Bluetongue infection rate in Missouri deer difficult to pin down
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Bluetongue infection rate in Missouri deer difficult to pin down

Date: August 30, 2012
By: Eric Stoyanov
State Capitol Bureau

JEFFERSON CITY - While extreme drought conditions are increasing the amount of deer infected with the bluetongue virus, state conservation officials said exact infection rates are difficult to determine.

There are currently 1,100 deer that are believed to have died from the bluetongue virus, said Emily Flinn, a state deer biologist with the Missouri Department of Conservation. However, Flinn said it is difficult to know the exact number of cases since diseased animals may not be noticed right away.

"It's a hard thing to judge that 80 percent of them have been reported or 30 percent have been reported," Flinn said.

The bluetongue virus is passed by midges, which are insects that are more prevalent during drought conditions, said Jason Sumners, another state deer biologist with the department.

"The appearance of the midge and the appearance of the infection is highly correlated with extreme summer drought and the conditions that we are experiencing now are ideal for that," Sumners said.

Typical symptoms include fever; excessive salivation; swollen neck, tongue or eyelids; sloughed or interrupted growth of hooves; and reduced activity and/or emaciation, according to the MDC. However, it is often difficult to notice these symptoms because deer often seem healthy even while infected.

"Usually, the animals appear to be in perfectly healthy condition, the exception that they are either extremely lethargic or already dead," Sumners said. "You typically find them near or in water sources, so at the edge of ponds or in the woods adjacent to a pond or a creek."

Deer tend to die within eight to 36 hours after they show signs of the virus.

The MDC has only confirmed six cases of the bluetongue virus, but Flinn said she believes the number exceeds the 1,100 estimate.

"[The 1,100 estimate] is not representative of the deer that succumb to the disease. That's the reports that we get from the public and then conveyed internally within us. We know that there's more deer that die from hemorrhagic than that number," Flinn said.

 In order to confirm whether the bluetongue virus is responsible for the death of deer, the spleen or the lung is collected within an hour after the deer dies and is sent to a laboratory in Georgia where they are able to confirm the virus, Flinn said.

The virus typically dies 24-hours after the animal dies. Therefore, the animal does not serve as a long-term source to pass on the disease.

"Humans do not get hemorrhagic disease, so handling and consumption of meat from deer that have recovered from the disease pose no health hazard," according to the MDC.

The virus is not only a problem in Missouri, but has been seen throughout the United States.

"I've seen reports anywhere from Pennsylvania to North Carolina, as well as Nebraska, Illinois, Iowa, and Kansas. Those range in amount of reports from several to a few hundred," Flinn said.

The conservation department asks people to report dead deer, especially deer found by ponds or bodies of water, so they are able to track the distribution and severity of the virus.  

Missouri Digital News is produced by Missouri Digital News, Inc. -- a non profit organization of current and former journalists.