Development of a Conceptual Framework for Integrated Vector Management in the Heterogeneous Malaria Ecosystem of Western Kenya Highlands

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Date
2023Author
PM, Wamae
GO, Otieno
EW, Kabiru
S, Munga
t SJ, Kibe
SO, Duombia
Githeko AK
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Show full item recordAbstract
Malaria heterogeneity in the highlands is due to range of factors
including seasonal weather changes, climate variability, land-use
changes, topography, drug resistance, and malaria control programs.
High coverage of long lasting insecticide treated nets is the basis of
vector control in epidemic prone western Kenya highlands. Long lasting
insecticide treated nets have effectively controlled malaria in the hypoendemic
zones, but not in meso-endemic and hyper-endemic zones
where significant residue of transmission remains despite control efforts.
Inadequate policy on integrated vector management application for
ecologically heterogeneous ecosystems hinders effective malaria control.
Advances in ecological and epidemiological studies have improved our
understanding on vector distribution determinants and malaria
transmission enabling us to effectively integrate indoor residual
spraying into the existing long lasting insecticide treated nets
programme.
Data on malaria vector abundance and parasite prevalence for
different malaria ecosystems within western Kenya highlands before
and after mass insecticide treated bed-net distribution campaigns was
gathered to assess the efficacy of the long lasting insecticide treated
nets based control efforts. Field tests were carried out to determine the
impact of combined indoor residual spray and long lasting insecticide
treated nets on vector indoor resting densities in zones where insecticide
treated nets alone had limited efficacy or zero efficacy was observed.
Female An. gambiae s.l resting densities of 0.1 mosquitoes/ house/night
were associated with a plasmodium falciparum (pf) prevalence rate of
10% or below. This observation enabled the development of a
framework for the inclusion of indoor residual spray in integrated vector
management with the suggestion that IRS should be applied in malaria
eco-epidemiological zones where An. gambiae s.l resting densities
exceeds 0.1 females/ house/ night.
Similarly, only those houses with a resting density of 0.1 females An.
gambiae s.l and above should be targeted during spraying. Such an
approach would significantly reduce the cost associated with indoor
residual spray and provides a rationale for judicious integration of
indoor residual spray within existing long lasting insecticide treated nets
control programmes.
Development of a Conceptual Framework for Integrated Vector Management in the Heterogeneous