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.
Majambere
Silas
S
School of Biological and Biomedical Sciences, Durham University, South Road, Durham, United Kingdom. smajambere@ihi.or.tz
Pinder
Margaret
M
Fillinger
Ulrike
U
Ameh
David
D
Conway
David J
DJ
Green
Clare
C
Jeffries
David
D
Jawara
Musa
M
Milligan
Paul J
PJ
Hutchinson
Robert
R
Lindsay
Steven W
SW
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