ABSTRACT

A study on mosquito vectors and lymphatic filariasis was conducted in twelve (12) communities in four (4) local government areas of Abia State, Nigeria. Four hundred and ninety eight (498) adult mosquitoes made up of five (5) genera and twelve (12) species were collected from the communities studied using human baiting, sweep net and pyrethrum knockdown count (PKC) methods. The mosquitoes collected were Aedes albopictus, Ae. luteocephalus, Ae. africanus, Ae. aegypti, Anopheles gambiae, An funestus, An nhI An mouchet An coustan Culex quinquefasciatus, Mansonia africana. Of these twelve (12), only four (4) species, Aedes albopictus, Ae. aegypti Culex quinquefasciatus and Anopheles gambiae (most predominant in the area) were infected with the nematode Wuchereria bancrofti, causative agent of lymphatic filariasis, which occurred in Ohafia and lsuikwuato L.G.As. A study of the physiological status of the female mosquitoes showed that more than half (54.4%) of the mosquitoes collected were blood fed with Anopheles gambiae recording the highest number (21.9%) of blood-fed mosquitoes. (29.0%) of the mosquitoes were gravid. The peak biting periods fell within the hours of 8-lopm (14.66%) and 12 -2am (13.65%). Mosquitoes collected indoors (38.35%) outnumbered those collected outdoors (33.94%), the PKC victims accounting for 27.71% of the mosquito collection. Two hundred and thirty (230) mosquito larvae dominated by those of Aedes aegypti, were also collected. Culex tigripes was observed to have fed on other larvae. Three hundred and sixty two (362) respondents filled the questionnaires in the communities studied while a total of two hundred and twenty nine (229) blood samples were collected from willing respondents. Of the latter, seventy persons (30.56%) had microfilariae in their blood (microfilaraemia) while twenty-two persons (6.01%) had clinical signs of lymphoedema and/or hydrocoele. The overall infection rate through the combined methods of microfilaraemia and clinical examination was 24.03% translating to eighty-seven (87) persons being infected. The age group 51-60 years recorded the highest rate of occurrence of (4.70%) through the combined methods of microfilaraemia and clinical examination. By microfitaraemia method of assessment, more females (30.87%) than males (30.0%) were infected while by clinical examination, more males (13.43%) than females (2.19%) understandably were infected. By the combined methods more females (14.04%) than males (9.94%) were infected suggesting occupational hazard just as all night guards were infected. Since infections with filariasis are associated with mosquito bites, the most effective control measure would seem to be avoidance of mosquito bites for which the poor natives resorted to the use of mosquito coils mainly. The communities having been confirmed to be endemic for lymphatic filariasis have qualified for mass drug administration with ivermectin and atbendazole. Vector control programmes put in place by the Federal, State and Local governments are advocated to reduce and possibly eliminate mosquito vectors of lymphatic filariasis. Health information was done by informing the people of the cause of, prevention and treatment of lymphatic filariasis as well as ways of treating and preventing associated problems through home-based prevention of disability due to lymphatic filariasis.