The dengue virus may actually make mosquitoes thirstier for human blood, new research has found.
In a study published last week in PLoS Pathogens, mosquito experts at the Johns Hopkins Bloomberg School of Public Health found that the dengue virus altered the production of proteins made by 147 different genes.
Some changes appeared to make the antennae more sensitive to odors — making them better at hunting humans, the virus’s only known mammalian host. Other changes in salivary gland genes appeared to make it easier for the virus to get into a mosquito’s saliva, ready for injection.
Those tests were done on a genome microarray — snippets of the DNA of Aedes aegypti mosquitoes coating a glass slide. But when the researchers tried to replicate the results in live mosquitoes, they could not prove they were hungrier.
“Since we can’t infect humans for our experiments, we think it’s a problem with the model,” said George Dimopoulos, lead author of the new study.
In his laboratory model, mosquitoes had to drink infected blood from a balloonlike membrane and then were offered mice to bite.
“Mosquitoes will feed on other animals if they get hungry, but it isn’t their favorite dish,” Dr. Dimopoulos said.
Up to 100 million people are infected with dengue each year; it is known as “breakbone fever” for the joint pain it causes. Up to 15,000 die of it annually, most of them children, according to the World Health Organization. There is no vaccine or cure.