Clark County sees 1st case of St. Louis encephalitis since 2007

Southern Nevada health officials reported a case of St. Louis encephalitis on Friday — the first human case of the potentially deadly mosquito-borne disease in Clark County since 2007.

A man over 50 who was hospitalized with a serious neuroinvasive form of the viral illness has since been released, according to a news release from the Southern Nevada Health District.

The release did not identify the man or say where he is believed to have contracted the disease.

Though most people infected with St. Louis encephalitis experience mild symptoms such as headaches and fever — or no symptoms at all – some become seriously ill. Symptoms can include neck stiffness, confusion, shaking, seizures, paralysis and coma. In rare instances, the disease can kill.

Southern Nevada has seen a sharp spike in positive tests for St. Louis encephalitis this year.

More than 33,000 mosquitoes collected by health district workers have been tested by the Nevada Department of Agriculture. Of those, nearly 17 percent tested positive for St. Louis encephalitis, according to the health district.

Health officials also are concerned about another illness transmitted by infected mosquitoes: the West Nile virus. The first case this year in Clark County was reported earlier this week.

Dr. Joseph Iser, chief health officer with the Southern Nevada Health District, said preventative measures against mosquito bites are the best defense against such illnesses.

“With the increased number of St. Louis encephalitis-positive mosquitoes in Southern Nevada this season, we are not surprised to receive confirmation of a human case of the illness,” he said. “It is another reminder to the community to protect themselves from bites and check their homes and yards for mosquito breeding sources.”

Contact Pashtana Usufzy at pusufzy@reviewjournal.com or 702-380-4563. Find @pashtana_u on Twitter.