Volume 11 Supplement 1

Challenges in malaria research

Open Access

Consistently high baseline estimates for the proportion of human exposure to rural African malaria vector populations that occurred indoors

  • Bernadette Huho1, 2, 3,
  • Olivier Briët2, 3,
  • Aklilu Seyoum4,
  • Chadwick Sikaala4, 5,
  • Nabie Bayoh6, 7,
  • John Gimnig8, 11,
  • Fredros Okumu1, 9,
  • Diadier Diallo10,
  • Salim Abdulla1,
  • Thomas Smith2, 3 and
  • Gerry Killeen1, 4
Malaria Journal201211(Suppl 1):P50

DOI: 10.1186/1475-2875-11-S1-P50

Published: 15 October 2012

Background

Insecticide treated nets (ITNs) and indoor residual spraying (IRS) are highly effective options for controlling malaria transmission in Africa because the most important vectors, which are from the Anopheles gambiae complex and the An. funestus group, prefer biting humans who are indoors at night. It is feared that sustained large scale use of ITNs and IRS can cause these vectors to shift biting in place and time where ITNs and IRS are not effective.

Materials and methods

Matched surveys of mosquito and human behavior from six rural sites in Burkina Faso, Tanzania, Zambia, and Kenya with ITN coverage ranging from 0.2% to 82.5% were used to calculate the proportion of human exposure to Anopheles gambiae sensu lato and An. funestus s.l. that occurs indoors (π i ) as an indicator of the maximum level of personal protection that ITN use can provide. The proportion of mosquitoes caught indoors (P i ) and between the first and last hours when most people are indoors (P fl ) were also calculated as underlying indicators of vector preference for feeding indoors or at night, respectively.

Results

The vast majority of human exposure to Anopheles bites occurred indoors (π i = 0.90-1.00). Neither An. gambiae s.l. nor An. funestus s.l. strongly preferred feeding indoors (P i = 0.46-0.63 and 0.22-0.72, respectively) but they overwhelmingly preferred feeding at times when most humans were indoors (P fl = 0.84-1.00 and 0.93-0.99, respectively).

Conclusions

These quantitative summaries of behavioral interactions between humans and mosquitoes establish baseline values against which behaviour observed in residual vector populations exposed to high ITN or IRS coverage can be compared. Longitudinal monitoring of these quantities is vital to evaluate the effectiveness of ITNs and IRS and to evaluate the need for development of complementary measures targeting the outdoor-biting vectors.

Authors’ Affiliations

(1)
Biomedical and Environmental Thematic Group
(2)
University of Basel
(3)
Swiss Tropical and Public Health Institute
(4)
Liverpool School of Tropical Medicine, Vector Group
(5)
National Malaria Control Centre, Chainama Hospital College Grounds
(6)
Centre for Global Health Research, Kenya Medical Research Institute
(7)
Centers for Disease Control and Prevention
(8)
Division of Parasitic Diseases, Centers for Disease Control and Prevention
(9)
London School of Hygiene and Tropical Medicine, Disease Control and Vector Biology Unit
(10)
Centre National de Recherche et de Formation Sur LePaludisme (CNRFP)
(11)

Copyright

© Huho et al; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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