Health officials remind rural residents that West Nile Virus infection can not only cause fatal encephalitis (inflammation of the brain) in humans but in horses as well. Even certain domestic and wild birds can contract the disease.

A single horse from Otero County, New Mexico,has tested positive for the disease this year. Since WNV was detected in New Mexico in 2003, 438 horses have been confirmed as victims of the disease. While more rare, other animals in New Mexico have contracted the disease as well, including bovine, porcine, llama and canines. A harbor seal at the Albuquerque zoo was also diagnosed with WNV in recent years.

In Texas this year, 27 horses have been diagnosed with Wet Nile Virus.

Dr. Kristy Murray, who led the research of the 2012 Texas WNV outbreak conducted by the National School of Tropical Medicine at Baylor College of Medicine in Houston, says last year's unexpected outbreak demonstrated the need for ongoing mosquito surveillance and the necessity of developing an effective human vaccine.

She says considering the cost of acute medical care and lost productivity caused by last year's outbreak, a minimum loss of $47 million can be blamed on the 2012 incident.

"When you look at what it is costing us as a society, it’s enormous. Last year it was easily $47 million for just acute medical care, and that’s a very, very conservative estimate,” Murray said.

Texas was the epicenter last year of the largest West Nile outbreak in U.S. history.

The study indicated a historical uptick in the number of cases every three years, but it also concluded there was no obvious reason for the extreme outbreak of WNV last year. But health officials warn that the greater question may be why the ratio of the more serious neuroinvasive disease is much greater this year than for the less invasive West Nile fever cases. Even during last year's historic outbreak 844 nueroinvasive cases compares to just over 1,000 milder cases. In contrast, nearly 65 percent of WNV cases this year are nueroinvasive.

Some 135 Texas counties reported at least one WNV case last year, but the largest number of cases was reported in North Texas. Tarrant County reported 259 confirmed cases (14 percent), 396 cases were reported in Dallas (21 percent), 183 in Denton (10 percent) and 64 in Collin (3 percent), according to the study. Those four counties had a combined incidence rate of 16 cases per 100,000 population, an extremely elevated ratio compared to normal years.

Officials say with the advent of cooler weather in November, the number of confirmed cases should decrease rapidly.


Also of interest from Southwest Farm Press:

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