late 1980s, but during the early 1990s in most others, national case searches were carried out to support the establishment of nat.lonal guinea worm eradication programmes. Annual case searches carried out by the early programmes were replaced ~y communitybased surveillance and, more recently still, by the implementation of a case~containment strategy34. This made it possible to monitor dracunculiasis incidence and to give a precise annual picture of the progress of the eradication effort (Box 2). In all countries except Sudan, there has been a sustained and rapid reductmn in the reported guinea P~,sitolo~ Today, vol. 13, no, I I, 1997
Reviews Norm incidence. The worldwide total fell from 892000 cases reported in lO89 to fewer than 35000 cases reported in 1996 (see Fig. 3). However, the picture is complicated by the situation in Sudan, where the national p r o g r a m m e started only recently and is hampered by the civil war. The increasing n u m b e r of cases reported from Sudan led to the global total increasing in 1996 for the first time in seven years. However, this was not a sign of failure to conh'ol the disease, but rather an indication of the increasing sensitivity of Sudan's surveillance, as it gets into its stride in both government- and rebel-held areas of the country. Costs a n d benefits Guinea w o r m eradication has thus been remarkably successful, reducing the global incidence (except in Sudan) by over 95% in the past seven years. Apart from the p r o g r a m m e ' s contribution to the improven'ent of the water supply in poor and remote rural communities, the reduction of incidence has, without doubt, had a major impact on disability, agricultural production, income generation and poverty reduction in endemic areas. This has been achieved at moderate cost, considering that the endemic areas include some of the most remote and undeveloped parts of the developing world. Excluding the cost of water supplies, which have other benefits, we estimate that less than US$30 million has been spent on guinea w o r m eradication since 1989. The community-based surveillance and health education delivery systems have an annual cost of abc,vt US$100-200 per village 2. This is likely to increase "~vhen case containment is stepped u p in the final phase; Cameroon's case containment cost US$230 per village in 1991 (Ref. 39). However, these systems can deliver other health interventions besides guinea ~:orm control, and the overall cost of p r o g r a m m e s shot;1d continue to fall as the endemic area shrinks. The final stretch
The i m p r o v e m e n t of surveillance and the rapid elimination of the last endemic foci are the next challenges. In most endew, ic countries, the remaining at-risk communities will be increasingly remote and inaccessible, with few options for water-supply improvements and poor access to education. This will make the final run towards eradication at least as difficult as the initial phase, which achieved dramatic reductions in incidence. The likely time-scale is demonstrated by the time taken by the six countries nearest the goal to count d o w n from their last thousand case~ (all six are s h o w n in Fig. 3), although most of these countries could concentrate their efforts and resources on a few limited endemic areas, and three (Cameroon, India a n d Pakistan) already had several years of experience of fighting guinea worm. In this context, the realism and appropriateness of the World Health Orgarfization's (WHO's) target of achieving eradication by 1995 (Ref. 40; Box 2) is ope,n to question. Certainly, s~me confused this objective, set primarily for advocac3, purposes, with a planning assumption, or sought to make people accountable for achieving it, or judged the commitment of colleagues by ~,hether or not they agreed that it was Parasitoloooy Todoy, vol. 13, ~o. I[. 1997
Box 2. Milestones in the Development of the Eradication Campaign
During the 1980s, awareness of dracunculiasis and the political will to eradicate it were mobilized gradually, in the context of the International Water Decade. In 1982, the US National Academy of Sciences organized a workshop h~ "vVashing~onon worldwide guinea worm control35. In 1984, the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, USA were appointed as the WHO Collaborating Center for Research, Training ~.nd Eradication of Dracunculiasis, In 1986, Global 2000 of the Carter Center. aI;o in Atlanta, became heavily involved in the eradicatLon effort. Soon afterwards, UNICEF also joined She cam|.aign. ~.~'1991, member states of WHO declare~i their r,~:,oiveto era ~icate guinea worm by 1995 ~'.ReL36) by adopting the ;e~,ol,,tion WHA44.5. In 1992, UNICEF and WHO created an Interagency Technical Team, based in Ouagadougo~l, Burkina Faso, "~o support eradication programmes in African endemic countries. !n 1993, WHO set up a Dracunculiasis E~-'-~i~ationPriority Programme in the division for Conho.~ of Tropical Disea~s, Geneva, Switzerland, with a b~ief to improve epidemiological surveillance, boost the eradication process and prepare for the certification of eradication. At the same time, crucial village-based epidemiological surveillance was re-inforced thanks to the creation of the joint WHO-UNICEF Programn~ on Mappinej and Geographic Information Systems for Dracunculiasis ;~radication. "/'he main aim of this programme, in close collaboration with ~ove.,'nments and partners, is to ~ro~ote thp ur,e of ~eogr~Fidc information ~y~,~eros37for'the managemev~,of epidemiological su..'veillance data from guinea worm programmes at world, continenta!, nati~'nal and local levels. In ~995, with drama~c progr~s already achieved and parts of endemic countries beginning to register zero cases, .~b.e Inten,ational Commission for the Certification of Dracunculiasis Eradication was appointed. It met first in Geneva, in March 1990 (Ref. 38). Its immediate priority is to certify eradication in those countries where the disease was endemic in the past, b~t has already disappeared. feasible. Donor agencies were of course attracted to the prospect of a time-limited programme with lasting benefits, but the risk was that they and others might lose interest after the deadline had pa ' ~ c i 41. In thE: event, donor support has not died, and every endemic country had at least set u p its eradication programme by the target date; the fact that some did so at the last minute suggests that the approaching deadline .,~purred them to do so, in which case it served its purpose. To certify eradication, evidence will be nc~ded of the absence of guinea v ¢ o ~ . . , for three consecutive years from all areas with a recent history of the disease. This requires that community-based surveillance systems remain active and effective in all areas at risk (reporting cases since the national survey) for three years after the emergence of the last worm. However, as the disease is eliminated from more and 455
Reviews O0000C
looooc ~
TOTAL
10000
except Sudan Nigeria Ghana
"~.~
\
~
~
"~
1000
India
Uganda Ethiopia
100
Chad
10
11
I
I
I
I "'1
~--~--t
