Wits scientists artificially infect mosquitoes with human malaria to develop treatment

14 January 2021 - 11:15
By Nomahlubi Jordaan
Wits University has partnered with local and global scientists to develop a treatment for malaria by infecting mosquitoes with human malaria.
Image: REUTERS Wits University has partnered with local and global scientists to develop a treatment for malaria by infecting mosquitoes with human malaria.

Wits University, in partnership with the University of Pretoria and global scientists, has artificially infected mosquitoes with human malaria and identified a new chemical compound to treat the disease.

“Scientists at the Wits Research Institute for Malaria (WRIM), in partnership with the University of Pretoria and colleagues in the US, Spain, and Switzerland, have identified novel antiplasmodial lead compounds for mass drug administration and vector control to eliminate malaria,” the university said in a statement.

It defines a vector as an organism that carries and transmits an infectious disease, as mosquitoes do with malaria. Lead compounds are chemical compounds that show promise as treatment for a disease and may lead to the development of a new drug.

Prof Lizette Koekemoer, co-director of the WRIM, and her team established a unique mosquito malaria infection centre in the faculty of health sciences at Wits University, where the mosquito transmission blocking experiments took place.

“The WRIM infection centre is the only facility in SA and in the southern African region that can artificially infect mosquitoes with the human malaria parasite,” Koekemoer said.

“The infection centre provided the expertise required to infect mosquitoes with the human malaria parasite, Plasmodium falciparum, and allowed for this unique study to be done.”

According to Wits university, drugs are used to control human malaria but resistance to these drugs develops rapidly. Furthermore, the drugs mainly target just one stage of the parasite’s life cycle and are not good candidates for blocking transmission.

“To expand drug suitability for malaria elimination strategies, drugs need to be able to act as a chemotype [a chemically distinct entity in a plant or microorganism] that blocks both human-to-mosquito transmission and mosquito-to-human transmission,” said the university.

Koekemoer, her colleagues at the research institute and co-authors, conducted “specialised” experiments to measure the reduction of infection in mosquitoes and the “killing effect” in the vectors.

“Scientists screened 400 chemical compounds available in the 'Pandemic Response Box', which is supplied by Medicines for Malaria Venture (MMV), to identify the compounds that are most effective across the life stages of the parasite that generally take place in the human host.

 “The Pandemic Response Box contains 400 diverse drug-like molecules active against bacteria, viruses or fungi. It is available free of charge, provided that researchers share data resulting from research on the molecules in the box with the public within two years of its generation.”

According to Wits, mosquitoes were fed infected blood that was treated either with or without the compound.

After eight to 10 days, the mosquito guts were removed and the number of parasites (called oocysts) counted and compared against those mosquitoes that received only an infected blood meal without treatment.

“Mass drug administration (MDA) is the administration of antimalarial drugs to target the parasite reservoir in humans, without necessarily testing whether those people are carrying the parasite that causes malaria.

“The World Health Organisation (WHO) recommends MDA for the elimination of the Plasmodium falciparum malaria parasite. However, the effort and cost required to implement MDA on a large scale is prohibitive.”