A parasitological survey, in rural Zanzibar, of pre-school children and their mothers for urinary schistosomiasis, soil-transmitted helminthiases and malaria, with observations on the prevalence of anaemia.

'Kick-out-Kichocho' is an integrated helminth-control initiative that is aimed at reducing the burden of urinary schistosomiasis and soil-transmitted helminthiases (STH) on Zanzibar Island (Unguja), in Tanzania. Like other initiatives based on preventive chemotherapy, the programme is mainly school-based and, consequently, pre-school children (aged < or =6 years) are not targeted specifically. To assess the importance of urinary schistosomiasis, STH and malaria, as well as the occurrence of anaemia and growth retardation among these younger children, an epidemiological survey has been undertaken, in a rural area of Unguja, among 152 pre-school children and their 113 mothers. In the pre-school children investigated, urinary schistosomiasis was rare because of the children's lack of contact with environmental water. Malaria was also rare in the children, probably as a consequence of the study season, the widespread use of insecticide-treated bednets and the good access to first-line antimalarial drugs. In contrast, the prevalences of infection with at least one soil-transmitted helminth and of anaemia were alarmingly high among the pre-school children, at 50.0% [95% confidence interval (CI)=40.4%-59.6%) and 73.4% (CI=?65.2%-80.5%), respectively; the corresponding values in the children's mothers were 35.2% (CI=25.4%-45.9%) and 25.9% (CI=18.0%-35.3%). In the rural study area, Kandwi was identified as a hamlet with particularly high levels of transmission of soil-transmitted helminths, and household aggregations of STH were common. To reduce the present health inequities, the future integration of pre-school children within ongoing anthelmintic-control programmes in schools is strongly recommended.

Control of urinary schistosomiasis on Zanzibar (Unguja Island): a pilot evaluation of the educational impact of the Juma na Kichocho health booklet within primary schools

To improve health education within primary schools, the health education booklet Juma na kichocho was evaluated during a study within 5 schools using key-informant questionnaires that recorded children's knowledge and attitude (KA) towards schistosomiasis before and after daily structured-use of booklets. A total of 229 schoolchildren (114 boys : 115 girls) of between 11 and 15 years of age were interviewed and re-assessed after a working school week. Existing and putative booklet-induced changes in KA scores for schistosomiasis were compared directly against equivalent KA scores for malaria. In total 47.4 percent of children were already aware that schistosomiasis was a water-borne disease while only 10.5 percent knew of its exact aetiology; after booklet intervention these levels increased to 54.6 and 15.7 percent, respectively. The majority of children still failed, however, to realise that re-infection could take place soon after treatment. While a positive increase was observed for children's total KA questionnaire scores for both malaria and schistosomiasis after booklet intervention, these were not statistically significant. In the context of control, further educational efforts are needed to promote and guide behavioural change, especially in relation to reduction of environmental water contact.

Control of urinary schistosomiasis on Zanzibar (Unguja Island): a pilot evaluation of the educational impact of the Juma na Kichocho health booklet within primary schools.

To improve health education within primary schools, the health education booklet "Juma na kichocho" was evaluated during a study within 5 schools using key-informant questionnaires that recorded children's knowledge and attitude (KA) towards schistosomiasis before and after daily structured-use of booklets. A total of 229 schoolchildren (114 boys : 115 girls) of between 11 and 15 years of age were interviewed and re-assessed after a working school week. Existing and putative booklet-induced changes in KA scores for schistosomiasis were compared directly against equivalent KA scores for malaria. In total 47.4% of children were already aware that schistosomiasis was a water-borne disease while only 10.5% knew of its exact aetiology; after booklet intervention these levels increased to 54.6 and 15.7%, respectively. The majority of children still failed, however, to realise that re-infection could take place soon after treatment. While a positive increase was observed for children's total KA questionnaire scores for both malaria and schistosomiasis after booklet intervention, these were not statistically significant. In the context of control, further educational efforts are needed to promote and guide behavioural change, especially in relation to reduction of environmental water contact.

Urinary schistosomiasis on Zanzibar: application of two novel assays for the detection of excreted albumin and haemoglobin in urine.

As part of a urinary schistosomiasis control programme on Zanzibar, an aged cross-sectional survey of 305 children from three schools on Unguja was conducted to investigate the relationships between levels of excreted albumin and haemoglobin in urine and Schistosoma haematobium infection status. Diagnosis was determined by standard parasitological methods, dipstick reagents for microhaematuria, visual inspection for macrohaematuria as well as collection of case-history questionnaire data for self-diagnosis. Prevalence of infection as determined by parasitology was 53.9% and approximately, one quarter of the children examined were anaemic (<11 g dl(-1)). A statistically significant negative association of blood haemoglobin levels of boys and S. haematobium infection intensity status was observed (rs=-0.23, P=0.005). Through sensitivity analysis of urine-albumin values it was determined that a concentration of above >40 mg l(-1), as measured with the HemoCue urine-albumin photometer, had sensitivity, specificity, positive and negative predictive values of 0.90, 0.83, 0.86 and 0.89 respectively against 'gold-standard' parasitology. There was a clear association of reported pain upon micturition for children with elevated urine-albumin levels, with an odds ratio of 20 to 1. Levels of excreted blood in urine were quantified with the HemoCue Plasma/Low Hb photometer. However, dipsticks remain the method of choice for urine-haemoglobin of 0.1 g l(-1) and below. Urine parameters over a 24-h period were assessed in a small sub-sample. Reductions in both albumin and haemoglobin excretion were observed in 11 children 54 days after praziquantel treatment. It was concluded that these rapid, high-through-put, portable HemoCue assays could play a role in better describing and monitoring the occurrence, severity and evolution of urinary schistosomiasis disease. The urine-albumin assay has particular promise as a biochemical marker of S. haematobium induced kidney- and upper urinary tract-morbidity.

