Wuchereria Bancrofti in Kwale District, Coastal Kenya: Patterns of Focal Distribution of Infection, Clinical Manifestations and Anti-Filarial IgG Responsiveness

Article JournalAcross-sectional study of bancroftian ®lariasis was conducted in 2 adjacent communities, Mvumoni and Kilore in Muhaka, Kwale District. Wuchereria bancrofti infection, clinical manifestations and anti-®larial 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 signi®cantly higher in Kilore (24%) than in Mvumoni (6±3%, P!0±001). Similarly, the prevalence of antigenaemia increased with age and also was signi®cantly higher in Kilore, 48±9%than in Mvumoni, 20±5% (P!0±001). Hydrocele, funiculitis, lymphangitis and lymphadenitis were also signi®cantly 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-®larial antibodies of 3 IgG isotypes were signi®cantly higher in Kilore than Mvumoni (P!0±001, for IgG1, IgG2, IgG4). These results emphasize the highly focal nature of bancroftian ®lariasis in this setting and demonstrate that anti-®larial antibody levels are related to transmission intensity