What is anthrax?
Anthrax is a serious infectious disease caused by a bacteria called Bacillus anthracis. This bacteria occurs naturally in certain species of animals in the southwestern part of Texas. Many different types of animals, as well as people, can get the disease.
Where in Texas does anthrax occur?
Although anthrax can occur anywhere in the state, the cases are most often confined to a triangular area bounded by the towns of Uvalde, Ozona and Eagle Pass. This area includes portions of Crockett, Edwards, Kinney, Maverick, Sutton, Uvalde, and Val Verde Counties. In these counties, many livestock producers routinely vaccinate livestock against the disease.
Why does anthrax occur in some years and not in others?
Anthrax outbreaks depend on two factors working together: the presence of anthrax spores in the soil, and suitable weather conditions. The bacteria grows and contaminates the surface soil and grass after periods of wet, cool weather, followed by several weeks of hot, dry conditions. Outbreaks in animals usually end when cool weather arrives and the bacteria becomes dormant. An outbreak may occur one year, but not the next. Death loss may occur in one pasture, while animals nearby remain healthy.
Anthrax in Animals
Which animals are usually affected by anthrax and how are they infected?
Grazing and browsing animals, such as cattle, sheep, goats, horses, and exotic and domestic deer are the species usually infected with anthrax. They inhale or ingest the anthrax bacteria as they eat plants which have been contaminated with the bacteria. Domestic and wild swine are fairly resistant to anthrax although they may become ill. Dogs, cats, and other carnivores are very rarely infected with anthrax, and symptoms in these species are usually much less severe than in deer and livestock.
What are the signs of anthrax disease in animals?
Signs of the illness usually appear 3-7 days after the anthrax spores are inhaled or swallowed but may occur sooner if a large number of spores are inhaled. Once symptoms begin, animals usually die within two days. Seriously-affected animals may stagger, have difficulty breathing, tremble, and finally collapse and die within a few hours. Animals with less serious cases may have a rise in temperature, a period of excitement followed by staggering, depression, unconsciousness, difficulty breathing, convulsions, and death.
How is anthrax diagnosed?
Symptoms may make a veterinarian suspicious of anthrax, but the disease can often be confused with other illnesses. Confirmed diagnosis can only be made through laboratory testing of the animal's blood.
How is anthrax treated?
It is usually hopeless to treat animals that are already showing signs of anthrax. Occasionally, if the disease is diagnosed soon after infection, antibiotics, along with adequate nursing care, may help.
Is an anthrax vaccine available?
A vaccine for livestock is frequently used in areas where anthrax is common, but the vaccine must be used before the animal is infected with the bacteria. The vaccine for livestock is not the same as the one for humans. No vaccine is available for pets.
Anthrax in People
How do people get anthrax?
Anthrax spores are not in the air or in water. However, you should avoid touching any animal carcasses you come across in the wild. People usually get anthrax through handling a dead or sick animal infected with anthrax or eating the meat from infected animals. Shearers, stockmen, and veterinarians, as well as other agricultural workers exposed to hides or raw wool have a slightly increased risk for anthrax exposure.
What are the symptoms of anthrax in humans?
Symptoms of disease vary depending on how the disease was contracted, but usually occur within 7 days after exposure. The three forms of human anthrax are inhalation anthrax (caused when the spores are inhaled into the lungs), cutaneous anthrax (caused when broken skin comes into contact with infected animals or hides), and intestinal anthrax (caused when undercooked meat from an infected animal is eaten).
Initial symptoms of inhalation anthrax infection may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal, unless the patient is treated before any symptoms occur.
The intestinal disease form of anthrax may follow the consumption of contaminated food and is characterized by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, and fever are followed by abdominal pain, vomiting of blood, and severe diarrhea. Like inhalation anthrax, the intestinal form is usually fatal.
The cutaneous form of the disease begins with itching at the site of the exposure, followed by the formation of a round, pimple-like sore. This sore will then form a blister which, after 2-6 days will become a hard, black scab (similar to the scab left after a deep burn). Untreated, between 5 and 20% of patients will die. However, with adequate antibiotic treatment very few deaths occur.
Direct person-to-person spread of anthrax is extremely unlikely, if it occurs at all. Therefore, there is no need to immunize or treat contacts of persons ill with anthrax, such as household contacts, friends, or coworkers, unless they also were also exposed to the same source of infection.
As a hunter, am I at risk for contracting anthrax?
The normal hunting season in Texas occurs in the cooler months of the year when anthrax bacteria is dormant and cases traditionally do not occur. Anthrax rapidly results in the death of infected animals, and diseased animals appear very ill before they die. There is very little risk of infection as long as hunters harvest only healthy animals, wear latex gloves and long sleeved shirts when field dressing them, and thoroughly cook the meat before eating it.
As a rancher, what can I do to protect myself and my animals from anthrax?
An effective anthrax vaccine for livestock and horses can be purchased through private veterinary practitioners, feed stores, or animal health product distributors. The injection can be administered by private veterinary practitioners or rancher personnel and is recommended for:
- livestock residing in or near an area where anthrax often occurs; and
- animals that will be moved into the area, such as horses transported to trail rides.
When administering the vaccine, wear a long-sleeved shirt and use latex or work gloves to prevent skin contamination with this vaccine. Consult your physician for treatment if you stick yourself with a needle, splash vaccine in cuts or scratches, or if you develop a sore after handling vaccine or livestock.
During an outbreak, white-tailed deer often suffer the most from the disease, as they cannot be rounded up and handled like domestic or farmed exotic livestock.
If your veterinarian diagnoses anthrax, he will recommend that you burn the carcass. Thorough burning prevents contaminating the ground with the anthrax bacteria. In fact, the Texas Animal Health Commission requires that property or livestock owners thoroughly burn carcasses of animals that may have died from anthrax. To protect yourself, wear long sleeves and gloves, and do not move or open carcasses, as this could further release the bacteria into the environment, causing further disease spread. Do not salvage hides, horns, antlers or any other tissue from the carcasses.
If the animal was housed in a barn, burn the animal's bedding, manure and the surrounding soil. To disinfect panels, trailers or equipment, use an ammonia-based disinfectant, labeled as effective for anthrax. Follow label directions to prevent respiratory irritation. Pastures cannot be disinfected with chemicals. Due to environmental concerns, do not use heavy oils or tires to burn carcasses. Fuels permitted by the Texas Natural Resource Conservation Commission (TNRCC) include gasoline, diesel or wood. Care should be taken to keep fires from getting out of control. In counties under a burn ban, burning must be coordinated with local fire authorities.
If possible, vaccinate and move healthy livestock to clean pastures, away from the carcasses.
Texas Department of State Health Services - Infectious Disease Control Unit
1100 West 49th Street, Suite T801, Mail Code: 1960 PO BOX 149347 - Austin, TX 78714-9347
(512) 458-7676 - Fax: (512) 458-7616 - E-Mail
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