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A Leishmanin survey in Giohar, Somalia
340 TRANSACTIONSOF THE ROYALSOCIETYOF TROPICAL MEDICINE AND HYGIENE. Vol. 61. No. 3. 1967.
A L E I S H M A N I N S U R V E Y IN G I O H A R , S O M A L I A BY
..
K. M. CAHILL
The Tropical Disease Center,* New York P. L. MAZZONI
A. Cecchi Hospital of Societa Nazionale Agricola Industriale, Giohar, Somalia AND HASSAN ADEN
The Secondary Hospital, Giohar, Somalia Introduction The first endemic focus of clinical kala-azar in the Somali Republic has recently been described by BARtIFVA(1965), who diagnosed 12 cases, proved by the demonstration of Leishman-Donovan bodies in splenic aspirates, within a 14 month period. All his patients came from the bush country surrounding the province capital town of Giohar (Figure). Only 9 previous cases of visceral leishrnaniasis had been reported •
t
/
/"
",
C,AMBOt E" ~
x,o
oEL IDEt~
AOALOU
The area under current investigation was west of the Uebi Scebeli River in the Giohar district.
*St. Clare's Hospital, 415 West 51 Street, New York, New York 10019. We wish to acknowledge the assistance of the Ministries of Health and Foreign Affairs of the Somali Republic, the cooperation of the directors of the Societa Nazionale Agricola Industriale in Giohar, Somalia, and the contribution of the Huisking Foundation in making this survey possible.
341
K. M. CAHILL~ P. L. MAZZONI AND HASSAN ADEN
from the entire Somali Republic and there have been no reports of cutaneous leishmaniasis in this area. As part of an intensive serological survey of the Giohar province (CAHILL and KAGAN, in preparation) a leishmanin skin test programme has recently been completed which supports Baruffa's contention that leishmaniasis is endemic in this area. Materials and methods A leishmanin skin test was performed according to standard methods (MANSON-BAHR et al., 1959; CAHILL, 1965) on 713 clinically healthy Somali tribesmen and boys of the Galgial, Scidle and Sciavello tribes, all lifetime residents of the Giohar province. They were randomly selected on a first-come, first-served basis. Because of the nomad occupations and the social structure of the Somali tribes (LEwis, 1961) which make testing of females difficult, no attempt was made to obtain all equal sex distribution in this initial survey. There were no significant differences in age and tribe within each of the test areas. Giohar is a semi-arid, scrub covered district bisected by the Uebi Scebeli river. Skin test centres were located in the riverine villages of Giohar and Mahaddei Uen, and at the wells of El Ad and E1 Gambole. All subjects had travelled widely as nomad camel herders throughout the province. Some of the major diseases of the Somalis have already been reported (CAHILL, DAVIES, and JOHNSON, 1966a). There are no published reports on the insect species of Giohar, but BARUFFA (1965) stated that he "observed sandflies everywhere, in the neighbourhood of villages and in the open woodland." Test subjects were questioned regarding a clinical history compatible with kala-azar, but the frequency of non-specific fever and splenomegaly in this holoendemic malaria zone made this approach useless. There were no typical active ulcers or healed scars of cutaneous leishmaniasis, but the possibility that it existed could not be ruled out. The leishmanin antigen is a phenol-killed suspension of L. donovani (Kenya strain) containing 5-8 million leptomonads per c.c., kindly prepared by Dr. R. A. Neal of the Wellcome Research Laboratories. 0.1 c.c. is injected intradermally on the forearm and the area is examined 48 hours later. Positive reactors have an indurated area greater than 5 mm. in diameter; erythema is usually present but is difficult to assess in darkskinned patients. Results of the present survey are summarized in the Table. TABLE
Persons
Positive
% Positive
Giohar
362
45
12
Mahaddei Uen
279
48
17
77 Total 718
17
22
E1 Ad-E1 Gambole
Discussion The leishmanin skin test is a useful epidemiological tool for assessing the presence and incidence of leishmania infections in an area (STAUBER, 1963). During severe clinical kala-azar the test is usually falsely negative (MANSON-BAHR, 1961) and is therefore not useful in diagnosis. Since it is positive in mild cases of kala-azar, however, as well
342
A-LEISHMANIN SURVEY IN GIOHAR~ SOMALIA
as after response to treatment, it is very helpful in prognosis for an individual. In addition, numerous surveys in epidemic kala-azar zones (VAN PEENEN and DIETLEIN, 1963; CAHILL, 1964; CAmLL et al., 1965a) have demonstrated its value as a epidemiological test. It was employed in this way in Somalia. In cutaneous leishmaniasis the test becomes positive within 10 days and remains positive until the anergy of old age or overwhelming illness diminishes its efficacy (CAmLL et al., 1965b). In areas where kala-azar is known to be hyperendemic, leishmanin skin test programmes have elicited positive rates ranging from 2 to 20%; in areas where cutaneous leishmaniasis is hyperendemic, positive rates over 80°//0 have been reported (CAHILL et al., 1965b). The results obtained in the Giohar province are most compatible with an endemic kala-azar area. Undoubtedly, malaria is not the sole cause of splenomegaly or fever there. The increased positive rates noted as one goes from the town of Giohar to the village of Mahaddei Uen, to the remote wells of E1 Ad and E1 Gambole suggest a woodland vector similar to that described in the kala-azar area of the Southern Sudan. An alternative explanation could be that antimalarial campaigns have reduced Phlebotomus vectors in towns and villages (CAHILL et al., 1965b). This area warrants further study as a new focus of kala-azar in a medically and entomologically virgin territory.
