Presence of Non-Tuberculous Mycobacteria Including Mycobacterium avium subsp. paratuberculosis Associated with Environmental Amoebae

Simple Summary: The prevalence of Johne's disease (JD) due to Mycobacterium avium ssp. paratuberculosis (Map), responsible for considerable economic losses in the dairy industry worldwide, remains very high. In addition, recent studies have shown that Map may hamper the success of bovine tuberculosis (bTB) eradication programs due to frequent co-infection of hosts. Therefore, the risk of Map contamination by environmental sources must be studied given achieving improved control of this enzooty. Our previous work showed that environmental amoebae could function as reservoirs and vectors of these pathogenic mycobacteria. This study aims to describe amoeba-mycobacteria co-occurrence by sampling the water points of cattle herds monitored for Map and Mycobacterium bovis (M. bovis) infection. Our study showed that a wide diversity of amoebae and non-tuberculous mycobacteria (NTM) species, including Map, live closely together in water troughs of herds monitored for JD or bTB. The exact association between amoebae and mycobacteria calls for further investigation.One of the obstacles to eradicating paratuberculosis or Johne's Disease (JD) seems to be the persistence of Mycobacterium avium subsp. paratuberculosis (Map) in the environment due to its ability to survive alone or vectorized. It has been shown that Map is widely distributed in soils and water. Previously, we isolated amoebae associated with Map strains in the environment of bovines from an infected herd. This work aims to verify our working hypothesis, which suggests that amoebae may play a role in the transmission of JD. In this study, we sampled water in the vicinity of herds infected with Map or Mycobacterium bovis (M. bovis) and searched for amoebae and mycobacteria. Live amoebae were recovered from all samples. Among these amoebae, four isolates associated with the presence of mycobacteria were identified and characterized. Map and other mycobacterial species were detected by qPCR and, in some cases, by culture. This study suggests that amoebae and Map may be found in the same environment and might represent a risk of exposure of animals to pathogenic mycobacteria. These data open up new perspectives on the control measures to be put in place to prevent contamination by Map.

Automated summary

The prevalence of Johne's disease (JD) caused by Mycobacterium avium ssp. paratuberculosis (Map) is high and poses significant economic losses in the dairy industry worldwide. Recent studies have shown that Map may hinder the eradication of bovine tuberculosis (bTB) due to frequent co-infection. This study investigates the co-occurrence of amoebae and mycobacteria in water troughs of cattle herds monitored for JD or bTB, and suggests that amoebae may play a role in the transmission of JD.