Anthrax

ANTHRAX

Anthrax is a bacterial disease of animals and man caused by Bacillus anthracis. It can occur almost anywhere around the world, but most commonly in tropical and sub-tropical countries.
The disease is spread through the sick animals' blood, faeces and other excretions to the environment where they sporulate (form spores) on exposure to air. Pasture, food and water supplies contaminated with spores are the usual source of infection to susceptible animals. Once infected, the animals develop the disease in a rapid course. Therefore, if anthrax is suspected, it is essential to confirm the diagnosis and then take prompt actions to prevent the widespread of the disease. Vaccinating animals annually a few weeks before the known expected season for outbreaks may be the most effective control method. In many countries, annual vaccination of ruminants is a legal requirement.
 
Clinical signs:
Anthrax may be peracute, acute and subacute. Peracute cases is the usual form in ruminants in which animals have a short illness of fever and difficulty in breathing, rapidly followed by collapse, convulsions and death. This form of the disease may last from a few minutes to a few hours and typically animals are found dead. After death, the most common features of the disease are discharges of thick and dark blood from mouth, nostrils, anus and vulva. In the acute forms, animals usually survive two to three days before death. The typical clinical signs of the acute cases are: high fever, depression, listless, congested and haemorrhagic visible mucous membranes (e.g. in the eyes and gums), difficulty in breathing, and oedematous swellings in ventral aspects of the body. Subacute cases last about a week and some may recover. In acute and subacute forms, female animals may abort and have a reduction in milk which may be bloodstained or yellow in colour.
 
Treatment:
Because of the rapid course of the disease, infected animals are often found dead or too sick to be treated. However, anthrax can be treated effectively if it is still in early stages when fever is the only clinical sign. The treatment for anthrax is to use antibiotics, such as oxytetracycline and penicillin, given at the maximum recommended dosages for at least five to six days.
 
Control measures:
When a anthrax case is diagnosed, all the animals in contact must be carefully examined for up to two weeks and their temperatures be taken regularly. If an animal is found to have fever, it should be given antibiotics immediately.
 
In the case that an animal died of anthrax, the carcass should not be opened and should be disposed by burial or burning  to prevent and minimise the spread of  the infection. Contaminated food, water, premises, etc. should be disinfected or even destroyed.
 
In areas where animals are at risk of anthrax, vaccination should be annually a few weeks before the known expected outbreak seasons. The live Sterne-strain spore vaccine is now used all over the world. It is relatively easy to prepare in the laboratory and safe to be used in all species. This vaccine has proven to be effective in field situations and can protect animals for about one year.