Summary A leishmanin skin test survey in the Giohar province of Somalia supports a recent report that kala-azar is endemic in this area. REFERENCES BA~UFFA, G. (1965). Trans. R. Soc. trop. Med. Hyg., 59, 705. CAHILL, K. (1964). Amer. J. trop. Med. Hyg., 13, 794. (1965). E. Aft. reed. J., 42, 213. , SAYED OMER, A. & EL MUBARAK,A. (1965a)..7. trop. Med. Hyg., 68, 151. , ANDERSON,G. & Ttr~GUN, N. (1965b). Bull. Wld Hlth Org., 32, 121. & KAGAN, I. The Pattern of Disease In Interior Somalia (in preparation). , DAVIES, J. & JOHNSON, R. (1966). Amer. J. trop. Med. Hyg., 15, 52. LEWIS, I. (1961). A Pastoral Democracy. London: Oxford University Press. MANSON-BAHR, P. E. C. (1961). E. Afr. reed. J., 38, 165. ~ , HEISCH, R. & GARNHAM,P. C. C. (1959). Trans. R. Soc. trop. Med. Hyg., 53, 380. STAUBER, L. (1963). Ann. N.Y. Acad. Sci., 113, 409. VAnPEENEN, P. & DIETLEIN, D. (1963). J. trop. Med. Hyg., 66, 171.
A L E I S H M A N I N S U R V E Y IN G I O H A R , S O M A L I A BY
..
K. M. CAHILL
The Tropical Disease Center,* New York P. L. MAZZONI
A. Cecchi Hospital of Societa Nazionale Agricola Industriale, Giohar, Somalia AND HASSAN ADEN
The Secondary Hospital, Giohar, Somalia Introduction The first endemic focus of clinical kala-azar in the Somali Republic has recently been described by BARtIFVA(1965), who diagnosed 12 cases, proved by the demonstration of Leishman-Donovan bodies in splenic aspirates, within a 14 month period. All his patients came from the bush country surrounding the province capital town of Giohar (Figure). Only 9 previous cases of visceral leishrnaniasis had been reported •
t
/
/"
",
C,AMBOt E" ~
x,o
oEL IDEt~
AOALOU
The area under current investigation was west of the Uebi Scebeli River in the Giohar district.
*St. Clare's Hospital, 415 West 51 Street, New York, New York 10019. We wish to acknowledge the assistance of the Ministries of Health and Foreign Affairs of the Somali Republic, the cooperation of the directors of the Societa Nazionale Agricola Industriale in Giohar, Somalia, and the contribution of the Huisking Foundation in making this survey possible.
