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Texas State Vet tells horse owners to vaccinate now as flood water recede

neuson11/Thinkstock Close-up of Mosquito
Close-up of a mosquito sucking blood.
Horse owners, however, understand that while the risk of WNV in humans falls short of being critical for most people, horses and other equine are in more jeopardy. The mortality rate in horses from WNV is reported to be around 30 percent. A recent outbreak of WMV in equine in Texas is a cause for concern according to the Texas State Veterinarian.

The Texas Animal Health Commission is urging horse owners in Texas to monitor their animals for signs and symptoms of West Nile Virus (WNV), Eastern equine encephalitis (EEE), and other mosquito-borne diseases, and recommends that horses be vaccinated against what could be a growing threat from these diseases.

Most people, especially those who live in Texas and other warm-weather or sub-tropical regions, are aware of the risks associated with West Nile Virus in humans. Each year when mosquitoes are most active, human cases of WNV are reported. While WNV cases are more prevalent in warmer, southern states, cases have been reported in all of the continental United States. The season for the virus, for both humans and equine, begins at the start of spring and continues through fall.

But the risk of a WMV infection in humans is a mixed bag. Because the disease can be contracted with little or no ill effects, many of us take for granted the many and often repeated annual warnings about the dangers of the disease.

While the Center for Disease Control in Atlanta warns there are no vaccines to prevent or medications to treat WNV, most people infected with the virus do not develop serious symptoms. Only about one in five people who are infected develop a fever or other, more serious symptoms. And only about one out of 150 to 200 infected people develop a fatal form of the illness. Generally, less than 200 people, or about one-percent, die from WNN in the United States annually.


Horse owners, however, understand that while the risk of WNV in humans falls short of being critical for most people, horses and other equine are in more jeopardy. The mortality rate in horses from WNV is reported to be around 30 percent. A recent outbreak of WMV in equine in Texas is a cause for concern according to the Texas State Veterinarian. Five new cases of West Nile virus this year have been confirmed at the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) as of Aug. 24, just a day before Hurricane Harvey hit the state, and one case of Eastern equine encephalitis was also confirmed, bringing the total to nine cases of serious mosquito-transmitted disease to the state's equine population so far.

The counties with positive cases include Limestone County, Erath County, Denton County, Austin County, Montgomery County, Lamar County, Polk County, McLennan County, and Wood County.

While WNV can claim as many as one-third of horses infected, EEE has a much higher mortality rate in horses, an estimated 80 to 90 percent. As mosquito populations rise, so does the risk of mosquito diseases, like WNV, EEE, Malaria, Dengue Fever, Yellow Fever, and other diseases that can infect humans, equine, birds, some forms of wildlife, and even house pets, according to the latest research.


Fortunately for horse owners, there are vaccinations available for WNV and EEE, and this seems to be the focus of the latest warnings from TAHC, especially following the vast amount of flooded areas across parts of the state following Hurricane Harvey. More two weeks after the storm hit, many fields are still inundated by flood waters, and the risk to both animals, like equine, and to humans, are greatly elevated in those areas

In cases of EEE in equine, TAHC warns the virus causes inflammation or swelling of the brain and spinal cord. General symptoms include central nervous system signs such as: head pressing, convulsions, lack of response to facial stimulation, fever above 103 degrees, ataxia, paralysis, anorexia, depression and stupor. Other symptoms may include irregular gait, teeth grinding, lack of coordination, circling, and staggering. All symptoms may not be exhibited by an infected horse.  

While WNV pose less risk to humans, EEE is considered a major risk to human health, and there are no human vaccines against it. Eastern equine encephalitis virus (EEEV) is also transmitted to the human population by the bite of an infected mosquito. Fortunately, Eastern equine encephalitis (EEE) is rare in humans, and only a few cases are reported in the United States each year. Most cases occur in the Atlantic and Gulf Coast states. Severe cases of EEE involving encephalitis, an inflammation of the human brain, begin with the sudden onset of headache, high fever, chills, and vomiting. The illness may then progress into disorientation, seizures, or coma. EEE is one of the most severe mosquito-transmitted diseases in the United States with approximately 33 percent mortality and significant brain damage in most survivors.

For human precaution, it has been recommended that to avoid mosquito bites you should avoid being outdoors during dusk and dawn. While this is true for mosquitoes that commonly carry the West Nile virus, other types of mosquitoes that are more likely to carry Zika, dengue and chikungunya are active during the day. When outdoors, no matter what time of day, adjust your dress accordingly and wear insect repellent containing DEET, picaridin or oil of lemon eucalyptus as your first line of defense against insect bites.

The Texas Department of State Health Services (DSHS) is responding to flooding and other effects of Hurricane Harvey in Texas. DSHS coordinates public health and medical services during disasters in the state, including the evacuation of health care facilities, providing shelters for people with special medical needs, and supporting the behavioral health of responders.


In the Coastal Bend area, flight crews had a scheduled safety rest day last night and will be flying again tonight, planning to complete Lavaca County and begin spraying over Jim Wells and Kleberg counties.

Along the upper Texas coast, the state is receiving support from the U.S. Air Force Reserve’s 910th Airlift Wing flying modified C-130 cargo planes staged out of Kelly Air Force Base in San Antonio. Earlier this week, approximately 156,000 acres over Brazoria, Chambers and Jefferson counties were treated. Officials say they plan to be working over those counties again in the days ahead. Flights over Harris County are planned to take place immediately. A total of approximately 2.01 million acres have been sprayed across all areas so far.

During aerial spraying, a small amount of insecticide is sprayed over a large area, one to two tablespoons per acre, say officials. When applied according to label instructions by a licensed professional, they report it does not pose a health risk to humans, pets or the environment. According to the EPA, people may prefer to stay inside and close windows and doors when spraying takes place, but EPA officials say it is not necessary.




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