Prevalence and distribution of paratuberculosis (Johne's disease) in cattle herds in Ireland

Abstract

A simple random survey was conducted in Ireland during 2005 to estimate the ELISA-prevalence of paratuberculosis, commonly called Johne's disease (JD), in the cattle population. Serum samples were collected from all 20,322 females/breeding bulls over 12 months-of-age in 639 herds. All samples were tested using a commercially available absorbed ELISA. The overall prevalence of infected herds, based on the presence of at least one ELISA-positive animal, was 21.4% (95% CI 18.4%-24.9%). Herd prevalence levels amongst dairy herds (mean 31.5%; 95% CI: 24.6%, 39.3%) was higher than among beef herds (mean 17.9%; 95% CI: 14.6%-21.8%). However, the animal level prevalence was similar. The true prevalence among all animals tested, was calculated to be 2.86% (95%CI: 2.76, 2.97) and for animals >= 2 yrs, it was 3.30% (95%CI: 3.17, 3.43). For animals in beef herds, true prevalence was 3.09% (95%CI: 2.93, 3.24), and for those in dairy herds, 2.74% (95%CI: 2.59, 2.90). The majority of herds had only one ELISA-positive infected animal. Only 6.4% (95% CI 4.7%-8.7%) of all herds had more than one ELISA-positive infected animal; 13.3% (CI 8.7%-19.7%) of dairy herds ranging from two to eight ELISA-positive infected animals; and, 3.9% beef herds (CI 2.4%-6.2%) ranging from two to five ELISA-positive infected animals. The true prevalence of herds infected and shedding Mycobacterium avium subspecies paratuberculosis is estimated to be 9.5% for all herd types; 20.6% for dairy herds; and 7.6% for beef herds. If ELISA positive animals <2-years-of-age are excluded, the true herd prevalene reduces to: 9.3% for all herd types; 19.6% for dairy herds; and 6.3% for beef herds based on a test specificity (Sp) of 99.8% and test sensitivity (Se) (i.e., ability to detect culture-positive, infected animals shedding at any level) of 27.8-28.9%.

Bayesian estimation of prevalence of paratuberculosis in dairy herds enrolled in a voluntary Johne’s Disease Control Programme in Ireland

“…Previous to this 239 study, only one HTP estimate had been published for paratuberculosis in Ireland (Good et al,240 2009). The posterior HTP estimate from the present study was higher than that reported in the 241 2009 study (0.206) (Good et al, 2009). However, the earlier study utilised frequentist methods 242 to estimate the true prevalence of herds with at least one infectious (shedding) animal and was 243 based on a serological test Se of 0.278-0.289.…”

“…was estimated at 20%, based on the results of a serological survey (Good et al, 2009), 50 considerably lower than estimates across Europe of greater than 50% (Nielsen and Toft, 2009). 51…”

Questionnaire identifying management practices surrounding calving on spring-calving dairy farms and their associations with herd size and herd expansion

“…More than 20% of Irish herds have diagnosed at least one positive paratuberculosis animal in their herd (Good et al, 2009); however 35% of respondents in the present study had never tested for the disease. The greater likelihood of the disease being diagnosed in larger herds agrees with previous research .…”

Persistence of Mycobacterium avium subsp. paratuberculosis at a Farm-Scale Biogas Plant Supplied with Manure from Paratuberculosis-Affected Dairy Cattle

“…However, M. avium subsp. paratuberculosis, as a causal agent of paratuberculosis (PTB), which affects most cattle herds worldwide, is not included in such studies (1,5,15). Moreover, M. avium subsp.…”