Baylor researchers link West Nile virus, neurological disorders years after original infection

Researchers from the Baylor School of Medicine released a report Tuesday that documents a link between West Nile virus and brain damage years after the original infection, even among those who did not experience any symptoms at the time of infection.

Baylor researchers released a report on their 10-year study at the 66th Annual Meeting of the American Society of Tropical Medicine and Hygiene. The study was the first to draw a definitive link between brain damage and neurological symptoms of the disease like tremors, muscle weakness, and memory impairment.

From 2002 to 2012, researchers tracked 262 people in the Houston area with a history of West Nile virus. Extensive neurological tests were conducted on a subgroup of 117 people, and 57 of them were found to be suffering from neurological deficits although they experienced mild or no symptoms at the time of infection.

“The issues we are seeing on the MRIs are consistent with what would occur from an infection that caused a lot of inflammation in the brain,” Kristy Murray, a researcher at Baylor National School of Tropical Medicine and lead study author, said. “Inflammation can lead to scarring as the brain starts to heal, and that scarring can cause damage.”

When the disease does progress into the West Nile virus neuroinvasive disease that causes inflammation of the brain, Baylor researchers found evidence of atrophy or degeneration in the cerebellum, the brainstem, and the thalamus. Those neurological deficits manifest in symptoms like impaired balance, breathing, speech, sleep cycles and tremors.

“Our findings add to a growing amount of evidence that West Nile virus is a serious health threat that deserves considerably more attention because there still are no drugs available to treat it and no vaccines to prevent it,” Murray said.

Since the mosquito-borne disease was first reported in the United States in 2000, up to 3 million people in the continental United States and Hawaii have been exposed to West Nile virus. The Centers for Disease Control and Prevention (CDC) has linked 2,000 deaths to the disease.

“It will be important to regularly assess people who have been infected with West Nile virus for early signs of neurological deficits and brain MRIs should be considered when symptoms are observed,” Shannon Ronca, a researcher at the Baylor National School of Tropical Medicine and a study co-author, said.