What Is Anthrax?
Learn the symptoms after exposure
Medically reviewed by Anju Goel, MD, MPH
Anthrax is a rare but serious infectious disease caused by the bacterium Bacillus anthracis. This bacterium is often found in the soil and infects animals. Its spores can be weaponized and turned into a powder.
Bacterial spores are dormant forms of bacteria that have evolved to survive harsh environments for a long time without resources to grow or multiply. They turn off all but the essential functions and wait for the time to be right again.
People get anthrax infections from anthrax spores. Depending on how a person is exposed, they can have varying effects. If spores are inhaled, they can be deadly. The effects are milder when only the skin is infected.
Anthrax is rare in the United States. Fewer than a dozen people a year come into contact with it, and most are exposed from working with animals, not from weaponized anthrax powder.
This article will describe what anthrax powder is, what anthrax does to humans and cattle, where anthrax comes from, and how contagious anthrax is. It will explain how anthrax spreads, the signs of anthrax exposure, and treatment options for anthrax.
Anthrax Powder History
The bacteria that create anthrax spores occur naturally. Anthrax bacteria can be grown in the lab to make anthrax powder. Anthrax powder is purified anthrax spores that have been processed so that they can spread through the air.
Anthrax can be used as a biological weapon because of several unique bacterial traits:
The bacterial spores are widespread.
Spores can be made in a lab.
Spores survive for a long time.
Spores can be put into powders, sprays, food, and water.
They are so small you can’t see, smell, or taste them.
Anthrax has been used as a bioterror weapon since World War I. The most significant use of anthrax in recent memory is a 2001 attack in the United States. Someone sent letters filled with a white anthrax powder to two U.S. Senators and news media offices.
Twenty-two people came into contact with anthrax (11 respiratory and 11 skin infections), and five died.
How Do Humans Encounter Anthrax?
Humans encounter anthrax from coming into contact with bacterial spores. These spores are present in the soil and can also infect animals.
A person might also get anthrax spores in an open wound on their hand from touching dirt, an infected animal, or animal products like wool, hides, or hair. They may also ingest them from eating an animal that had them or drinking water that contains spores.
Anthrax spores can be turned into a powder. These spores float in the air and can be inhaled. This type of anthrax has been used as a bioterror weapon and can be deadly.
If you think you’ve come in contact with anthrax powder, talk to a healthcare professional right away. If you have signs of anthrax poisoning, go to the ER immediately.
Animals get anthrax similarly; they come into contact with the spores in the soil, plants, or water. Farm animals in areas where there may be exposure to anthrax are typically vaccinated against anthrax to help prevent outbreaks.
Animals susceptible to anthrax infection include:
Is Anthrax Contagious?
Anthrax isn’t contagious the way a cold or the flu is contagious. You can’t “catch” anthrax poisoning from a person with the infection just by interacting with them.
Rarely, the infection may pass from one person to the other through secretions from an infected wound. When caring for someone with an anthrax skin infection, take precautions to avoid getting the fluid from the wound on your skin.
Signs of Anthrax Poisoning
When anthrax spores enter the body, they are “activated” and no longer dormant. They then multiply, spread in the body, and make toxins that can make you sick.
The signs of anthrax poisoning differ based on how you’ve come into contact with anthrax. All types of anthrax can be deadly if the infection spreads throughout the body.
Inhaling anthrax spores causes severe symptoms and can be deadly. You may breathe in these spores from the dirt while processing an animal product like wool or a weaponized powder.
Symptoms usually develop within a week after exposure but can take as long as two months. The infection first spreads to the lymph nodes in the chest and then to the rest of the body. It causes breathing problems and can send the body into shock.
Symptoms of inhaled anthrax include:
Fever and chills
Chest pain, cough, and shortness of breath
Headache, confusion, or dizziness
Nausea, vomiting, or stomach pains
Bouts of heavy sweating
Exhaustion and body aches
Anthrax on the Skin
The most common way people get infected by anthrax is by getting spores into a wound on the skin. This can cause an infection called cutaneous anthrax. Spores may come from an infected animal or the soil.
