Anthrax

Unique identifier / Notation

BI0201

Synonyms

Fièvre charbonneuse Charbon bactéridien (fr) Carbunco bacteridiano (es)

Anthrax is a disease caused by the spore-forming bacteria Bacillus anthracis. Anthrax is primarily a disease of herbivorous animals, although all mammals, including humans, can contract it. In humans, anthrax manifests itself in three distinct patterns (cutaneous, gastrointestinal, inhalational) (adapted from WHO, FAO, & OIE, 2008; CDC, 2020).

Primary reference(s)

CDC, 2020. Anthrax. Centres for Disease Control and Prevention (CDC). Accessed 11 October 2024.

WHO, FAO, and OIE, 2008. Anthrax in Humans and Animals. 4th Ed. World Health Organization (WHO), Food and Agriculture Organization of the United Nations (FAO), World Organisation for Animal Health (WOAH, formerly OIE). Accessed 11 October 2024.

Annotations

Additional scientific description

Human

The disease is generally regarded as being non-contagious. However, potentially it can be transmitted via direct contact with infected sores. When anthrax spores are ingested, inhaled or enter the body through skin abrasions or cuts, they can germinate, multiply and produce toxins.
More than 95% of human anthrax cases take the cutaneous form and result from handling infected carcasses or hides, hair, meat or bones from such carcasses.
Human case rates for anthrax are highest in Africa, the Middle East and central and southern Asia.
Anthrax can also be contracted in laboratory accidents and by heroin-injecting drug-users through injection of contaminated heroin.
There are three forms of anthrax, and all forms are potentially fatal if untreated, but the cutaneous form is more often self-limiting.
Cutaneous anthrax
- most common form (more than 95% of the cases), usually contracted when a person with a break in their skin, such as a cut or abrasion, comes into direct contact with anthrax spores generally from handling infected carcasses or hides, hair, meat or bones from such carcasses.
- the resulting itchy bump rapidly develops into a black sore. Some people then develop headaches, muscle aches, fever and vomiting.
Gastrointestinal anthrax
- caught from eating meat from an infected animal.
- It causes initial symptoms similar to food poisoning, but these can worsen to produce severe abdominal pain, vomiting of blood and severe diarrhoea.
Inhalational or pulmonary anthrax
- the most severe, and rarest, form of human anthrax caused when a person is directly exposed to a large number of anthrax spores suspended in the air and breathes them in.
- the first symptoms are similar to those of a common cold, but this can rapidly progress to severe breathing difficulties and shock.
All three forms (cutaneous, gastrointestinal, inhalational) are potentially fatal if untreated, but the cutaneous form is more often self-limiting. Data from pre-antibiotic and vaccine days indicate that 10%-40% of untreated cutaneous cases may be expected to result in death with some geographical and temporal variations (WHO, FAO, & OIE, 2008).
Bacillus anthracis has always been high on the list of potential agents with respect to biological warfare and bioterrorism. It has been used in that context on at least two occasions, prepared for use on several other occasions and been the named agent in many threats and hoaxes (WHO, FAO, & OIE, 2008).
Humans generally acquire the disease directly or indirectly from infected animals, or occupational exposure to infected or contaminated animal products. Control in livestock is therefore the key to reduced incidence in humans.

Animal

Anthrax is primarily a disease of herbivores (WHO, FAO, & OIE, 2008). Anthrax occurs on all continents and commonly causes high mortality, primarily in domestic and wild herbivores as well as most mammals and several bird species (WOAH, no date). Anthrax is preventable through control measures, including vaccination (Fasanella et al., 2021). Each country has a list of approved vaccines and antibiotics for use. Contact national veterinary services to learn what is allowed in the country before purchasing.
Anthrax is most common in agricultural regions with neutral or alkaline, calcareous soils. Bacillus anthracis forms highly resistant spores that can persist in the environment for decades and infect grazing animals.
Anthrax continues to be reported from many countries in domesticated and wildlife.
Anthrax outbreak in an enzootic area follows a prolonged hot dry spell, which in turn was preceded by heavy rains or flooding, or with rain ending a period of drought. The water allows anthrax spores to germinate.
In the livestock sector, where people become infected by handling animals or animal products that contain spores, people often develop skin infections. This can happen to veterinarians, agricultural workers, livestock producers or those employed in the processing of sick animals, bones, hides, wool and other animal products.
Anthrax develops without apparent clinical signs, with sudden death due to acute or hyperacute septicaemia and leakage of uncoagulated blood from natural openings.
In cattle, anthrax often occurs as an acute febrile disease. A steep rise in temperature is a typical sign. If no treatment is given, death usually occurs in 2-3 days. The urine may be blood-stained, and blood may exude from the rectum and other natural openings.

Metrics and numeric limits

Human

Infectious doses, which have not been established for humans, and the severity of the resulting infection clearly depend on several factors such as route of infection, nutritional and other states of health on the part of the infected person, and probably on the relative virulence of the infecting strain.
For the purpose of risk assessments, dependency on information from animal tests is unavoidable (WHO, 1998).

Animal

N/A

Key relevant UN convention / multilateral treaty

Codex Alimentarius (FAO and WHO, no date).

International Health Regulations (2005), 3rd ed (WHO, 2016).

WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (WTO, no date).

United Nations. 2023. Recommendations on the Transport of Dangerous Goods - UN Model Regulations. Available from: https://unece.org/transport/dangerous-goods/un-model-regulations-rev-23 Accessed 1 January 2025.

