Studies on filarial infection in Lamu and Tana river districts

Abstract

Brugia patei is a filarial worm that was discovered in cats, dogs and genet cats rn Pate Island (Lamu district) by BUCKLEY et el (1958). Subsequent epidemiological studies by HEISCH et al (1959) and NELSON et al (1962) indicated the presence of the parasite in Pate island but since then no further epidemiological work has been published. This work sought to find out if B. patel is still present in Pate islands, Kenya and, if so, to determine its prevalence in man (if any) and animals, with a view to establishing whether it plays any role r n human filariasis in the country. In determining the prevalence of Brugia patei blood samples (20 mm3) were , obtained from people of all ages , mainly at night in parts of Lamu and Tana River districts. In total 814 people were examined out of whom only 24 pe12P}e were found with microfilariae of Wuchereria bancrofti in their blood. None had li patei infection. One hundred and twenty nine cats and 67 dogs were examined but none was found with any filarial infection. Also a total of 4,950 mosquitoes were dissected but no larvae were recovered. The results of this work indicate that the only human filarial infection present in the areas covered is Wuchereria bancrofti and that Bregia patei seems to have disappeared from the Island it was first discovered In. The low level of bancrofti incidence found could be due to extensive mosquito control campaigns combined with mass treatment of the inhabitants with diethylcarbamazine citrate. But the disappearance of Brugia patei can be explained in terms of environmental changes over 30 years' period coupl ed wi th mosqui tocontrol campaigns. From the findings of this work and observations from other studies it may be concluded that filariasis is an easily controllable infection whose intensity can be greatly reduced through sound environmental management, vector control and mass treatment with an appropriate drug.