Open Outbreak

Anthrax

Also known as: Bacillus anthracis

Anthrax is a serious disease caused by the bacterium Bacillus anthracis. It mainly affects animals such as cattle, sheep, and goats, but humans can become infected through direct contact with sick animals or contaminated animal products. There are several forms of anthrax, including cutaneous (skin), inhalational (lungs), and gastrointestinal (digestive tract). Symptoms and severity depend on the form, with inhalational anthrax being the most dangerous. Anthrax does not spread from person to person. There are effective antibiotics and vaccines for prevention and treatment, but early diagnosis is important. Outbreaks are most common in areas where livestock are not routinely vaccinated. Anthrax has also been used in the past as a biological weapon, which makes it a disease of special concern for public health authorities.

Key facts

TransmissionAnthrax is transmitted to humans mainly through direct contact with infected animals or animal products. It can enter the body through skin cuts, inhalation of spores, or ingestion of contaminated meat. Human-to-human transmission does not occur.
IncubationSymptom onset occurs between one day and two months after infection, depending on the route of exposure.
Case fatalityUnknown (not directly reported in the sources found); severity varies by form, with inhalational anthrax being the most deadly.
Reproduction numberUnknown (not established for anthrax, as it does not spread person-to-person).
VaccineThere is a vaccine for anthrax, mainly used for people at high risk (such as certain workers and military personnel).
TreatmentAnthrax can be treated with antibiotics if given early. Supportive care may also be needed for severe cases.
ReservoirThe main reservoir is livestock, especially cattle, sheep, and goats.
Endemic regionsAnthrax is endemic in parts of Africa, Asia, and some areas of Europe and the Americas where livestock vaccination is not routine.

Transmission

Anthrax is not spread from person to person. People usually get anthrax by handling or coming into contact with infected animals or their products, such as hides, wool, or meat. The bacteria form spores that can survive in soil for decades. Infection can happen through cuts in the skin (cutaneous anthrax), breathing in spores (inhalational anthrax), or eating contaminated meat (gastrointestinal anthrax). Outbreaks often occur after people handle animals that have died suddenly, especially in areas where livestock are not vaccinated. Human-to-human transmission has not been reported.

Symptoms and severity

Symptoms of anthrax depend on how the bacteria enter the body. Cutaneous anthrax, the most common form, starts as a small blister that develops into a painless ulcer with a black center. Inhalational anthrax begins with flu-like symptoms, then can progress to severe breathing problems and shock. Gastrointestinal anthrax causes nausea, vomiting, abdominal pain, and severe diarrhea. The severity ranges from mild skin infections to life-threatening illness, especially if not treated quickly. Inhalational anthrax is the most dangerous form and can be fatal without prompt treatment.

Treatment and vaccines

Anthrax can be treated with antibiotics, especially if started early. Severe cases may require additional supportive care in a hospital. There is a vaccine for anthrax, but it is mainly given to people at high risk, such as laboratory workers, people who handle animals, and some military personnel. Routine vaccination of livestock in endemic areas is an important way to prevent outbreaks. Early diagnosis and treatment are key to reducing the risk of severe illness or death.

Where it occurs

Anthrax is found worldwide but is most common in areas where livestock are not routinely vaccinated. It is endemic in parts of Africa and Asia, and outbreaks have also been reported in Europe and the Americas. Recent outbreaks have occurred in Zambia and Thailand, often linked to contact with infected cattle or wild animals. The disease is more likely to appear in rural areas where people have close contact with livestock and where animal vaccination programs are not in place.

Recent history

There have been six major anthrax events reported by WHO since 1996. Recent outbreaks include a 2025 event in Thailand, where four people were infected after contact with cattle, and a 2023 outbreak in Zambia, with at least 26 human cases linked to sick livestock and wild animals. The United States experienced a high-profile anthrax event in 2001, which was related to deliberate release. Outbreaks are often associated with animal deaths and occur in regions where anthrax is endemic or where animal vaccination lapses.

What to watch

Anthrax is a concern when new outbreaks occur in regions where it was not previously found, or when there are large numbers of animal or human cases. Signals to watch include sudden deaths in livestock, clusters of human cases after animal contact, and any sign of inhalational anthrax, which is rare but severe. Resistance to antibiotics or shortages of vaccine could make outbreaks harder to control. Because anthrax has been used as a biological weapon in the past, any unusual pattern of cases, especially in urban areas or among people with no animal contact, should be investigated quickly.

Updated