The West Nile Virus season is here and showing signs that it could be the worst yet. West Nile, a life threatening mosquito borne illness, will continue to be a threat into late summer and early fall. In the past week, the Center for Disease Control reports 1,993 cases of WNV in humans, which have claimed 87 lives. That is the highest number recorded at this time of the year since WNV was first detected in the United States in 1999. Approximately 45 percent of cases reported this year are from Texas.
The CDC reports that over 70 percent of WNV in humans come from Texas, South Dakota, Mississippi, Oklahoma, Louisana and Michigan. Missouri health officials have recorded seven probable and confirmed cases for 2012. Missouri health officials also confirmed in late August that a 78 year old man from Laclede County, died from WNV.
In the past week, two more Missouri residents were diagnosed with WNV. A man from Southeast Missouri has been hospitalized in St. Louis after being diagnosed with the virus, and a St. Louis County woman has recovered from what health officials called a likely case.
The CDC says there are five things you should know about WNV. Most mosquitoes do not carry WNV, only one in every 500 mosquitoes is infected. Most people bit by WN mosquitoes do not get sick. Only one in every 150 people infected will develop a severe illness. Using mosquito repellent with DEET, dressing in long pants and long sleeves, being careful at dusk and dawn, and draining any standing water are all ways to prevent WNV. People over 50 years old are the most vulnerable. Last, seek medical care immediately if you have severe headaches or confusion, which are symptoms of severe illness.
The Oregon Health Department says, while no West Nile cases have been reported in Oregon County, prevention tips located on the CDC website should be followed.
After birds, horses are the animals most susceptible to WNV. The first WNV horse death in Missouri was reported in West Plains. A sample of the horse's blood was submitted to the University of Missouri, School of Veterinary Medicine Diagnostic Laboratory, and it confirmed WNV was at fault for the death for the seven year old brood mare.
After an infected mosquito bites a horse, the virus invades the brain and spinal system. According to the University of Nebraska Extension, once a horse has been bitten, it may take up to 15 days for symptoms to appear. Loss of appetite, depression, weakness of hind limbs, partial paralysis, fever, impaired vision, aimless wandering, and inability to swallow are a few of the symptoms.
There is a vaccine available for horses, but must be administered by a veterinarian. The initial vaccine is a two injection series, given three weeks apart. A single booster is recommended within six months of peak mosquito season in horses that have been given the two injection vaccine. It has been reported that the vaccine is 94 percent effective.