Infectious Diseases

31 August 2016

Just spraying adult mosquitoes won't curb Zika

Spraying affects adult Zika mosquitoes, but doesn't kill the eggs and larvae, and as a result it will reduce transmission, but may not eliminate the virus.


Female mosquitoes can transmit the Zika virus to their eggs and offspring, and this may make it harder to contain outbreaks, a new lab study suggests.

Larvicide important

Control programmes that focus only on adult mosquitoes may not halt Zika's spread, the researchers warned.

The researchers injected laboratory-grown Aedes aegypti mosquitoes, which spread the virus, with Zika and tracked its spread to their offspring.

Read: Hotter conditions allow Zika mosquito to flourish

"The implications for viral control are clear," said study co-author Dr Robert Tesh, of the University of Texas Medical Branch in Galveston.

"Spraying affects adults, but it does not usually kill the immature forms – the eggs and larvae," said Tesh. As a result, "spraying will reduce transmission, but it may not eliminate the virus."

Based on their findings, the study authors say larvicide should become an integral part of efforts to stop the spread of the virus.

Virus can be spread sexually

"Since Zika virus has emerged as a global health emergency, most research has focused on the virus and its effects on humans. There is far less research on the virus in its mosquito host," Tesh said.

Read: Zika mosquito puts up tough fight in Miami

"But if you want to control Zika, you also have to know about the behaviour of this virus in mosquitoes," he added.

Zika virus can cause severe brain damage in newborns whose mothers were infected during pregnancy. While mosquito bites are the main source of transmission, experts say the virus can also be spread sexually.

The study was published online in the American Journal of Tropical Medicine and Hygiene.

Read more:

5 things to know about the Zika virus

Volunteers sought for Zika vaccine

Brain infection also associated with Zika virus