Can Mosquitoes Carry COVID-19?

With people spending more time outdoors, mosquitoes can be the least of their concerns.

Mosquitoes are known to transmit diseases; that's why some people have been naturally worried about mosquitoes carrying SARS-CoV-2. Official guidance from the World Health Organization (WHO) says there's no information or evidence to suggest that COVID-19 can be transmitted through mosquito bites.

For a mosquito to become infected with a virus, it must be present in the blood the mosquito feeds on. "SARS-CoV-2 (the virus that causes COVID-19) is a respiratory virus that is almost exclusively contained within the lungs and respiratory tract of infected people, and rarely gets into the blood," Emily Gallichotte, PhD, a postdoctoral researcher in the department of microbiology, immunology, and pathology at Colorado State University, told Health.

Mosquitoes are very genetically different from humans. "This makes it challenging for viruses to have the ability to infect both of us," said Gallichotte. "We have different receptors on the surface of [our] cells and different replication machinery inside our cells."

Additionally, for a virus to pass to a person through a mosquito or other kind of insect bite—such as a tick bite—the virus must be able to replicate inside the insect. No type of coronavirus has been shown to do that.

"It's quite a complex process," former US Navy entomologist Joseph M. Conlon, who has extensive worldwide experience in mosquito control and is a technical advisor to the American Mosquito Control Association (AMCA), told Health. "First of all, the mosquito would have to pick up the requisite amount of virus during its bite. The virus must then not only survive the digestive process but replicate within the mosquito and pass through the gut wall to the coelom (main body cavity) of the mosquito. From there it must make its way to the salivary glands and be expressed by the mosquito as part of its salivary secretions."

Which Diseases Can Be Transmitted to Humans by Mosquitoes or Other Insects?

There are relatively few human viruses that can infect both humans and mosquitoes. "The vast majority of human viruses (such as influenza, HIV, and herpes) have been infecting humans for a very, very long time, and even though many of these end up in our blood, they are still unable to infect mosquitoes," said Gallichotte. "Conversely, there are many mosquito viruses that are unable to infect humans or any mammals. There are no known coronaviruses that can infect mosquitoes."

Viruses that can be spread to humans by mosquitoes include malaria, yellow fever, the virus that causes dengue fever, chikungunya virus, and West Nile virus, which all circulate in the blood of infected people. "West Nile virus is able to infect a mosquito to the point where the virus load is abundant in the salivary glands," Melissa Doyle, scientific program manager at the San Gabriel Valley Mosquito and Vector Control District (SGVMVCD), told Health. "When the mosquito bites a person, the virus is able to travel from the salivary glands into the human body."

Besides mosquitoes, ticks and fleas are also liable to pass diseases to humans. Ticks can cause serious illnesses like Lyme disease, Rocky Mountain Spotted Fever, or tularemia, while fleas can transmit typhus or cat scratch disease. This is why it is important to ensure that you engage in as much insect bite prevention as possible when outdoors.

Protecting Yourself From Insect-Transmitted Diseases

It's pretty clear that COVID-19 is the last thing you should be worrying about if a mosquito has been feasting on your leg. The disease cannot be spread by insects, as COVID-19 is a respiratory virus. Keep swatting mosquitoes and other bugs away, though. "Due to the heavy focus on COVID-19, many people may forget that disease threats may already be buzzing right outside their window," SGVMVCD Communications Director Levy Sun told Health.

The Centers for Disease Control and Prevention (CDC) provides measures for protecting yourself from mosquito bites, such as using insect repellant and wearing clothing that covers most of your body. The CDC also provides information about dealing with ticks, such as ways for preventing tick bites, checking for ticks, and removing ticks.

Tropical or subtropical areas tend to be most affected by insect-transmitted illnesses, according to the WHO. Therefore, if you plan to travel and your destination falls in one of those areas, doing some research can also help you figure out if there are any other precautions—such as medication and vaccination—that may be beneficial for avoiding any kind of insect bites during your trip.

Mosquitoes or no mosquitoes, it's still crucial to keep following healthy COVID-19 protocols to protect yourself and others. The CDC encourages individuals to get COVID-19 vaccinations and stay up to date with those vaccines. Additionally, continue to clean your hands frequently, practice social distancing, stay home if you're sick, and avoid close contact with anyone who is coughing and sneezing in an effort to prevent the spread of the disease.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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