Cutaneous anthrax is most common on the head, neck, forearms, and hands. It affects the skin and tissue around the site of infection. Signs of infection show up one to seven days after exposure to the spores.
Symptoms of anthrax positioning on the skin include:
A group of small (sometimes itchy) blisters or bumps
The bumps can turn into a painless sore with a black center
Swelling around the sore
Getting an anthrax infection through an injection deep under the skin or in the muscle is also possible. This has been reported in people in northern Europe who inject heroin. Researchers think the anthrax was in the heroin itself, not the environment. This has not been reported in the United States so far.
Anthrax can infect the gastrointestinal system, causing ingested anthrax. This may happen when you eat raw or undercooked meat from an infected animal. This is rare in the United States, where many animals get vaccinated against anthrax and inspected before slaughtering. It’s more common in other areas of the world where the vaccine is less common.
Infection with gastrointestinal anthrax can take one to seven days to show up after exposure. It can infect any part of the upper gastrointestinal tract, including the throat, esophagus, stomach, and intestines.
Symptoms of ingested anthrax include:
Fever, chills, or headache
Sore throat, hoarseness, and pain when swallowing
Nausea and vomiting, especially bloody vomiting
Diarrhea or bloody diarrhea
Red face and eyes
A swollen, bloated stomach that may be painful
Anthrax Exposure Without Symptoms
Symptoms may take days or weeks to develop after you’ve come into contact with anthrax.
If you’ve been exposed to anthrax, a healthcare provider can start treatment to help you fight off the infection. People exposed to anthrax can get an anthrax vaccine. They get three doses over four weeks. A healthcare provider will also give you antibiotics.
Treating Anthrax Poisoning
If you think you've been exposed and are showing symptoms, a healthcare provider will try to determine how you may have been exposed. If you may have inhaled anthrax, they'll order tests like chest X-rays or computed tomography (CT) scans.
They can test your blood for anthrax toxins or antibodies against anthrax. They can also test a sample of your blood, wound fluid, phlegm, or spinal fluid for anthrax bacteria.
If the anthrax infection is serious, you may need to stay in the hospital. You may need antibiotics that they can only give through a tube in a vein (IV), special procedures to clean the wound, or a machine to help you breathe.
In all anthrax cases, a healthcare provider will give you medicine to treat the infection and reduce symptoms.
Drugs used to treat anthrax infection include:
Antibiotics to fight the bacteria
Antitoxins to stop the effects of the anthrax toxin
You can survive anthrax poisoning. Anthrax poisoning is not always fatal. Especially with treatment, most people with anthrax survive.
Anthrax poisoning prognosis differs by how the person comes into contact with anthrax:
Anthrax infections in the skin are less dangerous but can still be severe. They can be deadly in up to 20% of people if they don’t get treatment. With treatment, almost all people survive.
Inhaled anthrax is almost always fatal without treatment. With aggressive treatment, about 55% of people survive.
Gastrointestinal anthrax kills more than half of people who don’t get treatment. With the right treatment, 60% of people survive.
Anthrax contamination is a serious disease caused by bacteria called Bacillus anthracis. These bacteria can live in soil and turn into spores, which are hard to destroy and can survive for years. Anthrax spores can enter your body through your skin, lungs, or stomach:
Skin anthrax is the most common type of anthrax. It starts with a small, painless bump on the skin that turns into a black, open sore.
Inhalation anthrax is the most serious type of anthrax. It can happen if you breathe in anthrax spores. Symptoms include fever, cough, chest pain, and difficulty breathing.
Gastrointestinal anthrax is the least common type of anthrax. It happens if you eat food contaminated with anthrax spores. Symptoms include nausea, vomiting, diarrhea, and fever.
A healthcare provider will treat anthrax infection with antibiotics and antitoxins. With treatment, most people with anthrax will survive. Without treatment, anthrax infections can be deadly.
The sooner you start treatment, the better your chances of recovery. Call a healthcare provider immediately if you think you may have been exposed to anthrax.