Malaria Vectors in Lake Victoria and Adjacent Habitats in Western Kenya

Abstract

The prevalence of malaria among the residents of the Lake Victoria basin remains high. The environment associated with the lake may maintain a high number of malaria vectors. Lake habitats including water hyacinths have been suspected to be the source of vectors. This study investigated whether malaria vectors breed in the lake habitats and adjacent backwater pools. Anopheline larvae were collected within the littoral zone of the lake and adjacent pools located along approximately 24.3 km of the lakeshore in western Kenya, and their breeding sites characterized. Three primary vector species, Anopheles arabiensis, Anopheles gambiae s.s. and Anopheles funestus s.s., and three potential vectors, were found in the lake habitats. Unexpectedly, An. arabiensis was the most dominant vector species in the lake sampling sites. Its habitats were uncovered or covered with short grass. A potential secondary malaria vector, Anopheles rivulorum, dominated the water hyacinths in the lake. Most breeding sites in the lake were limited to areas that were surrounded by tall emergent plants, including trees, and those not exposed to waves. Nearly half of adjacent habitats were lagoons that were separated from the lake by sand bars. Lagoons contained a variety of microhabitats. Anopheles arabiensis dominated open habitats, whereas An. funestus s.s. was found mainly in vegetated habitats in lagoons. The current study confirmed that several breeding sites are associated with Lake Victoria. Given that Lake Victoria is the second largest lake in the world, the lake related habitats must be extensive; therefore, making targeted vector control difficult. Further exploration is necessary to estimate the effects of lake associated habitats on malaria transmission so as to inform a rational decision-making process for vector control.

Advances and Perspectives in the Study of the Malaria Mosquito Anopheles funestus

“…In western Kenya, larva of An. rivulorum were recently found in hyacinth water protected by trees [39]. Similarly, An.…”

Lake Victoria

“…This species was introduced to the Lake in the 1980s by human activity and in areas where this weed is most prevalent, there has been a clear increase in the incidence of mosquitoborne illnesses. The plant has been shown to serve as a habitat for several species of mosquitoes [7] and vectors for other diseases. Since the early 2000s there has been a relatively successful management plan in place which makes use of weevils, insects that eat the weed.…”

Water hyacinth control in Lake Victoria: Transforming an ecological catastrophe into economic, social, and environmental benefits

“…There is evidence of negative health consequences of large water hyacinth mats (Gunnarsson and Petersen, 2007;Njuru et al, 2012). Higher rates of schistosomiasis, malaria, and poisonous snake populations have all been linked to the spread of water hyacinth (Gunnarsson and Petersen, 2007;Minakawa et al, 2012). 146-264 c * Includes only C sequestered in biomass, does not include avoided emissions from the anaerobic decomposition of the water hyacinth biomass in the open lake.…”

“…Water hyacinth sheets also serve as a breeding ground for various endemic diseases. There have been noted increases in the incidents and severity of malaria and schistosomiasis associated with water hyacinth sheets (Gunnarsson and Petersen, 2007;Minakawa et al, 2012).…”