Key Findings

To compare the level of ongoing malaria transmission that occurs outside dwellings at different times of night and indoors, in both high- and low-transmission settings.

• Significantly more infectious bites per person per year (entomological inoculation rate - EIR) were recorded in Burkina Faso (225.5ib/p/yr) than in Tanzania (8.34 ib/p/yr).

• Mosquito density was higher indoors than outdoors in both Burkina Faso and Tanzania. However, biting rates were higher outdoors than indoors.

• The mosquitoes in Burkina Faso laid eggs more frequently than mosquitoes in Tanzania. Of the mosquitoes in Tanzania, An. funestus laid eggs more frequently than An. arabiensis.

To quantify levels of pyrethroid insecticide resistance in the selected study sites and estimate its potential contribution to ongoing malaria transmission.

• Resistance to the pyrethroids commonly used in long-lasting insecticidal nets (LLINs) was high among all malaria vectors in Tanzania and Burkina Faso. Mortality was also very low when mosquitoes were exposed to bed nets in households from two settings.

To identify common human outdoor activities and environmental factors associated with ongoing malaria transmission in the different sites.

• Community members in both countries tended to spend most of the early night hours outdoors, moving inside only around midnight. No major means of protection against mosquitoes were used during this time before bed, following which bed nets are used).

• In Burkina Faso, a large number of people in the villages slept outside at night during the dry season due to hot climate. Again, no major protection against mosquitoes was used.

• In Tanzania, there was a widespread misconception that mosquitoes are not active until the period between midnight and 02h00. In Burkina Faso, some people believed malaria could be transmitted by eating certain foods, particularly those contaminated by mosquitoes. Mosquito bites were considered only one way of being infected by malaria.