Drivers

Anthrax has been classified as non-industrial and industrial anthrax, reflecting the occupation of the individual led to exposure; non-industrial anthrax, which occurs in farmers, butchers, knackers, veterinarians and so on, and industrial anthrax, which occurs in those employed in the processing of bones, hides, wool and other animal products. (WHO, 1998).

Anthrax is primarily a disease of herbivores. Typically, an outbreak in an enzootic area follows a prolonged hot dry spell, which in turn is preceded by heavy rains or flooding, or with rain ending a period of drought (WHO, FAO & OIE, 2008).

Impacts

Anthrax is a fatal disease in humans and animals. Anthrax is an infection caused by the spore-forming bacteria called Bacillus anthracis. It is a zoonosis (disease transmissible from animals to humans) that typically affects ruminants (such as cows, sheep, and goats). The bacteria produce extremely potent toxins which are responsible for the symptoms, causing a high lethality rate. Humans can catch the disease from infected animals or through contaminated animal products (EHO, 2016 a).

Multi-hazard context

Bacillus anthracis has always been high on the list of potential agents with respect to biological warfare and bioterrorism. It has been used in that context on at least two occasions, prepared for use on several other occasions and been the named agent in threats and hoaxes (WHO, FAO, & OIE, 2008).

Risk Management

Preventing the disease in animals will protect human health. Anthrax vaccines for livestock and humans exist. Anthrax provides a good platform for a ‘One Health’ approach which can be operationalised through locally adapted approaches for prevention and control. The control of anthrax among humans depends on the integration of veterinary and human health surveillance and control programmes. Routine cross-notification between the veterinary and human health surveillance systems and close collaboration between the two health sectors is particularly important during epidemiological and outbreak investigations (WHO 1998; 2024).

The Food and Agriculture Organization of the United Nations provides information on anthrax outbreaks via its guidance for improved prevention, control and heightened awareness. These efforts should be supported by enhanced intersectoral collaboration and coordination between the veterinary and medical authorities, particularly at the field level, for information and report exchange, integration of surveillance data, joint case investigations, coordination of community awareness messaging and implementation, and effective delivery of vaccination campaigns (FAO, 2018).

In the World Organisation for Animal Health (WOAH, formerly) Terrestrial Animal Health Code chapter on anthrax, it is reported that there is no evidence that anthrax is transmitted by animals before the onset of clinical and pathological signs. It provides guidance on early detection of outbreaks, quarantine of affected premises, destruction of diseased animals and fomites, and implementation of appropriate sanitary procedures at abattoirs and dairy factories will ensure the safety of products of animal origin intended for human consumption (WOAH, 2024).

Human

Hospitalization is required for all human cases of anthrax. Individuals potentially exposed to anthrax spores may be provided with prophylactic treatment. Anthrax responds well to antibiotics.
Human vaccines are in limited supply and used primarily for protection of selected individuals with possible occupational exposure to anthrax (WHO, 2016a).
Bacillus anthracis has always been high on the list of potential agents with respect to biological warfare and bioterrorism.
The high-risk groups from anthrax include
- Working in abattoirs
- Working in veterinary medicine (dealing with livestock)
- Handlers of animal skin, wool or dairy products in high-incidence areas for anthrax
- Laboratory workers dealing with Anthrax
- Injection drug users (heroin)

Animal

When anthrax is suspected in livestock or animals, immediately contact the Veterinary Service. Do not move or open the carcasses and do not allow people to take meat.
Control measures include the correct disposal of carcasses, disinfection and decontamination of contaminated materials, and decontamination of the environment.
Anthrax-specific control procedures on carcasses disposal are necessary to contain the disease and prevent its spread. Typically, the carcasses will be burnt or deep-buried at the death site to prevent the spreading of spores.
When buried, need to ensure that it is inaccessible to other animals, particularly scavengers, or people. Hazard signs should be posted around sites.
Because the spores survive in the soil for a long time, dredging or digging of an anthrax burial site may result in a new anthrax outbreak.
In villages, people contract gastrointestinal anthrax when they steal meat from buried anthrax-infected carcasses and eat/share. Hence, timely Risk communication and community engagement (RCCE) is crucial.

Monitoring

The section and the table below offer an overview of monitoring for anthrax. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.

Which institution(s) produce(s) Disaster Risk Data/Information?

WHO, Ministry of Health

FAO Reference Centres, WOAH Reference Centres

How is the Hazard Observed/Monitored/Forecast?

WHO, Ministry of Health

FAO empres-i+ https://empres-i.apps.fao.org/diseases

WOAH WAHIS https://wahis.woah.org/#/event-management

WHO supports countries to conduct all-hazards strategic risk assessment in the contexts of health emergencies and disasters, which results in the development of a country risk profile. Empowered with the country risk profile, inclusive of a seasonal risk calendar, countries can anticipate potential emergencies before they occur to trigger early alerts and inform early actions (WHO, 2021).

WHO's Early Warning, Alert and Response System (EWARS) has been designed to improve disease outbreak detection in emergency settings, such as in countries in conflict or following a natural disaster. It is a simple and cost-effective way to rapidly set up a disease surveillance system. EWARS is deployed during an emergency as an adjunct to the national disease surveillance system. WHO works with Ministries of Health and health sector partners to train local health workers to use the system. After the emergency, EWARS should re-integrate back into the national system (WHO, no date).