West Nile season begins early
Cattle Market & Farm Reports, Editorials
Jun 26, 2006
West Nile Virus has once again started to plague many western states. According to the Centers for Disease Control, active cases of the disease have been detected in mosquitoes and birds in California, Idaho, Utah, South Dakota and Wyoming, and nine other Midwest and East Coast states. In Texas, Mississippi and Colorado, the disease has already been transmitted to humans.
A spring and early summer which has dumped above normal amounts of precipitation in some West Coast states has contributed to the problem by offering mosquitoes more breeding grounds than in past years.
In Utah, parts of which are currently well above normal for precipitation, the problem this year comes six weeks sooner than last year. Utah County Department of Health spokesman Lance Madigan said the batch of mosquitoes that tested positive was in Goshen, UT. That area was the center of West Nile activity during the 2005 season.
“There’s a lot of marshy land down in the south end of the county,” Madigan said. “That’s why we’ve been planning on doing aerial spraying down there.”
Utah County officials also emphasized the need to vaccinate horses. The county led the state in equine cases of West Nile Virus in 2005.
The county regularly samples mosquito larvae found in standing water to locate pools of the disease. This is the first positive mosquito test in the state, although two magpies tested positive for the virus in Salt Lake County last month. In an effort to be proactive and limit the spread of the disease, the Utah Department of Agriculture and Forestry has offered $150,000 in grants this year to assist communities with mosquito spraying costs. Several other states, including South Dakota, have also set up grant programs in an effort to control the spread of mosquitoes which have been found to carry the disease. South Dakota’s grant program is expected to spend $518,000 this year in an attempt to limit the spread of the disease.
In Colorado, where much of the state is much drier than normal, one of only a handful of human cases so far nationally was confirmed in Weld County, located in the north central portion of the state. In western Colorado along the Utah border, officials have also found the disease in Mesa County in a bird submitted to the Department of Health for testing.
The impact of the disease on horses can be serious and, in many cases, fatal. Veterinarians in most states are recommending that horse owners vaccinate animals as soon as possible in an effort to minimize the likelihood of infection. Because the vaccine requires a series of shots, it is important to begin the vaccination process before the disease begins to spread more rapidly.
In horses that do become clinically ill, the virus infects the central nervous system and causes symptoms of encephalitis. Clinical signs can include: loss of appetite, depression, fever, weakness of hind limbs, paralysis of hind limbs, impaired vision, ataxia, head pressing, aimless wandering, convulsions, inability to swallow, circling, hyperexcitability, or coma.
In humans, infections are generally mild, and symptoms include fever, headache, and body aches, occasionally with skin rash and swollen lymph glands. More severe human infection may result in headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis, and rarely, death.
In order to avoid being infected, health department officials recommend the following precautions be taken to limit exposure to insect vectors of the disease:
• Drain standing water near the house and work areas.
• Avoid being outside at times when mosquitoes are most active, particularly at dawn and dusk.
• If you cannot avoid being outside at dawn and dusk, use a mosquito repellent which contains DEET to help prevent insect bites.
• When practical, wear long sleeve shirts and pants to limit the amount of skin exposure.
Although West Nile Virus is not frequently transmitted to humans, health department officials across the nation are urging caution this year and warn individuals who exhibit any of the symptoms listed above to contact their health care provider immediately.