Three Additional Mosquitoes Found Carrying Zika Virus

Mexican female mosquitoes Cx. coronator, Cx. tarsalis, and Ae. vexans reported with Zika virus

mexico city car interior

The Zika virus has been discovered in the salivary glands of five mosquito species caught in Mexico, including three previously unreported mosquito types.

These researchers believe this is the first report showing the presence of the Zika virus in wild-caught female mosquitoes Cx. coronator, Cx. tarsalis, and Ae. vexans.

But, they assume the Ae. aegypti mosquito is more likely to be the primary vector of Zika in the State of Jalisco, Mexico.

All of these virus isolates were from mosquitoes collected in Guadalajara, Jalisco, Mexico, where health authorities had reported one confirmed human Zika infection.

As of September 2017, there were 9,987 confirmed cases of Zika infection, including 5,925 pregnant women, in 26 out of 32 states of Mexico.

The Zika virus is a member of the Flaviviridae family and the genus Flavivirus; the presumptive primary vector of the virus is Aedes aegypti, which has demonstrated its ability to acquire and potentially transmit the virus in mosquitoes experimentally fed with infected blood.

Previous publications have evaluated the vector competence of Ae. aegypti using mosquitoes from other regions of the Americas.

In those cases where Zika was found in salivary glands, a CPE was observed at a similar dpi in 5 wild-caught mosquito species, which can be then considered as potential ZIKV vectors.

In addition, this study found a Zika-positive male pool of Cx. quinquefasciatus, suggesting the occurrence of vertical transmission, a further cause of concern.

If male mosquitoes are infected vertically, females from the same mother are probably also infected. Therefore, the number of mosquitoes with the potential to transmit the virus would increase.

Recent studies indicate that Zika arrived in Mexico from northeast Brazil in the second half of 2014 or early 2015. 

It was introduced first to the Mexican state of Chiapas in the southeast of the country and then was dispersed to 26 additional states.

In conclusion, these researchers suggest additional studies of female mosquitoes’ saliva from the different species are needed to confirm the presence of Zika and determine if they have a vector competence barrier to the virus.