Mosquito abundance, bed net coverage and other factors associated with variations in sporozoite infectivity rates in four villages of rural Tanzania.
BACKGROUND
Entomological surveys are of great importance in decision-making processes regarding malaria control strategies because they help to identify associations between vector abundance both species-specific ecology and disease intervention factors associated with malaria transmission. Sporozoite infectivity rates, mosquito host blood meal source, bed net coverage and mosquito abundance were assessed in this study.


METHODS
A longitudinal survey was conducted in four villages in two regions of Tanzania. Malaria vectors were sampled using the CDC light trap and pyrethrum spray catch methods. In each village, ten paired houses were selected for mosquitoes sampling. Sampling was done in fortnight case and study was undertaken for six months in both Kilimanjaro (Northern Tanzania) and Dodoma (Central Tanzania) regions.


RESULTS
A total of 6,883 mosquitoes were collected including: 5,628 (81.8%) Anopheles arabiensis, 1,100 (15.9%) Culex quinquefasciatus, 89 (1.4%) Anopheles funestus, and 66 (0.9%) Anopheles gambiae s.s. Of the total mosquitoes collected 3,861 were captured by CDC light trap and 3,022 by the pyrethrum spray catch method. The overall light trap: spray catch ratio was 1.3:1. Mosquito densities per room were 96.5 and 75.5 for light trap and pyrethrum spray catch respectively. Mosquito infectivity rates between villages that have high proportion of bed net owners and those without bed nets was significant (P < 0.001) and there was a significant difference in sporozoite rates between households with and without bed nets in these four villages (P < 0.001).


CONCLUSIONS
Malaria remains a major problem in the study areas characterized as low transmission sites. Further studies are required to establish the annual entomological inoculation rates and to observe the annual parasitaemia dynamics in these communities. Outdoor mosquitoes collection should also be considered.
Kweka
Eliningaya J
EJ
Tropical Pesticides Research Institute, Division of Livestock and Human Disease Vector Control, P.O. Box 3024, Arusha, Tanzania. pat.kweka@gmail.com
Nkya
Watoky M M
WM
Mahande
Aneth M
AM
Assenga
Charles
C
Mosha
Franklin W
FW
Lyatuu
Ester E
EE
Massenga
Charles P
CP
Nyale
Edwin M
EM
Mwakalinga
Stephen B
SB
Lowassa
Asanterabi
A
D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D003465:Culex / Q000469:parasitology*; D006801:Humans; D008137:Longitudinal Studies; D008288:Malaria / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission*; D009032:Mosquito Control / Q000379:methods*; D012424:Rural Population; D034101:Sporozoites; D013636:Tanzania / Q000453:epidemiology