# Once bitten: A longitudinal, observational study of successful malaria parasite transmission events between humans and mosquitos

> **NIH NIH R01** · DUKE UNIVERSITY · 2020 · $600,701

## Abstract

PROJECT SUMMARY
Malaria cases and deaths have declined significantly in sub-Saharan Africa as a result of the broad
deployment of vector control and clinical management tools. These tools are being supplemented by a new
generation of available strategies that are designed to reduce and possibly interrupt transmission. These
transmission-reducing interventions include transmission-blocking vaccines, mass administration of
endectocides (e.g. ivermectin) to undermine vector competence, adjunctive use of gametocytocides in infected
individuals, and mass screen and treat programs using sensitive diagnostics. These strategies will be most
efficiently employed by targeting them to human populations that are most likely to contribute to onward
malaria transmission. The existence of these “high transmitters” is suggested by the fact that, in many settings,
as few as 20% of individuals suffer 80% of infections, indicating that within heterogeneous human populations,
some people participate disproportionately in the continual cycle of malaria transmission. This group of
transmitters is also called the malaria `infectious reservoir', and by identifying stable or modifiable risk factors
for membership in this reservoir we can more efficiently target interventions to maximize their impact on
reducing malaria transmission. The specific objective of this project is to directly measure, under natural
conditions, which infected humans transmit malaria parasites to naturally-feeding mosquitoes and also which
humans are bitten by malaria mosquito vectors. We will directly test our central hypothesis in an observational
epidemiologic study of 75 households in in Webuye West, Kenya, where malaria transmission is seasonal and
perennial and is transmitted by Anopheles gambiae s. l. (88%) and An. funestus (12%). Within these
households, we will establish active and passive detection of malaria cases in human participants and weekly
sampling of resting mosquitos in their households. In Aim 1, we will directly record successful onward
transmission events from infected people to Anopheline mosquitos by collecting live, blood-fed mosquitos in
participant households, raising them for 7 days to allow parasite oocysts to develop, and genotyping parasites
in order to discretely match parasites and therefore ascertain the human source of the successful transmission
event. In Aim 2, we will quantify how the human infectious reservoir is shaped by vector biting bias, which is
typically non-random and highly overdispersed in human populations, using molecular fingerprinting of human
DNA to directly match individual household members to human blood meals that have been ingested by
mosquitoes. The results of these analyses will provide new insight into mosquito-human interactions that
enhance parasite transmission and will enable us to more precisely define the human reservoir. With this
understanding, we will enable better population-based estimates of transmission potential and furn...

## Key facts

- **NIH application ID:** 9978708
- **Project number:** 5R01AI146849-02
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Wendy PrudhommeOMeara
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $600,701
- **Award type:** 5
- **Project period:** 2019-07-16 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9978708

## Citation

> US National Institutes of Health, RePORTER application 9978708, Once bitten: A longitudinal, observational study of successful malaria parasite transmission events between humans and mosquitos (5R01AI146849-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9978708. Licensed CC0.

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