Assessment of twenty-four Hours Biting Patterns and Human Exposure Risk to Bites of Anopheles Mosquitoes in South-Eastern, Tanzania
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Date
2025-08
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NM-AIST
Abstract
Afrotropical malaria vectors are believed to bite nocturnally, leading to the predominant use of Insecticide-Treated Nets (ITNS), which primarily target indoor, nighttime-biting mosquitoes. However, recent evidence challenges this paradigm, showing that Anopheles biting can extend into the daytime when humans are active and beyond the reach of ITNS. This study investigated the diurnal and nocturnal biting patterns of the main malaria vectors, Anopheles arabiensis, and Anopheles funestus in rural south-eastern Tanzania, informing strategies for improved control and elimination. Host-seeking mosquitoes were collected hourly using miniaturized
double net traps (DN-Mini), indoors and outdoors over 24-hour periods between June and December 2023. Concurrently, human activities indoors and outdoors were monitored half- hourly to correlate with mosquito collections. Nocturnal biting by An. arabiensis peaked from 1900 h –2300 h, while An. funestus peaked from 0100 h – 0300 h. Daytime host-seeking collections accounted for 14.8% of both species. Diurnal biting by An. arabiensis peaked between 0700 h – 1100 h, and between 1800 h and 1900 h, while for An. funestus, the peaks were observed between 1000 h – 1200 h, and between 1700 h – 1900 h. Plasmodium falciparum infections were detected in both day and night-time collections of An. arabiensis but not in An. funestus. Common daytime activities potentially exposing residents during peak biting hours
included household chores, eating, sleeping (including due to sickness), resting under shades or verandas, and kids playing. From evenings onwards, exposures coincided with resting, chatting before bedtime, and kids playing. These findings show that the sole focus on interventions like ITNs that target nocturnal mosquito behaviours might be insufficient for elimination; hence, enhanced strategies targeting daytime biting mosquitoes supplemented with community engagement and education on the timing of mosquito activity are required to significantly reduce malaria transmission risk.
Sustainable Development Goals
SDG: 3- Good Health and Well-Being
SDG : 9- Industry, Innovation and Infrastructure
SDG : 11- Sustainable Cities and Communities
Keywords
Persistent malaria transmission, human behavior, day-biting Anopheles mosquitoes, Insecticide-Treated Nets, Ifakara