Single Bite, Multiple Problems

The American Society of Tropical Medicine and Hygiene is having its 65th annual meeting this week, and one of the abstracts that is raising eyebrows is this abstract on the possibility of co-infection of a mosquito with multiple Flaviviruses:

“Therefore, we determined the competence of Aedes aegypti (Poza Rica, Mexico) and Aedes albopictus (Florida) mosquitoes exposed to bloodmeals containing more than one Aedes-borne arbovirus. Specifically, mosquitoes were given a blood meal containing American strains of DENV-2, CHIKV or ZIKV in single infections, as well as combinations of the three viruses as double and triple infections. Mosquitoes were kept for 5, 7, 9 and 14 days extrinsic incubation, at which point mosquito bodies, legs and saliva were collected to determine infection, dissemination and transmission rates. Presence of viral RNA was determined by multiplex qRT-PCR for DENV-2, CHIKV and ZIKV in order to determine RNA levels for the individual viruses in mosquitoes exposed to more than one virus. Preliminary results suggest that coinfection may impact vector competence in a virus-specific manner.”

Basically, the mosquitoes seem to have the ability to carry multiple viruses at one time, making it perfectly possible that they could infect a person with these viruses in one bite. However, this is a lab study, and there is no evidence right now that this is the case in the real world. In fact, the authors (from Colorado State University) do state earlier in the abstract that “in 2015 an increase in CHIKV infections coincided with a drop in dengue cases in Mexico and Colombia. While this could be due to yearly variation, it could also be related to the introduction of CHIKV which may be outcompeting DENV in mosquitoes.”

The rest of the abstracts on West Nile and other Flaviviruses can be seen by clicking here.