Epidemic transmission of intestinal schistosomiasis in the seasonal part of the Okavango Delta, Botswana.

A well documented epidemic of human intestinal schistosomiasis caused by Schistosoma mansoni occurred at Maun in the seasonal part of the Okavango Delta, Botswana, building from very few cases in the 1950s and early 1960s to a peak prevalence of >80% in the 1980s. A retrospective analysis was performed on all available records of the prevalence of S. mansoni in the Maun area and the corresponding flow records of the Thamalakane River. These revealed a statistically significant correlation between prevalence and flow, but only when a lag period was introduced. The correlation was greatest with a lag period of 5-6 years between the rise and fall of discharge and the rise and fall of transmission. Since the hydrological events in the delta follow a cyclical pattern, another epidemic around 2020 appears likely.

Malaria diagnosis and treatment administered by teachers in primary schools in Tanzania.

A school health programme in Mwera Division, Pangani District included treatment of malaria attacks occurring in children during school time. A combination of symptoms (headache, muscle/joint pains, feeling feverish) and oral temperature > or = 37.5 degrees C was used for the diagnosis of malaria. Chloroquine (25 mg/kg given over 3 days) was used for treatment. Malariometric surveys on children aged 7-15 years (mean 10 years) were conducted once a year (1995-1997). Plasmodium falciparum accounted for 100% of infections and the parasite prevalence varied between 32.7 and 35.3% from 1995 to 1997. The number of malaria cases (cases/1000 registered school children) diagnosed and treated by school teachers was 159 (67) in 1995, 324 (124) in 1996, 348 (128) in 1997 and 339 (108) in 1998. Children in grades 1-4 (age 7-13) accounted for 64.6% of cases. Symptoms and oral temperature were recorded for 1258 children. Of those, 992 (78.9%) complained of fever and at least one other symptom when presenting to teachers, 98 (7.8%) had fever as their only complaint and 168 (13.5%) presented without a perception of fever, but with other symptoms. Of these children, 36 (21.4%) had a temperature > or =37.5 degrees C. The sensitivity of "feeling feverish" was 96.5% with a specificity of 54.5%. The positive predictive value of feeling feverish was 89.9% and the negative predictive value 78.6%. Blood slides were prepared from 55.3 and 37.2% of children diagnosed by teachers during 1995 and 1996, respectively, and 71.4% were found positive. Among children who fulfilled the algorithm criteria 75.0% had a positive blood slide. With little training and regular supervision it was feasible for school teachers to make a presumptive diagnosis of malaria. We conclude that teachers can play a major role in school health programmes and are willing to be involved in health matters as long as they are supported by health and educational authorities.

The impact of a school health programme on the prevalence and morbidity of urinary schistosomiasis in Mwera Division, Pangani District, Tanzania.

The prevalence of urinary schistosomiasis among schoolchildren in Pangani District (Tanzania) was assessed rapidly by a questionnaire approach. Based on the results, a strategy of selective treatment with praziquantel was adopted. Eleven primary schools in Mwera Division, Pangani District, with about 2500 schoolchildren were included in a control programme for urinary schistosomiasis. Macro- and microscopic haematuria diagnosed visually and with urine reagent strips was used as an indirect indicator of Schistosoma haematobium infection. Intensity of infection among children was monitored in class 5 (median age 14 years, range 11-17) by urine filtration techniques. Treatment was administered as 40 mg/kg praziquantel in a single dose at the beginning of the school year. The programme was implemented by schoolteachers and coordinated by the District Health Management Team in collaboration with the District Education Office. Teachers were responsible for carrying out all programme activities. Community participation was through collaboration with Teachers-Parents Associations and Village Health Committees. Coverage at yearly (1995-99) examination varied from 67.7% to 80.3%. Prevalence of haematuria decreased from 51.2% (range 22.2-89.5%) at baseline to 23.4% (range 5.8-56.7%) in 1999, a reduction of 54.3%. Macrohaematuria was 21.2% at baseline and 7.2% in 1999, a reduction of 66.0%. Prevalence of infection in class 5 was reduced by 71.4% and geometric mean intensity of positives reduced from 71 eggs/10 mL (95% confidence interval [CI] 52.5-97.7) to 28 eggs/10 mL (95% CI 25.7-55.0), a reduction of 60.6%. Teachers were highly committed, and secured community participation and a smooth implementation of the programme. The community accepted the introduction of a cost-recovery system, whereby parents pay for the treatment of children with episodes of visible haematuria during the school year. Communities also participated in the improvement of sanitary installations at the schools.

Integration of control of schistosomiasis due to S. mansoni within primary health care in Ngamiland, Botswana.

A schistosomiasis control programme integrated into the existing primary health care infrastructure was initiated in Ngamiland, Botswana in 1985 after it was reported that the prevalence of S. mansoni infection among school children in the main town was over 80%. The programme is oriented by a plan of action developed by a national schistosomiasis task force. The target population of the district of Ngamiland is about 75,000 with a population density of less than 1 person per square km. The objectives of reduction of prevalence by 75% and reduction of infections with greater than 100 eggs per gram of faeces by 90% within three years have been achieved within two years. Integration of diagnosis and treatment into the health clinics and health posts has been slower than anticipated. Health education, water supply and sanitation are considered to be the fundamental basis for maintenance of control.

