[afro-nets] Mosquito/Malaria Control (12)

[Maurice Odiere <MOdiere@ke.cdc.gov>]

Mosquito/Malaria Control (12)
-----------------------------

Hi Bill,

Various studies have shown that bednets may cause a shift in the
biting pattern to either early or late. I still need to check
for more literature and references, but in the meantime, please
have a look at the following studies:

1. Charlwood, J.D and Graves, P.M. (1987). The effects of perme-
thrin bednets on the population of Anopheles farauti in coastal
Papua New Guinea. Medical Veterinary Entomology 1:319-327.

2. Magesa S.M. et al., 1991. Trial of pyrethroid impregnated
bednets in an area of Tanzania holoendemic for malaria. Part 2:
Effects on the malaria vector population.
(Here they found a statistically significant shift effect in an
area called Mng'aza.)

3. Faculty of Tropical Medicine Annual report, 1996. Studies
done by Sucharit, Supat et al., in Thailand. (Anopheles minimus
species-a sub species in Thailand and their impact on malaria
control).

NB:
However, in their study, Mathenge et al., 2001 reported that
bednets had no effect on the nocturnal biting pattern of either
the local An. gambiae or An. funestus, and that malaria vectors
were unlikely to shift their biting times to periods before peo-
ple retired to bed in that local area.

Three factors may explain the early biting behaviour.

Nevertheless, it is not known what happens to mosquitoes that
fail to blood feed and exit early as a result of bednet-use (ei-
ther by deterrence or excito-repellency). My guess would be that
those mosquitoes may shift to feeding on other hosts, although
several studies have indicated that a shift in host selection
due to bednets would be highly unlikely (Magesa et al., 1991),
(Lindsay et al., 1993), (Mbogo et al., 1996).
Nice time.

Maurice.

--
Maurice R.Odiere (M.Sc-University of Nairobi)
CDC-Entomology section
P.0.Box 1578
Kisumu, Kenya
Tel (Office): +254-572-022-902
Cell: +254-721-845-777
mailto:modiere@ke.cdc.gov