 of Johne's in the nation's dairy herds. "It has appeared among our dairy cattle and is spreading, and we don't yet have the means, or possibly the will, to stop it.
"Experts agree that [Mp]...is excreted directly into the milk of infected cows...and that it happens before the animal shows signs of [Johne's disease]," says Collins. "The question is whether Mp in raw milk is sufficiently heat-resistant to withstand pasteurization. Four studies indicate that Mp is capable of surviving pasteurization, and two studies say it is not. It was found in pasteurized retail milk in England in 1996," results that were reproduced by Dr. Irene Grant, a respected researcher from Ireland.
Dusting for fingerprints
Shortly after Chiodini reported his successful efforts to cultivate Mp from Crohn's patients, he sent some of these cultures to Dr. John Hermon-Taylor, chairman of the department of surgery at St. Georges Hospital Medical School in London. An internationally recognized expert on Crohn's disease, Hermon-Taylor used these cultures to identify a unique genetic sequence in Mp, known as IS900.
This genetic "fingerprint" was then used by Hermon-Taylor to investigate whether Crohn's patients are more likely to be infected with Mp than other populations. In 1991, Hermon-Taylor reported that 65 percent of Crohn's patients tested positive for the presence IS900 (and thus the presence of Mp), whereas only 4.3 percent of ulcerative colitis patients and 12.5 percent of people without Crohn's disease tested positive.
Hermon-Taylor also received a small amount of funding to test retail milk in Great Britain for the presence of IS900. Between 1990 and 1994, his laboratory reported that 7 percent of the pasteurized milk they tested was positive for the DNA fingerprint of Mp. After culturing the milk for up to three and a half years, Hermon-Taylor says, "16 percent of the retail milk samples that originally tested negative came up with long-term cultures which tested strongly positive." Significantly, the same pasteurization process used in Great Britain is used in the United States.
Due to Hermon-Taylor's work, the British government announced last August -- garnering headline news there but not a word in the American press -- that experts from the Ministry of Agriculture, Fisheries and Food will spend 18 months investigating at least 1,000 samples of all types of milk for the bacterium.
"I've known that this organism is a strong candidate for causing chronic inflammation of the intestine in humans for a long time," says Hermon-Taylor. "But in order to cross a Rubicon that has very substantial implications, I had to be certain and even more certain. I became absolutely certain about three years ago. It's not a question of whether Mp can act as a human pathogen or not. It's a question of does it cause 50 percent of Crohn's disease or 90 percent of Crohn's disease? And my hunch is -- based on the evidence available, and more is needed -- it causes 90 percent."
In addition to the strong correlation between the genetic fingerprint for Mp and people with Crohn's disease, Hermon-Taylor says that when he treats patients with antibiotics known to be effective against mycobacterial infections, between two-thirds and three-quarters of his patients report improvements, some remarkable.
"I've seen people who were without hope get better like magic," says Hermon-Taylor. "I've been a doctor for nearly 40 years, and it's the best thing I've ever seen in clinical medicine."
One such patient who improved dramatically on Hermon-Taylor's antibiotic regimen is Vanessa Buchanon, who, coincidentally, holds a Ph.D. in microbiology. Buchanon, 28, from London, had been diagnosed with Crohn's and was receiving conventional treatment for about a year.
"In December 1997, I was really ill, and it was getting worse. It was then that my mom gave me an article about Hermon-Taylor. ...I phoned up his secretary and [wondered] if I could get treatment. He actually came to the phone and chatted with me for about a half an hour about the research he'd been doing.
"So I started the