1. Bacterial Isolation, Immunological Response, and Histopathological Lesions during the Early Subclinical Phase of Experimental Infection of Goat Kids with Mycobacterium avium subsp. paratuberculosis
- Author
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Saxegaard F, Evensen O, Sigurdardóttir Og, and Press Cm
- Subjects
DNA, Bacterial ,0301 basic medicine ,Pathology ,medicine.medical_specialty ,040301 veterinary sciences ,Paratuberculosis ,Bacteremia ,Enzyme-Linked Immunosorbent Assay ,Ileum ,Biology ,Polymerase Chain Reaction ,Incubation period ,0403 veterinary science ,Feces ,03 medical and health sciences ,Retropharyngeal lymph nodes ,Immune system ,medicine ,Animals ,Mesenteric lymph nodes ,Hypersensitivity, Delayed ,Lymph node ,DNA Primers ,Subclinical infection ,Goat Diseases ,General Veterinary ,Goats ,Complement Fixation Tests ,04 agricultural and veterinary sciences ,medicine.disease ,Immunohistochemistry ,Mycobacterium avium subsp. paratuberculosis ,Jejunum ,030104 developmental biology ,medicine.anatomical_structure ,Immunology ,Lymph Nodes - Abstract
The diagnosis of Mycobacterium avium subsp. paratuberculosis infection is difficult, especially in the early stages of disease. This is due to the long incubation period, the variable lag phase associated with bacterial proliferation, and the multifocal distrbution of slowly developing lestion. There are few previous studies of the early stages of experimental paratuberculosis in goats. In the present study, the ability of conventional diagnostic methods to detect M. a. paratuberculosis infection during the early stages of infection was assessed. Eight goat kids were experimentally infected with M. a. paratuberculosis and subjected to a series of immunological and bacteriological tests before being euthanatized at various times postinfection. At postmortem examination, the ages of the kids ranged from 1 1/2 to 12 months. Of the eight goats infected, three had histo-pathological evidence of paratuberculosis. Two of these goats were positive with bacteriology, but only one was also positive with all immunological tests. One animal had a positive immunological response, but infection could not be demonstrated by bacteriologic or histopathologic examination. Histopathologic lesions were found in the jejunum, in the ileum, and in one mesenteric lymph node, but only the mesenteric lymph nodes and one retropharyngeal lymph node gave positive results following bacteriologic culture. The disparity between the localization of histopathologic lesions and bacteriologic results emphasizes the need for exhaustive sampling to confirm a diagnosis during the early phase of an infection. It also highlights the need for a better understanding of the biology of M. a. paratuberculosis and its interaction with the immune system of the host.
- Published
- 1999
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