198919901991109219931994lg9519961997 Fig.3. Declinein the numberof reportedcases of guinea wormdisease,1989-1996,showingthe impactof eradication programmes.Notethe logarithmicscale.The incidencehas fallenat a similar.ratein the otherendemiccountries(not shown).(DatakindlyprovidedbyWHO andUNICEF.) more villages, the commitment of village w, lunteers and supervisors will be hard to maintain. Few volunteers or superv'sors will continue to visit every household or every village monthly (weekly in some countries) when the chance of finding guinea worm cases becomes vanishingly small. Communities beset by major health threats, such as malaria, diarrhoeal diseases or measles epidemics, will fail to understand the need for their village health worker to ignore these, whi~.e focusing on a disease that has almost disappeared. Integration: a marriage of convenience Of course, a single-minded effort must still be devoted to reducing guinea worm incidence, especially in villages that stilll report many cases; indeed, it would be dangerous to declare victory too early. However, it is also clear that effective case containment and surveillance can only bc mai:~tained for long enough to achieve eradication and certification if current strategies are adapted. An essential measure is to integrate surveillance measures specific to guinea worm disease within a more comprehensive approach to comm~.miW health, as advocated by WHO, UNICEF, Centers for Disease Control and Prevention and Global 2000 in a joint declaration in 1993 (Ref. 42). Villag~ volunteez~ visiting each household to de~ tect cases of guinea worm disease might, for example, take advantage of visits to record births, identify children to be immunized or promote the use of oral rehydration therapy (ORT). This makes health volunteers' work more interesting and motivating, especially
436
when guinea worm disease is absent for much of [he year, as is the case even in hyperendemic villages. Most endemic countries have understood the challenge and have begun or plam~ed such a diversification of activities. In many (Burkina Faso, Chad, Ivory Coast, Ghana, Mall, Niger and Ethiopia), this involves monitoring of immunization and surveillance for diseases includ~-d in the Expanded Programme of Immunization; in Senegal, guinea worm will become part of an integrated con~munity-based surveillance system including malaria, schis¢osomiasis, leprosy and onchocerdasis; in Mauritania, guinea worm eradication activities have been implemented wherever possible as part of an integrated community-based primary health care programme, including malaria control, ORT promotion, vitamin A distribution and health education. One disease targeted for elimination for which community-based surveillance will undoubtedly be necessary is neonatal tetanus43. Existing guinea worm surveillance systems cover only v~.llages currently or recently reporting cases, but these cnnld be used as sentinel villages for tetanus surveillance. In the more endemic areas, about one village in three has been under surveillance and benefited from the training and regular supervision of one or two village volunteers. The components of the guinea worm eradication effort (trained village health workers carrying out surveillance and offering health education, supported by monthly visits from their supervisors) are clearly a potential resource which could strengthen other aspects of primary health care. In many cases, the villagers have shown their readiness to participate in tackling health problems by organizing teachers and pupils, youth associations and women's groups to help the village volunteers detect new cases. Recent devel,.~pments in primary health care, particularly the geheralization of the Bamako Inigative in the endemic regions*~, are leading to the establishment of elected health committees to manage local health facilities ;rod to plan, finance and monitor public health activities in the community. These committees include elected representatives of all villages from the area covered. They are a unique resource in helping to build an effective surveillance system that is truly community-bahai in the full sense of surveillance, not only collecting data, but also responding to it. Such a system would also cover other conditions targeted for eradication or elimination, such as neonatal tetanus, poliomyelitis, leprosy, vitamin A deficiency and perhaps in the near future measles and other candidates. The feasibility of eradication of these diseases (as well as guinea worm) and the strategies and requirements for eradication or elimination were major topics at the recent workshop on the Eradication of Infectious Diseases, sponsored by the Univers;~ of Berlin, Germany ~s,
Perspective After the tremendous efforts of :he past decade, the centuries-old scourge of guinea worm is now likely to be the second h~man disease to be eradicated. The dramatic reductions in incidence so far are rightly unanimously hailed as a giant step towards eradication, but the next phase will be equally cha!lenging. To contain the last few cases and certify eradication could require several more yea~ of effort, Parasitology Today, voL 13, no. I I, 1997
Reviews during which programmes w i l l h a v e to m o v e p r o gressively from the current vertical strategy to a more b a l a n c e d m i x o f i n t e r v e n t i o n s s p e c i f i c to g u i n e a w o r m w i t h i n t e g r a t e d c o m m u n i t y - b a s e d a c t i v i t i e s , to guarantee cost-effective and sustainable success in e r a d i c a t i o n . T h e c o n t i n u i n g c i v i l w a r in S u d a n , w i t h h y p e r e r ~ ) e m i c f a c t i n t h e c o m b a t z o n e , is t h e c h i e f c o n s t r a i n t to a c c u r a t e p r e d i c t i o n o f a n e : a d i c a t i o n d a t e .
Acknowle ~gements The erad!e.:.tion of guinea worm disease is a collaborative endeavour towards whi::h many people have contributed their efforts and ideas, in addition to those cited above. The views expressed in this article reflect the views of the authors as individuals and not of their institutions of affiliation. References 1 Hopkins, D.R. (1983) Draeunculiasis: an eradicable scourge. Epidemiol. Rev. 5, 208-219 2 Caimcross, S. et al. (1996) Community participation in the eradication of Guinea worm disease. Acta Trap. 61,121-136 3 Ranque, P. et al. (1996) SituaSon actueUe de la campagne d'&radication de ta dracunculase. Med. Trap. 56, 289-296 (in French) 4 Muller, R. (1971) Dracuncnlu~; and dracunculiasis. Ad~,. Parasitot. 9, 73-151. 5 Muller, R. (1979) Guinea worm disease: epidemiology, control and treatment. Bull. WHO 57, 683-689 6 Watts, S.I. et al. (1989) Guinea worm: an in-depth ~tudy of what happens to mothers, families and communities. Sac. Sci. Med. 29,1043-1049 7 Hours, M. and Cairncross, S. (1994) Long lerm disability due to Guinea worm disease. Trans. R. Sac. Trap. Med. H~/g. 88, 559-560 8 Wurapa, F. et al. (1975) A clinical picture of Guinea worm disease in southern Ghana. Ghatu Med. [. 14,10-15 9 Pirame, Y. and BeC~lUet, R. (1969) Dracnncuiose et tetanus; ; p m p o s de 15 observations. Bull. Sac. Patl~ol. Exot. 29, 702-710 10 Anon. (1983) After smallpox, guinea worm? Lancet i, 161-162 'd Cochi, S.L. et al. (1997) Commentary; the nnfolding atory of global poliomyelitis eradication• ]. h:]ect. Ois. 175 (Suppl. l), S1 -$3
