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From calves to cattle: How are they infected with John's disease soon after birth?
Johne's disease is an infectious disease that primarily affects the small intestine of ruminants and causes a persistent and sometimes fatal infection. The disease is caused by the bacterium Mycobacterium avium subspecies paratuberculosis, which has afflicted many farm animals and infections have been reported around the world.
Newborn calves are most likely to become infected by ingesting traces of infected feces from their birth environment or from the mammary glands of their mothers.
Origin and transmission of John's disease
Studies have shown that cows can also transmit John's disease to their fetuses during pregnancy, or further through infected milk and colostrum. Therefore, the potential transmission route of Johne's disease exists from birth, which makes the prevention and control of the disease quite difficult.
Early signs and symptoms of infection
In cattle, the main signs of Johne's disease are diarrhoea and emaciation. Most cases present between 2 and 6 years of age. Early symptoms may be subtle and may be limited to weight loss, decreased milk production, or coarse hair coat. As the disease worsens, cows may develop a condition called "bottle jaw," which is swelling of the jaw caused by the loss of protein into the digestive tract.
In cattle, there is usually an incubation period of more than two years before clinical symptoms of Johne's disease appear, making early diagnosis a major challenge.
Pathophysiology of John's
Johne's disease mainly affects the last part of the intestine, the ileum. Here there are large collections of lymphoid tissue, called Peyer's patches, which recognize and respond to antigens in the environment. Unfortunately, when John's bacteria enter these lymphoid tissues, they are able to effectively evade the immune system's destructive mechanisms and multiply.
Control and management measures
In the United States, Johne's disease is listed as a reportable disease and farm animals should be tested regularly to maintain the health of the herd. For infected cattle, boiling milk is an effective method to kill John's disease.
Testing has shown that approximately 50% of the herd may be carriers with no clinical signs, resulting in potential losses to farm production.
Human Health Risks
Although Johne's is a ruminant organism, studies have shown that it may also affect humans with symptoms similar to Johne's, but this remains a research topic that needs further exploration.
ConclusionJohnsonella infection has profound consequences for the health and productivity of farm animals, therefore understanding its infection mechanisms is crucial to developing effective prevention and control measures. Ultimately, when we consider how best to protect the health of ruminants, can we find better ways to address this challenge?
