Experts warn about alarming spread of genetically diverse West Nile virus

New research indicates that residents of major cities could face higher exposure to West Nile virus due to a particular mosquito species. Culex pipiens form molestus, commonly referred to as the "London Underground mosquito," has attracted attention for its ability to bite both birds and humans.

Historically, it was believed that this mosquito evolved from its bird-feeding ancestor, Culex pipiens form pipiens, over the past 200 years as an adaptation to urban environments. To investigate this, scientists analyzed approximately 12,000 DNA samples from the species.

The study revealed that the human-biting variant of this mosquito likely originated more than 1,000 years ago, possibly in Ancient Egypt. Researchers also found that mosquitoes capable of feeding on both birds and humans are less common than previously thought, but they appear more frequently in densely populated urban areas. This dual-feeding behavior heightens the risk of spreading diseases like West Nile virus.

According to Lindy McBride, Associate Professor of Ecology and Evolutionary Biology and Neuroscience at Princeton University, the findings offer crucial insights into the genetic variation of this mosquito across regions, improving understanding of its role in transmitting West Nile virus from birds to humans.

Why This Research Matters

The study underscores how urban expansion forces wildlife to adapt, sometimes increasing disease risk for humans. In the case of the London Underground mosquito, while the hybrid bird- and human-biting form emerged over a millennium ago, modern city environments may boost their population, elevating the chance of vector-borne disease outbreaks.

Global warming and prolonged mosquito activity further exacerbate the risk. Higher temperatures extend mosquito seasons, creating ideal conditions for diseases like West Nile virus to spread.

Preventive Measures

Governments and organizations are actively addressing vector-borne diseases. For example, the World Health Assembly launched the Global Vector Control Response (GVCR) 20172030 to improve control measures.

Individuals can reduce their risk by wearing protective clothing, such as long sleeves and pants, and using insect repellent when outdoors.

Author: Ethan Caldwell