Anthrax A Special Lesson Produced by: Amber Dowd & Dr. Frank B. Flanders Revised July 2009 CTAE Resource Network Teachers should view notes pages for additional information on certain slides. View note pages by clicking on ‘View’ and then ‘Notes Page’.
Anthrax is no stranger to agriculture Anthrax has been on America’s mind in recent years because of terrorist attacks, however, anthrax has affected humans and animals for centuries.
Anthrax is rare on the East Coast. Farmers in the West, Midwest and parts of the South still deal routinely with anthrax. • Animal deaths from anthrax rarely make news. Deaths of wild animals such as deer and bison as well as domesticated animals is common.
The last documented case of anthrax in Georgia animals was in 1948. The environment in Georgia, and some other states, does not seem to be suitable for long-term survival of anthrax. The characteristics of Georgia soils (low pH and not as hot and dry as soils in the Western US) are thought to be a poor environment for anthrax spores. • Texas is one state in which anthrax is common. More than 1600 cattle died in Texas from anthrax during 2001.
What is Anthrax? • A disease of most mammals, including humans, that is caused by a rod-shaped, spore-forming bacterium called Bacillus anthracis.
Disease is defined as any deviation in the normal health of plants or animals. • Microorganisms that most commonly cause disease are bacteria, viruses and fungi. • Anthrax was the first microorganism ever linked specifically to a disease.
History of Anthrax • Although anthrax has recently become a greater threat to humans, it is suspected to have been around since biblical times. • The 5th and 6th plagues in the Bible’s book of Exodus may have been anthrax. • The “Black Bane,” a disease that that swept Europe in the 1600’s, was most likely anthrax.
In the 1870’s, Robert Koch, a German family doctor, accidentally discovered anthrax while trying to figure out the cause of death in an animal. • In 1876, he published a paper identifying the bacterium, genus and species bacillus anthracis, as the cause of anthrax.
In 1881, Louis Pasteur made anthrax the first bacterial disease for which a vaccine was available. • More than 6,000 cases in humans occurred in Zimbabwe between October 1979 and March 1980.
Anthrax Worldwide Military personnel deployed to areas with high risk for exposure are usually vaccinated.
Susceptibility All mammals appear to be susceptible to anthrax, but ruminants such as cattle, sheep, and goats are the most susceptible, followed by horses and swine.
Anthrax is a zoonotic disease, meaning it may spread from animals to humans. Examples of other zoonotic disease are, cat-scratch fever, rabies and ringworm. However, it does not spread from human to human.
Anthrax spores occur in many areas, such as soil, but only become a problem when ingested in a sufficiently large concentration. • Grazing animals may be more susceptible because they breath air close to the ground as they graze where anthrax spores are in greatest concentration.
“Anthrax zones” are areas where there is a high concentration of anthrax spores in the soil. • Anthrax zones in the US are primarily where the cattle drive trails of the 1800’s took place. • Spores can survive for many decades and are resistant to heat, sunlight, and drought.
How is Anthrax Contracted? • Animals are usually infected by ingesting soil-borne spores, such as in contaminated food or water. • Spores can be picked up directly from the soil or plants through grazing or from feed grown on infected soil. • It is possible for animals to become infected by inhaling dust containing anthrax spores.
Bites from flies and other insects that carry anthrax have also been reported to cause infection. • The incubation period of natural infection in animals is usually 3 to 7 days, with a range of 1 to 14 days.
Symptoms in Animals • Signs are fever up to 107º F, muscle tremors, respiratory distress, and convulsions. Death occurs quickly and often before symptoms are observed. • Animals that die of anthrax bloat quickly. Blood may come from the nose and other body openings.
Animals that die of anthrax don't have rigor mortis (stiffening of the body after death) because the blood does not clot upon death. • A toxin released by the bacteria prevents blood clotting in the bodies of animals that die of anthrax.
Swine, dogs, and cats usually have swelling of the neck. Carnivores apparently have some natural resistance to anthrax and recovery is not uncommon. • If a problem is suspected a vet should be called as soon as possible.
Preventing Infection • If anthrax is diagnosed, all the animals in contact must be examined for up to two weeks, and their temperatures need to be taken regularly. • If an animal is found to have a fever, it should be given antibiotics immediately. • When animals are at risk of anthrax they should be vaccinated annually. • The anthrax vaccine has proven to be effective in field situations and can protect animals for about one year.
