KANSAS CITY, Mo. —As if we didn't have enough reasons to stay inside.
Health officials say a potentially deadly mosquito-borne virus never seen in Kansas and rare in Missouri has made its Kansas City debut.
The La Crosse virus landed an 8-year-old boy in Children's Mercy Hospital for a week last August with meningitis, according to the Centers for Disease Control and Prevention.
The case is described in the CDC journal Morbidity and Mortality Weekly Report, released Friday.
About 50 to 100 La Crosse virus cases are reported each year, and 2 percent are fatal.
Named for the Wisconsin county where it was first identified in the 1960s, the virus is commonly found in the upper Midwest and Appalachian states. It usually causes mild illnesses with fever, headache, nausea and fatigue. But severe cases can mean seizures, coma, paralysis and brain damage.
The virus may be responsible for more area infections where fever and headaches are the main symptoms, but it is being missed.
"Physicians usually don't put this disease on their radar screens," said Philip Lo, a CDC epidemiologist stationed in Missouri. "It's likely that the disease is underdiagnosed and underreported."
Until the Kansas City case, the virus hadn't made an appearance in Missouri since 2002, when a 10-year-old girl in the northeastern part of the state became ill. Before that, the last Missouri case was in 1993.
"To have a case in the Kansas City area is really surprising for experts in the field, because they've never heard of it in this region," said Lo, lead author of the study on the Kansas City La Crosse virus case.
La Crosse virus is spread by the eastern treehole mosquito, Aedes triseriatus, a woodland pest found throughout Missouri and as far west as central Kansas.
The boy, who became ill last summer, had been playing in a wooded area on the eastern edge of Kansas City.
Treehole mosquitoes are a different variety from the kinds of mosquitoes that spread the West Nile virus.
La Crosse virus typically hits children under 16 years old the hardest.
The Kansas City boy who had the infection came down with headache, fatigue, nausea, vomiting and stomach pains. His parents took him to a hospital emergency room on July 29. Doctors there first thought the boy had strep throat and prescribed an antibiotic medication. Antibiotics don't work against viruses.
When he didn't improve, he ended up at Children's Mercy, with a 104-degree temperature. His neck hurt when he bent it. And he had a hard time tolerating light.
Preliminary tests for viruses and bacterial meningitis turned up negative. Spinal fluid went to an outside laboratory for advanced scrutiny for antibodies against a long list of viruses, including West Nile and the group of viruses that include La Crosse.
"I wasn't expecting it to be La Crosse virus, but I was happy to make a diagnosis," said Angela Myers, a pediatric infectious disease specialist at Children's Mercy.
"You have to have a high level of suspicion to test for La Crosse," she said. "It was definitely on our list, but we didn't think it was likely."
By the time Myers got the test results on Aug. 7, the boy's health had improved considerably. He was discharged from the hospital that day.
Most La Crosse virus cases are much less severe than what the boy experienced, Myers said. The symptoms are often vague and overlap with those of other viral infections.
When children get sick with a fever and headache, parents are likely to assume it's a routine summer virus and not make the connection to mosquitoes, Myers said.
"I believe it happens quite often," she said.
But a high fever coupled with an aversion to light or difficulty responding to questions are signs of serious illness that should be checked out by a doctor, Myers said.