Letting there be more mosquitoes may lead to fewer malaria deaths, say researchers

It may seem counter-intuitive at first but letting mosquitoes grow up and breed may be part of the solution to tackling the devastating impact of malaria. A team of researchers led by Dr Stephen Gourley of the University of Surrey's Mathematics Department have used mathematical modelling to examine why conventional insecticides used against the insects that transmit the disease responsible for millions of deaths a year, can quickly become ineffective in areas of intensive use. Their answers may lead to unprecedented advances in malaria control.

Mosquitoes can become resistant to commonly used insecticides surprisingly rapidly and spraying them while young simply imposes intense selection pressure favouring resistant insects.

Mosquito immune system engineered to block malaria

Researchers at the Johns Hopkins Malaria Research Institute demonstrated for the first time that the Anopheles mosquito's innate immune system could be genetically engineered to block the transmission of the malaria-causing parasite to humans. In addition, they showed that the genetic modification had little impact on the mosquito's fitness under laboratory conditions. The researchers' findings were published December 22 in the online journal PLoS Pathogens.

At left is a normal mosquito from the wild. The three mosquitoes to the right, with glowing eyes, are from three strains genetically engineered to better kill the malaria parasites in their guts. The mosquito at the far right, with yellow eyes, is a hybrid of the two other modified strains and was the most effective of the three at killing the parasite.

Credit: George Dimopoulos/JHU 

 

"The immune system of the Anopheles mosquito is capable of killing a large proportion -- but not all -- of the disease-causing parasites that are ingested when the mosquito feeds on an infected human," said George Dimopoulos, PhD, senior author of the study and associate professor in the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. "We've genetically engineered this immune system to create mosquitoes that are better at blocking the transmission of the human malaria parasite Plasmodium falciparum."