Five of Denton County’s Six West Nile Cases This Year Hit the Nervous System

Most people infected with West Nile virus never know they had it. The people appearing in Denton County’s official case count this year have not been so lucky.

The county’s sixth reported human case of West Nile virus this year was announced Tuesday, Oct. 13. The patient, a City of Denton resident, was diagnosed with West Nile neuroinvasive disease. Five of Denton County’s six reported cases this year have involved the neuroinvasive form.

That does not mean five out of every six West Nile infections become severe. Most infections cause no symptoms, and many mild cases are never diagnosed or reported. It does show that five of the six cases captured in the county’s official count were neuroinvasive.

Here’s why that number matters. Less than 1% of people infected with West Nile virus develop neuroinvasive disease. That severe form affects the central nervous system and can cause encephalitis, meningitis or acute flaccid paralysis. According to the CDC, approximately 10% of people who develop severe illness affecting the central nervous system die.

West Nile virus does not ordinarily spread from person to person. It is most commonly transmitted through the bite of an infected mosquito that has fed on infected birds. Standing water in a backyard birdbath, a low spot in the lawn or a clogged gutter can still provide a breeding ground in mid-October. Mosquito activity slows as temperatures fall, but the season is not necessarily over.

Older adults and people with weakened immune systems face a higher risk of severe illness. The incidence of neuroinvasive disease and the risk of death increase with age, with the highest incidence occurring among people age 70 and older. For everyone else, the likelihood of developing the dangerous form remains very low, but prevention still matters.

There is no licensed vaccine to prevent West Nile virus in people and no specific medicine that cures the infection. Treatment focuses on relieving symptoms and supporting patients through the illness.

The practical checklist is short. Drain standing water around your property. Use an EPA-registered insect repellent when spending time outside, particularly around dusk and dawn. Check window and door screens for holes or gaps. Denton County also maintains an interactive map showing local mosquito traps where mosquitoes have tested positive for West Nile virus at dentoncounty.gov.

FloMoBee previously reported on the county’s West Nile activity as cases accumulated through the summer and into the fall.