Bacterial diseases of animals
(Dr. Girish Chandra)
Anthrax is an infectious disease caused by a bacterium called Bacillus anthracis, which can change into spores that can last for a long time in the environment before germinating. It is carried by wild and domestic animals in Asia, Africa and parts of Europe.
It is a bacterial disease that affects humans and animals. It is caused by bacteria of the genus Leptospira. Symptoms of leptospirosis include high fever, severe headache, chills, muscle aches, and vomiting, and may include jaundice (yellow skin and eyes), red eyes, abdominal pain, diarrhea, or a rash. If the disease is not treated, the animal could develop kidney damage, meningitis, liver failure, and respiratory distress. In rare cases death occurs. Treatment is done with antibiotics.
Anaplasmosis is a type of tick fever that is caused by invasion of red blood cells by the rickettsial blood parasite Anaplasma ovis. In cattle, the disease is caused by A. marginale or A. centrale. Transmission is through insect vectors, especially horse flies, ticks and flies. Ticks are the natural vectors and a range of tick species has been shown to be capable of transmitting infection, e.g. Boophilus, Dermacentor, Rhipicephalus, Ixodes, Hyalomma, Argas and Ornithodoros. There is also some evidence that it can be transmitted to the fetus in the womb. Cattle over 2 years of age become very ill and approximately 50% die unless treated. Usually, once the cattle become infected, and if they survive, stay infected for life. They are "immune carriers"—they do not get sick, but act as a reservoir for other susceptible animals.
It is caused by the bacterium Francisella tularensis found in animals, especially rodents, rabbits, and hares. Symptoms of tularemia could include: sudden fever, chills,
headaches, diarrhoea, muscle aches, joint pain, dry cough and progressive weakness.
People can also catch pneumonia and develop chest pain, bloody sputum and can have trouble breathing and even sometimes stop breathing. Other symptoms include ulcers on the skin or mouth, swollen and painful lymph glands, swollen and painful eyes, and a sore throat.
- Use impervious gloves when skinning or handling animals, especially rabbits.
- Cook the meat of wild rabbits and rodents thoroughly.
- Avoid being bitten by deer flies and ticks.
Louse-borne relapsing fever
Borrelia recurrentis is the only agent of louse-borne disease. Pediculus humanus, is the specific vector. Louse-borne relapsing fever is more severe than the tick-borne variety.
It occurs in poor living conditions, famine and war conditions. Mortality rate is 1% with treatment but 30-70% without treatment. Diagnosis includes severe jaundice, severe change in mental status, severe bleeding, and prolonged QT interval on ECG.
Tick-borne Relapsing Fever
Other relapsing infections are acquired from other Borrelia species, such as Borrelia hermsii or Borrelia parkeri, which can be spread from rodents, and serve as a reservoir for the infection, via a tick vector. Borrelia hermsii and Borrelia recurrentis cause very similar diseases although the disease associated with Borrelia hermsii has more relapses and is responsible for more fatalities, while the disease caused by B. recurrentis has longer febrile and afebrile intervals and a longer incubation period.
Tick-borne relapsing fever is found primarily in Africa, Spain, Saudi Arabia, Asia, and certain areas in the Western U.S. and Canada. It is Borrelia duttoni transmitted by the soft-bodied African tick Ornithodoros moubata that is responsible for the relapsing fever found in Central, East and southern Africa.
There are three types of TB – human, avian, and bovine. Human TB is rarely transmitted to non-humans, avian TB is typically restricted to birds, and bovine TB – or cattle TB – is the most infectious, capable of infecting most mammals. Bovine TB is caused by the bacterium Mycobacterium bovis, which is part of the Mycobacterium tuberculosis complex. Bovine TB is spread through the exchange of respiratory secretions between infected and uninfected animals. Bacteria released into the air through coughing and sneezing can spread the disease to uninfected animals. Non-cerviid animals are most likely to contract TB from feeding on infected tissues from deer carcasses.
Infected lymph nodes will contain one or more necrotic nodules, which may vary in size and be filled with yellow-green or tan pus. Coughing, nasal discharge, and difficulty in breathing can result in cases where the lungs become severely affected. In some instances, superficial lymph nodes in the neck will develop large abscesses that may rupture and drain through the skin.