The pathogen mosquitoes that are spread by sucking our blood cause over half a million deaths and hundreds of millions of serious illnesses each year.
However, there is no scientific evidence that mosquitoes transmit SARS-CoV-2, the virus that causes COVID-19.
There is a lot more to learn about the coronavirus, but based on what we know today, it is highly unlikely that a mosquito would ingest the virus by biting an infected person, let alone being able to pass it on.
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Yes, mosquitoes can transmit other viruses
Female mosquitoes need the food in their blood to develop their eggs. Viruses use this biological requirement of mosquitoes to move from host to host.
In order for a mosquito to become infected, it must first bite an infected animal such as a bird, kangaroo, or person.
Mosquitoes can transmit a number of viruses, including dengue, yellow fever, chikungunya, Zika, and Ross River viruses. They can also transmit malaria, which is caused by a parasite.
However, they cannot transmit many other viruses, including HIV and Ebola.
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In the case of HIV, the mosquitoes do not infect themselves. In fact, if a mosquito bites an infected person, it is unlikely to ingest the virus because of the low levels of HIV circulating in their blood.
For Ebola, even if scientists inject the virus into mosquitoes, they won’t get infected. One study collected tens of thousands of insects during an Ebola outbreak but found no virus.
No, not a coronavirus
The new coronavirus spreads mainly via droplets that are formed when sneezing or coughing and by touching contaminated surfaces.
Although coronavirus has been found in blood samples from infected people, there is no evidence that it can spread via mosquitoes.
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Even if a mosquito had ingested a sufficiently high dose of the virus in a blood meal, there is no evidence that the virus could infect the mosquito itself.
And if the mosquito is not infected, it cannot pass it on to the next person who bites it.
Why some viruses and some not?
One can easily think of mosquitoes as tiny flying dirty syringes that carry droplets of infected blood from person to person. The reality is far more complex.
When a mosquito bites and ingests some virus that contains a virus, the virus quickly gets into the insect’s intestines.
From there, the virus has to infect and “escape” the cells in the intestines, infecting the rest of the mosquito body and spreading to the legs, wings and head.
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The virus then has to infect the salivary glands before it is transmitted by the mosquito with the next bite.
This process can take a few days to over a week.
But time is not the only barrier. The virus also needs to negotiate how it gets from the intestines, through the body, and then into the saliva. Every step in the process can be an impenetrable barrier to the virus.
This can be straightforward for viruses that have adapted to this process, but for others the virus perishes in the gut or is excreted.
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