Anthrax is an acute often a fatal zoonotic disease mainly of herbivores that is caused by a spore-forming bacteria known as Bacillus anthracis. The infected host releases the vegetative form of the bacilli into the ground which then sporulate on exposure to air. The anthrax spores are very resistant to inactivation through drying, heat, gamma radiation and other disinfectants which enable them to potentially survive in the environment for decades. Bacillus anthracis derived its name from the Greek word anthakis which means coal due to the cutaneous form that presents as a black coal-like lesion.
Anthrax mainly affects both domestic and wild herbivores such as goats, cattle, sheep, horses, camels and swine, deer, gazelles and antelopes, buffaloes, rhinos, mink among other hoofed herbivores with clinical cases being reported in non-human primates and rarely in birds. Humans acquire the disease through contact with infected animals or animal products.
Animals acquire this disease while grazing by swallowing pastures and vegetation contaminated with anthrax spores, they also acquire the disease from contaminated soils and processed feed products such as bone meals. Animals may also potentially get infected through inhalation of spores or entry through skin lesions.
People usually contract the disease after exposure to infected animals and animal products. In man, there are three forms of transmission leading to the three forms of the disease. People get infected when they eat or drink foods contaminated with the spores, when they inhale the spores or direct skin contact in cuts, abrasions or other breaks in the skin.
Anthrax is not contagious and cannot be acquired like flu or a cold from other people.
In animals, anthrax is almost always fatal with signs appearing 3 to 7 days after ingestion of inhalation of the spores. Infected animals may stagger, have difficulty breathing, tremble then collapse and die with bleeding from natural orifices, bloating of the carcass, incomplete rigor mortis and non-clotting of blood.
In man anthrax presents in 3 forms:
Anthrax can be suspected from the above clinical signs.
For confirmation, examination of a methylene blue stains blood smear to observe the capsulated bacilli endospores with culture back up may be used. Recently genetically based confirmation through polymerase chain reaction (PCR) is becoming popular.
Bacillus anthracis is high on the list of potential agents that would be used in biological warfare and bioterrorism. Biological agents are germs that can be used to sicken or kill people, livestock or crops. Bacillus anthracis is a potential biological agent because it is easily available in nature and can easily be cultured in a laboratory. It is odourless and colourless hence can also be easily released. Additionally, it has been used before (In 2001 in the U.S through the mail system, where 22 people got anthrax with 5 of them succumbing to anthrax)
In humans, anthrax can be treated through prompt administration of an antibiotic with Penicillin being generally used even in the treatment of suspected animal cases. Other antibiotics are also effective.
Anthrax is preventable through vaccination of in risk animals against the disease before they develop the disease. In Kenya, an inactivated vaccine is available for use. It is known as BLANTHRAX since it is a combination of a vaccine against black quarter and vaccine against anthrax. It is administered annually based on veterinary vaccines protocols in Kenya and farmers are advised to vaccinate their animals as advised. A human vaccine is also present however availability is low with vaccinations being given to military personnel in the USA.
Animals that die of anthrax contaminate the soil, therefore the carcasses should be incinerated or buried deep in the ground and concrete placed over the area. The soil around where the animal died should also be disinfected even-though anthrax spores are resistant to disinfectants.
CARCASSES SHOULD NOT BE OPENED TO PREVENT SPORULATION!!!
By Dr Mary Muthoni
Mary is a passionate Veterinarian. Other than making the lives of animals better, she also enjoys writing poems. You can connect with her on Twitter. For veterinary services, you can contact her on +254 715 259670.
Featured Image: Ken Gitau