Experts issue warning about concerning spread of West Nile virus: 'Varies genetically'

A recent study found that people in larger cities may be at a higher risk of West Nile virus from a certain type of mosquito.

What's happening?

Science.org shared a recent study on the urban mosquito species, Culex pipiens form molestus, also called the "London Underground mosquito."

Scientists have long thought that this mosquito evolved from its bird-biting form (Culex pipiens form pipiens) to the current one that bites both birds and humans over the past 200 years, as an adaptation to urbanization. 

However, researchers decided to test this theory by tracing the emergence of the mosquito's human-biting form. 

To do this, the research team extracted and analyzed around 12,000 DNA samples from this mosquito species. The results found that the human-biting form of the London Underground mosquito actually had its origins in what was likely Ancient Egypt over 1,000 years ago. 

The team also discovered that mosquitoes that bite both birds and humans are less prolific than previously believed, but they do occur more frequently in larger cities, which could indicate that urbanization increases the likelihood of a mosquito biting both. Because the biting of both species increases the risk of disease spread, particularly West Nile virus, this puts people in urban areas at greater risk.

According to News Medical, senior author and Associate Professor of Ecology and Evolutionary Biology and Neuroscience at Princeton University Lindy McBride, explained, "Our work provides new insight into how this mosquito varies genetically from place to place — insight that we think will help us better understand the role this species plays in transmitting West Nile virus from birds to humans."

Why is this study important?

This study shows how urbanization and the encroachment of growing human populations on wildlife species' natural habitats can cause these species to adapt. In the case of the London Underground mosquito, although the species actually began adapting into a hybrid human and bird-biting form over 1,000 years ago, modern urbanization may increase the number of these mosquitoes, thereby increasing the risk of vector-borne illnesses in humans. 

Considering that the continued use of dirty energy sources has increased global temperatures, allowing mosquitoes to be active for longer than typical, which creates optimal conditions for the spread of such illnesses, this means that the chances of contracting West Nile virus or a similar disease drastically rise.

What's being done to stop the spread of vector-borne illnesses?

Many governments and organizations are working to limit the spread of vector-borne illnesses. The World Health Assembly, for instance, approved the Global Vector Control Response (GVCR) 2017-2030 in 2017, aiming to strengthen vector control. 

Individuals can help protect themselves from mosquito bites by wearing long pants and long sleeves while outdoors and using bug spray.

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