Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. The disease most commonly occurs in wild and domestic mammalian species (cattle, sheep, goats, camels, antelopes, and other herbivores), and can be found in Asia, Africa and parts of Europe but it can also, rarely, occur in humans when they are exposed to infected animals or to tissue from infected animals or when anthrax spores are used as a bioterrorist weapon.
Incubation Period
Depeneding on the type of anthrax concerned: 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.
Transmission
Anthrax is not known to spread from one person to another person. B. anthracis spores can live in the soil for many years, and humans can become infected with anthrax by handling products from infected animals or by inhaling anthrax spores from contaminated animal products. Anthrax can also be spread by eating undercooked meat from infected animals. Rarel, Anthrax spores can be used as a bioterrorist weapon.
Types
There are three main forms of anthrax infection: cutaneous (skin), inhalation, and gastrointestinal.
1. Cutaneous. This is the most common form of anthrax infection (about 95%). It occurs through direct contact with the skins or tissues of infected animals when the bacterium enters a cut or abrasion on the skin. It tends to occur in people whose occupation brings them into contact with cattle and other animals. The skin infection begins as a raised itchy bump, often on the head, neck, forearms or hands, that resembles an insect bite. Wthin 1-2 days it develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the center. Lymph glands in the adjacent area may swell. If untreated with antibiotics the infection can spread to cause blood poisoning and in some cases can be fatal. With prompt antibiotic treatment recovery occurs.
2. Inhalation. This type of anthrax is much less common. It is caused by breathing in anthrax spores, usually in indistrial processes such as the tanning of animal skins and processing of wool or bones. Initial symptoms may resemble a common cold – sore throat, mild fever, muscle aches and malaise. After 2-6, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal.
3. Gastrointestinal. The intestinal disease form of anthrax is very rare but may follow the consumption of contaminated meat from an animal which has died of anthrax. It 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. Intestinal anthrax results in death in 25% to 60% of cases.
Another recently discovered form of anthrax is:
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.
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.
Prevention and treatment
A vaccine against anthrax exists, but 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.
There are a number of antibiotics which are effective against Anthrax, 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.