Is mosquito larval source management appropriate for reducing malaria in areas of extensive flooding in The Gambia? A cross-over intervention trial.
Larviciding to control malaria was assessed in rural areas with extensive seasonal flooding. Larval and adult mosquitoes and malaria incidence were surveyed routinely in four 100-km(2) areas either side of the Gambia River. Baseline data were collected in 2005. Microbial larvicide was applied to all water bodies by hand application with water-dispersible granular formulations and corn granules weekly from May to November in two areas in 2006 and in the other two areas in 2007 in a cross-over design. The intervention was associated with a reduction in habitats with late stage anopheline larvae and an 88% reduction in larval densities (P < 0.001). The effect of the intervention on mosquito densities was not pronounced and was confounded by the distance of villages to the major breeding sites and year (P = 0.002). There was no reduction in clinical malaria or anemia. Ground applications of non-residual larvicides with simple equipment are not effective in riverine areas with extensive flooding, where many habitats are poorly demarcated, highly mobile, and inaccessible on foot.
School of Biological and Biomedical Sciences, Durham University, South Road, Durham, United Kingdom. smajambere@ihi.or.tz
Silas
S
Majambere
Margaret
M
Pinder
Ulrike
U
Fillinger
David
D
Ameh
David J
DJ
Conway
Clare
C
Green
David
D
Jeffries
Musa
M
Jawara
Paul J
PJ
Milligan
Robert
R
Hutchinson
Steven W
SW
Lindsay
D000818:Animals; D000852:Anopheles / Q000382:microbiology* / Q000469:parasitology; D001413:Bacillus thuringiensis; D002648:Child; D017753:Ecosystem; D005260:Female; D055868:Floods; D005714:Gambia / Q000453:epidemiology; D006801:Humans; D007814:Larva / Q000382:microbiology; D008288:Malaria / Q000453:epidemiology / Q000517:prevention & control*; D010572:Pest Control, Biological / Q000379:methods*; D012621:Seasons