Health alert: Zimbabwe Online Health Centre

Bacillus anthracis, the causative agent of anthrax.

Anthrax is a zoonotic disease to which most warm-blooded animals are susceptible. The disease is more common in animals and humans are incidental hosts. Human infections usually result from contact with infected animals or animal products. Direct exposure to secretions from cutaneous anthrax lesions may result in secondary cutaneous infection, but there have been no known cases of person-to-person transmission of inhalation disease

Anthrax in humans
Three main forms of anthrax infection in human exist, depending on where anthrax spores enter the body:
 Cutaneous (or skin): due to spores entering a cut or break in the skin (about 95% of cases)
 Inhalation: from breathing airborne spores into the lungs (about 5% of cases)
 Gastrointestinal: from ingesting spores in raw or undercooked food (negligibly rare)

Clinical manifestations of anthrax in humans
 Fever (38-40oC), being the only systemic symptom, may be accompanied by chills or night sweats.

 Flu-like symptoms
 Cough, usually non-productive
 Chest discomfort, shortness of breath
 Fatigue
 Muscle aches
 Sore throat, followed by difficulty swallowing, enlarged lymph nodes, headache, nausea, loss of appetite, abdominal distress, vomiting or diarrhea
 A sore, especially on the face, arms or hands, that starts as a raised bump and develops into a painless ulcer with a black area in the center known as an eschar

Anthrax can enter the human body through
 The skin (cutaneous) contact with spores, spore contaminated materials or infected skin lesions  Infection usually requires an existing break in the skin to initiate infection, though in many cases this may be so small as to be unnoticed
 The lungs: inhalation of spores
 The intestines: ingestion of contaminated meat

People at risk of getting anthrax disease
Human cases usually occur in industrial or agricultural environments.

The most vulnerable groups to anthrax include
 Farmers
 Butchers and skinners
 Tanners
 Abattoir workers: e.g. meat inspectors, packers and graders
 Veterinary workers
 Leather/skin handlers
 Consumers of uninspected meat

 Food handlers
In Zimbabwe, most cases are not related to occupation. People are unwilling to forego the chance of eating meat or selling the hide even if it is from an infected animal.

In places where religious prohibitions (such as the apostolic sect in Zimbabwe) may prevent people handling and eating meat of animals that are sick or animals that die on their own, anthrax is uncommon.

Anthrax in animals
Most warm blooded species are susceptible to anthrax. The anthrax disease commonly occurs in wild and domesticated herbivorous animals that ingest or inhale the spores while grazing or foraging.

Clinical manifestations of anthrax in animals

The signs and symptoms of the diseases include
 Cease feeding and drinking
 Staggering and falling
 Tremor, convulsions
 Massive oedema
 Swollen neck region lymph nodes in dogs and pigs
 Difficulty in breathing
 Bleeding from all orifices due to failure of blood clotting
 Sudden death in cattle, sheep and goats

Note: Most infected animals die within a few days after infection
The characteristic findings on dead animals include

 A rapidly decomposing carcass with a
blotted abdomen
 Dark tarry blood stained exudates from all natural openings
 Absence of rigor mortis
 Un-clotted intravenous blood
 Septicemia indicated by small petechial hemorrhages throughout
 the body
 Enlargement and softening of the spleen, and liver
 Subcutaneous swelling (mainly neck and throat)

Note:
Since intense bacteraemia precedes death all the organs in the animal are infected. Even sun- dried bones from a rotten carcass remain an important source of infection. Meat and milk from infected animals should not be consumed.

Carcasses suspected of anthrax should NEVER be opened as this precipitates spore formation and contamination of the environment

High risk transmission areas in Zimbabwe
 Areas where previous outbreaks have occurred
 Drought prone areas (Region IV and V)
 Areas with Calcium rich soils
 Overstocked areas, mainly over-populated communal farming areas

Prevention and control in animals
Vaccination
 Vaccinate animals within 12 kilometers radius from the nucleus of the outbreak area

 Annual cattle vaccinations are recommended for high risk areas
Treatment of sick animals
 Isolation and treatment of all symptomatic animals will be done using Penicillin or Tetracycline
followed by immunization of the animals on completion of treatment
 The animals should not be used for food until a few months have passed

Prevention and control in human
 Avoid eating meat and milk from affected areas

 If anthrax is suspected avoid contact, skinning the animals and avoid contaminating the areas with animal products

 Avoid skinning and opening up the carcasses as this releases the bacteria and promotes spore
formation which contaminates the environment
 Protect carcasses of suspect cases from scavenging animals

 Report all cases of animal sudden death to the police, Veterinary Department or Health Workers
 In the event that the Veterinary Officer cannot be found, bury the carcass 2 metres deep with
quick lime or burn with paraffin/fire wood
 Seek early treatment if one develops unexplained wound during the time when animals are
dying mysteriously
 Allow mass vaccination of animals by the Veterinary Officers
 Do not buy uninspected meat from vendors
 Avoid handling of carcasses and products of suspected infected animals: hides, milk, dried
meat, etc…

Zimbabwe Online Health Centre

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