Observed management practices in relation to the risk of infection with paratuberculosis and to the spread of Mycobacterium avium subsp. paratuberculosisin Swiss dairy and beef herds

Abstract

BackgroundMany studies have been conducted to define risk factors for the transmission of bovine paratuberculosis, mostly in countries with large herds. Little is known about the epidemiology in infected Swiss herds and risk factors important for transmission in smaller herds. Therefore, the presence of known factors which might favor the spread of paratuberculosis and could be related to the prevalence at animal level of fecal shedding of Mycobacterium avium subsp. paratuberculosis were assessed in 17 infected herds (10 dairy, 7 beef). Additionally, the level of knowledge of herd managers about the disease was assessed. In a case–control study with 4 matched negative control herds per infected herd, the association of potential risk factors with the infection status of the herd was investigated.ResultsExposure of the young stock to feces of older animals was frequently observed in infected and in control herds. The farmers’ knowledge about paratuberculosis was very limited, even in infected herds. An overall prevalence at animal level of fecal shedding of Mycobacterium avium subsp. paratuberculosis of 6.1% was found in infected herds, whereby shedders younger than 2 years of age were found in 46.2% of the herds where the young stock was available for testing. Several factors related to contamination of the heifer area with cows’ feces and the management of the calving area were found to be significantly associated with the within-herd prevalence. Animal purchase was associated with a positive herd infection status (OR = 7.25, p = 0.004).ConclusionsNumerous risk factors favoring the spread of Mycobacterium avium subsp. paratuberculosis from adult animals to the young stock were observed in infected Swiss dairy and beef herds, which may be amenable to improvement in order to control the disease. Important factors were contamination of the heifer and the calving area, which were associated with higher within-herd prevalence of fecal shedding. The awareness of farmers of paratuberculosis was very low, even in infected herds. Animal purchase in a herd was significantly associated with the probability of a herd to be infected and is thus the most important factor for the control of the spread of disease between farms.

Risk factors for Mycobacterium avium subsp. paratuberculosis (MAP) and Mycobacterium bovis coinfection at individual animal level in southern Chile cattle populations

“…A higher proportion of individuals in the coinfected group also belonged to herds where calves were fed with colostrum from multiple cows and also with waste milk. This is not surprising since the main MAP transmission route in ruminants is oral, by ingestion of food or water contaminated with feces from infected animals, including ingestion of the bacterium from contaminated pastures (Doré et al 2012;Künzler et al 2014). Furthermore, in a study of subclinically infected cows, MAP shedding in colostrum (22.2 % of cows) was 3 times higher than in milk (8.3 %) (Streeter et al 1995), indicating the importance of discarded milk (colostrum and milk) as a way of transmission.…”

“…It has been reported that husbandry practices could allow the entrance of some infectious agents into a herd or the transmission among other animal population groups (Diéguez et al 2008;Humblet et al 2009;Kennedy et al 2014;Künzler et al 2014). The negative impact of both mycobacteria species on animal and public health, and given its complicated infection biology, seems to be important issues to be addressed.…”

Johne's disease: reliability of environmental sampling to characterize Mycobacterium avium subspecies paratuberculosis (MAP) infection in beef cow-calf herds

“…Although MAP was only proven in the faeces of two animals, Bayesian estimates of true prevalence indicated that 20% [95% confidence interval (CI) 3 -38] of herds had at least one MAP-positive cow with a within-herd prevalence of positive herds of 22% (95% CI 8-42). In a Swiss study, a within-herd prevalence of 6•4% in seven infected beef herds was detected by faecal culture and PCR in pools of three [20]. The number of animals sampled in these herds ranged from 25 to 130 with an average number of 56 animals aged >1 year.…”

Fecal culture and two fecal-PCR methods for the diagnosis of Mycobacterium avium subsp. paratuberculosis in a seropositive herd

“…Nevertheless, we expected to find a higher proportion of MAP-positive animals (by ELISA, as well as, by fecal culture and PCR) in the study herd, considering inappropriate herd management practices present and known to be risk factors for the disease (e.g. presence of animals born at other dairies, exposure of calves 0-6 weeks to adults feces, feces spread on forage fed to any age group (Collins et al, 1994;Goodger et al, 1996;Jakobsen et al, 2000;Wells and Wagner, 2000;Diéguez et al, 2008;Tiwari et al, 2009;Sorge et al, 2012;Künzler et al, 2014;Fernández-Silva and Ramírez-Vásquez, 2015;Vilar et al, 2015). When a test combination is considered, it must be taken into account that some infected cows produce antibodies for several years prior to the fecal-shedding of detectable quantities of MAP.…”