Johne's Disease: A Hidden Threat

Abstract

Paratuberculosis, which is also known as Johne's disease, is a chronic, progressive enteric disease of ruminants caused by infection with Mycobacterium paratuberculosis. Cattle become infected with M. paratuberculosis as calves but often do not develop clinical signs until 2 to 5 yr of age. The clinical disease is characterized by chronic or intermittent diarrhea, emaciation, and death. Although animals with clinical disease are often culled from the herd, animals with subclinical paratuberculosis may cause economic losses because of reduced milk production and poor reproductive performance. Although the economic impact of paratuberculosis on the national cattle industry has not been determined, it is estimated to exceed $1.5 billion/yr. The diagnosis of subclinical paratuberculosis is difficult. Bacteriologic culture is the most definitive method of diagnosis, but culture is time consuming and labor intensive. Serological assays are not very useful because animals do not develop an antibody response until the clinical stages of disease. Development of assays to measure cell-mediated immunity is critical to accurate detection of paratuberculosis in subclinically infected animals. Although not considered a zoonotic agent, M. paratuberculosis has been identified in intestinal biopsy tissue from patients with Crohn's disease, an inflammatory enteritis in humans. Currently, the potential human health risk is being addressed by research evaluating pasteurization of dairy products in the US.

Characterization of Novel Coding Sequences Specific to Mycobacterium avium subsp. paratuberculosis : Implications for Diagnosis of Johne's Disease

“…Detection of M. avium subsp. paratuberculosis, especially during the often-lengthy subclinical phase of the disease, remains difficult due to intermittent shedding of small numbers of bacteria and a lack of effective diagnostic reagents (22).…”

Frequência de anticorpos para paratuberculose em bovinos no semiarido paraíbano

“…Em outros países a prevalência de anticorpos é variável; nos Estados Unidos e Canadá varia de 4,73% a 18% (Pence et al 2003, Sorensen et al 2003, Paolicchi 2004, na Austrália de 9% a 22% e na Argentina, na província de Buenos Aires, de 7,2% a 19,6% (Paolicchi 2004). Nos Estados Unidos estima-se que a paratuberculose ocasiona perdas anuais de 1500 milhões de dólares e que a indústria leiteira perde de 200 a 250 milhões de dólares por ano (Stabel 1998, Paolicchi 2004. No Canadá, as perdas econômicas são estimadas em 15 milhões de dólares por ano na indústria leiteira (Mckenna et al 2006).…”

NlpC/P60 domain‐containing proteins of Mycobacterium avium subspecies paratuberculosis that differentially bind and hydrolyze peptidoglycan

“…Crystallization of the selenomethionine-substituted protein was carried out using an identical protocol. Crystals of the truncated MAP_1204 protein were grown by hanging drop vapor diffusion by mixing 1 lL protein at 10 mg/mL in ddH 2 O with 1 lL of 1:1 diluted precipitant solution containing 22% (w/v) polyethylene glycol 3,350, 10% (v/v) 2-propanol, and 0.1M sodium HEPES, pH 7.5. We also obtained crystals of a third NlpC/P60 protein, MAP_1203, but these crystals did not diffract X-rays in an interpretable manner.…”

“…This disease, termed Johne's disease, has a worldwide distribution and >90% prevalence in U.S. dairy cattle herds, 1 which results in an economic toll of more than 200 million dollars annually. 2 The bacterium is transmitted from cow-to-calf via the fecal-oral route and through contaminated milk. Thus, a multipronged research approach that encompasses epidemiology, pathogenesis, diagnostics, vaccine development, and ideal herd management strategies is warranted to reduce the impact of Johne's disease on farms.…”