12 Watts, S.]. (1996) No transmission of dracunculiasis in Egypt for two centuries. World Health Forum 17,181-183 13 Eberhard, M.L. et aL (1990) Chemoprophyl~dic drug trials for treatment of dracunculiasis using the Dracuncnlus isiguisferret model. !. Hehninthel. 64, 79-86 14 Chippaux, j.P. (1991) Mebendazole treatment of dracunculiasis. Tra~ls. R. Sac, Trap. Mcd. Hyg. 85, 280 15 Hopkins, D.R. and Ruiz-Tiben, E. (1991) Strategits for dracunculitsla eradication. ~
Parasitology Today. vol, 13. no. I I, 1~97
cole: Its effets de la dracuncuiose darts une agriculture de subsistance. Revue d'deonomie du D~veloppement 1, 23-26 (in French) 25 Brieger, W.R. et aL (1990) Farmers' loss due to Guinea worm disease: a pilot study.]. Trap. Med. Hyg. 93,106--111 26 Tayeh, A. and Cairncross, S. (1996) The impact of dracunculiasis on the nutritional status of children in South Kordofan, Sudan. Ann. Trap. Paediatr. 16, 221-226 27 Nwosu, A.B.C et al. (1982) Endemic dracontiasis in Anambra State of Nigeria: geographical distribution, clinical features, epidemiology and socioeconomic impact of the disease. Ann. Trap. Meal. Parasitd. 76,187-200 28 Setodji, A. (1979) La DraeuneuJoseen Milieu Togolais: Situation de la Circonscription du Hobo, presented to Ecole des Assistants M&3icanx, Univemity of Cotonou, B~nin Republic 29 Johnson, S. and ]oshi, V. (1982) Dracuntiesis in Western Rajasthan, India. Trans. R. .Sac. Trap. Med. Hyg. 76, 36--40 30 Slot!, N.R. (194,-) This wormy world. ]. Parasitol. 32,1-18 31 Duke, B.L (1976) Filarulsis,TDR/WP/76.tO.1976:3, WHO 32 Watts, S.J. (1987) Dracunculitsis in Africa in 1986: its geographical extent, incidence and at risk population. Am. J. Trap. Med. Hyg. 37,119-125 33 World Health CYcganization (1990) Drscuncullesis - Nigeria. • Wkly EpidemioL Rec. 65, 385--387 34 Anon. (1994) Case Contai,ment Strategy for Eradication of Dracuncutiasis in Africa, Centers for Disease Control and Prevention with Global 2000, United Nations Children's Fund and WHO 35 National Research Counc:l (1983) Opportunities [or Control of Dracunculiasis; Rept,rt of a Works.~ap,National Academy Press 36 Hopkins, D.R. and Ru~z-Tiben, E. (1990) Dracunculiasis eradication: target 1995. Am. ]. Trap. Med. Hyg. 43, 290-300 37 Clarke, K.C et aL (1991) The use of remote sensing and geographic information systems in UNICEF's draconculiasis (Guinea worm) eradication effort, Prey. Vet. Med. 11,229-235 38 ~World Health Organization (1996) Dracunczdh~si~.Ceriifio~lia, of Eradi~'ation, Offset publicafio, REH 71, 81.-83 39 Greet, G. et ~.!. (1994) Cameroon: an African model for final stages of Guinea worm eradication. Am. J. Trap. Med. Hyg. 50, 393-400 40 Tayeh, A. and Cairncross, S. (1993) Dracunculissis eradication by 1995. Will endemic countries meet the target? Health Policy aad Plamting 8,191-207 41 Cairncross, S. (!995) Victory over Guinea worm; partial or pyrrhic? Lancet 346,1440 42 World Health Organization/United Nations Children's Fund/ Center~ for Disease Control and Prevention/Global 2000 (1993) latcgrated Sun.cillance it; Dracu',c;dia~i~ Era~icatia;t Prc,~raa;;~;c~, Joint Statement by WHO, UNICEF, Global 2000 and the WHO Collaborating Center at C[3C 43 Nokes, D.J. and Cutts, F.T. (1993) Immunization in the developing world: strategic challenges. Trans. R. Sac. Trap. Meal. Hyg. 87, 353-354 44 Jarrett, S.W. and Ofusu-Amah, S. (1992) Strengthening health services for MCH in Africa: the that four years of the Bamako Initiative. Health Policy and Planning, 7,164-176 45 Dawdle, W.R. and Hopkins, D.R., eds The Eradication of Infectious Diseases, John Wiley & Sons (in press)
R K e n t a r t t d ~ in ~ l m - Tnm4s join'nab Workiflg with wocm¢ new detivey ~ c u ~ , by R.W. WaU=o ( l ~ 7 ) ~ ~ 399-4OO
for mecromoleTod~, 2,
Feod webs: a plea ~ r I~rasttes, by D.J. MarcqlSese and D.K. Cone (1997) Trends/n Eta/off aad Evo/uOon 12. 320-325 An onwelcorne parum~ p a r u l ~ chor~lp-ap~ of the ho~c cell c,/ck~, by ICM, le_"amerand i_H. Johnsson 0997) Trends /n M:cr~/o/off S, 169-170 Current apFoache~ f~r re~ond,~ontng process water and its use in food ~ om.-~dom, by ~;J~ h h ~ , K.T. Raikowdd and kJ. Pllller ( 1 ~ } Trends in F0ed So/erie T,~..-~,,.~ 8, Lt-74
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in the Onchocerciasis Control Programme area of West Africa. Am1. Trap. Med. Parasitoi.87, 65-82 31 Crosskey, R.W. (1987) A taxa summarj for the Simulium damnosum complex, with special reference to distribution outs.;de the control areas of West Africa. Ann. Trap. IVied. Parasitol.81,181-192 ?? Zimrnerman, P.A., To~, L. and Unnasch, T.R. (1'~,3) Design of Onchocerca DNA probes based upon analysis of a repeated sequence family. MoL Biachem.ParesitoL58, 259-268 33 Tang, J. et aL (1995) The $inralium danmosura species complex: phylo~enetlc analysis ~ d nmlccular identification based ~p-an mitochondriallyencoded ~ e sequences. InsectMol. Biol.4, 34 To~, L. et m. (1997) Veclor-parasite t~ran~mission complexes for onchocerctasis in West Africa. Lancet349,163.-166 35 Quill~v~r~,D. et aL (1978)Etudedu c0mplexe$im~iium damnasum en Afrique de l'Ou¢~ ~lIL Etude de 1,1bi~.cotogie et du pouvok vectettr des femelles de savane. Comparaison avec lea femelles de for~t. Cab.ORSTOM ~'. Ent. Md'd.Parasitd,16,151-164(in French) 36 Meredith, S.E.C'., Cheke, R.A. and Garms, R. (1983) Variation and distributim~ o~ forms of $imulium damnoanm ¢emplex from West A~ica. Ann. Trap. Med. Paresitol.77, 627--640 37 Herder, S. (1996) Vaxlabillt~ g&m_tL~qued'Onchvcerca volvu|us (Leuckari, 18(~:.1.Relations ave¢ le faci~ &pid6mioingique de I'onchocercose. Th&~eset Dacumcnts Microfichds no. !45 (institut Fran~ais de Recherche Scientifique pour le D~veloppement en Cool, ration, ed.), p. 115 (in French) 33~9WHO (1996)Planof Or~ratlonsfor t;w FifthPlul~ (1998-2002),WHO Hougard, J-M. el aL (1994) De la n~.¢~it~ de n~ner ~ terme lea activit~s de iutte antivectorielle du programme de intie contre I'onchocetcose en A~rique de I'Ouest: rappel des enjeux et proposition d'un bud~,t a minima pmsr la p&,'iode 1998-206Z Parasite1,295-303 (in French) 40 Plaister, A.P. et aL (1997) The required duration of combined annual iverme~n treatment and v,',ctor control in ).he Onchocerciasis Control Pmsramme in West Africa. Bull. WHO 75, 237-245 4! Katholi, C.R. ct aL (1995) Determininfl the prevalence of Onchocerca volvulus infection in vector populations by polymerase chain reaction screening of pool~ of b l ~ k flies. I. Infect. Dis. 172,1414-1417 42 WHC (1996) Mt~thlg on OperationalResearchand Strategies.Report of ;he Experl AdvisoryCamminee, OCP/EAC 17.2, WHO 43 Hougard, J-M. et al. La lulte c o n ~ la nuisance simnlidienne, une consequence de i'm'r~ des activit@s de lutte contre le vecleur de i'onchoeercese en Afrique de I'Ouest. Faram Mo~:dialde la Sant~(in French) (in press)
