Dam Mycobacterium avium subspecies paratuberculosis (MAP) infection status does not predetermine calves for future shedding when raised in a contaminated environment: a cohort study.

Ad P Koets,Susanne WF Eisenberg,Victor PMG Rutten

doi:10.1186/s13567-015-0191-2

Abstract

Uptake of Mycobacterium avium subsp. paratuberculosis (MAP) by calves in the first days of life from colostrum, milk and faeces is regarded an important moment of transmission. The objective of this study was to quantify the association between the MAP status of dams as determined by the presence of MAP DNA and antibody in colostrum and that of DNA in faeces and the environment with subsequent MAP shedding of their daughters. A cohort of 117 dam-daughter pairs giving birth/being born on eight commercial dairy farms with endemic paratuberculosis was followed where colostrum, faecal and environmental samples (dust) were analysed for the presence of MAP using an IS900 real-time PCR. Antibodies in colostrum were measured by ELISA. Analysis of dust samples showed that on all farms environmental MAP exposure occurred continuously. In significantly more colostrum samples (48%) MAP DNA was detected compared to faecal samples (37%). MAP specific antibodies were present in 34% of the colostrum samples. In total MAP DNA was present in faecal samples of 41% of the daughters at least once during the sampling period. The association between faecal shedding in the offspring and the dam MAP status defined by MAP PCR on colostrum, MAP PCR on faeces or ELISA on colostrum was determined by an exact cox regression analysis for discrete data. The model indicated that the hazard for faecal shedding in daughters born to MAP positive dams was not significantly different compared to daughters born to MAP negative dams. When born to a dam with DNA positive faeces the HR was 1.05 (CI 0.6; 1.8) and with DNA positive colostrum the HR was 1.17 (CI 0.6; 2.3). When dam status was defined by a combination of both PCR outcomes (faeces and colostrum) and the ELISA outcome the HR was 1.26 (CI 0.9; 1.9). Therefore, this study indicates that neither the presence of MAP DNA in colostrum, MAP DNA in faeces nor the presence of MAP antibodies in colostrum of the dam significantly influences the hazard of MAP shedding in their subsequent daughters up to the age of two years when raised in a contaminated environment.

Highlights

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis or Johne’s disease in cattle
Our current study indicates that the MAP status of the dam does not predetermine calves for future MAP shedding when these calves are raised in a MAP contaminated environment
The number of colostrum samples containing MAP DNA was significantly higher compared to the faecal shedding or presence of antibodies

Summary

Introduction

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis or Johne’s disease in cattle. The disease is characterized by chronic diarrhoea, weight loss and loss in milk production [1] It occurs in countries worldwide with herd prevalence’s in Europe and the US of over 50% [2,3]. Infected dairy cattle shed MAP intermittently in their faeces with increasing amounts when clinical disease develops [1]. Calves born to MAP positive dams have a higher infection risk due to the possibility of in-utero transmission [9] and due to contact with infectious faeces and uptake of infectious colostrum at parturition [10,11,12]. Paired dam-daughter data supporting the general opinion of the higher MAP infection risk of calves born to MAP positive dams is scarce. A retrospective study identified a higher risk for cows to be ELISA positive when their dams were ELISA positive as well [10]

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