Mycobacterium avium subsp. paratuberculosis (Map) is the known cause of Johne's disease of both domestic and wild ruminants and has been implicated as a possible cause of Crohn's disease in humans. The organism is shed in the faeces of infected animals and can survive for protracted periods in the environment and hence could be present in water catchment areas receiving agricultural runoff. A limited study was undertaken in Northern Ireland to test for Map in raw waters entering nine water treatment works (WTWs) over a one year period. Three detection methods were employed: IMS-PCR (IS900-based) and culture on Herrold's egg yolk medium (HEYM) and in BACTEC 12B medium. Of the 192 samples tested 15 (8%) tested positive by one or more of the three detection methods. Map was successfully isolated from 8 water samples, 3 by BACTEC culture and 5 by culture on HEYM. Although the highest incidence of Map was found in spring, overall there was no statistically significant difference between the seasons. No significant correlation was found between numbers of coliforms or faecal coliforms and presence of Map. In general, an increased incidence of Map was found in those WTWs that had a high mean pH value over the sampling period. This work indicates the need to determine the efficacy of water treatment processes to either kill or remove Map from raw water to assess the possible risks posed by recreational contact with water sources.

Sponsorship

Attendance at this congress was sponsored by the EU-funded project SSPE-CT-2004-501903 (VENoMYC).