Anthrax: Background Information

What is anthrax?

Anthrax is a bacterial infection caused by the organism Bacillus anthracis. The disease occurs most often in wild and domestic animals in Asia, Africa, and parts of Europe: humans are rarely infected. The bacterium can exist in a form known as a spore which allows survival in the environment (for example, in the soil).

Defra factsheet on anthrax in animals

What are the symptoms in humans?

There are two main forms of anthrax infection: cutaneous and inhalation.

In cutaneous (skin) anthrax, a lesion appears on the skin, often on the head, neck, forearms or hands. This lesion starts as a small bump and develops into a characteristic ulcer with a black centre. It is rarely painful, but if untreated the infection can spread to cause blood poisoning. If untreated, the disease can be fatal in 5% of cases, but with prompt antibiotic treatment recovery occurs.

Inhalation anthrax is normally much less common. Symptoms begin with a flu-like illness followed by respiratory difficulties and shock after 2-6 days.

Injection anthrax - since December 2009, a signficant number of drug users in Scotland and England have been found to have anthrax infection. It is likely that they contracted the infection from using heroin contaminated by anthrax spores. See here for Q&As  and here for further information.

Intestinal anthrax is a very rare form of food poisoning, and results in severe gut disease, fever and blood poisoning.

Inhalation, injection and intestinal anthrax are serious infections which can be fatal. They can be treated effectively with antibiotics if identified early enough, but this may be difficult as the initial symptoms are similar to other illnesses.

How do you catch anthrax?

Cutaneous anthrax is caught through direct contact with the skins or tissues of infected animals, and tends to occur in those whose occupation brings them into contact with cattle (and other animals) in countries where the animal form of the disease is prevalent. In the UK this mostly occurs among people working with animal products (e.g., hides from abroad).

Inhalation anthrax is caused by breathing in anthrax spores, usually in industrial processes such as the tanning of animal skins, and processing of wool or bones from abroad. A recent case in London  was related to making drums from animal hides.

Intestinal anthrax is very rare, but occurs from eating contaminated meat from an animal which has died of anthrax.

Recent cases in drug users in Scotland and England have been acquired through using heroin.

It is extremely unusual for anthrax to be spread from person-to-person. Airborne transmission from one person to another does not occur; direct contact with anthrax lesions in a case of cutaneous anthrax can lead to subsequent cutaneous infection, but this is uncommon.

How long can you have the infection before developing symptoms?

With inhalation anthrax, symptoms usually develop within 48 hours of exposure, but in other forms of anthrax symptoms may not appear for up to a week.

How can anthrax be prevented or treated?

There is a vaccine against anthrax, and this is recommended only for those at highest risk, for example, those handling dead animals ( e.g., abattoir workers, tanners) and laboratory staff who may be handling the organism. Vaccination is not normally recommended for the general public.

Anthrax can be treated effectively with a variety of antibiotics, but successful treatement depends on early recognition of the disease.

Post-exposure prophylaxis with antibiotics can be very effective in preventing disease in exposed persons if given early enough.

How common is anthrax?

Anthrax is uncommon in the UK - until the recent outbreak in heroin users, only a handful of cases had been notified over the last decade (more information). Infections are more common in countries where the disease is common in animals, including countries in South and Central America, southern and eastern Europe, Asia, and Africa.

Last reviewed: 22 December 2010