Months into a drought-ridden summer, news of a record year for a mosquito-borne disease comes as a surprise for those who connect mosquitoes with moisture.
Missouri's first death from the West Nile virus was announced Monday. Missouri health officials say a Laclede County man who died earlier this month is the state's first fatality blamed on the mosquito-borne illness.
The Missouri Department of Health and Senior Services says the 78-year-old victim contracted the illness in late July. A spokeswoman for the state health department declined to be more specific about where the man lived, but the Lebanon Daily Record reported he was a Lebanon resident.
The state says three other people have are believed to have contracted the West Nile virus.
Kansas has also had one confirmed death. On Friday, the Kansas Department of Health and Environment reported a significant surge in the number of people affected, the first upswing since 1993.
Ten years ago, the West Nile virus was the scary newcomer to infectious disease, the topic of a slew of news stories, and the subject of local spraying efforts meant to eradicate the mosquitoes that brought the disease to people after the bugs got it from birds.
In many places, spraying has since ceased. As exposure led to immunity, infection numbers dropped. Then, in 2012, the numbers shot back up.
"I'm not sure why that number has shot up so much," said Kansas State University agriculture expert Rick Miller.
Miller said the drought meant fewer breeding grounds for mosquitoes, and the calls coming into the Johnson County K-State Extension offices suggest that there are actually fewer of the pests than in years past.
"We get calls all the time on the different insects," Miller said. "I can tell you I have gotten one mosquito call so far this year."
That suggests the surge in infection is connected not to the number of carriers but something else.
In Kansas, from 2008-2010, five cases was the median annual rate of infection. In 2011, there was one. So far this year, there have been 19 suspected cases, five of them confirmed.
Dr. Lyle Petersen, director of the Division of Vector-borne Infectious Diseases here at the Centers for Disease Control and Prevention, said recently that experts have no certain explanation. He did, however, raise one element that sets this summer apart.
"Hot weather seems to promote West Nile virus outbreaks," said Petersen.
Many of the worst outbreaks worldwide, Petersen explained, have been in abnormally hot weather, and lab tests back up the significance of high temperatures.
"Hot weather, we know, from experiments done in the laboratory, can increase the transmissibility of the virus through mosquitoes," Petersen explained, "and that could be one contributing factor."
Another factor could be complacency and people no longer using insect repellents as consistently as they did in earlier years. The other obvious possibility is something the CDC is still looking at.
"We have no information yet about whether the virus is mutated," said Petersen. "But, there are certainly plenty of reasons why this outbreak could be occurring now...other than that."
Metro-area residents have see an increase in all kinds of bugs because of the mild winter, but Miller says with mosquitoes, the impact there is that they surfaced a month or so earlier than usual, not in greater number.
For the more information on why the number of cases are higher this year, click here for data from the Centers for Disease Control and Prevention.
Copyright 2012 KCTV (Meredith Corp.) All rights reserved. The Associated Press contributed to this report.
Tuesday, September 16 2014 3:01 PM EDT2014-09-16 19:01:19 GMT
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