- Anthrax is a bacterial infection acquired through direct contact with infected animals or animal products, consumption of contaminated meat, or inhalation of airborne anthrax bacterial spores.
- Risk is very low for travelers.
- Symptoms of anthrax differ based on the mode of transmission and include itching and skin lesions covered by blackened dead tissue, nausea, vomiting, fever, and influenza-like illness.
- Consequences of infection can include respiratory failure, shock, infection of the blood and internal organs, inflammation of the brain membranes, and death.
- Prevention includes avoiding contact with infected livestock and animal products and consumption of contaminated meat.
- Anthrax vaccine is not routinely recommended for travelers unless otherwise indicated for occupational reasons. A preexposure vaccination series is 5 doses over 18 months.
- Vaccine side effects are most commonly injection-site reactions, tiredness, headache, and muscle aches.
- Duration of vaccine protection is 1 year after completing the series. Annual boosters are required to maintain immunity.
- Postexposure prevention includes a vaccination series consisting of 3 doses given over 4 weeks, combined with antibiotic use.
Anthrax is a global infectious bacterial disease that presents as cutaneous (skin; most common), gastrointestinal, or inhalation anthrax depending on the route of transmission (contact, consumption, or inhalation). Domestic and wild animals may become infected when they inhale or ingest spores in contaminated soil, plants, or water, and the illness may be transmitted to humans upon contact with such infected animals or animal products. Risk is very low in travelers unless a bioterrorism event occurs. Anthrax is responsive to vaccine-, antimicrobial-, and antibody-based treatments.
Anthrax occurs globally, but most commonly in agricultural regions with inadequate control programs for anthrax in livestock (e.g., herbivore mammals such as cattle, sheep, goats, camels, and antelope) in Central and South America, sub-Saharan Africa, central and southwestern Asia, and southern and eastern Europe. Occurrence of anthrax is uncommon in industrialized countries.
Anthrax is transmitted via 3 major routes: skin, digestive tract, and lungs.
Skin infection can result from direct contact with infected animals or their contaminated wool and hides, usually in agricultural settings (e.g., ranches, slaughterhouses, veterinary clinics, butcher shops) or industrial settings (e.g., wool or hide processing factories).
Digestive tract infection (rare) may result from consumption of contaminated meat.
Lung infection (rare), almost exclusively associated with intentional transmission through bioterrorism, results from inhalation of anthrax bacteria spores.
Risk is very low for travelers but increases for persons consuming contaminated meat, handling contaminated animal hide, wool, or other products, heroin users, laboratory workers, or persons typically targeted by terrorists (intentionally transmitted anthrax).
Symptoms of anthrax most commonly appear within 7 days of exposure and may vary, depending on the mode of transmission.
Cutaneous anthrax begins with itching, followed by a painless, skin lesion (usually appearing on the face, neck, or arms) that changes from a bump to a blister then to an ulcer covered with blackened dead tissue. Fever, extreme tiredness, headache, and swollen glands may also occur.
Gastrointestinal anthrax presents with nausea, vomiting, fever, and abdominal pain and tenderness.
Inhalation anthrax begins like a viral respiratory illness, followed by shortness of breath, mild fever, and muscle aches. Breathing becomes more difficult, and low blood pressure occurs.
Anthrax in injection-drug users (injection anthrax) commonly occurs as injection-site pain, swelling, and excessive bruising.
Consequences of Infection
Inhalation anthrax may result in shock and inflammation of the membranes around the brain. Rarely, gastrointestinal anthrax may spread and cause generalized infection of the blood and internal organs. Injection anthrax can spread throughout the body faster and may be harder to recognize than skin anthrax. Death occurs in 20% to 90% (inhalation anthrax) of symptomatic cases depending on the mode of transmission, time of treatment initiation, and medical management.
Need for Medical Assistance
Persons who have been exposed to or develop symptoms of anthrax (e.g., unexplained fever or new skin lesions) after travel and persons with respiratory symptoms after exposure to an unknown white powdery substance should seek immediate medical attention for evaluation of the need for postexposure treatment.
Vaccine, antimicrobials, antibodies, or immune globulin must be started as soon as possible following exposure and may reduce the duration and severity of illness.
Travelers going to countries where anthrax is common and vaccine coverage of livestock is low should avoid:
- Contact with livestock and animal products
- Consumption of meat from animals of uncertain origin.
Preexposure vaccination is not indicated for travelers without other reasons for vaccination (e.g., military personnel or occupational exposure). Postexposure vaccination is recommended for unvaccinated persons who may have inhaled anthrax spores.
The most common side effects of anthrax vaccine include pain, redness, and swelling at the injection site. Occasionally, headache, fever, chills, and muscle aches occur. Serious side effects are rare but can include extensive swelling of the forearm.
Persons with underlying medical conditions or who have concerns about the vaccine should speak to their health care provider before vaccine administration.
The preexposure series consists of 5 doses (given at 0, 1, 6, 12, and 18 months). An alternative 6 dose regimen is licensed. A booster dose is given annually thereafter if risk of exposure continues.
The postexposure series consists of 3 doses (given at 0, 2, and 4 weeks) plus at antibiotics for at least 42 days.