Two research studies on novel bug hunting were reported this week. Large scale larviciding in Tanga region was reported in MalariaWorld. And genetically modified mosquitos developed in Tanzania were reported by ‘The Multilateral Initiative on Malaria Society’ on LinkedIn.
‘A large-scale mosquito larviciding in Tanga Region, Tanzania, reduced mosquito densities to varying degrees across malaria transmission risk strata’ by Gavana et al was published online by Nature. The large-scale pilot study in Tanga Region from June 2022 to April 2024 targeted three councils representing high, moderate, and low malaria epidemiological risk strata. Six rounds of larvicide application were conducted, each lasting eight weeks and scheduled according to local rainfall patterns. The outcomes examined were Larval density, adult mosquito abundance, human biting rate, sporozoite rate (in Mosquitos) and the entomological inoculation rate (the number of infectious bites a person receives).
The authors conclude that the study provides evidence that the larviciding intervention in Tanga Region contributed to reductions in late-stage mosquito larvae and adult An. gambiae s.l. and Culex populations in moderate and low-risk areas. However, the intervention was not associated with any reductions in Anopheles mosquitoes in the high-risk strata and generally there was no effect on An. funestus populations, which may limit its overall impact on malaria transmission.
The authors state that the larvicides used, Bactivec® and Griselesf®, are safe to non-target organisms. They report no data with respect to the occurrence of malaria.
The second novel research topic, gene drive mosquitos, was addressed here on August16, August 29, and August 18, 2024. I remain sceptical that such ‘Frankenstein’ creatures would survive in the wild against their evolved cousins. The LinkedIn post states that the research was published in Nature but provides no link. It is the first time a gene drive-compatible mosquito strain has been created in Africa, by African scientists.
The team from Tanzania’s Ifakara Health Institute (IHI) and National Institute for Medical Research (NIMR), partnering with Swiss TPH and Imperial College London through the Transmission Zero program, genetically modified Anopheles gambiae mosquitos to prevent Plasmodium falciparum parasites from developing. Using antimalarial traits from naturally occurring molecules in frogs and honeybees, the modified mosquitos create a biological barrier to transmission that passes from generation to generation.
The research was conducted in a state-of-the-art Containment Level 3 facility at IHI’s campus, meeting rigorous biosafety standards. Before field trials, comprehensive risk assessments, regulatory engagement, community consultation, and resistance monitoring are required.