ABSTRACT
Background & objectives: The study was aimed at determining the prevalence and intensity of Wuchereria bancrofti microfilaraemia in a high altitude region of south-eastern Nigeria, and ascertaining the prevalence of clinical signs and symptoms associated with the filarial infections. Methods: Thick smear of 50 l finger-prick blood collected at night between 2200 and 0200 hrs from consenting persons were stained with Giemsa and examined microscopically in a cross-sectional study. Consenting individuals were examined for various gradations of hydrocele, limb and scrotal elephantiasis by qualified medical personnel. Results: The prevalence of W. bancrofti microfilaraemia was 4.3%, highest in the older people but comparable in both sexes. The overall microfilarial (mf) geometric mean intensity (GMI) among mf positive individuals was 123 mf/ml of blood (138 mf/ml for males and 110 mf/ml of blood for females); and rose significantly with increasing age (one-way analysis of variance; p < 0.001). Prevalence of clinical manifestations was: hydrocele (7.1%), scrotal elephantiasis (4%), and limb elephantiasis (6%). The mf GMI was significantly higher among those without hydrocele or limb elephantiasis than among those with the clinical manifestations (t-test; p <0.05 for both tests); the opposite was the case for scrotal elephantiasis, (t-test; p <0.01). Conclusion: Filariasis is endemic in the high altitude region of south-eastern Nigeria. The chronic clinical manifestations observed there underscore the need for urgent combination therapy interventions.
ABSTRACT
Background & objectives: The study was aimed at elucidating the prevalence and intensity of Mansonella perstans microfilaraemia in the Emohua Local Government Area, Nigeria, and ascertaining the abundance, circadian, and the annual biting patterns of the Culicoides vector. Methods: Thick smear of 50 μl finger-prick blood stained with Giemsa was examined microscopically in a cross-sectional study. Vector landing collection on human bait was employed in a longitudinal study of the vector biting patterns, carried out between July 2005 and August 2006. Results: Of 1486 individuals examined, 11.2% of both males and females were positive for M. perstans microfilaraemia. Microfilaraemia appeared early in life. The overall geometric mean intensity among those with positive microfilaraemia was 117 mf/ml (121 mf/ml for males and 113 mf/ml for females). The differences in geometric mean intensity between different age groups were statistically significant (one-way analysis of variance; p <0.05), being highest in the oldest age group (266 mf/ml). A total of 1183 female Culicoides sp were caught from September 2005 to August 2006. The abundance of Culicoides sp was seasonal. The circadian biting activity had a broad peak between 0700 and 1200 hrs. The monthly biting rates ranged from zero bite per person per month in January 2006 to 1151 bites per person per month in June 2006. The annual biting rate was 7382 bites per person per year. Conclusion: Majority of those with positive microfilaraemia were poor socioeconomically, underscoring the need for health education and application of effective control measures against Culicoides biting midges in Emohua.