Lifespan's A - Z Health Information Library

Inhalation or respiratory anthrax is an infectious disease caused by breathing in the spores of the bacteria Bacillus anthracis.

Anthrax commonly affects hoofed animals such as sheep and goats, but humans can get sick from anthrax, too. Historically, the main risk factor for getting anthrax was some type of contact with contaminated animal hides, hair, bone products, and wool. Inhalation anthrax was most commonly contracted when workers breathed in airborne anthrax spores, which were released during industrial processes such as tanning hides and processing wool.

Breathing in spores means a person has been exposed to the disease, but it doesn't mean they'll get symptoms. The bacteria spores must "germinate," or sprout ( the same way a seed might before a flower grows) before the actual disease occurs. The process can take up to 60 days.

Antibiotic therapy following known or suspected exposure can help prevent the disease.

Once the spores germinate, they release of several toxic substances (toxins), which cause internal bleeding, swelling, and tissue death.

The main form of inhalational anthrax is marked by a bloody infection of the lymph nodes in the chest, a condition called hemorrhagic mediastinitis. Up to half of affected individuals may also have a hemorrhagic meningitis.

There are usually two stages of inhalation anthrax:

1. Stage one can last from hours to a few days. Symptoms may resemble a cold or the flu, and can include fever, headache, cough, shortness of breath, and chest pain.
2. Stage two often develops suddenly, and is fatal in up to 90% of individuals, due to a build up of toxins in the body. Shock typically occurs.

• Initial stage -- fever, chills, sweating, fatigue, malaise, headache, cough, shortness of breath, and chest pain
• Second stage -- fever, severe shortness of breath, and shock

This list of symptoms is based on a relatively small number of people who have had inhalation anthrax. Additional symptoms may be present. Some of the symptoms listed may be absent.

• If inhalation anthrax is suspected, a chest X-ray, blood cultures, and sputum cultures may be obtained. Initial chest X-rays are likely to show abnormalities such as fluid surrounding the lungs or abnormally wide space between the lungs.
• Samples may need to be sent to a special lab for more definitive testing, including PCR, immunofluorescence, and immunohistochemistry.
• A spinal tap for CSF culture and a gram stain also may be performed.

Several antibiotics are effective against anthrax  including penicillin, doxycycline, and ciprofloxacin (Cipro). Inhalation anthrax is usually treated with ciprofloxacin plus another antibiotic agent.

The length of treatment is currently about 60 days for individuals exposed to anthrax, since it may take spores that long to germinate.

The prognosis of inhalation anthrax once it reaches the second stage is poor, even with antibiotic therapy. Up to 90% of cases in the second stage are fatal.

• Hemorrhagic meningitis
• Mediastinitis
• Shock
• ARDS (adult respiratory distress syndrome)

Notify your health care provider if you have been exposed to anthrax, whether or not you develop symptoms. Your doctor will determine whether you need treatment (if you've developed symptoms) or preventative antibiotics. 

There are two primary modes of prevention of anthrax.

Vaccination has been developed and is given in a 6-dose series. This vaccine is available to select U.S. military personnel, but not the general public.  

For individuals who have been truly exposed to anthrax (but have no signs and symptoms of the disease), preventive antibiotics may be offered, such as ciprofloxacin (Cipro), penicillin, or doxycycline, depending on the particular strain of anthrax.

There is no known transmission of anthrax from person to person.People living with individuals with anthrax do not need antibiotics unless they have also been exposed to the same source of anthrax.

Reissman DB, Whitney EA, Taylor TH Jr, et al. One-Year Health Assessment of Adult Survivors of Bacillus anthracis Infection.JAMA. 2004;291:1994-1998.

Inglesby TV, O'Toole T, Henderson DA, et al. Anthrax as a Biological Weapon, 2002. JAMA.160;2002;287:2236-2252.