Skip to content ↓

Anthrax Questions and Answers

From the MIT Medical Department

Q. What is anthrax?

A. Anthrax is an infectious disease caused by the spore-forming bacterium Bacillus anthracis. The bacteria can infect all warm-blooded animals including humans. Under the right conditions the bacteria can make spores, almost like a seed, which are quite durable and in themselves harmless. These spores can survive in the soil or in containers for years. When the spores are then placed in the proper conditions (such as a living animal), they become the active and dangerous bacteria.

Q. How common is anthrax and who can get it?

A. Anthrax bacteria and infections are most common in agricultural regions where they occur in animals. The parts of the world where anthrax can be easily found include South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East. Anthrax is also found in southern regions of the United States. In humans, the disease has been usually caused by occupational exposure of a handler's skin to infected animals or their products and generally is of the cutaneous form. Pulmonary anthrax is extremely rare. Anthrax of any type has not been reported in Massachusetts in over 30 years.

Q. How is anthrax spread?

A. Bacillus anthracis spores can live in the soil for decades. A person may become infected with anthrax by inhaling anthrax spores from soil (infectious dose is 8,000-50,000 spores) or by handling wool or hair from infected animals (which can cause skin exposures). Sores or cuts in skin increase the chance of getting infected with spores. Infection of the intestinal tract can occur by eating undercooked meat from diseased animals. Anthrax spores do not usually spread in the air or wind; they are heavy and settle quickly on ground surfaces.

Q: What do the spores look like?

A: The spores are microscopic and it requires large numbers to be seen. The amount needed to cause a serious illness if inhaled is little more than a pinch. In nature, spores are described as brownish in color.

Q. What are the symptoms of anthrax disease?

A. The symptoms vary depending upon the type of infection:

Cutaneous: Most anthrax infections in the past have occurred when the bacterium enters a cut or abrasion on the skin, usually hands and forearms, such as when handling contaminated wool, hides, leather or hair products (especially goat hair) of infected animals. Opening a letter or package which is filled with spores could also cause such an infection. A boil-like fluid filled lesion appears which eventually forms an ulcer with a very dark, black center. Anthrax gets its name from the Greek word for "coal." A swelling of the lymph glands may also occur close to the skin infected area. Skin lesions can occasionally spread throughout the body causing serious illness and if untreated can cause death in 25% of cases.

Inhalation: Initial symptoms may resemble influenza with fever, fatigue, a dry cough, chest discomfort, and body aches. After a period of improvement from hours to days, the symptoms may progress to severe breathing problems, and chest pain. Inhalation anthrax in over 80% of cases results in death several days after onset of the acute symptoms through the spread of the bacteria and toxins it produces. Actual infection of the lungs, pneumonia, does not generally occur. Intensive treatments unfortunately is ineffective when full symptoms are present.

Intestinal: The intestinal disease form of anthrax may follow the consumption of contaminated meat and is characterized by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood, and severe diarrhea.

Q. How soon after being infected do symptoms appear?

A. Symptoms of disease usually occur within 1-6 days with most cases occurring within 48 hours. Low doses of exposure can cause longer incubation periods for inhalation anthrax (up to 60 days).

Q. Can anthrax be spread from person-to-person?

A. There are no reports of the disease spreading from person to person. It is therefore not "contagious."

Q. How is anthrax diagnosed?

A. Anthrax is diagnosed by getting bacteria from samples of blood, skin lesions, or respiratory secretions. Nasal swabs are being used to test individuals for possible exposure in the current cases of known anthrax attacks. However, the nasal swab test is not reliable and cannot rule-out nor diagnose anthrax. The Massachusetts Department of Public Health is advising clinicians and the public not to seek these tests. In cases of known or highly suspicious anthrax exposure, public health and law enforcement officials are providing both testing and treatment guidelines and medications.

Q. What is the treatment for anthrax?

A. Penicillin or ciprofloxacin are the preferred drugs, but erythromycin, tetracycline, or chloramphenicol can also be used. Other quinolones are probably also effective but untested. To be effective for inhalation anthrax, treatment should be initiated within a few days of exposure. For cutaneous anthrax, treatment is effective if begun when characteristic rash is identified. If left untreated, anthrax disease can be fatal. Stockpiles of these medications are positioned by the federal government to be delivered within 12 hours of an actual large scale attack.

Local hospitals and MIT Medical have adequate antibiotic supplies to immediately treat the limited number of persons who might be exposed in a mail-associated attack. In accordance with all public health authorities, the policy of MIT Medical is to discourage the individual stockpiling of antibiotics. Such hoarding of antibiotics could lead to inappropriate patient decisions to self medicate, incomplete courses of antibiotics that might select for resistant organisms, the eventual use of expired medications and the depletion of national supplies for medically indicated uses.

Q. Is there a vaccine to prevent anthrax?

A. The anthrax vaccine licensed for human use in the United States is a cell-free filtrate vaccine, which means parts of dead bacteria are used as opposed to live bacteria. Currently, the vaccine is not FDA approved and stockpiled supplies are limited for use for essential military personnel.

Q: What do I do if I get a posted letter or parcel associated with an unknown powder?

A: Do not open the envelope or package. If already opened, put down and cover or place in a plastic bag if close by. Leave the room after turning off fans or ventilation (if possible), close the door. Do not touch anything until you wash your hands with soap and water (do not use bleach on your hands). Do not leave the area or let others enter the room.

Either you or someone else should call Campus Police (x100). You will be asked some questions about your suspect item. Remain calm. The police will arrive in minutes and take control of the situation. Anyone who was in contact with the item should remain in the area for questioning. Further information about appropriate response in such situations is found at:, which is updated daily.

Q: What will happen if I call the MIT police about an unknown powder?

A: The Campus Police and someone from the Environmental, Health and Safety Office (EHS) will come immediately to the location. If upon questioning or observation the source of the powder becomes obvious and non-threatening, it will be cleaned up.

If circumstances suggest a potential for an anthrax attack, the Cambridge Fire Department Hazardous Materials (HAZMAT) team will be called to the scene. The HAZMAT team will put on protective equipment, contain and remove the questionable items, and decontaminate the immediate area. They will then release command of the area back to MIT (police and EHS) who will determine if anything more needs to be done before permitting re-occupancy. Even though the incident may be felt to have a very, very low risk of an actual anthrax attack, as a precaution surrounding objects and surfaces that may have contacted the item may be cleaned with bleach.

Q: What happens to the specimens sent to the MA State Lab?

A: Specimens taken by the Cambridge Fire Department are transported to the State Lab for analysis. The specimens are examined under a microscope initially and then planted on growing media. Growing anthrax bacteria can be identified usually within 24 to 48 hours. When the results are known, the Cambridge Board of Health is notified, and they then call the EHS Office who will then communicate to the affected individuals and the MIT community at large. Positive results are likely to be reported out within 3 days, negatives may take up to a week. As of November 1, over 1000 samples statewide have been evaluated and none have been found to contain anthrax.

Q. Where can I find more information about anthrax and other infectious diseases?

A. Start at the up to date CDC website at

Related Topics

More MIT News