The Sunday News
SUSPECTED cases of anthrax in recent weeks in some sections of Binga District inspired me to come up with this article. It is important here to underline the word suspected because a confirmation could not be obtained at the time of writing this article. However, suspicious anthrax-like signs were picked and observed from kids at a local clinic.
The kids had been in contact with pigs. Anthrax is a highly infectious and fatal disease of mammals and humans caused by a relatively large spore-forming rectangular-shaped bacterium called Bacillus anthracis.
Anthrax is a zoonotic disease and is mostly common in wild and domestic herbivores such as cattle, sheep, goats and antelopes but can also be seen in people exposed to tissue from infected animals or contaminated animal products.
Depending on the route of infection, host factors and potentially strain-specific factors, anthrax can have several different clinical presentations. In herbivores anthrax commonly presents as an acute septicemia with a high fatality rate while in dogs, people, horses and pigs, it is usually less acute although still potentially fatal.
B anthracis spores can remain viable in soil for many years. During this time they are a potential source of infection for grazing livestock but generally do not represent a direct risk of infection for people. Grazing animals may become infected when they ingest sufficient quantities of these spores from the soil.
Feed contaminated with bone or other meal from infected animals can serve as a source of infection for livestock, as can hay muddy with contaminated soil. Raw or poorly cooked contaminated meat is a source of infection for zoo carnivores and omnivores. Anthrax resulting from contaminated meat consumption has been reported in pigs, dogs and people.
Spores transmitting B anthracis are relatively resistant to extremes of temperature, chemical disinfection and desiccation.
Opening up the carcass (necropsy) is discouraged because of the potential for blood spillage and vegetative cells to be exposed to air, resulting in large numbers of spores being produced. Post-mortem examinations should not be undertaken on suspected anthrax cases until a blood smear has proved negative. Because of the rapid pH change after death and decomposition, vegetative cells in an unopened carcass quickly die without sporulating.
Clinical signs of anthrax are sudden death often within two or three hours of the animal being apparently normal. This is by far the most common and telling sign of anthrax death in your animals. The clinical course ranges from peracute to chronic.
The peracute form which is common in cattle and sheep is characterised by sudden onset and a rapidly fatal course.
Staggering, dyspnea (difficult breathing), trembling, collapse, a few convulsive movements and death may occur with only a brief evidence of illness.
In acute anthrax of cattle and sheep, there is an abrupt fever and a period of excitement followed by depression, stupor, respiratory or cardiac distress, staggering, convulsions, and death. Often, the course of disease is so rapid that illness is not observed and animals are found dead.
Rumination ceases, milk production is materially reduced and pregnant animals may abort. There may be bloody discharges from the natural body openings such as nose and anus. Rigor mortis (stiffening of limbs after death) is frequently absent or incomplete with marked bloating and rapid body decomposition.
The blood is dark and thickened and fails to clot readily. If a carcass is opened accidentally, the spleen is usually swollen and there is bloodstained fluid in all body cavities.
Due to the rapidity of the disease treatment is seldom possible, although high doses of penicillin have been effective in the later stages of some outbreaks. Where an outbreak has occurred, carcasses must be disposed of properly without opening them because exposure to oxygen will allow the bacteria to form spores and spread the infection.
The premises should be quarantined until all susceptible animals are vaccinated. The anthrax causing spores survive for a long time and can withstand extremely harsh conditions such as very high temperature. This means that in endemic areas even if no outbreak has been reported in a long time the risk of an infection resurfacing is always there. Uyabonga umntaka MaKhumalo.
Feedback: 0772851275 or email: [email protected]
