Scientists: Brain damage linked to West Nile virus

Researchers find symptoms years after first diagnosis.

Experts who work on the mosquito-borne West Nile virus have long known that it can cause serious neurological symptoms, such as memory problems and tremors, when it invades the brain and spinal cord. Now researchers have found physical evidence of brain damage in patients years after their original infection, the first time for such documentation using magnetic resonance imaging, or MRI. Brain scans revealed damage or shrinkage in different parts of the cerebral cor- tex, the outer surface of the brain, that handles much of the brain’s higher levels of activity, like memory, attention and language. “Those areas correlated exactly with what we were seeing on the neurological exams,” said Kristy Murray, an associate professor of pediatric tropical medicine at Texas Children’s Hospital and Baylor College of Medicine and lead author of the study. “The thought is that the virus enters the brain and certain parts are more susceptible, and where those susceptibilities are is where we see the shrinkage occurring.” Results of the study, which has not yet been published, were presented Tuesday at the annual meeting of the American Society of Tropi- cal Medicine and Hygiene. The 10-year study of 262 West Nile patients is one of the largest assessments studying the long-term health problems associated with West Nile infections. Most people who are infected do not develop symptoms. About 20 percent will develop fever, and than less 1 percent have the most severe type of infection that causes inflammation of the brain or surrounding tissues. Researchers at Baylor tracked the patients from 2002 to 2012. Some had experienced only mild or no symptoms. But over time, “we were surprised at how many [patients] we saw who had gotten worse, or had new neurological problems,” Murray said.