MAP in the Environment

MAP in Food

MAP in Beef Products

Purpose of this document

The purpose of this document is to review scientific research which has shown that live bacteria of the pathogenic bacterial species Mycobacterium avium subspecies paratuberculosis may be present in the retail beef supply of the United States. This document contains a summary and detailed review of this scientific evidence, and a discussion of the human health implications of this evidence.

Since MAP is not classified as a human pathogen, meat, milk and other products from animals infected with MAP may be continually entering the human food chain. There is a wealth of evidence which appears to indicate that MAP is capable of surviving the food processing methods that we employ to protect us from disease, such as cooking and pasteurization. This scientific evidence is thoroughly reviewed and discussed in this section as well as the  MAP in Dairy Products, and Retail Testing sections of our website.  


Scientific research has been conducted in the USA and Europe which demonstrates the following

  • Mycobacterium avium subspecies paratuberculosis causes a chronic and fatal intestinal disease in a wide range of animal species 1.

  • Mycobacterium avium subspecies paratuberculosis has been implicated in causing the human disease Crohn's disease 3. Crohn's disease is a chronic, debilitating and potentially fatal disease. The number of Americans who suffer from Crohn's disease has never been satisfactorily recorded, but is somewhere between 400,000 and 1,000,000 3. Each year, at least 20,000 Americans are clinically diagnosed as having Crohn's disease 3.
  • All Mycobacterium avium subspecies paratuberculosis bacteria isolated from the intestines of sufferers of Crohn's disease are of the bovine subtype, i.e. the bacteria found in cattle 5.

  • Mycobacterium avium subspecies paratuberculosis infection in cattle is known as Bovine Johne's Disease (BJD).

  • BJD is a "systemic infection", meaning that viable Mycobacterium avium subspecies paratuberculosis bacteria may be present in tissues taken from cattle with the disease 1.

  • Since there is no effective treatment for BJD, cattle that are heavily infected with BJD are usually destroyed. Dairy cattle that have been destroyed because of BJD ("cull cattle") are frequently used in the production of ground beef that enters the human food chain 13, thus potentially exposing humans to the risk of Mycobacterium avium subspecies paratuberculosis infection.
  • The prevalence of Mycobacterium avium subspecies paratuberculosis in thin, sound, market cows at slaughter is 34% in cull dairy cows and 2.6% in cull beef cows15.

  • Current USDA data indicates that the prevalence of BJD in beef cattle is 0.9% of animals and 7.9% of herds 14.

  • Mycobacterium avium subspecies paratuberculosis is a highly heat resistant pathogenic bacterium which when present in the human food chain 6, may not be killed by standard techniques for cooking beef 7-9.


Bovine Johne's Disease(BJD) is a Systemic Infection of Cattle

Bovine Johne's Disease is a systemic infection of cattle 1. MAP, the bacterium which causes BJD, can infect cattle in three different ways

  1. Intracellularly. MAP colonizes and multiplies inside the white blood cells of infected cattle.

  2. Extracellularly (blood-borne) . In the advanced stages of Bovine Johne's Disease, when the numbers of MAP bacteria present in the white blood cells have reached a sufficient number, and have overcome the immune system of the infected cow, the bacteria then spread outside the white blood cells and into the cow's blood stream, infecting the cow's internal organs, and potentially its muscle tissue.

  3. Fecal contamination. Cattle with Bovine Johne's Disease shed up to 45,000,000,000 (45 billion) MAP bacteria per pound of feces 1. When the animal is slaughtered, it is impossible to ensure that the feces do not contaminate the various tissues that are taken from the cow, as is evidenced by the numerous E. coli food poisonings and related beef product recalls in recent years.

    Cow with diarrhea, caused by BJD

The food safety methods for testing of beef and beef products mandated by the USDA Food Safety and Inspection Service (FSIS) are only capable of detecting fecal contamination of meat. They are not capable of detecting intracellular and extracellular MAP that may be present in blood, muscle tissue and various internal organs from the cow. For a detailed discussion of this topic, see the page Food Safety and Inspection Service.



MAP Is More Heat Resistant Than Other Disease Causing Bacteria

Sung and Collins 6 used standard food microbiology techniques to determine the thermal tolerance of MAP. They measured the D-values and Z-values of MAP, which are the standard measurements needed to determine the heating temperatures and times necessary to kill the bacterium. The higher the D-value of a bacterium, the more resistant is that bacterium to heat.

