The Jackson County medical examiner is investigating a recent death for West Nile virus. If confirmed, it would be the earliest fatality in a calendar year from the mosquito-borne disease in Missouri history.
Angie Jeffries, a spokeswoman for the Jackson County medical examiner, confirmed reports that West Nile is suspected in the May 23 death of an 8-year-old boy from Independence, and her office has sent a sample to the Missouri Department of Health to test for the virus. But she said nothing is definitive yet.
“The case is still under investigation,” Jeffries said via email. “The medical examiner has requested several additional tests.”
Since the state began tracking West Nile virus in humans in 2002, most cases have occurred between July and September each year.
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The earliest confirmed fatality in Missouri was the death of a 75-year-old Laclede County man who contracted the illness May 28, 2014. Before that, the earliest was a 70-year-old man from Adair County who contracted the illness June 1, 2005.
Christopher Rogers, a research associate who tracks West Nile-carrying mosquitoes for the Kansas Biological Survey, said cases usually occur later in the year because mosquitoes have to hatch and then get the virus from birds before the mosquitoes can transmit it to humans.
“Mosquito populations as a whole tend to spike in June, July and August, but we mostly see mosquitoes carrying West Nile (at the) end of July through September,” Rogers said. “They’re more prone to carrying it later in the year.”
Rogers said “it’s uncommon” to see cases in May in this region.
But with milder winters and wetter springs the last few years, mosquito season is coming earlier. KDHE put out a news release last year on June 10 warning that mosquito counts, including those of the Culex species that carry West Nile, were already high in Sedgwick County.
Until this year that was the only county the Kansas Biological Survey examined. But this year Rogers said the University of Kansas department is expanding mosquito surveillance to a few more locations and will continue to add more counties if it gets more funding.
Health officials say the best ways to prevent mosquito-borne diseases are to wear long sleeves and pants, use window screens to keep mosquitoes out of the home and apply insect repellant before going outside.
The Kansas Biological Survey is also studying the range of the mosquito species that carry the Zika virus, the Aedes aegypti and Aedes albopictus. Those species have been found in some parts of Kansas and Missouri, but the only confirmed cases of Zika in the area so far have been in people who traveled to other countries and imported it.
Zika is a relatively mild illness except when it occurs during pregnancy, when it can cause the birth defect microcephaly. A study of almost 1,500 pregnant women with Zika in the continental United States found that it caused birth defects in about 5 percent of cases.
There were about 5,000 confirmed cases of Zika in the continental United States last year, according to the Centers for Disease Control. But only 224 were believed to be from local mosquitoes and all of those cases were in Florida or Texas.
There’s been no confirmed cases of locally acquired Zika in the continental United States yet this year. But Claude-Alix Jacob, the president of the National Association of County and City Health Officials, said local health officials should stay wary.
“With summer coming, the Zika threat will get worse,” Jacob said.