Global Eradication of Guinea W o r m H. Peri(~s and S. Cairncross Little more than a decade ago, it was estimated that over three millio, cases a[ dracunciiliasis occurred worldwide, Since then, the tmmbers have falle:t dramatically, thanks to the water supply initiatives of the 1980s and, more recently, the national guinea zoorm era3ication programmes implemented in a score of endemic couh~ries. Hervd Perils and Sandy Cairncross discnss how eradicat;o, will require the containment of cases in the remaining endemic areas, together with the simultaneous strengthening of surveillance to permit the certification of eradication. This aim requires existing strategies to be adapted to maintain thei, efficacy and also to improve their sustainability and costeffectiveness. Sudan with its civil u~r, and more than a Herv~ Perils is at the UNICEF RegionalO~ce for We_--tand Cenb~l Africa,04 E~P443, Abidjan 04, Ivory Coast.West Africa. Sandy Ch!ri~r3es is at the London School of Hygieneand Tropical Medione, Kc.pF,=lSu'cet, London. LIK ~A:CIE%iT. Tel: +44 ITI 9'17 221 I, Fax: +44 171 636 7343,
e-mall: sc~rm:r~shtm.ac.uk Pora.~il.ology Toduy, vol. 13, no, I I, 1997
hlmdred thousand reported cases, remains a major obstacle to rapid achievement of the goal. D r a c u n c u l i a s i s , o r g u i n e a w o r m d i s e a s e , is a p a i n f u l and debilitating human condition, caused when an adLqt f e m a l e of t h e n e m a t o d e Dracunculus medine,lsis e m e r g e s ~~radually f r o m the s u b c u t a n e o u s tissue, u s u a l l y o n the legs. T h e d i s e a s e is e n d e m i c in r u r a l , p o o r a n d u s u a l l y w a t e r - s h o r t c o m m u n i t i e s of s u b - S a h a r a n Africa ( m o s t l y in t h e S a h e l Belt a n d G u l f of G u i n e a ) , a n d vestigial fact r e m a i n in p e r t s of t h e A r a b i a n p e n i n s u l a a n d t h e I n d i a n s u b c o n ~ n e n t . It is t h e o n l y d i s e a s e t h a t is t r a n s m i t t e d e x c l u s i v e l y in d r i n k i n g w a t e r . A l t h o u g h d r a c u n c u l i a s i s kills f e w p e o p l e , it c a u s e s f r e q u e n t c o m p l i c a t i o n s a n d l o n g - l a s t i n g disabilities, a n d a l s o h a s f a r - r e a c h i n g socio--economic effects in affected c o m m u n i t i e s . T h i s ancient, s c o u r g e h a s c a u g h t m a n y p e o p l e ' s i m a g i n a t i o n b e c a u s e of its s t r i k i n g clinical m a n i f e s tation, the a g e - o l d t r e a t m e n t o f w i n d i n g the w o r m 431
Reviews of the cyclopoid family (cyclops), which then become infected. The larvae require a development ~'~ period of about two weeks to ~~ become infective. The disease can Infec(ed ~ individ~ ~; then be transmRted to a new host through the inadvertent swallowing of infected cyclops (0.8 mm long) in drinking water. When _ they are ingested, cyclops (which are not themselves dangerous to drink) are killed by stomach acid, but the infective larvae pass through the gut wall of the duodenum, and begin to mature in the ~ ~ connective tissue of the abdominal or thoracic cavity. The worms mature sexually and meet and mate in the subcutaneous tissue, , .~..~ - infected I ~k approximately a hundred days t' I cyclops/ %. after infection. After mating, the male worms become encapsulated ! ovozo,p..~ 7 / and die. The female moves down the muscle planes and, after 10-14 months, the mature worm begins to release a fluid full of newly formed larvae. This around a stick (possibly the inspiration for the symsets off an allergic reaction causing a blister, through bol of the meclical profession), and its Power to parawhich the worm will emerge, repeating the life lyse entire villages during severe disease outbreaks. cyde 4's (Fig. 1). In the early 1980s, dro :m~culiasis was identified as a The painful ulcers and ab~cesses (usually on the suitable candidate for eradication because of ks vulfeet or legs) can cause a long period of disability, nerability to simple preventive measures. Thanks to a depending on the site of emergence and any complihigh level of mobilization L-f the international comcations. The degree of disability ranges from mild munity, a successful global programme of eradication (causing pain or a limp, but allowing the sufferer to is under way 1-3. work) to severe, when the victim is unable to leave the village and even the house to work or to attend The disease school. It can last from a few days to several months The first description of the life cycle of D. mediuensis if there are complications, if joints are attacked or if was made by the Russiar~ r~ahi~alist A.P. Fedchenko there are multiple infections6. Some complications in 1871. It was an important milestone in tropical medresulting in long-term disability are caused by nonicine as it was the first record of an arthropod intermeemergent worms. For instance, many cases of arthritis diate host of a human pathogen4, a few years before have been reported after irruption of a worm in a Manson's famous description of the role of Culex mosjoimL However, secondary infection is the principal quitoes in the transmission of bancroftian filafiasis. complication, affecting roughly half of the cases8, The female D. mcdineasis is one of the longest including lethal complications such as tetanus. One nematodes known, r,:,~suring 550-800 mm long by study found that 15 out of 211 cases of tetanus seen in 1.7-2.0 mm in diameter. The male is only about Ouagadougou Central Hospital, Burkina Faso (7.1%) 40 mm long. This great disparity in the length of the had contracted the infection from a wound caused by sexes Ls one of the features ~parating the dracunan emerging guittea worm 9. culids from the fllarial nematodes, with which they were formerly included. Feasibility of eradication With a silent incubati~r, period of 10-14 months, Following the success of the smallpox eradication the disease is characterized by the e~ergence c~! the campaign ~°, guinea worm disease is the next target mature female, causing a painful blister. ~ occurs for a future eradication, although poliomyelitis has most frequently on the lower limb at or lx~ow the knee, with a preference for the foot and ankle joint, also been su~ce.~-~,d as a competitor u. Table 1 combut sometimes in other locations such as the genitals, pares deacunculiasis and poliomyelitis as candidates for eradication with their predecessors, smallpox back, breasL tongue or eye. When the affected part of the patienVs body is immersed in water (for instance, (successful) and malaria (failed). Dracunculiasis seems to be a less likely candidate during household water collection or work in the fields, and when the patient wets it to relieve the for eradication than smallpox and poliomyelitis, not burning pain), water contact stimulates the female only because of the lack of immunity and of vaccines, worm to emerge further through the ruphtred blister chemovrovhvlaxis or treatment, but also because the and to release hundreds of thousands of microscopic principal c¢;r/~l measures require a change in behavlarvae into the "water. tour. Guinea worm does not Pose a threat of epiWhen the worm's larvae rare washed into a pond or demics outside its traditional endemic areas, so that shallow well, they are ingested by small crustaceans potential partners and donors have no direct national 432
Dro~nculos
Fig I. Life cycle of medin~a. (Hateria! kindly provided by CDC. Adanta, USA.)
