Insects transmit diseases when, probing for blood vessels, they inject saliva together with viral, bacterial, or parasitic pathogens into the skin of mammalian hosts. A study in mice published on June 16, 2016 in PLOS Pathogens suggests a critical role of mosquito saliva in the outcome of dengue virus infection.
In tropical regions, Aedes mosquitoes transmit dengue virus (DENV) as well as other closely related viruses such as Zika. DENV infects almost 400 million humans every year. There are four types of DENV. They are referred to as serotypes 1-4 because, following infection, individuals have distinct antibody profiles in their blood serum, resulting from specific immune responses to each of the four virus types.