Preventing the spread of the Zika virus has just become more challenging, as findings of a new research have revealed another obstacle that health experts and authorities would have to deal with in their bid to eliminate the mosquito-borne virus.
Researchers have found that adult female mosquitoes that spread Zika can pass the virus to the offspring in their eggs, suggesting that there is a need for pesticide programs that can get rid of both adult mosquitoes and their eggs.
In a new study published in The American Journal of Tropical Medicine and Hygiene on Monday, Aug. 29, researchers found that just as with many related viruses such as the Yellow fever, West Nile and dengue, the Zika virus can be transmitted by adult female mosquitoes to their larvae.
For the research designed to test if Zika virus can be vertically transmitted between adult mosquitoes and their offspring, the researchers infected female Aedes aegypti and Aedes albopictus with the virus. None of the offspring of the infected Aedes albopictus mosquitoes were infected, but one in every 290 Aedes aegypti mosquitoes — the main carrier of Zika virus — was infected.
"The MFIR for Ae. aegypti was comparable to MFIRs reported for other flaviviruses in mosquitoes, including dengue, Japanese encephalitis, yellow fever, West Nile, and St. Louis encephalitis viruses," the researchers wrote in their study.
"The results suggest that vertical transmission may provide a potential mechanism for the virus to survive during adverse conditions."
Study author Robert Tesh, from the University of Texas Medical Branch, said controlling Zika could be difficult since the virus can be transmitted to mosquito offspring.
The researchers said that while spraying can affect adult mosquitoes, it does not often kill the eggs and the larvae, which means that spraying can only reduce the spread of the disease but would not completely get rid of the virus.
The mosquito's eggs can also lie dormant for months during the dry season but still manage to hatch once it rains. This means that even with a few infected eggs, the virus could keep circulating in mosquito populations regardless if people have developed immunity or during dry spells or cold snaps when adult mosquitoes die.
"I think it just another survival mechanism for the virus to make it through the season," Tesh said.
The Zika virus is known to cause serious birth defects such as microcephaly in the unborn child of infected pregnant women. The virus has also been linked to Guillain-Barré syndrome.