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

Authors: Palmer, Mitchell; KANIPE, CARLY - Oak Ridge Institute For Science And Education (ORISE); Cox, Rebecca; Robbe Austerman, Suelee; Thacker, Tyler

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2019
Publication Date: 8/1/2019
Citation: Palmer, M.V., Kanipe, C., Cox, R.J., Robbe Austerman, S., Thacker, T.C. 2019. Characteristics of subclinical Mycobacterium avium ssp. paratuberculosis infection in a captive white-tailed deer herd. Journal of Veterinary Diagnostic Investigation. 31(6):844-851. https://doi.org/10.1177/1040638719873028.
DOI: https://doi.org/10.1177/1040638719873028

Interpretive Summary: Paratuberculosis, also known as Johne’s disease is caused by the bacterium Mycobacterium avium subsp paratuberculosis (Map) and results in chronic diarrhea that is not responsive to treatment in cattle, goats, sheep and wild ruminants. In cattle, most infections occur during calfhood followed by a prolonged incubation period of 1-2 years before cows shed Map bacteria in their feces and become a source of infection for other animals. A serious problem in dairy cattle, paratuberculosis can result in decreased milk production and decreased reproductive success. It is estimated that for every cow in a herd showing clinical signs of paratuberculosis such as diarrhea, there are 25-30 other cattle infected but not showing clinical signs. These animals can also becom a source of infection for herd mates. Deer farming has been practiced for decades in countries such as New Zealand, but represents a newer industry in the US. Deer are farmed much like domestic animals and are subject to many of the same diseases. Little is known about paratuberculosis in deer. In this study we demonstrated that, similar to dairy herds, for every deer diagnosed with paratuberculosis there are many harboring the disease, that later may act as a source of infection to herd mates. This information will be of use to deer farmers as they try to manage paratuberculosis and improve the health of their animals.

Technical Abstract: Paratuberculosis (Johne’s disease) is caused by Mycobacterium avium subsp paratuberculosis (Map), and effects 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 years or more before cows shed culturable numbers of Map bacilli in their feces. As disease progresses, infected animals develop intractable diarrhea, weight loss, protein losing enteropathy and emaciation. Paratuberculosis has been described in various species of deer, including red deer and white-tailed deer. In deer, clinical signs are similar to those seen in cattle, specifically, chronic diarrhea, weight loss and declining body condition. In red deer two different clinical syndromes have been described; sporadic disease in mixed ages of deer characterized by low morbidity and high mortality, and severe outbreaks in young deer, characterized by high morbidity and high mortality. The paucity of naturally occurring clinical cases in white-tailed deer makes conclusions regarding clinical disease course, clinical syndromes or fecal shedding patterns difficult. In a cohort of 32 clinically normal deer from a herd with a history of periodic clinical paratuberculosis, 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 that reported for subclinical cattle or bison and necrotizing granulomas described in subclinical red deer and elk were not seen.