Sung and Collins found that of three well-known pathogenic bacteria MAP is the most heat resistant. It is more heat resistant than both Mycobacterium avium and Mycobacterium bovis (which causes tuberculosis in humans). To quote their study:-


"When we then compared M. avium with M. paratuberculosis, we found that the D-values of M. avium 6317 were significantly lower than those of the combined M. paratuberculosis clinical strains and ATCC 19698 at every temperature tested (P < 0.03). Therefore, of these three mycobacteria, the microorganism used to set pasteurization standards, M. bovis, is the most sensitive to heat, followed by M. avium and then M. paratuberculosis."




Cooking temperature required to kill MAP

The USDA Food Safety and Inspection Service 7 recommends the following cooking techniques for cooking beef and beef products:-


"A consumer preparing hamburger patties and depending on visual signs to determine safety by using the brown color as an indicator is taking a chance that pathogenic organisms may survive. A hamburger cooked to 160 °F (71.1 °C ), regardless of color, is safe  .......  A roast or steak that has never been pierced in any way during slaughter, processing or preparation and has reached an internal temperature of 145 °F (62.8 °C ) is safe to eat."


Merkal et al 8, 9 found that prolonged exposure to a temperature of 165 °F (73.8 °C ) is required to guarantee safe killing of Mycobacterium avium. As Sung and Collins 6 demonstrated, MAP is significantly more resistant to heat than Mycobacterium avium, leading to the conclusion that MAP is not killed by the beef cooking techniques recommended by the USDA.

Since many people, contrary to the advice of the USDA, cook beef and ground beef products to a much lower temperature, because they prefer their beef "rare", those people are obviously at a high risk of consuming viable MAP bacteria.

The solution to this food safety problem is not to rely upon cooking techniques to kill this pathogenic bacterium, but to prevent MAP infected beef from reaching the food chain in the first place.


The Risk of Contracting Tuberculosis When Eating Beef from Mycobacterium Tuberculosis-Infected Cattle

Francis 10 pointed out in 1973 that there was a "very small risk" of contracting tuberculosis from eating the beef of cattle infected with Mycobacterium tuberculosis, a bacterium which is related to MAP. However, it must be noted that this statement was based on the assumption that extensive precautions were taken to prevent Mycobacterium tuberculosis infected beef from reaching the human food chain, since Mycobacterium tuberculosis was recognized as a human pathogen, i.e. that it was known to cause disease in humans. To quote Francis 10:-


"In the past it was necessary to emphasise the public health importance of bovine tuberculosis to arouse interest in the eradication of the disease. This is no longer necessary as virtually all cattle owners and Governments recognise the desirability of control. However, the possibility of danger to public health from the flesh of tuberculous* cattle, although very small can never be absolutely denied and there are aesthetic objections that have persisted for over 2,000 years to eating the flesh of obviously tuberculous* animals."

*A "tuberculous" cow is a cow that is infected with Mycobacterium tuberculosis or Mycobacteria bovis.


Since MAP is not classified as a human pathogen, despite significant evidence suggesting that MAP may cause disease in humans 2-5, beef from MAP infected cattle is not prevented from entering the human food chain. Beef producers are largely unfamiliar with Johne's Disease. And while both the USDA and the National Cattlemen's Beef Association talk about controlling this disease, there is no federally mandated Bovine Johne's Disease control program. Many states have no Bovine Johne's Disease control program, and in states where there are BJD control programs, these programs are voluntary.


Study Assessing the Prevalence of Johne's Disease in Dairy and Beef Cows at Slaughter

In a  2001 study entitled "Isolation of Mycobacterium paratuberculosis (M.ptb) from thin market cows at slaughter," (Rossiter, C.A., Henning, W.R., J. Anim. Sci., Vol. 79, Suppl.1/J. Dairy Sci. Vol. 84, Suppl. 1/Poult.Sci. Vol. 80, Suppl. 1/ 54th Annu. Rec. Meat Conf., Vol. II)15 , 189 Dairy Cows and 350 Beef Cows  were sampled for MAP at three large slaughter plants.    The study had two objectives:

  1. Assess the prevalence of Johne's disease in sound, thin dairy and beef cows at slaughter, at high risk of clinical infection; and
  2. Assess M.ptb dissemination to liver (L) and two lymph nodes, the superficial cervical (SC) and the popliteal (P), associated with muscle used in ground product.

Researchers found the prevalence of MAP in thin, sound, market cows at slaughter is 34% in cull dairy cows and 2.6% in cull beef cows.  The concluding remarks of the study are:   "Prevalence and risk associated with disseminated M.ptb should be further characterized."  