individual
~.~
~
infected individual (I year I later) /
Non-infected t ~',.?~"~',.
~
/~~
Parosi~e."~gy Today.vol.13,rao,I I. 1997
Reviews
1 Table I. Characteristics o f past and p r e s e n t eradication candidates ~
Malaria b
Smallpox
Poliomyelitis
Dracunculiasis
+ -
+ +
+ +
+ +
-
+ +
+ -
+ +
L i m i t e d e n d e m i c area
+
+
Seasonal transmission
+
+
+
+
+/+
++ + -
~-
+ +
+ +
+ -
Agent N o animal r e s e r v o i r No mobile vector
Host L i m i t e d c a r r i e r state Easy diagnosis
Distribution
T h r e a t t o w e s t e r n c o u n t r i e s and visitors Intervention
Effective drugs exist P r e v e n t i o n cheap and c o m p l e t e P r e v e n t i o n needs n o b e h a v i o u r change Adapted from Ref. I. b Characteristics favouring eradica¢ion are marked ' + ' .
interest in its eradication, except for h u m m i t a r i a n motives. However, this seems not to have impeded the first phase of eradication, thanks to the personal involvement of former US President Jimmy Carter, the support of James Grant of the United Nations Children's Fund (UNICEF) and the strong commitment of governments and ti:eir funding partners. Several aspects of guinea v~orm disease favour its eradication prospects 2. First, no animal reservoirs have been identified. That people are the sole reservoir seems to be confirmed by the failure of the disease to reappear in former endemic countries such as lran, the ex-Soviet Union, Gambia and Egypt ~2. The parasite seems not to survive beyond its one-year transmission cycle, a n d there are no long-term c.arriers to be feared. The disease is easily diagnosed a~,d is well k n o w n in the endemic areas. Transmission can easily be prevented (i:}ox l), not only by the relati~.ely costly measure of installing safe water supplies, but also by simple a n d affordable alternative measures, such as filtering water through a cloth. The intermediate host is susceptible to chq.~mical treatment, and lives in stagnant water so that it cannot transmit infection over a long distance. However, infected .people cannot be identified during tbp one-year incubation period before emergence of the worm, and are therefore the m e a n s by which the disease is disseminated. Socio-economic impact o~ dracunculiasis Most cases of dracunculiasis go unreported: it is only very rarely ~. fatal disease, it occurs in poor remote rural areas, the disease itself m a k e s travel to a health iacility difficult, and it is usually followed by spontaneous recovery even in the absence of a n y treatment -~. The n u m b e r of dra.:unculiasis cases has therefore always been dramatically underestimated, and the disease has often been considered as an exotic olriosit3,', of minor public hea]th importance. As late as 1993, its very inclusion in the World Development Report 23 was hotly debated by the editorial team. However, in endemic areas, its social, nutritional, educational a n d economic consequences and the costs incurred by individuals, households and communities have bee~i well documented 6. In most endemic regions, the peak incidence of the disease coincides with the planting or harvesting Parasitology Today, vol. "13, no. I I,
•997
period of seasonal crop production, so that, .;n hyperendemic areas, agricultural losses directly attributable to disability from dracunculiasis can be substan:;o;~,~-=~. i~L South Kordofan, Sudan, a s t u d y of the impact of dracunculiasis in adults on the nutritional status of their children found that, in affected families, 16.6% of children aged 0-6 years were affected by wasting (ie. were two or more standard deviations below the reference median of weight for their height), compared with only 6% in other households 26. In the forest zone to the south, where the peak incidence is in the dry season, school absenteeism is more often mentioned as a consequence. Not only do the children themselves suffer from the diseas,% but they also miss school w h e n they are obliged to stand in for their disabled parents in the fields In Anambra State, Nigeria, before the eradication effort began, the absentee rate was found to treble during the guinea worm season 27.
Box I. P r e v e n t i v e Strategies
Despit.e the lack of available treatmel~t, chemoprophylaxis or vaccine1~14,dramatic reduc~ons in the incidence of guinea worra disease have been made possible by the combination of several complementary preventive interventions'5,16 in endemic or at-risk communities, mainly: (l) the provision of a safe water supplylT.la; (2) health education, combined with the provision of cloth fillers to prevent the consumption of unsafe drinking waterl'~.2°; (3) early case containment, including simple treatment and bandaging of cases, an~ raising community awareness to ensure that sufferers ~void contact with water-supply sourcest~; and (4) vector-control measures, through the treatment of ponds with insecticide non-toxic to humans, to kill the cyclops intermediate host2122. Interventions (2) and (3) can be implemented at village level by trained community volunteers. Eradication programmes initially gave priori .ty to direct implementation of activities by water agencies and health services, but there has been an increasing awareness of the effectiveness of involving village volunteers in surveillance, prevention and early case containment, and a progressive shift towards a more communi~-based and participatory approach2. 433
Reviews
~ f
°~':
D •
I D
Dracunculiasis-endemic 3racunculiasis-endemic countries Dracunculiasis-endemic villages Other countries
Fi~. 2. Geographical distribution of guinea worm in Africa. 1996. The shaded areas are the endemic countries, and individual endemic villages are shown by dots A few cases have also been found in Yemen (not shown). The data from Ghana refer to 1994, and those from Nigeria to 1993. [Hate~ai kindly provided by the joint WHO-UNICEF Programme on Mapping and Geographic Infor~.ation Systemsfor DracunculiasisEradication (HealthMap). WHO/CTD, Geneva.]