PIP: In 1983, the Ministry of Health in Botswana integrated a schistosomiasis control program into the existing primary health care system in the Ngamiland district. The prevalence of Schistosoma mansoni infection was 80% among school children in Maun (the main village), 65% in Seronga, and 50% among adults working in a rice irrigation project. The primary objective of the program was to reduce the prevalence of S. mansoni by 75% and to lessen heavy infections (100 eggs/gram of feces) by 90% among school children by January 1988. 2 mobile health teams with regional teams in the clinics and health posts executed the program. A knowledge, attitude, and practice survey revealed that 75% of the people in 1 village alone did not know about schistosomiasis nor associated its symptoms with the disease. A health inspector surveyed all villages in the district to learn of those with few or no latrines and/or an inadequate water supply. The mobile teams collected and examined stool specimens from school children. They concentrated their efforts on those schools in the villages of Maun and Shakawe where prevalence was 10%. The community survey of adults and children not in school revealed that overall prevalence stood at 19.4%, but prevalence among the 15-24 year old age group was 46.3%. A nurse or a health assistant treated all infected individuals with 40 mg/kg praziquantel. The program has successfully integrated health education, adequate water supplies, and sanitation into the health care system in Ngamiland. In 2 years, the program was able to reduce prevalence by 77.4% and to reduce heavy infections by 90.7% among school children using the praziquantel treatment. In addition, 50 latrines have been constructed in pilot villages and 150 more have been planned.

An outbreak of suspected water-borne epidemic non-A non-B hepatitis in northern Botswana with a high prevalence of hepatitis B carriers and hepatitis delta markers among patients.

From June to December 1985 273 cases of hepatitis and jaundice were diagnosed in Maun, northern Botswana. It was known before the outbreak that most adults were immune to hepatitis A virus, most had markers indicating past infection with hepatitis B virus (HBV), there was a mean prevalence of 13.6% (57/418) HBsAg carriers, and a proportion of people had antibodies to hepatitis delta virus (HDV). There was evidence that faecal contamination of water supplies preceded the outbreak; the epidemic curve suggested that there was a major common source of infection; the disease appeared to have affected 1-2% of the population; 90.3% (214/237) patients for whom information is available were aged 20 years or older; the disease was generally mild and affected pregnant women most severely. 49 patients were admitted to hospital and at least 4/273 died. There were prevalences of 47% (28/60) HBsAg and 69% (37/54) anti-HDV reactors among patients bled 1-43 d after the onset of illness. The main features of the outbreak conformed to published descriptions of water-borne epidemic non-A non-B hepatitis and it is postulated that the disease was most severe in patients with active HBV infection and in those with HDV superinfection, so that such patients were disproportionately represented amongst those seeking medical attention.

The effect of praziquantel against Schistosoma mansoni-infections in Botswana.

Chemotherapy of all infected individuals, using praziquantel 40 mg/kg in a single dose, was the initial component of the recently introduced control programme against Schistosoma mansoni-infections in Ngamiland, Botswana. To evaluate the effect of praziquantel in Ngamiland, 81 children were selected at random from three strata of intensities of infection. Six weeks after treatment a duplicate of Kato fecal thick smear was made. When eggs of S. mansoni were found, a new stool sample was collected and a hatching test performed. Only in case of a positive hatching test was the child considered to be infected: Cure rates between 78.6 and 90.0%, and reductions in egg output among noncured between 84.6 and 98.0% were found.

Schistosoma mansoni: intensity of infection and morbidity among schoolchildren in Matlapaneng, Ngamiland, Botswana.

Recent surveys in Ngamiland, Botswana, indicate increasing prevalence of Schistosoma mansoni infections. With the introduction of a schistosomiasis control programme, 354 of 373 schoolchildren were examined quantitatively for eggs of S. mansoni, and 317 were examined clinically for hepato- and splenomegaly. 80.5% of the children examined parasitologically were found infected. Among these the arithmetric mean egg output was 744.7 and the geometric mean 307.3 eggs per gram of faeces (epg), 46.0% were excreting more than 400 epg. 23 children were found to have an enlarged liver, whereas none was found with enlarged spleen. 21 of these had schistosomiasis. The prevalence of hepatomegaly was highest among those excreting above 1600 epg. Also the mean size of the enlarged livers increased with intensity of infection.

Simplified data collection and analysis in a Schistosoma mansoni endemic area.

Proper data collection and analysis is one of the important factors to successfully carry out the surveys in Schistosoma mansoni endemic areas. The data needed can be divided into three main categories i.e. pre-survey, during the survey and follow up data. Various factors are considered important for correct data collection. Without proper data collection and analysis, future planning of the programme, monitoring of the operation, modifications, correct interpretation of the results and evaluation of the programme cannot be done. Hence correct decision on the future of the programme cannot be made by professional, technical and administrative authorities. Data collection forms could be designed as required, keeping in mind the objectives of the programme.

Cobalamin absorption determined by the stool spot test. Reliability in patients with uremia or disorders of the ileum.

A cobalamin absorption test, the stool spot test (SST), which makes use of radioactive cobalamin and a nonabsorbable isotope, 51Cr-trichloride, has been shown to produce reliable results in patients with pernicious anemia and in healthy controls. The reliability of the SST in patients with bowel disorders and in patients with decreased renal function was investigated by comparing with both whole-body counting and the Schilling test. Fourteen patients with bowel disorders and eight patients with uremia joined the trial. The SST correlated highly significantly with the whole-body counting method. However, the precision of the SST was poor in patients with decreased bowel transit time and inferior to that in the uremic patients. In one of two patients with decreased bowel transit time the two isotopes were shown to have different transit times, thus invalidating the test. In patients with uremia the SST was significantly more reliable than the Schilling test. It is concluded that the SST is reliable also in patients with uremia but may not be reliable in patients with intestinal disorders and decreased bowel transit time. In these patients collection of larger stool samples is recommended.