Evidence for the occurrence of Schistosoma intercalatum at Albert Nile in northern Uganda.

During a field investigation in Rhino Camp at Albert Nile in northern Uganda, 77.8% of 636 persons excreted Schistosoma mansoni ova that were detected by the Kato-Katz method. Six patients, 8-17 years of age, had terminally spined schistosome eggs in their stools. These findings were confirmed when preserved specimens were examined at the Institute of Medical Parasitology in Bonn using a concentration technique. The mean +/- SD length of 36 terminally spined eggs was 156 +/- 6 microns and the mean +/- SD width was 59 +/- 3.6 microns. Urine filtration in the study patients revealed no schistosome eggs in the urine. It is concluded that these findings provide evidence for the occurrence of S. intercalatum at Albert Nile in northern Uganda.

Evidence for a long-term effect of a single dose of praziquantel on Schistosoma mansoni-induced hepatosplenic lesions in northern Uganda.

Treatment with praziquantel reduces the prevalence and intensity of Schistosoma mansoni infection. However, reversibility of periportal fibrosis of the liver, which potentially leads to fatal complications, is not unequivocally substantiated. In the Nile District of Uganda, 460 patients were parasitologically (Kato-Katz method) and ultrasonographically examined during October 1991, October 1992, and May 1994. Treatment with praziquantel at a dosage of 40 mg per kilogram of body weight was given in October 1991 and October 1992 to 460 individuals (group A). Another 192 patients were seen during the baseline study in October 1991 and missed the follow-up in October 1992 but took part in the second follow-up in May 1994. Thus, they received praziquantel only once in October 1991 (group B) and had an interval of 2.7 years until the next investigation in May 1994. Periportal thickening (PT) of the liver was assessed by ultrasound at each time point. Praziquantel therapy reduced the prevalence of S. mansoni in group A from 84% in 1991 to 31% in 1992 and 30% in 1994. The respective intensities of infection (geometric means of egg output) were 81 eggs per gram (epg) of stool in 1991, 31 epg in 1992, and 30 epg in 1994. Periportal thickening was found in 46% of patients in 1991, 32% of patients in 1992, and 35% of patients in 1994. Reversibility of PT was influenced by age (markedly lower reversibility in individuals older than 30 years) and sex (women and girls responded less favorably than did men and boys). Surprisingly, no significant difference was detected between group A and group B with respect to reversibility of PT The outcome between the 2 groups did not differ significantly. This may indicate that a single dose of praziquantel (as given to group B) may have a longer lasting effect than previously thought, that is, more than 2.5 years.

Transmission of Schistosoma mansoni in Rhino Camp, Uganda.

Non-participant observations totalling 204 hours relevant to the transmission of Schistosoma mansoni infection were carried out in Rhino Camp at the shores of Albert Nile in North Uganda. A cross-sectional study of 636 individuals from Rhino Camp revealed a prevalence of S. mansoni infection of 77.8%. Occupational and domestic purposes were the most important reasons for water contact, whereas recreational purposes ranked lower and mainly concerned children. Both sexes were equally active in water contacts. A distinct preference of Nile water was noted despite availability of borehole water in the area. It is concluded that control measures against schistosomiasis have to take into consideration that water contact for recreational purposes might be minimized, whereas it is expected to be extremely difficult to reduce occupational and domestic water contacts.

PIP: Rhino Camp is one of the most important fishing and farming villages along the shores of Albert Nile in West Nile Province, Uganda. Ajagoro and Diova water contact sites were selected to observe water contact activities in November 1991 for 17 days during the rainy season. Cumulatively, 204 hours of observations during all times of the day were done by 2 experienced persons. The observation period covered 12 hours a day. Water contact activities were recorded up to 10 times per hour, 11-20 times per hour, and more than 20 tines per hour. A total of 157 individuals, 5-50 years old, were interviewed about tribal origin, reasons for water contact, previous status in exile, and attitudes towards Nile water. 636 individuals consisting of 155 school children, 208 fishermen and families, 247 individuals seeking admission to the study and 26 officials provided up to 2 stool samples. Fishing and water fetching was the most frequent reason for water contact at the sites. Water activities were highest in the morning and early afternoon and decreased markedly towards the evening. Children, fishers, subsistence cultivators, business people, and civil servants were involved in water activities. Children 5-9 years old were few, but individuals 10-39 years old had the highest frequencies of water contacts. A considerable proportion of observed water contacts were made by people who had been exiled from Zaire or Sudan. Individuals 10-39 years old made water contacts almost exclusively for domestic and economic reasons. Those below 5 years old came for recreational purposes. Prevalence of S. mansoni infection was 77.8% in the cross-sectional survey performed in 636 individuals. 5.5% of those had more than 500 eggs per gram stool. Little is known about the impact of water contact activities on the intensity of schistosomiasis in the area. Therefore, further ecological research is needed for future control of schistosomiasis at the community level along the river Nile.