Currel:t ep|fiemio!ogical status Dracuncul~asis is still endemic in 19 countries, all but ~'wo of which (India and Yemen) ~rc in Africa (Fig. 2). It has disappeared spontaneously from the hi.~torical loci of infection in the Americas, where it was imported by the slave trade, and from the ancient loci in the Middle East and Central Asia. Pakistan is the only country so far to have demonstrably .eliminated the disease in the current eradication effort, but preliminary data indicate that India may also have eliminatecl it; the last known case there was in July 1996. It is difficult to estimate the total number of cases that occurred annually worldwide before the establishment of national guinea worm eradication prosrammes with ~ctive surveiliance, because of the very low rate reporting of guinea worm cases in health facilities3. Studies in Nigeria and in Togo in the 1970s27~ f,und ~.hat only 5% and <4% of cases studied, respec~.ively, had been reported to the he~lth system. Another study of 985 sufferers in Rajasthan, India in 1978-1979 showed that none bad visited a health facility'. 'Guesstimates' of the global incidence of dracunculiasis over the years have fallen gradually from Stoll's original estimate of 48 million cases in 1947 (Ref. 30) ~.o 10 million in 1976 (Ref. 31) and 3.3 million in 1986 (Ref. 32); the last figure referred to Africa alone, but k by 1986, there were fewer thau 30000 cases elsewhere. As each country conducted a national search (or cases, most in ,the early 1990s, it was found that there 454
J
were many times more cases than had been suggested by routine passive reporting, but fewer than the previous estimates; adding together the maximum number of cases ever reported by each endemic country gives a total of 1.3 million, of which half is the ~gure from Nigeria in 1988 (Ref. 33). To some extent, the progreasi~e decline in the estimates probably reflects a genuine fall in the number of cases; anecdotal evidence abounds of villages where the disease was endemic until hand pumps were installed. Rural water-supply programmes, particularly those implemented in a number of endemic countries after the Sahel drought of the early 1980s, probably contributed to this. However, it is also likely to reflect the increasing precision of the estimates, possibly inflated for advocacy purposes. Beginning in a few endemic countries in the late 1980s, but during the early 1990s in most others, national case searches were carried out to support the establishment of nat.lonal guinea worm eradication programmes. Annual case searches carried out by the early programmes were replaced ~y communitybased surveillance and, more recently still, by the implementation of a case~containment strategy34. This made it possible to monitor dracunculiasis incidence and to give a precise annual picture of the progress of the eradication effort (Box 2). In all countries except Sudan, there has been a sustained and rapid reductmn in the reported guinea P~,sitolo~ Today, vol. 13, no, I I, 1997
Reviews Norm incidence. The worldwide total fell from 892000 cases reported in lO89 to fewer than 35000 cases reported in 1996 (see Fig. 3). However, the picture is complicated by the situation in Sudan, where the national p r o g r a m m e started only recently and is hampered by the civil war. The increasing n u m b e r of cases reported from Sudan led to the global total increasing in 1996 for the first time in seven years. However, this was not a sign of failure to conh'ol the disease, but rather an indication of the increasing sensitivity of Sudan's surveillance, as it gets into its stride in both government- and rebel-held areas of the country. Costs a n d benefits Guinea w o r m eradication has thus been remarkably successful, reducing the global incidence (except in Sudan) by over 95% in the past seven years. Apart from the p r o g r a m m e ' s contribution to the improven'ent of the water supply in poor and remote rural communities, the reduction of incidence has, without doubt, had a major impact on disability, agricultural production, income generation and poverty reduction in endemic areas. This has been achieved at moderate cost, considering that the endemic areas include some of the most remote and undeveloped parts of the developing world. Excluding the cost of water supplies, which have other benefits, we estimate that less than US$30 million has been spent on guinea w o r m eradication since 1989. The community-based surveillance and health education delivery systems have an annual cost of abc,vt US$100-200 per village 2. This is likely to increase "~vhen case containment is stepped u p in the final phase; Cameroon's case containment cost US$230 per village in 1991 (Ref. 39). However, these systems can deliver other health interventions besides guinea ~:orm control, and the overall cost of p r o g r a m m e s shot;1d continue to fall as the endemic area shrinks. The final stretch
The i m p r o v e m e n t of surveillance and the rapid elimination of the last endemic foci are the next challenges. In most endew, ic countries, the remaining at-risk communities will be increasingly remote and inaccessible, with few options for water-supply improvements and poor access to education. This will make the final run towards eradication at least as difficult as the initial phase, which achieved dramatic reductions in incidence. The likely time-scale is demonstrated by the time taken by the six countries nearest the goal to count d o w n from their last thousand case~ (all six are s h o w n in Fig. 3), although most of these countries could concentrate their efforts and resources on a few limited endemic areas, and three (Cameroon, India a n d Pakistan) already had several years of experience of fighting guinea worm. In this context, the realism and appropriateness of the World Health Orgarfization's (WHO's) target of achieving eradication by 1995 (Ref. 40; Box 2) is ope,n to question. Certainly, s~me confused this objective, set primarily for advocac3, purposes, with a planning assumption, or sought to make people accountable for achieving it, or judged the commitment of colleagues by ~,hether or not they agreed that it was Parasitoloooy Todoy, vol. 13, ~o. I[. 1997
Box 2. Milestones in the Development of the Eradication Campaign
During the 1980s, awareness of dracunculiasis and the political will to eradicate it were mobilized gradually, in the context of the International Water Decade. In 1982, the US National Academy of Sciences organized a workshop h~ "vVashing~onon worldwide guinea worm control35. In 1984, the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, USA were appointed as the WHO Collaborating Center for Research, Training ~.nd Eradication of Dracunculiasis, In 1986, Global 2000 of the Carter Center. aI;o in Atlanta, became heavily involved in the eradicatLon effort. Soon afterwards, UNICEF also joined She cam|.aign. ~.~'1991, member states of WHO declare~i their r,~:,oiveto era ~icate guinea worm by 1995 ~'.ReL36) by adopting the ;e~,ol,,tion WHA44.5. In 1992, UNICEF and WHO created an Interagency Technical Team, based in Ouagadougo~l, Burkina Faso, "~o support eradication programmes in African endemic countries. !n 1993, WHO set up a Dracunculiasis E~-'-~i~ationPriority Programme in the division for Conho.