Anopheles gambiae and Anopheles arabiensis population densities and infectivity in Kopere village, Western Kenya.
BACKGROUND
This study was conducted in a sugar belt region of western Kenya interfacing epidemic and endemic malaria transmission. We investigated Anopheles gambiae sensu stricto (ss) and Anopheles arabiensis species compositions and densities, human host choice, and infectivity.


METHODS
Mosquitoes were captured using pyrethrum spray catch technique and first identified based on morphology; species were confirmed by PCR. Blood meal preference and sporozoite rates were determined by ELISA. Parity rates and entomological inoculation rates (EIR) were determined. Seasonal densities were compared against environmental temperatures, relative humidity and rainfall.


RESULTS
In total 2,426 An. gambiae were collected.  Out of 1,687 female blood-fed mosquitoes, 272 were randomly selected for entomological tests. An. gambiae ss and An. arabiensis comprised 75% (205/272) and 25% (68/272) of the selection, respectively. An. gambiae ss had higher preference for human blood (97%; n=263/272) compared with An. arabiensis, which mostly fed on bovines (88%; n=239/272).  The sporozoite and parity rates were 6% (16/272) and 66% (179/272) for An. gambiae ss and 2% (4/272) and 53% (144/272) for An. arabiensis respectively, while EIR was 0.78 infective bites/person/night.  Climate (ANOVA; F=14.2; DF=23) and temperature alone (r=0.626; t=3.75; p=0.001) were significantly correlated with vector densities.


CONCLUSIONS
An. gambiae ss are the most efficient malaria vector mosquito species in Kopere village. Because An. gambiae ss largely rests and feeds indoors, use of indoor residual spray and insecticide-treated nets is likely the most suitable approach to malaria vector control in Kopere village and other parts of Kenya where this species is abundant.
Department of Medical Microbiology and Parasitology , School of Medicine, Moi University, Eldoret, Kenya. obalaandrew@yahoo.com
Andrew Ambogo
AA
Obala
Helen L
HL
Kutima
Henry D N
HD
Nyamogoba
Anne W
AW
Mwangi
Chrispinus J
CJ
Simiyu
Gideon N
GN
Magak
Barasa O
BO
Khwa-Otsyula
John H
JH
Ouma
D000818:Animals; D000852:Anopheles / Q000145:classification / Q000254:growth & development* / Q000469:parasitology*; D004199:Disease Vectors; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D006813:Humidity; D007630:Kenya; D010961:Plasmodium / Q000276:immunology / Q000302:isolation & purification; D011156:Population Density; D011891:Rain; D012621:Seasons; D034101:Sporozoites / Q000276:immunology; D013696:Temperature; D014887:Weather