Fact check: Can mosquitoes transmit coronavirus?

Fact check: Can mosquitoes transmit coronavirus?
Can mosquitoes transmit coronavirus? A study from Italy says no. (Photo by: Education Images/Universal Images Group via Getty Images/Universal Images Group via Getty)

A study released in June by Italy’s national health agency ISS suggests it is unlikely that mosquitoes can spread the novel coronavirus, echoing other studies that have come to the same conclusions.

The results bolstered the studies cited by the World Health Organization and the Centers for Disease Control and Prevention that have said that no evidence exists that indicates mosquitoes are capable of spreading the virus either among themselves or transmitting it to humans.

As the weather has turned warmer and people who have been staying in their homes for the past months have ventured outside, questions have arisen over whether the insects can spread the virus since they can spread other diseases.

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In the Italian study, neither the tiger mosquito – which can transmit diseases like Eastern Equine Encephalitis (EEE), Zika virus, West Nile virus, Chikungunya and dengue fever – nor the common mosquito could transmit SARS-CoV-2.

“Research has shown that the virus, once penetrated inside the mosquito by an infected blood meal, is unable to replicate itself and therefore be subsequently inoculated by the mosquito through a puncture,” a statement from the ISS said.

The study was performed in collaboration with IZSVe, a research organization for animal health and food safety.

"The research showed that the virus, once given to the mosquito through a meal of infected blood, was not able to replicate," Italian health officials said in a statement, which ruled out the transmission of COVID-19 through mosquito bites.

According to an article by Pro Publica, the U.S. Department of Agriculture is studying whether COVID-19 can be spread by mosquitoes. The study noted that the World Health Organization and independent experts say such transmission “is virtually impossible.”

Joseph Conlon, a former U.S. Navy entomologist and technical adviser for the American Mosquito Control Association, said the possibility of mosquito transmission of the coronavirus is “nil,” Pro Publica reported after gaining access to a USDA internal memo.

If mosquitoes can spread other viruses, why not COVID-19?

“Mosquitoes cannot transmit the disease,” said Tarik Jasarevic, a WHO spokesman, because the virus does not widely circulate in blood and is more prevalent in the lungs and the respiratory tract. The diseases they do spread are more easily spread via blood, not the respiratory tract, allowing mosquitoes to take blood from someone who has had a virus and pass it along to someone else.

Even if a mosquito did pick up a high enough dose of the virus from a host who has it, there is little evidence that COVID-19 could infect the mosquito. If the mosquito doesn’t have it, it cannot pass it to anyone else.

The novel coronavirus would have to survive the harsh environment of the gut of a mosquito to have a chance to infect the insect.

The CDC website says, “At this time, CDC has no data to suggest that this new coronavirus or other similar coronaviruses are spread by mosquitoes or ticks. The main way that COVID-19 spreads is from person to person. See How Coronavirus Spreads for more information.”