Micro-Organisms in Milk Cause Crohn's Disease

LONDON, UK, January 27, 2000 (ENS) - A bug present in retail pasteurised milk in the UK causes Crohn's disease, a leading medical researcher at St George's Medical School, London has found. The micro-organism is believed to exist in up to 54 percent of the dairy herds in Western Europe and North America.

Professor John Hermon-Taylor detailed his evidence to the Medical Journalists Association at The Royal Society of Medicine, London on Monday.

For years, the cause of Crohn's disease has eluded researchers and no lasting cure has been found. Crohn's disease is not a killer but it does ruin the lives of sufferers. Symptoms of the intestinal affliction include chronic diarrhoea, daily abdominal pain, weight loss, extreme tiredness and psychological problems.

The medical charity Action Research has funded Professor Hermon-Taylor's pioneering research into the disease for over 20 years at St George's Hospital Medical School, London. Action Research has funded four research projects into Crohn's disease since 1979, spending a total of over 750,000. The research developed new methods for testing for the micro-organism and indicated its presence both in milk and in humans.


Cows in Ireland (Photo courtesy Irish Dairy Board)
The bug, an organism known as MAP (Mycobacterium avium subspecies paratuberculosis), is not completely killed by normal milk pasteurisation methods and is present in people with Crohn's disease.

Professor Hermon-Taylor says, "The problems currently caused by MAP in the milk supply constitute a public health disaster of tragic proportions for which a range of remedial measures are urgently needed, and for which the government must take responsibility."

Hermon-Taylor told the medical journalists, "Both through our own work and new research evidence from the USA I am absolutely certain that MAP causes a substantial proportion of Crohn's disease."

Anne Luther, director general of Action Research, said "The extent of this problem appears far greater than CJD and Aids in the UK, yet previous calls for government action appear to have gone unheeded."

MAP is a specific member of the class of organism known as Mycobacteria, of which the tuberculosis and leprosy organisms are the most notorious members. MAP contains fragments of foreign DNA that has converted it from a harmless organism into a pathogen.


Milk and milk-based foods (Photo courtesy Utah State University)
Crohn's disease severely affects an unknown number of people, believed to be up to 80,000 people in the UK. It is thought that there are 4000 to 8000 new cases every year. These figures will remain uncertain until the government makes the disease notifiable, which means statistics are collected upon diagnosis.

It is estimated to cost the nation as much as 240 million each year in direct health care costs in the UK alone.

The MAP organism can live in cattle and other animals for years without causing visible disease.

Professor Hermon-Taylor estimates that between 21 and 54 percent of the dairy herds in Western Europe and North America harbor the MAP organism in a "sub-clinical" state where the disease is present but not apparent.

Those cows that have the MAP organism in their bodies secrete MAP into their milk and onto pastures even if they do not appear diseased.

MAP is tougher than tuberculosis and is not completely inactivated by pasteurisation. During pasteurisation milk is heated to 72 degrees Celsius for fifteen seconds, a process that is supposed to destroy all harmful micro-organisms. But Professor Hermon-Taylor says that residual MAP is present in retail pasteurised milk in the UK.

MAP is probably present in water supplies in some areas, Professor Hermon-Taylor says.

Until recently, scientists were not able to say what causes Crohn's disease. MAP can now be detected by improved culture systems and DNA tests in the inflamed gut of a high proportion of people with Crohn's disease. This is confirmed from recent work from St. George's Hospital, London and the University of Central Florida.


Cows being milked (Photo courtesy Utah State University)
In the United States, preliminary studies have isolated MAP from the breast milk of women with Crohn's disease who have recently given birth but not in breast milk from women who do not have Crohn's. This finding was reported in "The American Journal of Gastroenterology, 2000."

Recent evidence from a top research group in Los Angeles led by Dr. Jonathan Braun has shown that nine out of ten people with Crohn's disease have antibodies in their blood which recognise a specific mycobacterial protein in MAP. Dr. Braun's results were reported in the journal "Infection and Immunity 1999."

MAP is difficult to kill with antibiotic drugs, but a new treatment developed at St. George's Hospital, London using antibiotics active against MAP has shown that a substantial proportion of Crohn's disease patients get better, some lastingly. A randomised controlled trial of this treatment throughout Australia began in September 1999.

Professor Hermon-Taylor recommends that the UK government reverse the decision to allow the sale of unpasteurised milk in the UK and increase the stringency of milk pasteurisation.

Dairy herds should be tested for MAP using an up-to-date molecular techniques, says Hermon-Taylor.

He strongly suggests that detailed research for MAP in the environment and water supplies be carried out.

Crohn's disease should be made a notifiable condition on which statistics are collected, Hermon-Taylor says.

Research must be done to sequence the DNA Genome of MAP of both the cattle and human strain, he says, and this would lead to the development of therapeutic vaccines for humans, and preventative vaccines for animals.

MAP is a specific cause of chronic infection of the intestines in many animals including, so far, four types of primates.