Interdependence of domestic malaria prevention measures and mosquito-human interactions in urban Dar es Salaam, Tanzania.
BACKGROUND
Successful malaria vector control depends on understanding behavioural interactions between mosquitoes and humans, which are highly setting-specific and may have characteristic features in urban environments. Here mosquito biting patterns in Dar es Salaam, Tanzania are examined and the protection against exposure to malaria transmission that is afforded to residents by using an insecticide-treated net (ITN) is estimated.


METHODS
Mosquito biting activity over the course of the night was estimated by human landing catch in 216 houses and 1,064 residents were interviewed to determine usage of protection measures and the proportion of each hour of the night spent sleeping indoors, awake indoors, and outdoors.


RESULTS
Hourly variations in biting activity by members of the Anopheles gambiae complex were consistent with classical reports but the proportion of these vectors caught outdoors in Dar es Salaam was almost double that of rural Tanzania. Overall, ITNs confer less protection against exophagic vectors in Dar es Salaam than in rural southern Tanzania (59% versus 70%). More alarmingly, a biting activity maximum that precedes 10 pm and much lower levels of ITN protection against exposure (38%) were observed for Anopheles arabiensis, a vector of modest importance locally, but which predominates transmission in large parts of Africa.


CONCLUSIONS
In a situation of changing mosquito and human behaviour, ITNs may confer lower, but still useful, levels of personal protection which can be complemented by communal transmission suppression at high coverage. Mosquito-proofing houses appeared to be the intervention of choice amongst residents and further options for preventing outdoor transmission include larviciding and environmental management.
Geissbühler
Yvonne
Y
Swiss Tropical Institute, Department of Public Health and Epidemiology, Socinstrasse 57, PO Box, 4002 Basel, Switzerland. Y.Geissbuehler@unibas.ch
Chaki
Prosper
P
Emidi
Basiliana
B
Govella
Nicodemus J
NJ
Shirima
Rudolf
R
Mayagaya
Valeliana
V
Mtasiwa
Deo
D
Mshinda
Hassan
H
Fillinger
Ulrike
U
Lindsay
Steven W
SW
Kannady
Khadija
K
de Castro
Marcia Caldas
MC
Tanner
Marcel
M
Killeen
Gerry F
GF
D000818:Animals; D006801:Humans; D007299:Insect Bites and Stings / Q000517:prevention & control*; D008288:Malaria / Q000517:prevention & control*; D009032:Mosquito Control / Q000379:methods*; D011156:Population Density; D013636:Tanzania