A ninth West Nile virus death was confirmed Thursday, a trend public health officials say will likely continue even as the season winds down in Oklahoma.
“It would be expected that we may have more West Nile virus-related deaths, even into the fall or early winter, because sometimes those deaths occur weeks to months after their initial illness or hospitalization,” said Kristy Bradley, epidemiologist at the state Health Department.
After weeks of record-breaking reports of the virus in Oklahoma, it appears the season is coming to a close.
Bradley said the Health Department analyzed surveillance data and determined the season's peak was in the first part of August. Since that time, the numbers of reported cases have declined.
“That's an encouraging finding,” Bradley said. “However, it doesn't mean the season is over completely. We don't want people to let down their guard because we've still had pretty warm days here in Oklahoma, and we know the risk of transmission of West Nile by biting of mosquitoes will continue until late October or early November.”
The Health Department reported Thursday that a Muskogee County man older than 65 died from the virus.
There have been 154 confirmed cases of the virus this year, the most Oklahoma has seen since the virus entered the U.S. in 1999.
Nationwide, there have been 3,545 cases this year, the most reported to the Centers for Disease Control and Prevention through the last week in September since 2003.
About 70 percent of the cases have been reported from eight states — Texas, Mississippi, South Dakota, Michigan, California, Louisiana, Oklahoma and Illinois, according to the CDC.
West Nile virus is mosquito-borne and can cause two types of illness: West Nile fever or a severe neurological disorder.
More than 80 percent of people bitten by an infected mosquito do not contract the virus. People older than 50 are at the highest risk of developing the virus and its more serious symptoms.
Public health officials recommend residents wear mosquito repellent with DEET or another approved active ingredient such as Picaridin or oil of lemon eucalyptus.
It's important to remove standing or stagnant water from around your home, for it can serve as a mosquito breeding ground.
Bradley said even though the season is on the decline, people who were infected by the virus have a long road ahead of them.
“A certain proportion of our persons that became ill in late July and August have been very, very ill, and they've remained hospitalized or remained in a rehabilitation facility and may not be able to completely recover from this illness,” Bradley said.
West Nile virus can cause severe neurological disorders, affecting a person's ability to swallow and walk. Because of its paralytic effect, patients are susceptible to other illness, such as aspiration pneumonia, she said.
Bradley said patients who don't develop the severe neurological disease can still suffer long-term complications, such as involuntarily tremors, trouble concentrating and new-onset depression.
“There will be some ongoing medical as well as psychological resources that will need to be made available in our state because of this outbreak,” Bradley said.
As for what the state can expect next year, Bradley said there's some seasonal data that may offer insight.
“We would probably expect that it would be a milder season next year because we tend to see these outbreaks every three to four years,” she said. “A lot of times, you see in an area where there's been a significant outbreak, the incidence drops for two or three years.”
She said areas that were hit hard this year, such as Carter County, Pittsburg County and Oklahoma County, might see fewer cases than counties in western Oklahoma, which didn't see very many cases of West Nile virus this year.