Johne’s disease (paratuberculosis) is a chronic contagious disease affecting primarily the small intestines of ruminants, found worldwide.
Cause: A bacterium Mycobacterium avium SS. Paratuberculosis. (MAP)
Primary Source: The feces of infected goats
Other Sources: Milk and in utero
Cattle and sheep
Age Infected: Any ages but kids in their first month after birth are most susceptible and are the ones most likely to develop clinical signs later in life
Route of Infection: Oral. Kids within a few days of birth start to eat feces as a means of establishing the normal flora in their gastrointestinal tract. Along with the good bugs, they can pick up harmful ones. Although the organism is very hearty it cannot replicate outside the body, but in the feces it is resistant for several months to heat, cold and drying.
Clinical Symptoms:
Rapid to chronic weight loss, terminally the goat may develop diarrhea. These symptoms occur primarily in adults it is rare to see on the disease in kids under a year of age. Another classical symptom is the animal continues to eat well. Most of the other chronic wasting disease such as the scrapie and caseous lymphadenitis result in weight loss and the poor appetite. Bottle Jaw (oedema under the jaw) has been seen in severely affected goats.
Postmortem Findings:
The intestinal tract (ileum) involved will be thickened and the associated lymph nodes enlarged. This is called a granulomatous enteritis and interferes with the ability of the gastrointestinal tract absorb nutrients.
Morbidity and mortality:
In endemic herds only a minority develop clinical signs, the mortality rate is approximately 1% with up to 50% of the herd as asymptomatic carriers
Human Risks
Research has found there may be a link to Crohn’s disease.
Purchasing Goats:
At the time of purchase, the goat may appear normal, so it is important to be very thorough in investigating the herd the goat is from. This entails looking at the records of the herd, inspecting the herd itself. in addition,you must ask many questions of the owner. Ask If the owner has a high cull rate of mature animals, if yes, you should explore the reasons why? You should also investigate the pedigree of the goat you are purchasing and to ask if the mother, grandmother and daughters are still in the herd. If they are not and you should find out what happened to them. If the owner is unwilling to supply this information to you then I would advise you not to purchase the goat. Most experienced producers know whether they have the disease are not.
Diagnostic testing is done to:
· determine if the disease is present or not
· determine the extent of the infection
Your veterinarian can help you and you may want to visit the following website
http://www.aphis.usda.gov/animal_health/lab_info_services/approved_labs.shtml
Two types of diagnostic tests are available:
1) Organism based tests:
a) Culture: This test isolates the organism if it is present within the environment or the feces. Unfortunately, the organism is very slow to grow and the culture may not show any organism for up to two months of incubation. Samples can be taken from the environment, the soil, water, individual animals or several animals collectively.
b) PCR: This test looks at the genetic material in the organism and not the organism itself. This test has only been validated in cattle
2) Antibody based tests This is an indirect test, which measures the level of antibodies in blood or milk.
a) Eliza test designed to test a large number of samples. Only one test has been validated in United States for sheep and goats
b) Agar Gel Immuno Diffusion test (AGID) looks for antibodies in the blood the results are reported as negative, positive, or suspect. Correlates well with fecal load and fecal shedding
Control; http://www.gov.mb.ca/agriculture/livestock/sheep/pdf/bsa15s00.pdf
Have AGID tests done on all goats on an annual basis. Cull all positive animals or consider other options. All infected animals should be identified and managed in such a way that their feces do not contaminate the environment or the water. Most effective way of doing this is slaughtering the goat as soon as the first symptoms appear.
Control involves protecting newborn kid from infection this is accomplished by feeding the milk (colostrum) that does not contain the organism, and keeping the environment free of contaminated feces and water
http://www.johnes.org/goats/faqs.html#3
