The Zika virus could potentially be transmitted by an even more common species of mosquitoes, Brazilian scientists announced this week, raising concerns that the outbreak in Central and Latin America could become harder to contain.
Until now, Zika virus transmission was thought to be limited to certain species of mosquitoes in the Aedes genus, most often the species Aedes aegypti, which is also known to spread viruses such as dengue and chikungunya. But this week, scientists at the Oswaldo Cruz Foundation in Recife, Brazil reported that they were able to infect the Culex quinquefasciatus mosquito with the virus in a laboratory setting.
In an ongoing trial, the researchers infected 200 Culex quinquefasciatus mosquitoes by injecting them with Zika-infected rabbit blood. They found that the virus was able to circulate to the salivary glands of the mosquitoes, suggesting that they could possibly transmit the virus by biting a person.
“We saw an ease of infection and an ease of dissemination of the virus to the salivary glands,” said lead investigator Constancia Ayres.
More research is needed to determine if the Culex quinquefasciatus can actually transmit Zika virus in the natural environment, and if the mosquito may already be carrying it in the wild. If evidence confirms that it can spread the virus, the implications could be quite serious.
In Brazil, where Zika has spread rapidly since its emergence in May 2015, the Culex quinquefasciatus mosquito is about 20 times more common than the Aedes aegypti. “Culex quinquefasciatus also exists in more temperate climes, such as the southern United States, where it is known to carry the West Nile virus, and can survive winters. Unlike Aedes aegypti, Culex quinquefasciatus could keep a virus in circulation during cold months,” Reuters reports. This raises the possibility that Zika could spread faster and further than previously expected.
Zika virus, which was declared a public health emergency by the World Health Organization (WHO), has been linked to a severe birth defect called microcephaly, as well as the neurological disorder Guillain-Barre Syndrome.
However, there are still many questions about the virus that remain to be answered, including its potential for human-to-human transmission through sexual activity, and whether other mosquito species are capable of spreading it. Researchers in Africa have found evidence that more than 20 species of mosquito can carry Zika, but it’s not clear if they can all effectively transmit the virus to humans. There are also concerns that climate change may help expand the range of Zika-carrying mosquitoes.
There is no vaccine or specific treatment for Zika, which has now spread to dozens of countries throughout the Caribbean, Central America, South America, and–most recently–the United States. Health officials are urging individuals in affected countries to take protective measures, including limiting body surface exposure and using insect repellents to avoid mosquito bites. Meanwhile, pregnant women have been advised to avoid traveling to regions where Zika transmission is ongoing.