Characterising vector behaviours and the risk of malaria infections in communities in Southern Malawi

Despite a decline in malaria cases over the past two decades, the disease is still a leading public health problem in Malawi. Malaria is endemic throughout the country and almost 95% of the entire population is at risk. The disease is passed from one person to another through the bite of an infected mosquito. Malaria mosquitoes usually bite at night when people are asleep indoors, which led to the development and implementation of chemical-based anti-mosquito measures placed indoors, namely treated bed nets and indoor residual spraying. However, mosquitoes have developed behavioural avoidance of chemical-based interventions over time, and bite early in the evening before people go to bed, early in the morning after people get out of bed, and outside during these times. Malaria transmission is also determined by peoples’ behavioural patterns and activities, such as when they move inside, when they go to sleep, and whether they use bed nets while sleeping. The relationship between mosquito biting and peoples’ behaviour is poorly understood in Malawi. This project seeks to better understand behaviours of local mosquito populations that transmit malaria, both indoors and outdoors, and estimate human-mosquito contact patterns in Southern Malawi. Adult mosquitoes will be collected both inside and outside houses to determine malaria mosquito species, preferred vertebrate hosts, infection rates, biting times, and proportion of malaria mosquitoes resting and feeding indoors and outdoors. A questionnaire survey will be carried out among residents to estimate the amount of time spent under a bed net, out of a bed net or outdoors during hours when malaria mosquitoes are active. This data together with mosquito biting activity will be quantified and used to determine whether majority of human exposure to mosquito bites occurs indoors, when people are awake, or when people are asleep. This information will be useful in the design of vector control measures appropriate for these malaria mosquito populations.