Outdoor Feeding of Malaria Vectors Increases with ITN Use in Tanzania
Author Information
Author(s): Tanya L. Russell, Nicodem J. Govella, Salum Azizi, Christopher J. Drakeley, S. Patrick Kachur, Gerry F. Killeen
Primary Institution: Ifakara Health Institute
Hypothesis
Wide-scale ITN use would precipitate a change in the vector population, investigating possible shifts in human-biting time or location over a 12-year period.
Conclusion
High usage of ITNs can dramatically alter African vector populations, leading to reduced indoor transmission and increased outdoor biting.
Supporting Evidence
- ITN use reduced malaria transmission intensity by 94%.
- By 2009, the proportion of human contact with An. funestus bites occurring indoors dropped to only 50.5%.
- An. gambiae s.l. showed less nocturnal activity by 2009 compared to 1997.
Takeaway
When people use more mosquito nets, the mosquitoes start biting outside instead of inside the house.
Methodology
The study used human landing catches to estimate indoor and outdoor biting profiles of malaria vectors over three time points: 1997, 2004, and 2009.
Potential Biases
Potential confounding factors include changes in land-use or human behavior over time.
Limitations
The study did not include a comparison site without ITNs, which would have been ethically inappropriate.
Participant Demographics
The study involved households from two villages in the Kilombero Valley, Tanzania.
Statistical Information
P-Value
p = 0.0018
Confidence Interval
95% CI
Statistical Significance
p<0.0001
Digital Object Identifier (DOI)
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