OKLAHOMA CITY — Infectious diseases once unknown in Oklahoma are now a threat to the health of its residents as maladies such as the West Nile virus, chikungunya virus and Heartland virus spread across the globe, according to state health officials.
The Oklahoma Department of Health reported in May that a Delaware County resident died from complications of the Heartland virus, the first recorded case of the tick-borne virus in the state and only the second person to die from the disease in the nation.
Last month, the agency said a Tulsa County resident who traveled to Haiti on a mission trip was the first Oklahoman to test positive for the chikungunya virus, a mosquito-borne disease that is not indigenous to the U.S.
And the Health Department reported Thursday that a Major County resident was the first recorded case in Oklahoma this year of the West Nile virus, another mosquito-borne disease that killed 8 Oklahoma residents and sickened 84 in 2013.
State epidemiologist Dr. Kristy Bradley says the diseases are showing up in Oklahoma because of changes in climate, the urbanization of previously forested areas of the world and people traveling to once-remote regions.
"You don't have to venture too far outdoors before you are exposed to potential disease exposure," Bradley said Friday. "It almost seems inevitable that these vectors are going to encroach closer and closer to us."
West Nile virus was not known in the U.S. until 1999 and first appeared in Oklahoma in 2002. It was previously confined to Africa, western Asia, the Middle East and parts of Europe.
"Now, we have that as a seasonal disease threat that we have to contend with every year," Bradley said.
Spread through the bite of an infected mosquito, West Nile symptoms usually occur within two weeks and can include headache, fever and tiredness. But the virus can also cause severe neurologic disease such as meningitis, paralysis and encephalitis.
The chikungunya virus, first reported in Africa in the 1950s, was confirmed in islands in the Caribbean just last year. Since then, the Pan American Health Organization says 250,000 suspected human cases of the disease have been identified in more than 20 nations in the Caribbean, Central America and South America.
"It really has caught on with quite a firestorm," Bradley said. "That's quite an epidemic that's occurring there."
Chikungunya does not often cause death, but symptoms can be severe including high fever and severe pain in multiple joints.
The Heartland virus was first identified in Missouri in 2009 and the Oklahoma case was only the tenth confirmed. Other cases have occurred in Missouri and Tennessee. Symptoms can include fever, fatigue, headaches, muscle aches, loss of appetite, nausea, bruising easily and diarrhea.
Bradley said there are no vaccines for the Heartland virus or the other infectious diseases and no specific treatments.
"It comes down to prevention being the key," she said. The Health Department recommends the use of insect repellents, wearing long sleeves and pants when outdoors and avoiding bushy and wooded areas to avoid bites from ticks and mosquitoes.
"You want to keep the mosquitoes off of your bare skin," Bradley said. "That's the first line of defense."