"Right now, Texas has half the West Nile cases in the nation," Dr David Lakey, Texas state health commissioner, told reporters at a press conference last week. "Dallas County has half of the cases in the state, so about a quarter of all the cases in the United States are in this county. This isn't business as usual."

According to Texas Department of Health (TDA) figures, 465 West Nile cases have been confirmed in Texas this year, including 17 related deaths, which is on track for the most cases since the disease first reached the state late last century. Ten deaths and more than 200 cases this year have been reported in Dallas County alone.

In rural Texas, WMV poses little threat to livestock, but horses and birds are subject to infection. In 2011 six cases of equine WMV were confirmed in Texas. Horses and humans are, in fact, the most likely mammals to show signs of the disease. Infections with West Nile virus have been documented in other mammals as well with evidence of illness in cats, dogs, sheep, goats, bats, llamas, wolves, and rodents.

When evaluating a cow with signs of general lethargy or neurological impairment, West

Nile Fever remains very low on the diagnostic list. But health officials warn that any evidence of neurological disease in cattle should be seriously considered.

Controlling WMV on the farm and ranch involves eliminating mosquito breeding grounds. In addition to stock ponds and water troughs, old tires, feed buckets and any other container that holds water is a potential breeding ground. In addition, overflowing septic systems can pose a serious problem.

High risk times of the day when mosquito bites are most common include early mornings and early evenings, and farm and ranch workers should use an approved insect repellant containing Deet, the most effective repellant, when working outdoors.

The CDC reports that as of August 14, 43 states have confirmed West Nile infection in people, birds or mosquitoes this year, with more than80 percent of cases from six states: Texas, Mississippi, Louisiana, Oklahoma, South Dakota and California.

The 693 human cases reported to CDC through the second week in August is the highest number for that time of year since the virus was first detected in the United States in 1999. At least 26 people have died nationwide.