NIH Funds Studies to Understand Neurological Effects of West Nile Virus

As additional states continue to report that mosquitoes are testing positive for West Nile virus, researchers have received funding to study how infections caused by the virus affect the brain and explore new treatment options.

West Nile virus cases have yet to be reported in Alaska or Hawaii; however, every summer, the remainder of US states are at risk for outbreaks from the mosquito-borne disease. The flavivirus has been making its way across the country since 1999 through a range of mosquito species, and is not transmitted through person-to-person or animal-to-person contact. Thus, mosquito control and personal protection with insect repellants remain key to preventing the spread of West Nile virus. Around the country, local efforts to control mosquito populations and reduce West Nile virus transmission include the use of larvicides in standing bodies of water to kill mosquito eggs and larvae, as well as the use of adulticides to kill mature mosquitoes that may carry the virus. To prevent exposure, the Centers for Disease Control and Prevention (CDC) recommends applying an insect repellant containing ingredients such as DEET, picaridin, IR3535, and oil of lemon eucalyptus, as well as taking extra precautions outdoors during the dawn and dusk hours, when mosquitoes are most active.

Already this season, health departments around the US are reporting the detection of mosquitoes testing positive for West Nile virus. On June 5, the Oklahoma City-County Health Department (OCCHD) announced that the virus had been isolated in several mosquito samples collected through local surveillance efforts. The OCCHD urged residents to help health officials eliminate or treat any standing water to prevent further mosquito breeding.

“The recent rain and warmer weather provide a favorable environment for mosquitoes to carry the virus,” said OCCHD director Phil Maytubby in a press release. “A few basic steps like removing any sources of stagnant water in flower pots, pet bowls, chimeneas, old tires, wheelbarrows, birdbaths and even kid’s toys will cut down on the mosquito population. Survey your property after a rain to get rid of mosquito habitats.”

The Illinois Department of Public Health has also recently reported the state’s first West Nile virus-positive mosquitoes for the season. In 2016, 61 counties in the state reported that either the virus had been identified in mosquitoes, birds, or humans, which resulted in 152 confirmed human cases and 5 related deaths.

In California’s Merced County, local health officials recently reported the area’s first West Nile virus-positive mosquito following a winter of above average rainfall and heavy snow pack. Seven counties in California have now reported the virus in mosquitoes, while 6 counties have reported birds dying as a result of infection. To date, there has only been 1 human infection.

In a timely announcement, the National Institutes of Health’s (NIH) National Institute of Allergy and Infectious Diseases has awarded a $7.7 million federal grant to researchers investigating the neurological effects of infection with West Nile virus. While less than 1% of people infected with the virus will develop serious neurological illness, such severe disease can result in long-term health issues or even death. Researchers from Georgia State University, the University of Pennsylvania, and Florida State University will apply the NIH grant towards investigating how the virus affects brain cells and engineered brain models known as organoids. The goal, says researcher Margo Brinton, PhD, is to learn which types of human neural cells can be infected by the West Nile and Zika viruses.

“The organoids provide a way to obtain good models of the human brain without using human embryos to obtain the initial cells,” explains Dr. Brinton. “The further development of brain organoids that represent different regions of the brain will provide more accurate human brain models that can be used to understand the differences between these two different neurotropic viruses that are members of the same virus family but have very different disease effects in humans.”