Vector Species Composition and Malaria Infectivity Rates in Mkuzi; Muheza District; North-Eastern Tanzania

Entomological surveys were conducted in Mkuzi village in Muheza District; north-east Tanzania from April to September 2003. The objectives were to determine the species composition and infectivity rates of mosquitoes in Mkuzi village. Mosquito collection was done using CDC light trap and pyrethrum spray catch (PSC) techniques. The light trap: spray catch ratio was 2.2:1. A total of 2157 mosquitoes were collected (light trap= 1483; PSC= 674). Anopheles gambiae s.s. accounted for 56.7(N=1224) of all mosquitoes collected. Other species were An. funestus complex (19.2) and Culex quinquefasciatus (24.1).The mosquito density per room was 74.15 and 33.7 for light trap and PSC techniques; respectively. A total of 1637 Anopheles mosquitoes were tested for circumsporozoite protein by Enzyme linked Immunosobent Assay (ELISA). The overall infectivity rate for circumsporozoite protein for P. falciparum in Anopheles mosquitoes was 21.14(346/1637). Species-specific infectivity rates were 22.7(278/1224) in An. gambiae s.s. and 24.0(68/283) in An. funestus funestus; 0(0/80) for An. rivulorum and 0(0/50) for An.parensis. Blood meal analysis indicated that 92.3of An. gambiae s.s; 88.9of An. funestus s.s.; 64.5of An. rivulorum and 67.7of An. parensis had taken blood meal from human hosts. In conclusion; malaria transmission in Mkuzi area of Muheza district is mainly by the highly anthropophagic An. gambiae s.s. and An. funestus s.s. More studies are needed to identify the seasonal variation of species composition and transmission dynamics in this village

Has the HIV Epidemic in Rural Mwanza; Tanzania Reached a Plateau?

Data from studies in Mwanza Region in Tanzania suggest stabilising HIV prevalence. The objective was to determine the factors that may have contributed to the relatively stable pattern of the HIV prevalence observed in the comparison communities of the Mwanza STD treatment trial in rural Mwanza Region; Tanzania between 1991 and 2001. Socio-demographic; sexual behaviour and HIV prevalence data in two surveys conducted 10 years apart in the same communities using similar sampling schemes were compared. The age standardised HIV prevalence was 3.8(95CI: 3.2-4.6) in 1991 and 4.3(95CI: 2.8-6.4) in 2001 for males (Z= - 0.56; P= 0.58); and 4.5(95CI: 3.8-5.3) in 1991 and 3.9(95CI: 2.6-5.6) in 2001 for females (Z= 0.64; P= 0.52). Participants in the 2001 survey reported significantly fewer lifetime and recent sexual partners (12 months); Sexually Transmitted disease syndromes (12 months) and significantly more condom use at last sex with casual partners than those in the 1991 behaviour survey. We conclude that STD/ HIV infection prevention activities in rural Mwanza may be responsible for changes in risky sexual behaviour and have successfully impeded the spread of HIV infection. These activities should therefore be enhanced to reduce HIV incidence even further. In addition; modelling studies are needed to assess whether mobility of HIV infected people out of rural communities may stabilise the prevalence of the HIV infection in the general populations