Zika RNA discovered in Brazilian A. albopictus mosquitoes

Researchers found fragments of Zika virus RNA in Aedes albopictus mosquitoes collected in a Brazilian state hit by the Zika outbreak, according to Healio.

Chelsea Smartt, PhD, associate professor at the Florida Medical Entomology Laboratory at the University of Florida, and her colleagues said finding Zika RNA in mosquitoes hatched from eggs collected in an area where the virus was circulating is concerning. However, it is not proof that A. albopictusis a competent vector of Zika. A different mosquito, A. aegypti, has been the principal bearer for Zika and the main driver of the recent outbreak in America.

“Our results mean that Aedes albopictusmay have a role in Zika virus transmission and should be of concern to public health,” Smartt declared in a news release.

“This mosquito is found worldwide, has a wide range of hosts and has adapted to colder climates. The role of this mosquito in Zika virus transmission needs to be assessed.”

Smartt and colleagues collected mosquito eggs in August 2015 from three sites in Camaçari, Bahia. Almost 110,000 people in Bahia were infected during the Zika outbreak. They extracted RNA from the adult bodies of 39 A. Albopictus mosquitoes — 20 female and 19 male. Five mosquitoes (three female and two male) had Zika virus RNA.

Smartt and colleagues said the findings were “consistent with the potential for vertical or sexual transmission” of Zika virus by A. Albopictus mosquitoes and said the evidence was, however, inconclusive. Vertical and/or sexual transmission of Zika has been seen in several Aedes species, but not A. Albopictus.

“Detecting Zika RNA fragments without finding live Zika virus suggests that either the female parent was not itself infected with live Zika virus or it was not able to transfer live Zika virus to her eggs,” Smartt said.

The researchers eliminated contamination as an explanation for the results of their study. They explained there was no Zika in their laboratory before the tests and the genetic sequences were different from the virus samples they eventually had. They said there was no proof of false-positive results.

“Zika virus RNA in field-collected eggs from mosquitoes where there is current [Zika virus] transmission is concerning,” Smartt and colleagues concluded. “Samples of mosquitoes, including those resulting from field-collected eggs that are returned to the laboratory from regions with [Zika virus], must be treated with the potential that resulting adult mosquitoes or their offspring might be positive for [Zika virus] RNA. These mosquitoes must be characterized for live [Zika virus] to ensure they are uninfected or they must be treated as if they did contain infectious [Zika virus] and maintained under the appropriate required safety and containment practices.”