Mathematical model helps target malaria-carrying mosquitos

Lauren M. Childs, an assistant professor of mathematics in the Virginia Tech College of Science, has helped build a mathematical model used in the development of a new compound that targets the reproductive cycles of adult mosquitoes known to carry malaria.

The synthetic chemical compounds DBHs – that’s short for dibenzoylhydrazines – disrupt the biological processes in female mosquitoes by mimicking 20E, or 20-hydroxyecdysone, a vital hormone associated with the reproductive cycle of mosquitoes. Work on the compound was completed at the Harvard T.H. Chan School of Public Health.

Childs was a research scientist at Harvard working with Caroline Buckee, also of Harvard and co-leader author of the study, before joining the Virginia Tech Department of Mathematics, part of the College of Science, in summer 2015.

Findings from study were published last month in the journal PLoS Pathogens.

Childs’ mathematical model of the mosquito life cycle used experimental results from lab work with DBH for parameterization. Coupled to an epidemiological model of malaria infection, the data science results were compared to the effectiveness of insecticides that are being used to kill the same malaria-spreading mosquitos in Africa.

“Our mathematical model is a useful tool to demonstrate the potential of the DBH compounds as an alternative to insecticides,” said Childs.

Researchers treated Anopheles female mosquitoes – which carry the malaria parasite Plasmodium falciparum – with DBH. Treated mosquitos were found to produce and lay fewer eggs, failed to mate successfully, and died more quickly than mosquitoes not treated with the compound. The effects were greater in accordance with the higher doses of DBH. Mosquitoes treated with DBH also were less likely to become infected by the malaria parasite. Another bonus: The nontoxicity of DBH also makes it safe to use around people. The next step is to move the research from the lab to the field.

“As insecticide resistance is spreading, new intervention methods to control mosquitoes are urgently needed,” said Flaminia Catteruccia, associate professor of immunology and infectious diseases at Harvard and co-senior author of the study. “Our study provides a new strategy based on the use of a nontoxic compound that prevents transmission of malaria parasites without killing the mosquito.”

Malaria infects more than 200 million people a year and results in nearly 500,000 deaths, mostly of young children, according to the World Health Organization.

DBH cannot, however, be directly used in the fight against the Zika virus that made international headlines recently. While malaria is carried by Anopheles mosquitoes, Zika is transmitted by a different mosquito species: Aedes.

Co-lead authors of the study were Harvard Chan School researchers Francisco Cai and Evdoxia Kakani. The study was partially supported by the private, nonprofit Bill & Melinda Gates Foundation and the National Institutes of Health.

Additional reporting by Todd Datz of the Harvard T.H. Chan School of Public Health.

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