PARA agrees with that statement and urges the beef and dairy industries to take immediate measures to ensure that this MAP-contaminated beef does not end up in Happy Meals of our children

MAP in Beef Products Made From Dairy Cattle with BJD

In the United States, there has historically been a higher prevalence of Bovine Johne's Disease in dairy cattle than in beef cattle. This is partly because the conditions in which dairy cattle are kept are more physically confined, and encourage and accelerate the spread of BJD. Furthermore, there is extensive lack of awareness of BJD among dairy cattle farmers.

In the 1997 USDA report "Johne's Disease on US dairy operations" 11, it was reported that between 20% and 40% of US dairy herds are infected with BJD. As noted by the National Johne's Working GroupNew window link indicator 12, "..... estimates of Johne's Disease based on clinically diseased cattle still only represent the 'tip of the iceberg' of infection, and on a herd level, may represent only 5% of the total number of infected cattle (Whitlock, 1992). This hidden nature of Johne's Disease is one reason for its lack of recognition as an important bovine pathogen by many dairy producers."

The NJWG went on to reportNew window link indicator 12 that 10% of US dairy operators "had not heard of it [BJD] before", 35% of dairy operators "recognized the name, but not much else" and 37% of dairy operators "knew some basics".

Furthermore, results of a new USDA survey will be published in the Spring of 2003 based on data collected in 2002.  With Johne's disease increasing at an alarming rate, undoubtedly the new figures will be higher, perhaps significantly higher, than those in 1996.) 

When a dairy cow is diagnosed with Bovine Johne's Disease, the standard recommendation given to farmers by veterinarians is to send the animal to slaughter. Such cattle are known as "cull cows". From there, most of these animals will be used in the production of food for humans. To quote McDowell & McElvaine (USDA) 13:-


"When Johne's disease is diagnosed in a cow on a dairy farm, the standard recommendation is to send the animal to slaughter. In the late stages of the disease, M. paratuberculosis may be spread systemically throughout the animal. Most of these cull dairy cows pass ante-mortem inspection and enter the slaughter system for production of ground beef. Whether by systemic infection or contamination from feces, these cattle pose a great risk for contamination of the final product (ground beef) with M. paratuberculosis".


If we consider the following combined facts

  • There is a high prevalence of Bovine Johne's Disease in US dairy cattle.

  • Cattle that are clinically diseased with BJD are slaughtered in an attempt to control BJD in the herd.

  • Flesh from those clinically diseased cattle is used to make ground beef for human consumption.

Then we can be certain that flesh from BJD-diseased cattle is turning up on dinner plates across the United States. Since burgers, made from ground beef, are popular food with children, it would appear that there is a high risk that our children are being exposed to MAP, through consumption of paratuberculous ground beef, on a regular basis.


MAP in beef products made from beef cattle with BJD

In 1984, 2.9% of US dairy cattle had Bovine Johne's Disease. Since BJD is a "hidden" disease (not a reportable disease), and was not the subject of mandatory control program, in 1997 between 20% and 40% of US dairy herds contained BJD-diseased cattle. Some researchers estimate that if there are one or two diseased animals in a herd, then the number of subclinically BJD-diseased animals may be as high as half the animals in the herd.

1997 USDA data indicates that the prevalence of BJD in beef cattle is 0.9% of animals and 7.9% of herds.

Since MAP is not classified as a human pathogen, beef from BJD diseased beef cattle is permitted to enter the human food chain.

Lack of awareness among beef producers is even greater than in dairy producers. The USDA Center for Animal Health Monitoring 14 reports that 69.8% of US beef producers "had not heard of it [BJD] before", 2.4% of beef producers "recognized the name, but not much else" and 5.5% of beef producers "knew some basics".

In conclusion, we can be virtually certain that beef from beef cattle infected with Mycobacterium avium subspecies paratuberculosis enters the human food chain.


All of the above research demonstrates that Bovine Johne's Disease is endemic in herds of cattle which supply the human food chain.

Despite a wide range of evidence which strongly suggests that MAP may be a cause of disease in humans, and particularly may be responsible for the chronic Inflammatory Bowel Disease known as Crohn's disease, the dairy and beef industries continue to ignore the problem of Bovine Johne's Disease.

As a final cautionary comment to the beef industry, we would remind the industry that, if evidence finally appears that MAP is actually the cause of Crohn's disease, consumers could lose faith in beef as healthy and nutritious food. The market for beef may collapse, just as the market for British beef collapsed when British consumers discovered that they could contract Creutzfeld-Jakob Disease from eating beef from cattle with Mad Cow Disease.

