Mosquitoes Don't Spread COVID-19, Study Finds

According to a new study from Kansas State University, mosquitoes cannot transmit the virus responsible for COVID-19. The study, published in Scientific Reports on July 17, revealed that SARS-CoV-2 cannot reproduce within mosquitoes and cannot be transmitted to humans through a bite.

The World Health Organization (WHO) previously stated that “there has been no evidence to suggest that the new coronavirus could be transmitted by mosquitoes." But this claim lacked any experimental backing—until now.

To conduct their study, researchers selected three species of mosquitoes; Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus. This selection represents the most important groups of mosquitoes that transmit diseases to humans.

To ensure that the mosquitoes became infected with SARS-CoV-2, the researchers used an intrathoracic inoculation, meaning they injected the virus directly into the cavity containing circulatory fluid. For a virus to be transmissible by a mosquito, it must be able to travel through the circulatory system and replicate. This allows the viruses to find and infect the salivary gland, which is the final step in the process before the infection is passed to the host.

Researchers observed that there were no traces of COVID-19 virus within the insects after 24 hours. This means the virus was unable to replicate within the mosquitoes and was eventually eliminated by natural defenses.

According to David Claborn, director of the Master of Public Health Program at Missouri State University, the anatomy and physiology of the mosquito is not conducive to transmitting COVID-19. While Claborn was not affiliated with the Kansas State University study, he is an entomologist—a scientist who studies insects.

Claborn tells Verywell that mouth of a mosquito contains channels for both sucking blood and for pumping out anti-coagulant saliva to the feeding site—e.g., your arm.

“If the virus does not replicate within the mosquito and get into the salivary glands, it's very unlikely that it will be transmitted when the mosquito feeds," he says.

Why You Should Still Protect Yourself From Mosquitoes

While it’s certainly good news that mosquitoes are one less COVID-19 risk factor, they're by no means harmless. In fact, according to WHO, mosquitoes are responsible for over a 400,000 deaths per year worldwide from malaria alone.

The eastern equine encephalitis (EEE) and West Nile virus are two dangerous mosquito-borne diseases that are currently present in the United States.

Claborn says the majority of EEE cases occur around the east coast, with Florida typically recording the highest number of cases. Still, that number is not very high; the Centers of Disease Control and Prevention (CDC) reported only 13 EEE cases in humans in Florida between 2009 and 2018. So far this year, Massachusetts has reported EEE, but only in mosquito samples. West Nile, on the other hand, occurs in almost every state.

According to Claborn, symptoms of these diseases can range from “relatively mild flu-like symptoms to neuro-invasive diseases that can lead to paralysis or death.”

How To Protect Yourself

Claborn recommends covering your skin with protective clothing to avoid bug bites, especially in the evening when many mosquitoes are active. Insect repellants also do the trick. But he says that you should purchase repellants with DEET as the active ingredient: "They're the most effective and long-lasting," he says.

One thing you shouldn't rely on? Sonic repelling devices or mosquito traps. Claborn says that these traps often bring even more mosquitoes into the general vicinity.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.