Treatment of Infected Animals • Because of the rapid course of the disease, infected animals are often found dead or too sick to be treated. • Anthrax can be treated if it is still in the early stages when fever is the only clinical sign. • The treatment for anthrax is to use antibiotics for at least five to six days.
Disposing of Infected Animals One reason for the low human rate of infection may be that most ranchers recognize the signs of anthrax in animals, know how to avoid exposure and to dispose of dead animals.
Contact with infected blood or tissue should be avoided by wearing gloves. • Wash-up after contact with an infected animal is imperative. • Burying infected animals only preserves the organism deep within the soil and is not recommended.
Animals that die of anthrax should be burned on-site in a very hot fire. Dragging them to another area only spreads the disease.
Anthrax in Humans • The disease occurs when spores enter the body, germinate, multiply, and release toxins. • In humans, anthrax is fairly rare; the risk of infection is about 1/100,000. • Exposure to the bacteria causes the body to produce antibodies for the disease. • Most exposure is from working with infected animals.
Human anthrax has three major clinical forms: • cutaneous • inhalation • gastrointestinal • If left untreated, anthrax in all forms can lead to septicemia and death.
Cutaneous (Skin) Anthrax is the most common. It is contracted through a cut or abrasion on the skin.
Inhalation anthrax is the most deadly, resulting in death 95-100% of the time. • An estimated 8 to 10 thousand spores must be inhaled to contract the disease.
A deadly but far less common form of anthrax in humans is gastrointestinal anthrax, contracted from eating undercooked, infected meat. • It is fatal 20-60% of the time without treatment, but is very rare, because animals usually die within 12 to 48 hours after contracting anthrax. • Farmers generally know not to butcher and eat animals that die of unknown causes.
The last case of inhalation anthrax in the United States before 2001 was in 1976 in California. • The last case of cutaneous anthrax before 2001 occurred in North Dakota in 2000.
Am I at risk? • The average person has a very small chance of being exposed to anthrax, however, everyone should be extremely watchful and careful, especially around sick animals. • USDA inspections of commercially processed meat keeps our food supply safe. • A person can be exposed without having the disease.
Symptoms in Humans • Fever (greater than 100° F) • Flu-like symptoms (most common) • Cough, chest discomfort, shortness of breath, fatigue, muscle aches • Sore throat, difficulty swallowing, enlarged lymph nodes, headache, nausea, loss of appetite, abdominal distress, vomiting, or diarrhea • A sore on the face, arms or hands, that starts as a raised bump and develops into a painless ulcer with a black area in the center
Diagnosis and Treatment • Anthrax can be diagnosed by testing for antibodies or bacteria in blood. • Antibiotics, such as Cipro, are used to treat anthrax.
Anthrax as a Weapon • To some military planners, anthrax is the single greatest biological warfare threat. • Even though there are world treaties against using biological and chemical weapons, it is suspected that countries are still producing them.
The first attempt to use anthrax as a biological warfare agent occurred in World War I, when Norwegian police arrested a German agent carrying two vials of the bacteria to be used to infect reindeer ferrying supplies to allied forces in Europe. The spores were still viable when scientists analyzed them in 1998.
In World War I almost every country involved had a biological warfare program that included anthrax. • During World War II, Britain experimented with anthrax as a biological warfare agent on a British island. • After the war, the island was burned to decontaminate it. However, after burning, the concentration of anthrax was the same as before it was burned. Britain needed 36 years to clean up the island.
Anthrax is considered a viable biological weapon because: • it produces spores that are hard to kill and that last for decades. • it kills quickly. • it can be ground to a fine powder that can be suspended in the air. • it is easy and cheap to produce. • it has a potential for mass destruction.
Anthrax in the Mail • In 2001, terrorists began sending anthrax through the mail. • In some instances, anthrax exposures have occurred with several persons becoming infected, and some have died. • To prevent exposure everyone should learn how to recognize a suspicious package or envelope.
Summary Anthrax: • has been around since biblical times • is a disease agricultural producers have always had to deal with • can be used as a deadly biological weapon • is common along the cattle trails of the west • is caused by a bacteria • is a manageable disease unless spread maliciously