The Summer season brings mosquitoes with it. We know that some of them can transmit diseases, so the question is: can mosquitoes transmit the coronavirus?
There are many insects that transmit diseases, and they generally do so through viruses, bacteria and parasites. Mosquitoes fit this bill. In fact, many people remember that the mosquito of the genus Anopheles is a carrier of malaria, as transmitted by a plasmodium.
Here are some mosquitoes that are carriers of infectious diseases:
- Chikungunya is also transmitted in Italy, by tiger mosquitoes
- Dengue is a flu-like disease, widespread in both tropical and sub-tropical countries
- Japanese Encephalitis (JE) is the leading cause of viral encephalitis
- Rift Valley Fever is widespread in Kenya and recently also in Saudi Arabia and Yemen
- Yellow Fever, perhaps among the best known because it’s quite widespread across Africa, and vaccination is strongly recommended in case of travel to the areas where it’s present
- Zika Virus infection, sadly infamous in recent years for its numerous infections in South America and its transmission from mother-to-fetus during pregnancy
Can COVID-19 be transmitted from mosquitoes to humans?
First, SARS CoV-2 has rarely been found in the blood of infected people (beware that the virus, not simply its RNA and even less, the antibodies that are the signal that our immune system has reacted and are not actual carriers of the infection!).
Second, a virus, in order to be transmitted from a mosquito to a human, must be able to replicate within the mosquito. No coronavirus, including SARS, has ever demonstrated that it can accomplish this. The process is, in fact, quite complex — because the virus should survive the journey through the mosquito’s digestive system and then reach the salivary glands where it should replicate, in order to be injected into the bloodstream of the person stung by the mosquito. This process has required adaptive co-evolution of the mosquito, and the virus in the cases listed above and can be estimated over thousands of years.
And finally, relatively few viruses are able to infect mosquitoes and then humans. The vast majority of viruses that infect humans, such as influenza and HIV that are RNA viruses such as SARS-CoV-2, do not infect insects. Also, there are no known coronaviruses that infect mosquitoes.
The only factor that needs to be taken into account here is that in case of infection with mosquito-borne viruses, our immune system would be less efficient and therefore we would be more vulnerable in case of COVID-19 infection. This is a very rare situation, at least in Italy.
Prevention! Although annoying, they’re important for our ecosystem
Regardless of the possible (but unlikely) co-infection by COVID-19 and a mosquito-borne disease, it’s always important that municipalities sanitize public areas with larvicides and adulticides, in order to keep mosquito proliferation in urban areas low.
Let’s not forget, however, that the presence of mosquitoes — together with other insects — is fundamental in nature because they are part of the food chain of many other animals, and are important in keeping the ecosystem (of which we’re a part) in balance.
The complete eradication of an autochthonous species; that is to say that it has always lived in a certain environment, but which we consider to be as annoying as mosquitoes, has an impact on many other species that we like to see (or listen to their songs, as in the case of birds) — that would be deprived of an important portion of their diet — could have to move away, in order to survive.
This post is also available in: Italiano