Johne's disease, a chronic intestinal infection caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP), typically becomes obvious in cattle between 2 and 5 years of age.
However, it's important to understand that the disease can manifest at different ages depending on various factors, including:
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Strain of MAP: Some strains are more virulent than others, leading to earlier signs of illness.
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Immune system: Animals with compromised immune systems may develop symptoms earlier.
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Exposure level: Animals exposed to high levels of MAP may show signs earlier.
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Management practices: Poor hygiene and overcrowding can increase the risk of infection and accelerate disease progression.
The initial stages of Johne's disease are often subtle, making it challenging to detect. As the disease progresses, signs become more apparent, including:
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Diarrhea: Persistent watery diarrhea is a hallmark symptom.
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Weight loss: Affected animals often lose weight despite maintaining a good appetite.
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Reduced milk production: Dairy cattle may experience a decline in milk production.
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Loss of condition: The animal's overall health deteriorates, leading to a gaunt appearance.
Early detection and intervention are crucial to manage Johne's disease effectively. Testing for MAP can help identify infected animals, even before clinical signs appear.
