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- Although rabies has been eradicated in certain European countries, North America, Japan and South Korea, it still poses a significant threat to humans and animals worldwide.
- Rabies is described as the only infectious disease with a 100% mortality rate in any species, including humans.
- According to The Cattle Site, the Lyssavirus, which is secreted in saliva, is the culprit behind this zoonotic disease.
- According to Rabies: A guide for the Medical, Veterinary and Allied Professions, “apart from behavioural changes, there are no definitive, species-specific clinical signs of rabies. Rabies can mimic many other diseases, but it always has a neurological component”.
- Rabies is a notifiable animal disease in South Africa and is regulated by the Animal Diseases Act, 1984 (Act 35 of 1984).
Although rabies has been eradicated in certain European countries, North America, Japan and South Korea, it still poses a significant threat to humans and animals worldwide. According to the World Organization for Animal Health (WOAH), this fatal viral disease is especially prevalent across large parts of Africa and Asia.
In an information sheet titled SA’s alarming outbreak of rabies in dogs: Vaccination and awareness are key to prevention by the University of Pretoria, rabies is described as the only infectious disease with a 100% mortality rate in any species (including humans) once clinical signs appear.
Moreover, the disease can occur anywhere in South Africa. The rural regions of KwaZulu-Natal, the Eastern Cape, Rustenburg and its surrounding areas in the North West, the northern parts of Limpopo, as well as the eastern and south-eastern parts of Mpumalanga are all high risk regions. A rising number of rabies cases has been reported since 2021, with the Eastern Cape having reported the most.
Rabies in animals
According to The Cattle Site, the Lyssavirus, which is secreted in saliva, is the culprit behind this zoonotic disease (transmissible from animal to human). The virus causes acute inflammation of the nervous system and eventually the brain (encephalitis). All mammals are susceptible to the rabies virus. In almost all cases, saliva is the main method of transmission (this typically occurs when an animal or human is bitten by an infected animal).
Transmission takes place when saliva comes into contact with broken skin or the mucous membranes of the eyes, nose or mouth. According to the UP information sheet, stray dogs are one of the foremost sources of transmission; however, the black-backed jackal, bat-eared fox and yellow mongoose also play a role.
In another information sheet from the KwaZulu-Natal branch of the National Animal Health Forum, the disease can take hold in a herd of cattle when one of the animals is bitten by an infected dog or jackal (typically the main carriers of the rabies virus). The infected animal (dog/jackal) will present with clinical signs and succumb within three to four days.
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Clinical signs in animals
According to Rabies: A guide for the Medical, Veterinary and Allied Professions, “apart from behavioural changes, there are no definitive, species-specific clinical signs of rabies. Rabies can mimic many other diseases, but it always has a neurological component”.
There are two rabies syndromes, namely the ‘furious’ or ‘dumb’ form. Animals with the furious form become aggressive, salivate profusely, and foam around the mouth due to its inability to swallow. Cattle’s vocal cords in particular are affected, and their bellow will typically be loud and hoarse. Animals’ hind legs become paralysed, and cattle develop paresis (they keep pushing as if they were constipated).
Excessive salivation in cattle, especially if accompanied by an unsteady gait, is a red flag. An animal may also present with the ‘object in throat’ syndrome; if a person attempts to dislodge it, the rabies virus can be transmitted via a cut or sore on the person’s hand on arm.
In the dumb form, wild animals appear to be tame and will even lose their fear of humans (e.g. walk into a house). Paralysis in the later stages of both forms is not eliminated.
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Rabies is a notifiable animal disease in South Africa and is regulated by the Animal Diseases Act, 1984 (Act 35 of 1984). Vaccination can prevent it, and avoiding contact with wild animals is an important precaution. Parties at risk of contracting the disease must be armed with the correct knowledge regarding safety.
According to the Animal Health Forum, modern vaccines are effective, but once the first symptoms appear it is already too late, and death is inevitable. A typical vaccination programme involves the administration of inactivated vaccines that are safe for all age groups and circumstances. At three months of age all dogs and cats should already have been vaccinated against rabies, with a booster dose given a year later. Usually, repetitions are only necessary every three years.
In regions in which rabies is prevalent, annual vaccination of animals is recommended. As a rule, cattle and sheep are not usually vaccinated, but if rabies has been diagnosed on a farm, calves can be vaccinated as early as three months of age, as well as adult animals. Annual vaccination is necessary.
Rabies is a highly contagious and deadly zoonotic disease that can be effectively prevented through timely immunisation. – Christal-Lize Muller, Stockfarm
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