The British beef industry gambled that Mad Cow Disease could not cause disease in humans. They lost their bet!

PARA continues to send the following message to the US beef and dairy industries:-


Do not take the chance of possibly making the same mistake as the British beef industry! Act now to eradicate Bovine Johne's Disease and MAP from herds of food animals, before it is too late! You must do this, to be absolutely certain that you are protecting the health of your consumers, and to protect the future of your own industry. If beef becomes conclusively associated with the dreadful disease known as Crohn's disease, your markets could collapse as the British market did, and they may never recover. If this happens, the image of beef as being necessary for good nutrition, carefully propagated and nurtured by you for decades, could be destroyed.




Hyperlinked references will appear in a new browser window

Mycobacterium avium subspecies paratuberculosis is a pathogenic (disease-causing) bacterium, which causes chronic intestinal disease in a wide range of animals, including sub-human primates and cattle.
Mycobacterium avium subspecies paratuberculosis cultured from the intestines of sufferers of Crohn's disease is of the bovine subtype.

11984Ruminant Paratuberculosis (Johne's disease):- The current status and future prospectsNew window link indicator.
Chiodini RJ, Van Kruiningen HJ, Merkal RS.
Cornell Veterinarian 74(3):218-262
21998Mycobacterium paratuberculosis Cervical Lymphadenitis followed five years later by terminal ileitis similar to Crohn's DiseaseNew window link indicator.
Barnes N, Clarke C and Finlayson C, Hermon-Taylor J.
British Medical Journal 7th Feb 1998.
31998 Scientific facts about Mycobacterium paratuberculosis and Crohn's disease
41989Crohn's disease and the mycobacterioses: a review and comparison of two disease entitiesNew window link indicator.
Chiodini RJ
Clin Microbiol Rev 2:90-117
51995Characterization by restriction endonuclease analysis and DNA hybridization using IS900 of bovine, ovine, caprine and human dependent strains of Mycobacterium paratuberculosis isolated in various localities.
Pavlík I; Bejcková L; Pavlas M; Rozsypalová A; Kosková S
Vet Microbiol, 45:311-318.

Of the mycobacteria that may be present in retail beef, Mycobacterium avium subspecies paratuberculosis appears to be the most heat resistant.  
Mycobacterium avium subspecies paratuberculosis
may not be killed by recommended beef cooking temperatures.  Tissue from BJD infected cattle is used in the production of ground beef for human consumption.
BJD is not controlled in the United States at either a federal or a state level.


61998 Thermal tolerance of Mycobacterium paratuberculosis.New window link indicator
Sung N, and MT Collins.
Applied and Environmental Microbiology 64 (3), 999-1005.
71998 Technical Information:- Kitchen ThermometersNew window link indicator
USDA-FSIS, Food Safety and Inspection Service
81980 Inactivation of Mycobacterium bovis in meat products.New window link indicator.
Merkal RS; Whipple DL.
Appl Environ Microbiol:1980 Aug: 40(2):282-4.
91979 Heat inactivation of Mycobacterium avium-Mycobacterium intracellulare complex organisms in meat products.New window link indicator.
Merkal RS; Crawford JA; Whipple DL.
Appl Environ Microbiol:1979 Nov: 38(5):831-5.
101973 Very small public health risk from flesh of tuberculous cattleNew window link indicator.
Francis J.
Aust. Vet. Journal:1973 Oct: 49:496-497.
111997 Johne's Disease on U.S. Dairy OperationsNew window link indicator
US Department of Agriculture report, October 1997.
121996 Proceedings of the 100th annual meeting of the US Animal Health AssociationNew window link indicator
131997 Long-term Sequelae to foodborne diseaseNew window link indicator
McDowell RM and McElvaine MD.
Rev. sci. tech. Off. int. Epiz:1997: 16(2), 337-341
141997 National Animal Health Monitoring System (NAHMS) Beef '97New window link indicator
USDA-APHIS, Animal and Plant Health Inspection Service
152001   Isolation of Mycobacterium paratuberculosis (M.ptb) from thin market cows at slaughter New window link indicator     Rossiter CA, Henning, WR.  J. Anim. Sci., Vol. 79, Suppl.1/J. Dairy Sci. Vol. 84, Suppl. 1/Poult.Sci. Vol. 80, Suppl. 1/ 54th Annu. Rec. Meat Conf., Vol. II


Source:   Contact PARA:
Paratuberculosis Awareness & Research Association, 1999-2003.