341
K. M. CAHILL~ P. L. MAZZONI AND HASSAN ADEN
from the entire Somali Republic and there have been no reports of cutaneous leishmaniasis in this area. As part of an intensive serological survey of the Giohar province (CAHILL and KAGAN, in preparation) a leishmanin skin test programme has recently been completed which supports Baruffa's contention that leishmaniasis is endemic in this area. Materials and methods A leishmanin skin test was performed according to standard methods (MANSON-BAHR et al., 1959; CAHILL, 1965) on 713 clinically healthy Somali tribesmen and boys of the Galgial, Scidle and Sciavello tribes, all lifetime residents of the Giohar province. They were randomly selected on a first-come, first-served basis. Because of the nomad occupations and the social structure of the Somali tribes (LEwis, 1961) which make testing of females difficult, no attempt was made to obtain all equal sex distribution in this initial survey. There were no significant differences in age and tribe within each of the test areas. Giohar is a semi-arid, scrub covered district bisected by the Uebi Scebeli river. Skin test centres were located in the riverine villages of Giohar and Mahaddei Uen, and at the wells of El Ad and E1 Gambole. All subjects had travelled widely as nomad camel herders throughout the province. Some of the major diseases of the Somalis have already been reported (CAHILL, DAVIES, and JOHNSON, 1966a). There are no published reports on the insect species of Giohar, but BARUFFA (1965) stated that he "observed sandflies everywhere, in the neighbourhood of villages and in the open woodland." Test subjects were questioned regarding a clinical history compatible with kala-azar, but the frequency of non-specific fever and splenomegaly in this holoendemic malaria zone made this approach useless. There were no typical active ulcers or healed scars of cutaneous leishmaniasis, but the possibility that it existed could not be ruled out. The leishmanin antigen is a phenol-killed suspension of L. donovani (Kenya strain) containing 5-8 million leptomonads per c.c., kindly prepared by Dr. R. A. Neal of the Wellcome Research Laboratories. 0.1 c.c. is injected intradermally on the forearm and the area is examined 48 hours later. Positive reactors have an indurated area greater than 5 mm. in diameter; erythema is usually present but is difficult to assess in darkskinned patients. Results of the present survey are summarized in the Table. TABLE
Persons
Positive
% Positive
Giohar
362
45
12
Mahaddei Uen
279
48
17
77 Total 718
17
22
E1 Ad-E1 Gambole
Discussion The leishmanin skin test is a useful epidemiological tool for assessing the presence and incidence of leishmania infections in an area (STAUBER, 1963). During severe clinical kala-azar the test is usually falsely negative (MANSON-BAHR, 1961) and is therefore not useful in diagnosis. Since it is positive in mild cases of kala-azar, however, as well
342
A-LEISHMANIN SURVEY IN GIOHAR~ SOMALIA
as after response to treatment, it is very helpful in prognosis for an individual. In addition, numerous surveys in epidemic kala-azar zones (VAN PEENEN and DIETLEIN, 1963; CAHILL, 1964; CAmLL et al., 1965a) have demonstrated its value as a epidemiological test. It was employed in this way in Somalia. In cutaneous leishmaniasis the test becomes positive within 10 days and remains positive until the anergy of old age or overwhelming illness diminishes its efficacy (CAmLL et al., 1965b). In areas where kala-azar is known to be hyperendemic, leishmanin skin test programmes have elicited positive rates ranging from 2 to 20%; in areas where cutaneous leishmaniasis is hyperendemic, positive rates over 80°//0 have been reported (CAHILL et al., 1965b). The results obtained in the Giohar province are most compatible with an endemic kala-azar area. Undoubtedly, malaria is not the sole cause of splenomegaly or fever there. The increased positive rates noted as one goes from the town of Giohar to the village of Mahaddei Uen, to the remote wells of E1 Ad and E1 Gambole suggest a woodland vector similar to that described in the kala-azar area of the Southern Sudan. An alternative explanation could be that antimalarial campaigns have reduced Phlebotomus vectors in towns and villages (CAHILL et al., 1965b). This area warrants further study as a new focus of kala-azar in a medically and entomologically virgin territory.
Summary A leishmanin skin test survey in the Giohar province of Somalia supports a recent report that kala-azar is endemic in this area. REFERENCES BA~UFFA, G. (1965). Trans. R. Soc. trop. Med. Hyg., 59, 705. CAHILL, K. (1964). Amer. J. trop. Med. Hyg., 13, 794. (1965). E. Aft. reed. J., 42, 213. , SAYED OMER, A. & EL MUBARAK,A. (1965a)..7. trop. Med. Hyg., 68, 151. , ANDERSON,G. & Ttr~GUN, N. (1965b). Bull. Wld Hlth Org., 32, 121. & KAGAN, I. The Pattern of Disease In Interior Somalia (in preparation). , DAVIES, J. & JOHNSON, R. (1966). Amer. J. trop. Med. Hyg., 15, 52. LEWIS, I. (1961). A Pastoral Democracy. London: Oxford University Press. MANSON-BAHR, P. E. C. (1961). E. Afr. reed. J., 38, 165. ~ , HEISCH, R. & GARNHAM,P. C. C. (1959). Trans. R. Soc. trop. Med. Hyg., 53, 380. STAUBER, L. (1963). Ann. N.Y. Acad. Sci., 113, 409. VAnPEENEN, P. & DIETLEIN, D. (1963). J. trop. Med. Hyg., 66, 171.