Entomological assessment of the potential for malaria transmission in Kibera slum of Nairobi, Kenya

Background & objectives: Malaria in urban and highland areas is emerging as a significant publichealth threat in Kenya which has seen a dramatic increase in malaria transmission in low riskhighland areas. The objectives of the study were to find and incriminate potential vectors of malariain Kibera, Nairobi.Methods: One hundred and twenty houses within Lindi area of the southern central section ofKibera slum in Nairobi were chosen randomly and global positioning system (GPS) mapped. Dayresting indoor mosquitoes were collected from January 2001 to December 2003. Larvae werecollected between 2002 and 2004 and reared in the insectary to adults.Results: A total of 176,993 mosquitoes were collected. Out of this, 176,910 were Culex fatigansand 83 were Anopheles gambiae s.l. Mosquito population peaked during the long rains in April toMay and the short rains in November and December. Blood meal analysis of An. gambiae s.l.female mosquitoes revealed 0.97 human blood index. No mosquito was found positive forPlasmodium falciparum sporozoites. Anopheles gambiae s.l. mosquitoes were found breeding inpolluted water and 95% of the larvae were identified as An. arabiensis.Interpretation & conclusion: Anopheles gambiae s.l., malaria vector is present in Nairobi and itbreeds in polluted water. Anopheles arabiensis is predominantly preferring humans as blood mealsource, thus, showing ecological flexibility within the species.