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JOHNE'S INFORMATION CENTER - University of Wisconsin Ñ School of Veterinary Medicine
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Monday, March 19, 2018
MAP in Michigan Tap Water

Research article
This publication focuses on improved methods for detecting mycobacteria in water, specifically “nontuberculous mycobacteria” (NTM), of which MAP is a member. Mycobacteria researchers may benefit from these new more sensitive genetic detection techniques.

MAP is one of the most virulent of the NTM bacteria. The study tested domestic water (DW), i.e. tap water, collected in Ann Arbor, Michigan. The DW treatment plant there obtains 80-85% of its water from the Huron River. The rest comes from groundwater wells.

Of interest to readers of this website is that MAP was found as one of the several NTM at 6 of 15 water age time points; see green bars in Fig. 4 of the publication. Water age is the time between leaving the DW treatment plant and reaching the consumer’s household. The authors estimated the concentration of MAP at 35,000 MAP/liter of water: a lot, but only small fraction of all NTM found in the tap water.

Comment: Finding MAP in tap water is not new, but it is concerning. The technology used for MAP detection does not allow determination if the MAP were alive or dead. In addition, the source of MAP in tap water is unknown. What science does know is that MAP replicates primarily in ruminant animals. However, MAP can replicate in free-living amoeba and persist in biofilms of the type found on pipes in water distribution systems. The Huron River watershed is home to over 4,500 dairy cattle and 1,800 goats. Their MAP-infection status is unknown.

Link to full Open Access article in mBio, a publication of the American Society for Microbiology


Wednesday, March 14, 2018
Another study finds live MAP in pasteurized milk

Research article

A survey of retail purchased semi-skimmed pasteurised milk (n = 368) for Mycobacterium avium subspecies paratuberculosis (MAP) was conducted between May 2014 and June 2015 across the midlands of England using the Phage-PCR assay. Overall, 10.3% of the total samples collected contained viable MAP cells, confirming that pasteurisation [British spelling] is not capable of fully eliminating human exposure to viable MAP through milk. Comparison of the results gained using the Phage-PCR assay with the results of surveys using either culture or direct PCR suggest that the phage-PCR assay is able to detect lower numbers of cells, resulting in an increase in the number of MAP-positive samples detected. Comparison of viable count and levels of MAP detected in bulk milk samples suggest that MAP is not primarily introduced into the milk by faecal contamination but rather are shed directly into the milk within the udder. In addition results detected an asymmetric distribution of MAP exists in the milk matrix prior to somatic cell lysis, indicating that the bacterial cells in naturally contaminated milk are clustered together and may primarily be located within somatic cells. These latter two results lead to the hypothesis that intracellular MAP within the somatic cells may be protected against heat inactivation during pasteurisation, accounting for the presence of low levels of MAP detected in retail milk.

Comment: At least six peer-reviewed scientific reports have found live MAP in retail HTST pasteurized milk. Given that all other slow-growing mycobacteria are proven zoonotic pathogens (pathogens capable of causing disease in humans), it is imperative that the medical community conclusively establish if MAP presents a risk to human health or not.

Link to journal article


Wednesday, March 7, 2018
Successful eradication of Johne’s disease from a large dairy goat herd

Research publication from the journal Veterinary Record. Abstract:
This retrospective analysis and report describes the successful eradication and posteradication surveillance programme for Johne’s disease (Mycobacterium avium subspecies paratuberculosis (MAP)) in a closed herd of dairy goats. In 1994, MAP’s presence in the goat herd was first suspected through individual annual serological screening and then subsequently confirmed through faecal culture and histopathology in 1997 when implementation of a more aggressive programme of testing and eradication of the diseased animals began. This programme included frequent serological screening of all adult goats using ELISA and agar gel immunodiffusion assays. Faecal cultures for bacteria were performed on suspect or positive animals and for all goats found dead or euthanized, and tissues were submitted for histopathology and acid-fast staining. Additional disease eradication measures included maintaining a closed herd and minimising faecal-oral transmission of MAP. Following a more aggressive testing regimen and euthanasia of goats with positive faecal culture, the herd was first considered free of MAP in 2003 and has remained free to the present day.

Comment: This study and others, demonstrates that Johne’s disease can be eradicated from goat herds. If it can be done in this herd of over 500 goats, it clearly can be done in small herds. Diagnostics have improved greatly since this herd began their eradication program with ELISA and PCR being today’s best diagnostic tools.

Link to full report


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