Mosquitoes contaminated with West Nile virus are frequent in lower-income areas of Baltimore


In a new study published in the Journal of Medical Entomology, University of Maryland (UMD) researchers found higher rates of mosquitoes infected with West Nile virus in low-income areas in urban areas of Baltimore, Maryland.

These preliminary data continue working with the Cary Institute of Ecosystem Studies, building on previous work finding larger mosquitoes (which may be more likely to transmit disease) in low-income areas. They provide another piece of the puzzle that indicates a higher risk of mosquitos. transmitted diseases like the West Nile virus in these neighborhoods already grappling with environmental injustices and poorer health outcomes.

This paper highlights the need to do more research in low-income communities to inform policies and programs that can protect the health of the most vulnerable.

To effectively combat environmental injustices, we need to understand where they occur and why. Urban mosquito sampling often takes place in city parks or other areas where traps are easily accessible to staff. However, we have to make sure that we look for mosquitoes in the neighborhood that differ in socio-economic status. Representative monitoring is the first step. Only when we identify where the risk of disease is actually greatest can we direct public health resources to communities that need them most. “

Sarah Rothman, Principal Investigator and PhD candidate, Environmental Science & Technology, University of Maryland

According to Paul Leisnham, Associate Professor of Environmental Science & Technology at UMD, this study is a first step in the fight against environmental justice and establishes another important link between low-income neighborhoods and risky mosquito populations.

“Two types of mosquito have been shown to be more infected, the invasive tiger mosquito and the northern house mosquito. In previous studies, we have shown that mosquito incidence and the height of women, two other environmental parameters that promote virus transmission, are also greater Now we’ve introduced another piece of the puzzle that points to higher risks in lower income areas. “

Leisnham spends a lot of time interacting with locals in urban Baltimore through its research and expansion efforts, highlighting an important point for mosquito population growth that isn’t exactly intuitive: “Less trash, fewer mosquitos.” Surprisingly, mosquitoes can reproduce in an amount of water as small as that which collects in a bottle cap left outside in a shaded area for four or five days. If the water collects in a shady container and does not enter the soil through managed rainwater practices, it can easily become a breeding ground for mosquitoes that can spawn hundreds of biting adults.

Cary Institute’s disease ecologist, Shannon LaDeau, said, “More people are living in cities. At the same time, many other species are adapting to urban life. Invasive species like the tiger mosquito are increasingly thriving in urban temperate areas. Below us and fundamentally change the risk of local diseases occurring. People who live in areas with abandoned infrastructure are more at risk because tiger mosquitoes thrive in less cultivated landscapes. “

As the link between vacant lots, more trash and more mosquitos is made, more research is needed to further link these environmental inequalities to higher human infection rates. “The incidence of West Nile virus in the human population is often underestimated,” says Rothman. “Most cases are asymptomatic, and mildly symptomatic cases can easily be confused with other illnesses similar to the flu.

We are particularly likely to miss cases in underserved populations with limited access to quality medical care. Since it is difficult to track the prevalence of West Nile virus in humans, we recommend additional sampling of the virus in mosquitoes. Additional research could also help us understand why lower-income areas have patterns with higher mosquito infection rates and how these patterns are influenced by environmental factors such as weather. “

“It’s important, especially in populations from lower-income areas, as they are often immunocompromised by other infections, including HIV and likely COVID-19,” added Leisnham. “The CDC [Centers for Disease Control and Prevention] reported that the US is unprepared for mosquito and tick-borne risks based on surveys by local health authorities. “

Rothman stresses the need for this work to improve environmental justice in low-income areas of cities like Baltimore. “Our research supports the belief that residents of these neighborhoods are at a disproportionate risk of mosquito-borne diseases,” says Rothman. “We need additional research to understand and address the underlying factors and ultimately to protect city dwellers.”


Journal reference:

Rothman, SE, et al. (2020) Higher West Nile Virus Infection in Mosquitoes from Aedes albopictus (Diptera: Culicidae) and Culex (Diptera: Culicidae) from low-income areas in Urban Baltimore, MD. Journal of Medical Entomology.

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