By Corrie Pelc — Fact checkedby Alexandra Sanfins, Ph.D.
A number of viruses, such as Zika and West Nile, can spread through bites by mosquitoes that carry them. Medical News Today spoke with experts to find if mosquitoes could also carry and transmit the SARS-CoV-2 virus that causes COVID-19.
Medical News Today spoke to a variety of experts to find out if mosquitoes can transmit the SARS-CoV-2 virus. And if they do not now, is there potential for them to do so in the future?
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The answer is “no,” according to Dr. Daniel Markowski, technical advisor for the American Mosquito Control Association.
“There is no evidence that mosquitoes can acquire and transmit the SARS-CoV-2 virus,” he told MNT.
In order to understand the mechanisms that prevent mosquitoes from carrying and spreading the SARS-CoV-2 virus, Dr. Markowski explained it is important to understand how mosquitoes transmit virionsTrusted Source, or viral particles.
“Typically, the mosquito must first feed on an infected host, that is circulating enough virus in their blood to have some present in the small amount taken during a mosquito’s blood meal,” he explained.
“Secondly, the virus must survive the insect’s midgut, which has a host of immune responses similar to our own. Not only must they survive inside the mosquito’s midgut, they need to replicate and ultimately bind to receptor sites on the wall of the midgut and pass through that barrier into the mosquito’s body cavity,” Dr. Markowski added.
Once inside the body cavity, Dr. Markowski explained that the virus needs to get past the mosquito’s immune system and make its way into the insect’s salivary glands, all while continuing to replicate.
“Now with the next blood meal, they can be passed to a new host while the mosquito feeds,” he continued. “As you can see, it’s a fairly long and complex journey each virus makes to go from one host to the next via a mosquito bite. And not many viruses have evolved over the millennia to successfully complete that journey, which is why many viruses such as flu, coronavirus, and monkeypox are not mosquito-borne viruses.”
In July 2022, a team of researchers including Dr. Stephen Higgs, associate vice president for research and director of the Biosecurity Research Institute at Kansas State University, published a studyTrusted Source that found that even under extreme conditions, the SARS-CoV-2 virus did not replicate in mosquitoes.
Because of this, the researchers stated, mosquitoes would be unable to transmit the virus to people even if the mosquito fed upon someone infected with the SARS-CoV-2 virus.
“We really did not expect that it would infect mosquitoes because, for whatever reason, coronaviruses just do not infect mosquitoes or other arthropods,” Dr. Higgs told us.
“What we did in our original paper was to inject SARS-CoV-2 into mosquitoes. We know that by using this approach you can sometimes infect a resistant mosquito with a virus that would not normally infect it. Even with that unnatural approach SARS-COV-2 did not infect and multiply in the mosquitoes,” he noted.
We asked Dr. Higgs whether, with the emergence of new SARS-CoV-2 variants, due to mutations within the virus, mosquitoes might ever come to carry it.
“I really do not think so because I do not think that these changes could turn a non-mosquito infecting virus into one that could infect a mosquito,” he told us.
“Years ago we proved that just one amino acid change of chikungunya virus could make it more infectious to mosquitoes, but that was for a virus that already infected mosquitoes,” he explained.
Dr. Markowski was slightly more cautious in his prediction, but he agreed with Dr. Higgs, by and large:
“As soon as you say something can never happen — it probably will! However, I think it’s highly unlikely that mosquitoes could transmit the SAR-CoV-2 virus in the future. The number of mutations that would have to occur to allow this process, would make it statistically improbable. If there were evidence of this truly being possible, I think we would have seen it long ago with other viruses, such as influenza, polio, etc.”