How Mosquitoes' Saliva Can Worsen Diseases They Transmit
A mouse study conducted by researchers at Baylor College of Medicine in Houston suggests that substances in mosquito saliva trigger immune system responses that can increase the severity of the diseases they transmit.
Mosquito-borne diseases like dengue fever, malaria, and Zika, West Nile, and Chikungunya virus are serious problems throughout the world. According to the World Health Organization, about 100 million dengue virus infections and 22,000 deaths occur each year, mostly in children, and nearly half of the global population is at risk for malaria.
For this study, the researchers used immunodeficient mice given human stem cells, creating an immune system similar to that of humans, to examine factors that could affect the development of dengue fever. They found that mosquito-bite delivery of the virus produced more severe symptoms than needle-injection delivery, due at least in part, to immune system responses caused by mosquito saliva.