Characteristics of subclinical Mycobacterium avium ssp. paratuberculosis infection in a captive white-tailed deer herd

Abstract

Paratuberculosis (Johne’s disease) is caused by Mycobacterium avium ssp. paratuberculosis (MAP), and affects both domestic and wild ruminants, including cattle, goats, sheep, and deer. In cattle, most infections occur during calfhood followed by a prolonged incubation period of 1–2 y or more before cows shed culturable numbers of MAP bacilli in their feces. As disease progresses, infected animals develop protein-losing enteropathy, intractable diarrhea, and weight loss. In a cohort of 32 clinically normal deer from a herd with a history of periodic clinical paratuberculosis, we found that subclinical infection was characterized by high rates of infection, common involvement of mesenteric lymph nodes, minimal lesion formation, few intralesional acid-fast bacilli, and low-level fecal shedding of MAP. The characteristics of subclinical paratuberculosis in white-tailed deer resemble those of cattle and red deer, although microscopic lesions were less common in subclinical deer than reported for subclinical cattle, and we did not see necrotizing granulomas as described in subclinical red deer and elk.

Ability of mycobacterial pathogens to establish a persistent infection is lost by deletion of a single gene,rel, regulator of the stringent response

“…Multiple studies with BCG have shown that, although virulence is reduced, BCG can still establish a persistent infection. This was demonstrated in early studies reported by Lurie in 1934 (16) and more recent studies reviewed in (8,17,18). It could be inferred from the Mtb studies by Dahl et al, that deletion of rel in BCG would have the same effect as deletion in Mtb.…”

Vaccination of White-Tailed Deer with Mycobacterium bovis Bacillus Calmette–Guérin (BCG): Effect of Mycobacterium avium ssp. paratuberculosis Infection

“…It is apparent that subclinical infections were present. In a previous report, Map was isolated from the tissues of white-tailed deer in a Map-endemic setting, even though several samples of feces had been PCR negative and culture negative for Map prior to necropsy [79]. Thus, it is apparent that Map-infected white-tailed deer may shed Map intermittently over long periods of time and that examination of feces by direct PCR and bacteriological culture, even when done semi-annually over a 2-3-year period, is not sufficient to identify all Map-infected deer.…”

High clonality of Mycobacterium avium subsp. paratuberculosis field isolates from red deer revealed by two different methodological approaches of comparative genomic analysis

“…For this reason, according to the new Animal Law Regulation 429/2016, by being a natural MAP reservoir, the red deer is a potential epidemiological risk for MAP transmission in the surrounding area. From a clinical perspective, the manifestations of paratuberculosis in red deer closely resemble those observed in cows: persistent diarrhoea, weight loss, and deteriorating body condition as the disease advances ( 4 ). For a genetic perspective, three major MAP strain types were initially identified according to the host species and based on restriction endonuclease analysis, DNA hybridisation, and pulsed-field gel electrophoresis (PFGE): ( i ) Type I or S type for sheep; ( ii ) Type II or C type for cattle; and ( iii ) Type III or “intermediate” between Type I and Type II ( 5–8 ).…”