~ of Tropical Disea~s, Geneva, Switzerland, with a b~ief to improve epidemiological surveillance, boost the eradication process and prepare for the certification of eradication. At the same time, crucial village-based epidemiological surveillance was re-inforced thanks to the creation of the joint WHO-UNICEF Programn~ on Mappinej and Geographic Information Systems for Dracunculiasis ;~radication. "/'he main aim of this programme, in close collaboration with ~ove.,'nments and partners, is to ~ro~ote thp ur,e of ~eogr~Fidc information ~y~,~eros37for'the managemev~,of epidemiological su..'veillance data from guinea worm programmes at world, continenta!, nati~'nal and local levels. In ~995, with drama~c progr~s already achieved and parts of endemic countries beginning to register zero cases, .~b.e Inten,ational Commission for the Certification of Dracunculiasis Eradication was appointed. It met first in Geneva, in March 1990 (Ref. 38). Its immediate priority is to certify eradication in those countries where the disease was endemic in the past, b~t has already disappeared. feasible. Donor agencies were of course attracted to the prospect of a time-limited programme with lasting benefits, but the risk was that they and others might lose interest after the deadline had pa ' ~ c i 41. In thE: event, donor support has not died, and every endemic country had at least set u p its eradication programme by the target date; the fact that some did so at the last minute suggests that the approaching deadline .,~purred them to do so, in which case it served its purpose. To certify eradication, evidence will be nc~ded of the absence of guinea v ¢ o ~ . . , for three consecutive years from all areas with a recent history of the disease. This requires that community-based surveillance systems remain active and effective in all areas at risk (reporting cases since the national survey) for three years after the emergence of the last worm. However, as the disease is eliminated from more and 455
Reviews O0000C
looooc ~
TOTAL
10000
except Sudan Nigeria Ghana
"~.~
\
~
~
"~
1000
India
Uganda Ethiopia
100
Chad
10
11
I
I
I
I "'1
~--~--t
198919901991109219931994lg9519961997 Fig.3. Declinein the numberof reportedcases of guinea wormdisease,1989-1996,showingthe impactof eradication programmes.Notethe logarithmicscale.The incidencehas fallenat a similar.ratein the otherendemiccountries(not shown).(DatakindlyprovidedbyWHO andUNICEF.) more villages, the commitment of village w, lunteers and supervisors will be hard to maintain. Few volunteers or superv'sors will continue to visit every household or every village monthly (weekly in some countries) when the chance of finding guinea worm cases becomes vanishingly small. Communities beset by major health threats, such as malaria, diarrhoeal diseases or measles epidemics, will fail to understand the need for their village health worker to ignore these, whi~.e focusing on a disease that has almost disappeared. Integration: a marriage of convenience Of course, a single-minded effort must still be devoted to reducing guinea worm incidence, especially in villages that stilll report many cases; indeed, it would be dangerous to declare victory too early. However, it is also clear that effective case containment and surveillance can only bc mai:~tained for long enough to achieve eradication and certification if current strategies are adapted. An essential measure is to integrate surveillance measures specific to guinea worm disease within a more comprehensive approach to comm~.miW health, as advocated by WHO, UNICEF, Centers for Disease Control and Prevention and Global 2000 in a joint declaration in 1993 (Ref. 42). Villag~ volunteez~ visiting each household to de~ tect cases of guinea worm disease might, for example, take advantage of visits to record births, identify children to be immunized or promote the use of oral rehydration therapy (ORT). This makes health volunteers' work more interesting and motivating, especially
436
when guinea worm disease is absent for much of [he year, as is the case even in hyperendemic villages. Most endemic countries have understood the challenge and have begun or plam~ed such a diversification of activities. In many (Burkina Faso, Chad, Ivory Coast, Ghana, Mall, Niger and Ethiopia), this involves monitoring of immunization and surveillance for diseases includ~-d in the Expanded Programme of Immunization; in Senegal, guinea worm will become part of an integrated con~munity-based surveillance system including malaria, schis¢osomiasis, leprosy and onchocerdasis; in Mauritania, guinea worm eradication activities have been implemented wherever possible as part of an integrated community-based primary health care programme, including malaria control, ORT promotion, vitamin A distribution and health education. One disease targeted for elimination for which community-based surveillance will undoubtedly be necessary is neonatal tetanus43. Existing guinea worm surveillance systems cover only v~.llages currently or recently reporting cases, but these cnnld be used as sentinel villages for tetanus surveillance. In the more endemic areas, about one village in three has been under surveillance and benefited from the training and regular supervision of one or two village volunteers. The components of the guinea worm eradication effort (trained village health workers carrying out surveillance and offering health education, supported by monthly visits from their supervisors) are clearly a potential resource which could strengthen other aspects of primary health care. In many cases, the villagers have shown their readiness to participate in tackling health problems by organizing teachers and pupils, youth associations and women's groups to help the village volunteers detect new cases. Recent devel,.~pments in primary health care, particularly the geheralization of the Bamako Inigative in the endemic regions*~, are leading to the establishment of elected health committees to manage local health facilities ;rod to plan, finance and monitor public health activities in the community. These committees include elected representatives of all villages from the area covered. They are a unique resource in helping to build an effective surveillance system that is truly community-bahai in the full sense of surveillance, not only collecting data, but also responding to it. Such a system would also cover other conditions targeted for eradication or elimination, such as neonatal tetanus, poliomyelitis, leprosy, vitamin A deficiency and perhaps in the near future measles and other candidates. The feasibility of eradication of these diseases (as well as guinea worm) and the strategies and requirements for eradication or elimination were major topics at the recent workshop on the Eradication of Infectious Diseases, sponsored by the Univers;~ of Berlin, Germany ~s,
Perspective After the tremendous efforts of :he past decade, the centuries-old scourge of guinea worm is now likely to be the second h~man disease to be eradicated. The dramatic reductions in incidence so far are rightly unanimously hailed as a giant step towards eradication, but the next phase will be equally cha!lenging. To contain the last few cases and certify eradication could require several more yea~ of effort, Parasitology Today, voL 13, no. I I, 1997
Reviews during which programmes w i l l h a v e to m o v e p r o gressively from the current vertical strategy to a more b a l a n c e d m i x o f i n t e r v e n t i o n s s p e c i f i c to g u i n e a w o r m w i t h i n t e g r a t e d c o m m u n i t y - b a s e d a c t i v i t i e s , to guarantee cost-effective and sustainable success in e r a d i c a t i o n . T h e c o n t i n u i n g c i v i l w a r in S u d a n , w i t h h y p e r e r ~ ) e m i c f a c t i n t h e c o m b a t z o n e , is t h e c h i e f c o n s t r a i n t to a c c u r a t e p r e d i c t i o n o f a n e : a d i c a t i o n d a t e .
