Wuchereria bancrofti in Kwale District, Coastal Kenya: patterns of focal distribution of infection, clinical manifestations and anti-filarial IgG responsiveness.

A cross-sectional study of bancroftian filariasis was conducted in 2 adjacent communities, Mvumoni and Kilore in Muhaka, Kwale District. Wuchereria bancrofti infection, clinical manifestations and anti-filarial IgG responsiveness were determined before the long rains, a time coinciding with a low transmission season. The prevalence of microfilaraemia increased gradually with age and was significantly higher in Kilore (24%) than in Mvumoni (6.3%, P < 0.001). Similarly, the prevalence of antigenaemia increased with age and also was significantly higher in Kilore, 48.9% than in Mvumoni, 20.5% (P < 0.001). Hydrocele, funiculitis, lymphangitis and lymphadenitis were also significantly more common in Kilore than in Mvumoni. In comparing the 2 communities, levels of IgG4 responsiveness in antigen-positive persons were higher in Kilore than Mvumoni (P = 0.034), but this was related to higher antigen loads in persons in Kilore than in Mvumoni. In antigen-negative persons, anti-filarial antibodies of 3 IgG isotypes were significantly higher in Kilore than Mvumoni (P < 0.001, for IgG1, IgG2, IgG4). These results emphasize the highly focal nature of bancroftian filariasis in this setting and demonstrate that anti-filarial antibody levels are related to transmission intensity.

Effect of piped water supply on human water contact patterns in a Schistosoma haematobium-endemic area in Coast Province, Kenya.

The effect of a piped water supply on human water contact in a Schistosoma haematobium-endemic area in Coast Province, Kenya was studied. After the construction of five community standpipes and one shower unit, there was a 35.1% reduction in the number of people observed using river water, a 44.1% reduction in the frequency of contact with river water, and a 25.4% reduction in the amount of contact. The frequency of river water contact per person also decreased significantly, but the amount of contact per person did not decrease. The total frequency of contact decreased significantly except for washing clothes by the river, washing utensils, and fishing. The frequency per person did not change for most of the activities and significantly increased for washing clothes. The frequency of river water contact in households with high piped water consumption showed a significant decrease compared with those with low piped water consumption. The volume of consumption of piped water was inversely proportional to the distance from the home to the community standpipe. These results indicate that in the study area, the effect of a piped water supply on river water contact behavior was heterologous while the total river water contact decreased significantly, and that the piped water had a beneficial effect on some villagers but very little effect on others.

The microfilarial periodic pattern of Wuchereria bancrofti in Kenya.

Microfilarial periodic pattern of Wuchereria bancrofti in Kenya was confirmed by the statistical method proposed by Aikat and Das (1977). Fifteen microfilarial positive individuals were brought to Nairobi from Malindi, which is one of the filariasis foci on the coastal area of Kenya. From each individual a 60-microliter finger prick blood film was made every 2 hours throughout one complete 24-hour cycle. The blood films were dried for at least 48 hours and dehaemoglobinized. The fluid was filtered using Nuclepore membrane to recover any detached microfilariae. The films were stained with Giemsa and microfilariae were counted. The peak time was 0056 h (4 minutes to 1 a.m.) and the periodicity index was 117.08, confirming the nocturnal periodicity.

Enzyme-linked immunosorbent assay as a diagnostic method for schistosomiasis haematobium. Standardization and application in the field.

An enzyme-linked immunosorbent assay was employed for the quantification of antibodies to Schistosoma haematobium in both human serum and urine samples. The serum ELISA was reproducible with coefficients of variation in intra-day tests and inter-day tests being 2.54-3.64% and 5.04-7.48%, respectively. The specificity of serum ELISA was 100% and its sensitivity was 97%. When the eggs recovered from patients' urine were used for antigen, there occurred non-specific reactions, which were markedly decreased by pepsin treatment of the eggs. In addition, urine could also be used for detecting egg-positive persons with a specificity of 91% and a sensitivity of 97%. However, under field conditions, the specificity of urine ELISA was 82% and its sensitivity was 92%.