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Intestinal helminths in northern Namibia: a reply
TRANSACTIONS OF me
ROYAI. SOCIETY OF TROPICAL MEDKINE
1Correspondence Intestinal
helminths
1 in northern
Namibia
Drs Evans and Joubert (1989: Trunsactions, 83, 681-683) wrote that ‘As far as we could ascertain, no similar survey has been carried out in this [Kavango] area’. Their reoort studied neonle in Rundu. Kavango, one of the northern areas 03 Namibia (the former south-west Africa). I should like to point out that a minor survey on the prevalence of intestinal parasites in Ovamboland and in Kavango (west of Rundu) was carried out in 19741976 (Kyronseppl & Goldsmid, 1978: Transactions, 72, 16-21). There seem to be quite a few differences in the prevalence figures in these two studies, some of which are surprisingly great, such as those for hookworm: up to 73.8% in our study compared with 6.8% in that by Evans and Joubert. We found Strongyloides fuelleborni in 8.2% and Schistosoma haematobium in 4.9%, neither of which species is mentioned by Evans and Joubert. The differences can partly be explained by the study method: we carefully studied 2 concentrated faecal samples whereas in the latter study the results were based, probably, on one sample only from each individual. How much the habits concerning hygiene among the local population have changed within 10 years is not known. Hannu Kyriinseppii Aurora Hospital Nordenskioldinkatu 20 SF-00250 Helsinki 2January 1990 Finland
Intestinal reply
helminths
in northern
Namibia:
a
We are most grateful to Dr Kyronseppa for pointing out a very relevant reference to a survey conducted by himself and Goldsmid (1978: Trunsactions, 72, 16-21) in 4 hosp¶tals in Owambo and north-western Kavango territories, Namibia, which we inadvertently missed in our report. We agreed that there is a difference between their hookworm results, which ranged from 9.7% at Nakayale Hospital (northern Owambo) up to 73.8% at Nkurenkuru Hospital (north-west Kavango) and our 6.8%, derived from hospital reports at Rundu State Hospital. Our 6.8% (285/4174), on the other hand, does not differ greatly from their 9.7% (101103) at Nakayale Hospital, except in the total numbers tested, but the absolute reasons for the difference are somewhat speculative without prevalence data from the field. At this juncture we wish to add that. from our observations of the different environmental conditions and scattered nature of the villages and water contact situations in Kavango east of Rundu, we suspected that there might well be a sporadic distribution of the intestinal helminths in the region and hence we did suggest that, for a more accurate assessment, surveys should be conducted in several different villages and that schoolchildren would provide the best indicators. Such an undertaking might resolve the differences encountered. It should also be pointed out that the 4174 patients in our study were
897
AND HYGIENE (1990) 84, CORRESPONDENCE
drawn from all over Kavango, including villages more than 5 km or so inland from the Okavango river. Although we did record the presence of cases of Strongyloides, we did not specify the species, having assumed that identity was based on the time-honoured method of the nresence of rhabditoid larvae in faeces as being those of S. stercorulis. However, through subsequent survey work, including microscopy and cultures of free-living Strongvloides (unpublished data), we can within reasonable bounds say that S. stercorulis (based on rhabditoid larvae in faeces and on the identification of free-living males: R. W. Ashford., personal communicationj is widely dispersed m northern Kavango territory, the Cuando River floodplain of East Caprivi (Schutte et al., unpublished data), the Kaudom Game Reserve and parts of Bushmanland (Evans, Markus & Steyn, 1990: American Journal of Tropical Medicine and Hygiene, 42, 243-247), and, further, based on egg morphology alone, we are reasonably confident that S. fuellebomi is also present but rare in Bushmanland and East Canrivi (uersonal observations). We regard the record by Kyronseppii and Goldsmid of Schistosoma haematobium in faeces (3/61=4.9%) at Nkurenkuru Hospital near the Okavango River in north-western Kavango Territory as extremely interesting since we did not have any reports on urine tests. But we also wonder whether the eggs could have been misidentified S. intercalatum, which can be confused with S. haematobium. The former are normally found in the faeces of man, while the finding of S. haematobium in faeces is uncommon even in areas of high endemicity and then most often in females, especially of the younger age-groups (P. S. Visser, personal communication; and our unpublished observations), probably through contamination of the faecal specimen when bottles for urine and faeces are handed out at the same time. Furthermore, Geldenhuys et al. (1967: South African Medical Journal, 41, 767-771) found a 56% prevalence of S. haematobium in urine, but no S. haematobium in faeces, during an earlier survey. Importantly, what Dr Kyronseppa has done is to highlight the necessitv of combining hosoital and area surveys to establish the prevalences and distribution of various intestinal nematodes. Without venturing into any detail, it is known that there was a large-scale movement of people into Kavango in recent years, which may well have initiated significant changes in the disease patterns or introduced-species new t&these areas, which could be monitored through hospital and field surveys. A. C. Evans J. J. Joubeti Research Institute for Diseases in a Tropical Environment P.O. Box 634 Nelspruit 1200 8 May 1990 Republic of South Africa Y
