Is aging raw cattle urine efficient for sampling Anopheles arabiensis Patton?

Background: To ensure sustainable routine surveillance of mosquito vectors, simple, effective and ethically acceptable tools are required. As a part of that, we evaluated the efficiency of resting boxes baited with fresh and aging cattle urine for indoor and outdoor sampling of An. arabiensis in the lower Moshi rice irrigation schemes. Methods: A cattle urine treatment and re-treatment schedule was used, including a box with a piece of cloth retreated with urine daily, and once after 3 and 7 day. Resting box with piece of black cloth not treated with urine was used as a control. Each treatment was made in pair for indoor and outdoor sampling. A 4 by 4 Latin square design was used to achieve equal rotation of each of the four treatments across the experimental houses. Sampling was done over a period of 6 months, once per week. Results: A total of 7871 mosquitoes were collected throughout the study period. 49.8% of the mosquitoes were collected from resting box treated with urine daily; 21.6% and 20.0% were from boxes treated 3 and 7 days respectively. Only 8.6% were from untreated resting box (control). The proportion collected indoors was similar to 2 folds greater than the outdoor. Of all mosquitoes, 12.3% were unfed, 4.1% full fed, 34.2% semi-gravid and 49.4% gravid. Conclusion: Fresh and decaying cattle urine odour baited resting boxes offer an alternative tool for sampling particularly semi-gravid and gravid An. arabiensis. Evaluation in low density seasons of An. arabiensis in different ecological settings remains necessary. This sampling method may be standardized for replacing human landing catch

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 92.3 % of An. gambiae s.s, 88.9% of An. funestus s.s., 64.5% of An. rivulorum and 67.7% of 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