Investigations into phlebotomine Sand flies in Nairobi area

Abstract

studies were commenced to collect and identify the phlebotomine sandflies found in Nairobi. The studies were also aimed at determining their numbers as well as assessing the effects of seasonal changes on the sandfly population. Four trapping methods viz. light traps, sticky traps, aspiration and human baits were employed. Using the entomological keys of Kirk and Lewis (1951) and a pictorial key developed by Mutinga for Kenyan sandflies, 8 species and one undescribed species were recorded over a period of 6 months. The identified species included Phlebotomus guggisbergi, Phlebotomus rodhaini, Sergentomyia adleri, Sergentomyia squamipleuris, Sergentomyia clydei, Sergentomyia teesdalei, Sergentomyia harveyi.and Sergentomyia bedfordi and undescribed species. The undescribed species was the most abundant among the collected sandflies whereas ~. adleri was the least in abundance. Most of the sandfly species trapped showed seasonal prevalence. The sandflies occurred in large numbers at the onset of the rains. The sandfly population . decreased drastically however, during the heavy rains. The seasonal variation in numbers was closely related to the weather conditions. stepwise regression realized a formula that could be used to predict the number of sandflies of a particular species that one expects to catch at any given time. Detailed results are discussed elsewhere in this thesis. The sandflies were found in termite morinds, animal burrows, caves and dugouts some of which were near human habitations. Most of the sandflies were collected from termite mounds and animal burrows. The sandflies also showed prevalence for micro-habitats. The results of these studies have demonstrated clearly that Nairobi has a number of sandfly species some of which are potential vectors of leishmaniasis. For example, ~. clydei is a suspected vector of lizard leishmaniasis in Kenya and it readily bites man. Phlebotomus guggisbergi a cave dweller, readily bites man inflicting a lot of pain. The vectorial capacity of this species needs to be investigated. More work needs to be done so as to identify the unknown species and also to reveal its vectoral potential.