A Franklin County woman has recovered from a rare case of St. Louis encephalitis, a disease spread by infected mosquitoes.
She had symptoms and sought medical attention this summer, according to the Benton Franklin Health District.
The district said tests recently confirmed that St. Louis encephalitis was the cause of the woman’s illness.
She is believed to have been infected in Franklin County over the summer.
The last time St. Louis encephalitis was detected in Washington state was in 2005, when it was discovered in a flock of chickens raised by the Benton County Mosquito Control District for West Nile virus surveillance, according to the health district.
The Centers for Disease Control and Prevention said there were one to three cases in Washington state between 2003 and 2022.
But the Benton Franklin Health District said the last case in Washington, from someone infected in the state rather than through travel, was reported in 1972.
The Washington State Department of Health said in an earlier report that several outbreaks of Western Equine Encephalitis and St. Louis Encephalitis between 1939 and 1942 in Eastern Washington resulted in numerous human cases and several deaths.
The Tri-City Herald reported a 2003 case in a Tri-Cities man that the Department of Health said was “almost certainly” St. Louis encephalitis caused by a mosquito bite.
The 36-year-old Pasco man told the Herald at the time that a virus had invaded his spine, causing some paralysis, and invaded his brain, causing inflammation and swelling. He continued to suffer for months.
But the case does not appear to have been positively confirmed as St. Louis encephalitis.
The public health risk from infected mosquitoes, whether carrying West Nile virus or St. Louis encephalitis, is low, according to the health district.
The recent cold snap has reduced mosquito activity in the Tri-Cities area.
“Although the likelihood of new infections has decreased over the season, it is essential that everyone remains vigilant and takes steps to prevent mosquito bites to reduce the risk of contracting not only SLE (St. Louis encephalitis ) but also other diseases transmitted by mosquitoes. ” the district said in a statement.
St. Louis encephalitis is transmitted primarily through the bite of an infected mosquito. But as with West Nile virus, many infected people have no symptoms.
But some people get sick and may develop encephalitis – inflammation of the brain – or meningitis – inflammation of the membranes that surround the brain and spinal cord, according to the CDC.
Precautions are the same as for West Nile virus prevention.
Use insect repellent, wear long-sleeved shirts and pants, and drain standing water.
“In the future, we may see more cases of mosquito-borne illnesses in different locations due to climate change,” said Erin Hockaday, senior surveillance and investigations manager for the Tri-Cities Health District. “Diseases carried by insects, such as mosquitoes, may become more common and spread to new areas as the climate warms. »