West Nile Virus in Missouri:  Increased Risk of Human Disease July through October

As Missourians plan outdoor activities for the upcoming Fourth of July holiday, they should remember to pack insect repellent to ward off mosquitoes that can carry West Nile Virus. 

Human cases of West Nile Virus typically surface in July in Missouri and can continue through October. Though the number of Missouri cases has decreased over the past six years, the virus still poses the risk of serious illness, debilitation and even death, said Dr. Howard Pue, the public health veterinarian for Missouri. 

Last year’s total of 15 cases in the state was a record low in the seven years the virus has been present in Missouri. But Pue warned that the drop in 2008 likely resulted from cool early summer temperatures as well as frequent rainfall, which had the effect of flushing out many mosquito breeding locations. 

“The number of people affected by WNV disease and the location of intense outbreaks will change each year,” said Pue.  “I am concerned that people are unaware of their personal risk or have let down their guard. We all must do what we can to protect ourselves, our family and our community from WNV.”

Nearly 450 Missourians have become ill and 24 have died from West Nile Virus since the virus was first reported in the state in 2002.  Many cases are not reported, so the true number of WNV-related illnesses is certainly higher.  It is clear that West Nile Virus is now well established in Missouri and across the United States, Pue said.

One in five persons infected with WNV will develop symptoms, although most will have only a mild, flu-like disease.  For most, illness lasts a few days. But the illness can last several weeks, even in otherwise healthy people. Symptoms can include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash.

Pue warned that some people, particularly those over 50 and those with underlying medical conditions, can develop severe disease with life-altering consequences. The virus can cause polio-like paralysis or encephalitis and meningitis, two conditions that cause inflammation around the brain.  These diseases cause neurological damage and can be fatal.

To defend against mosquitoes and the risk of West Nile Virus, use these simple but effective techniques:

·         When outdoors, use insect repellents with DEET, picaridin, or oil of lemon eucalyptus.  Re-apply if mosquitoes start to bite, always following label instructions;

·         Wear long sleeves and pants when mosquitoes are most active -- between dusk and dawn;

·         Fix or install window and door screens;

·         Eliminate potential mosquito breeding sites by emptying standing water.  Change the water in outdoor pet dishes daily and rinse out birdbaths and potted plant saucers weekly.  Empty children’s wading pools, store buckets indoors, and turn in old tires for recycling.