Anthrax diagnosis, treatment and handling

Although 2021 hasn’t seen the number of anthrax cases registered in 2019, recent Texas Animal Health Commission reports of cattle deaths in the Rolling Plains and a horse death in the High Plains are gaining attention.

The Texas A&M Veterinary Medical Diagnostic Laboratory, TVMDL, typically diagnoses two to three positive cases of anthrax in livestock and wildlife every summer. This year, TVMDL has confirmed seven positives. Although these numbers are still slim compared to more active years and a report from Val Verde County is not surprising, the positives from Hardeman and Armstrong counties are, as they are not areas of Texas with a historic presence of anthrax.  

Historically, anthrax typically occurs in an area referred to as the “Anthrax Triangle.” This area in Southwest Texas is bordered by Uvalde, Ozona and Eagle Pass. It tends to have weather and soil conditions that make it more anthrax prone. In 2019, there were 23 confirmed positive cases in several species, including exotic antelope, goats, horses, white-tailed deer and cattle, primarily from this region.

“TVMDL works to ensure the health of our state’s livestock resource and a safe food supply,” said Terry Hensley, DVM, assistant agency director for TVMDL. “Although TVMDL has not confirmed as many positive cases this year as 2019, these current cases serve as excellent reminders for all veterinarians and animal owners across the state to remain observant for potential cases of anthrax. Contact your veterinarian immediately if you have suspicion of anthrax in an animal to discuss potential testing.”

Working together, against anthrax

When it comes to identifying, tracking and stopping the spread of diseases like anthrax, TVMDL is one of many partners working together to protect Texas livestock.

In accordance with state and federal regulations, TVMDL must report certain high-consequence diseases to various regulatory agencies. These include the Texas Animal Health Commission, the Department of State Health Services and, in the case of a potential bioterrorism agent like anthrax, the U.S. Centers for Disease Control and Prevention and the U.S. Department of Agriculture, as well. Once reported, regulatory agencies work with affected parties to control the spread of the disease.

Additionally, Texas A&M AgriLife is keeping producers and county agents who might be affected by the outbreak updated. Recent anthrax guidance for Texas producers has been provided by Texas A&M AgriLife Extension Service experts Tom Hairgrove, DVM, Ph.D., cattle veterinary specialist, and Ron Gill, Ph.D., beef specialist, both in Bryan-College Station, and Joe Paschal, Ph.D., livestock specialist, Corpus Christi, all in the Texas A&M Department of Animal Science.

Hairgrove said he has been discussing and teaching about anthrax in animals every day for the past month.

“The big anthrax concern this year is the location of the cases,” he said. “For perspective, an AgriLife Extension meeting that was pulled together with only 24-hours advance notice in Hardeman County attracted 150 people to the courthouse – standing room only – and another 50 people attended virtually.”

A wide variety of state experts participated in the meeting to answer questions over the two-hour period, stakeholders’ concerns included wanting to know how to protect themselves and when they should vaccinate.

In addition, area veterinarians have been asked to view a number of potential cases and are working with veterinarians in historical areas that have had outbreaks on a more frequent basis, Hairgrove said.

“We know the time to vaccinate livestock for anthrax is not now, unless you actually have confirmed anthrax case or are suspicious it might be a case of anthrax,” he said. “And if it is not confirmed and you are not quarantined, use common sense and don’t take your cattle to town to risk spreading anthrax at the sale barn if you suspect something.”

Hairgrove said individuals thinking about the anthrax vaccine who have not had suspected cases should wait until March and April, so the cattle will be protected during the time they will be most stressed with exposure during the summer. The vaccine only protects about six months.

What is anthrax?

Anthrax is endemic in certain areas of Texas, so TVMDL always expects to get a few positives every year. Caused by Bacillus anthracis, anthrax is a spore-forming bacterium that is naturally occurring in soil in certain parts of Texas and around the world.

It is typical to see an increase in anthrax after wet, cool weather that is followed by hot and dry conditions. Outbreaks usually end when the weather cools again. Animals can ingest the anthrax bacteria when they consume contaminated grass and hay or inhale the spores.

Bacillus anthracis spores can lie dormant in soil for several years, even decades. Typically, the bacterium infects grazing animals through ingestion of contaminated soil. Animals such as livestock and wildlife may also be exposed to anthrax through inhalation and through the skin; however, those are less common routes of transmission.

Anthrax is on the federal list of potential bioterrorism agents and is a zoonotic disease – a disease that can also infect humans. Therefore, anyone handling animals suspected of exposure to anthrax should take necessary precautions, such as wearing long sleeves and gloves.

Anthrax in livestock and wildlife

Clinical signs and common symptoms of anthrax in cattle, sheep, goats and deer may include fever, disorientation, labored breathing, muscle tremors, congested mucous membranes and collapse. It is possible for sudden death to occur without the presence of clinical signs. An animal can appear healthy and be dead within a matter of a few hours. In addition to the above clinical signs, horses may show signs of colic, enteritis and swelling of the neck and lower abdomen.

TVMDL encourages animal owners who have an interest in testing for anthrax to first contact a private veterinarian who can assist with evaluating suspect animals and the proper collection of samples. Once testing has been conducted, a TVMDL veterinary diagnostician can consult with private veterinarians and animal owners on additional testing and sampling requirements.

Protecting animal and human health

In addition to anthrax surveillance testing, TVMDL offers over 700 tests for a variety of diseases and conditions from clients across Texas, the U.S. and other countries.

For more information on anthrax and other TVMDL test offerings, visit https://tvmdl.tamu.edu or call the College Station laboratory at 1-888-646-5623 or the Canyon laboratory at 1-888-646-5624. To learn more about precautions when handling suspected anthrax samples and disposal of anthrax-infected carcasses, visit the Department of State Health Services website.