Acknowle ~gements The erad!e.:.tion of guinea worm disease is a collaborative endeavour towards whi::h many people have contributed their efforts and ideas, in addition to those cited above. The views expressed in this article reflect the views of the authors as individuals and not of their institutions of affiliation. References 1 Hopkins, D.R. (1983) Draeunculiasis: an eradicable scourge. Epidemiol. Rev. 5, 208-219 2 Caimcross, S. et al. (1996) Community participation in the eradication of Guinea worm disease. Acta Trap. 61,121-136 3 Ranque, P. et al. (1996) SituaSon actueUe de la campagne d'&radication de ta dracunculase. Med. Trap. 56, 289-296 (in French) 4 Muller, R. (1971) Dracuncnlu~; and dracunculiasis. Ad~,. Parasitot. 9, 73-151. 5 Muller, R. (1979) Guinea worm disease: epidemiology, control and treatment. Bull. WHO 57, 683-689 6 Watts, S.I. et al. (1989) Guinea worm: an in-depth ~tudy of what happens to mothers, families and communities. Sac. Sci. Med. 29,1043-1049 7 Hours, M. and Cairncross, S. (1994) Long lerm disability due to Guinea worm disease. Trans. R. Sac. Trap. Med. H~/g. 88, 559-560 8 Wurapa, F. et al. (1975) A clinical picture of Guinea worm disease in southern Ghana. Ghatu Med. [. 14,10-15 9 Pirame, Y. and BeC~lUet, R. (1969) Dracnncuiose et tetanus; ; p m p o s de 15 observations. Bull. Sac. Patl~ol. Exot. 29, 702-710 10 Anon. (1983) After smallpox, guinea worm? Lancet i, 161-162 'd Cochi, S.L. et al. (1997) Commentary; the nnfolding atory of global poliomyelitis eradication• ]. h:]ect. Ois. 175 (Suppl. l), S1 -$3
12 Watts, S.]. (1996) No transmission of dracunculiasis in Egypt for two centuries. World Health Forum 17,181-183 13 Eberhard, M.L. et aL (1990) Chemoprophyl~dic drug trials for treatment of dracunculiasis using the Dracuncnlus isiguisferret model. !. Hehninthel. 64, 79-86 14 Chippaux, j.P. (1991) Mebendazole treatment of dracunculiasis. Tra~ls. R. Sac, Trap. Mcd. Hyg. 85, 280 15 Hopkins, D.R. and Ruiz-Tiben, E. (1991) Strategits for dracunculitsla eradication. ~
Parasitology Today. vol, 13. no. I I, 1~97
cole: Its effets de la dracuncuiose darts une agriculture de subsistance. Revue d'deonomie du D~veloppement 1, 23-26 (in French) 25 Brieger, W.R. et aL (1990) Farmers' loss due to Guinea worm disease: a pilot study.]. Trap. Med. Hyg. 93,106--111 26 Tayeh, A. and Cairncross, S. (1996) The impact of dracunculiasis on the nutritional status of children in South Kordofan, Sudan. Ann. Trap. Paediatr. 16, 221-226 27 Nwosu, A.B.C et al. (1982) Endemic dracontiasis in Anambra State of Nigeria: geographical distribution, clinical features, epidemiology and socioeconomic impact of the disease. Ann. Trap. Meal. Parasitd. 76,187-200 28 Setodji, A. (1979) La DraeuneuJoseen Milieu Togolais: Situation de la Circonscription du Hobo, presented to Ecole des Assistants M&3icanx, Univemity of Cotonou, B~nin Republic 29 Johnson, S. and ]oshi, V. (1982) Dracuntiesis in Western Rajasthan, India. Trans. R. .Sac. Trap. Med. Hyg. 76, 36--40 30 Slot!, N.R. (194,-) This wormy world. ]. Parasitol. 32,1-18 31 Duke, B.L (1976) Filarulsis,TDR/WP/76.tO.1976:3, WHO 32 Watts, S.J. (1987) Dracunculitsis in Africa in 1986: its geographical extent, incidence and at risk population. Am. J. Trap. Med. Hyg. 37,119-125 33 World Health CYcganization (1990) Drscuncullesis - Nigeria. • Wkly EpidemioL Rec. 65, 385--387 34 Anon. (1994) Case Contai,ment Strategy for Eradication of Dracuncutiasis in Africa, Centers for Disease Control and Prevention with Global 2000, United Nations Children's Fund and WHO 35 National Research Counc:l (1983) Opportunities [or Control of Dracunculiasis; Rept,rt of a Works.~ap,National Academy Press 36 Hopkins, D.R. and Ru~z-Tiben, E. (1990) Dracunculiasis eradication: target 1995. Am. ]. Trap. Med. Hyg. 43, 290-300 37 Clarke, K.C et aL (1991) The use of remote sensing and geographic information systems in UNICEF's draconculiasis (Guinea worm) eradication effort, Prey. Vet. Med. 11,229-235 38 ~World Health Organization (1996) Dracunczdh~si~.Ceriifio~lia, of Eradi~'ation, Offset publicafio, REH 71, 81.-83 39 Greet, G. et ~.!. (1994) Cameroon: an African model for final stages of Guinea worm eradication. Am. J. Trap. Med. Hyg. 50, 393-400 40 Tayeh, A. and Cairncross, S. (1993) Dracunculissis eradication by 1995. Will endemic countries meet the target? Health Policy aad Plamting 8,191-207 41 Cairncross, S. (!995) Victory over Guinea worm; partial or pyrrhic? Lancet 346,1440 42 World Health Organization/United Nations Children's Fund/ Center~ for Disease Control and Prevention/Global 2000 (1993) latcgrated Sun.cillance it; Dracu',c;dia~i~ Era~icatia;t Prc,~raa;;~;c~, Joint Statement by WHO, UNICEF, Global 2000 and the WHO Collaborating Center at C[3C 43 Nokes, D.J. and Cutts, F.T. (1993) Immunization in the developing world: strategic challenges. Trans. R. Sac. Trap. Meal. Hyg. 87, 353-354 44 Jarrett, S.W. and Ofusu-Amah, S. (1992) Strengthening health services for MCH in Africa: the that four years of the Bamako Initiative. Health Policy and Planning, 7,164-176 45 Dawdle, W.R. and Hopkins, D.R., eds The Eradication of Infectious Diseases, John Wiley & Sons (in press)
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Feod webs: a plea ~ r I~rasttes, by D.J. MarcqlSese and D.K. Cone (1997) Trends/n Eta/off aad Evo/uOon 12. 320-325 An onwelcorne parum~ p a r u l ~ chor~lp-ap~ of the ho~c cell c,/ck~, by ICM, le_"amerand i_H. Johnsson 0997) Trends /n M:cr~/o/off S, 169-170 Current apFoache~ f~r re~ond,~ontng process water and its use in food ~ om.-~dom, by ~;J~ h h ~ , K.T. Raikowdd and kJ. Pllller ( 1 ~ } Trends in F0ed So/erie T,~..-~,,.~ 8, Lt-74
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