Y
2
Y
1
;-
ROYAI. SOCIETY OF TROPICAL MEDKINE
1Correspondence Intestinal
helminths
1 in northern
Namibia
Drs Evans and Joubert (1989: Trunsactions, 83, 681-683) wrote that ‘As far as we could ascertain, no similar survey has been carried out in this [Kavango] area’. Their reoort studied neonle in Rundu. Kavango, one of the northern areas 03 Namibia (the former south-west Africa). I should like to point out that a minor survey on the prevalence of intestinal parasites in Ovamboland and in Kavango (west of Rundu) was carried out in 19741976 (Kyronseppl & Goldsmid, 1978: Transactions, 72, 16-21). There seem to be quite a few differences in the prevalence figures in these two studies, some of which are surprisingly great, such as those for hookworm: up to 73.8% in our study compared with 6.8% in that by Evans and Joubert. We found Strongyloides fuelleborni in 8.2% and Schistosoma haematobium in 4.9%, neither of which species is mentioned by Evans and Joubert. The differences can partly be explained by the study method: we carefully studied 2 concentrated faecal samples whereas in the latter study the results were based, probably, on one sample only from each individual. How much the habits concerning hygiene among the local population have changed within 10 years is not known. Hannu Kyriinseppii Aurora Hospital Nordenskioldinkatu 20 SF-00250 Helsinki 2January 1990 Finland
Intestinal reply
helminths
in northern
Namibia:
a
We are most grateful to Dr Kyronseppa for pointing out a very relevant reference to a survey conducted by himself and Goldsmid (1978: Trunsactions, 72, 16-21) in 4 hosp¶tals in Owambo and north-western Kavango territories, Namibia, which we inadvertently missed in our report. We agreed that there is a difference between their hookworm results, which ranged from 9.7% at Nakayale Hospital (northern Owambo) up to 73.8% at Nkurenkuru Hospital (north-west Kavango) and our 6.8%, derived from hospital reports at Rundu State Hospital. Our 6.8% (285/4174), on the other hand, does not differ greatly from their 9.7% (101103) at Nakayale Hospital, except in the total numbers tested, but the absolute reasons for the difference are somewhat speculative without prevalence data from the field. At this juncture we wish to add that. from our observations of the different environmental conditions and scattered nature of the villages and water contact situations in Kavango east of Rundu, we suspected that there might well be a sporadic distribution of the intestinal helminths in the region and hence we did suggest that, for a more accurate assessment, surveys should be conducted in several different villages and that schoolchildren would provide the best indicators. Such an undertaking might resolve the differences encountered. It should also be pointed out that the 4174 patients in our study were
897
AND HYGIENE (1990) 84, CORRESPONDENCE
drawn from all over Kavango, including villages more than 5 km or so inland from the Okavango river. Although we did record the presence of cases of Strongyloides, we did not specify the species, having assumed that identity was based on the time-honoured method of the nresence of rhabditoid larvae in faeces as being those of S. stercorulis. However, through subsequent survey work, including microscopy and cultures of free-living Strongvloides (unpublished data), we can within reasonable bounds say that S. stercorulis (based on rhabditoid larvae in faeces and on the identification of free-living males: R. W. Ashford., personal communicationj is widely dispersed m northern Kavango territory, the Cuando River floodplain of East Caprivi (Schutte et al., unpublished data), the Kaudom Game Reserve and parts of Bushmanland (Evans, Markus & Steyn, 1990: American Journal of Tropical Medicine and Hygiene, 42, 243-247), and, further, based on egg morphology alone, we are reasonably confident that S. fuellebomi is also present but rare in Bushmanland and East Canrivi (uersonal observations). We regard the record by Kyronseppii and Goldsmid of Schistosoma haematobium in faeces (3/61=4.9%) at Nkurenkuru Hospital near the Okavango River in north-western Kavango Territory as extremely interesting since we did not have any reports on urine tests. But we also wonder whether the eggs could have been misidentified S. intercalatum, which can be confused with S. haematobium. The former are normally found in the faeces of man, while the finding of S. haematobium in faeces is uncommon even in areas of high endemicity and then most often in females, especially of the younger age-groups (P. S. Visser, personal communication; and our unpublished observations), probably through contamination of the faecal specimen when bottles for urine and faeces are handed out at the same time. Furthermore, Geldenhuys et al. (1967: South African Medical Journal, 41, 767-771) found a 56% prevalence of S. haematobium in urine, but no S. haematobium in faeces, during an earlier survey. Importantly, what Dr Kyronseppa has done is to highlight the necessitv of combining hosoital and area surveys to establish the prevalences and distribution of various intestinal nematodes. Without venturing into any detail, it is known that there was a large-scale movement of people into Kavango in recent years, which may well have initiated significant changes in the disease patterns or introduced-species new t&these areas, which could be monitored through hospital and field surveys. A. C. Evans J. J. Joubeti Research Institute for Diseases in a Tropical Environment P.O. Box 634 Nelspruit 1200 8 May 1990 Republic of South Africa Y
Y
2
Y
1
;-