New insights into the transmission biology of urinary schistosomiasis in Zanzibar.

A better understanding of the transmission biology of urinary schistosomiasis in Zanzibar, Tanzania was only possible after the development of molecular DNA markers for identification of Bulinus africanus group snails, the potential intermediate hosts of Schistosoma haematobium. Hitherto, identification of natural populations of B. globosus and B. nasutus was problematic and the intermediate host status and distribution of either species remained speculative. By recourse to molecular markers, snail distribution maps could be drawn, revealing an allopatric distribution and, more importantly, leading to the discovery that B. nasutus played no role in transmission. Indeed, in Unguja the area of active transmission of S. haematobium to humans is confined within the distribution of B. globosus. This strong relationship may prove useful for predicting the distribution of urinary schistosomiasis within Zanzibar and, if snail schistosome compatibilities persist, in other areas nearby, e.g. coastal Tanzania and Kenya. The transmission biology of urinary schistosomiasis in Zanzibar is reviewed, the paper reports on ongoing malacological studies in Zanzibar and Kenya and finally closes by posing the question whether medical malacology forms an essential component associated with mass-scale chemotherapy control programmes.

Urinary schistosomiasis in schoolchildren on Zanzibar Island (Unguja), Tanzania: a parasitological survey supplemented with questionnaires.

The distribution of urinary schistosomiasis in schoolchildren on Zanzibar Island (Unguja) was surveyed in May 2001 to test a potential correlation with the distribution of snail species of the Bulinus africanus group and to record contemporary baseline epidemiological data. Quasi-random samples of 40 schoolchildren of mixed sexes were selected from each of 10 schools. Schistosoma haematobium infections were detected upon the basis of micro-haematuria with subsequent confirmation by microscopy examination for schistosome eggs. At the time of urine collection, each child was interviewed with a suite of 12 questions prepared as a standardized questionnaire. Total prevalence of urinary schistosomiasis (known locally as kichocho) was 12% although schistosome infections were absent in 5 schools. Schools located west of 39 degrees 19'E and north of 6 degrees 10'S harboured nearly all of the infections; the highest prevalence (55%) was found at Kinyasini where many B. globosus habitats occur nearby. The general level of understanding of kichocho was low (24%) and individual self-diagnosis was poor (sensitivity, 8.5%; specificity, 85%). Grouped freshwater-contact patterns of schoolchildren differed significantly between schools and correlated well with prevalence of infections within schools. Across the island the area of active transmission of S. haematobium to humans appears confined within the distribution of B. globosus. There was no epidemiological evidence to suggest any involvement of B. nasutus in local transmission, confirming previous laboratory findings. In areas where B. globosus occurs, targeted snail control should be considered, to reduce schistosome transmission.

A comparative trial of a single-dose ivermectin versus three days of albendazole for treatment of Strongyloides stercoralis and other soil-transmitted helminth infections in children.

A randomized trial carried out in rural Zanzibar comparing a single dose of 200 micrograms/kg of ivermectin and 400 mg/day for three days of albendazole for treatment of strongyloidiasis and other intestinal nematodes is described. In 301 children with Strongyloides stercoralis infection, treatment with ivermectin or albendazole resulted in cure rates of 83% and 45%, respectively. While both drugs were very effective against Ascaris lumbricoides, Trichuris trichiura was cured only in 11% (ivermectin) and 43% (albendazole) of the subjects, although the mean eggload was reduced by 59% and 92%, respectively. Ivermectin was ineffective against hookworms, while albendazole resulted in a cure rate of 98%. No severe side effects were recorded and mild side effects were of transient nature for both treatments. Therefore, ivermectin provides a safe and a highly effective single dose treatment for S. stercoralis and A. lumbricoides, while it is not an alternative for the treatment of T. trichiura and hookworm infections.

Metrifonate in the control of urinary schistosomiasis in Zanzibar.

Selective population chemotherapy using three doses of metrifonate (7.5 mg/kg body weight each time) at two-week intervals was assessed in an entire community in Kinyasini district in Zanzibar, United Republic of Tanzania. The objectives of the study were to (1) reduce the prevalence of heavy infections (defined as greater than or equal to 50 S. haematobium eggs per 10 ml of urine) by 75% in two years, and (2) reduce the overall prevalence of infection by 50% in two years. A total of 4113 people were examined at least once during the two-year period. In the initial survey the highest proportion of infected individuals was in the 10-14-year age group, and in all subsequent surveys in the 5-9-year age group. The age group with the highest proportion of heavily infected individuals was 5-9 years for all surveys. The overall reduction of prevalence of infection from survey 1 to survey 4 was 52.9% and the prevalence of heavy infection was reduced by 62.2%. The conversion rates (negative to positive in two consecutive surveys) were highest in the longest interval of 12 months and the rates of reversion (positive to negative in two consecutive surveys, without a history of treatment) were highest in the shortest interval of 4 months. Some statistically significant relationships were observed between the number of doses and the egg reduction rates. However, for the egg-negative rates, no statistically significant relationship was observed. In the 4-month interval a 67.6% egg-negative rate was observed among those who took at least one dose; with the 12-month interval a 48.3% egg-negative rate was observed. Thus, selective population chemotherapy with metrifonate was shown to reduce the prevalence and intensity of infection due to S. haematobium over a 24-month period.