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One little Holstein dairy cow from a Yakima, Washington farm introduced mad cow into America’s food supply and changed the world forever.  Can you imagine the response when consumers discover 9 out of 10 of the herds in the US (89%) are infected with leukemia virus?¹  This means millions of cows presently have live, infectious, leukemia viruses – bovine leukemia virus – living inside them.  These viruses are known to cause cancers of the immune system, called leukemias and lymphomas, in these cows.  More startling will be the reaction when they learn that consuming tainted beef has already infected as many as 74% of people living in the US.¹

Hopefully, this will be a wake-up call that turns people from sausages to sweet potatoes and porterhouse to potatoes.  A revolution is long overdue, especially since scientists have known about this health hazard for more than 35 years.  Yet, you have heard little or nothing about leukemia viruses infecting your food supply because of the spin placed on this information by the cattle industry and the United States Department of Agriculture.   They have taken the position: “until proven guilty beyond any doubt, eating live leukemia viruses is perfectly safe.”  Crude testing methods available during the past two decades have failed to find evidence of widespread infection in humans from this cancer-causing virus.

Now however, that excuse for keeping the public in the dark is gone forever. Using state-of-the-art detection methods, in December of 2003 researchers from the University of California, Berkeley published their findings that three-fourths (74%) of people from their community – a study population of 257 humans – have been infected with bovine leukemia viruses.  This conclusion was based on the discovery of antibodies against this infectious agent in the people’s blood.¹  The investigators hedged on the relevance of their conclusions by taking the position that this common presence of antibody could have been from dead, thoroughly cooked, viruses, as well as live, highly infectious ones.  Anyone who remembers eating burgers or steaks “pink on the inside” knows exposure to live viruses is universal.  The virus resides in white blood cells (blood lymphocytes) where circulating antibodies are unable to neutralize it. Therefore, once an animal is infected with the virus, it is infected for life. (This is the case with humans, too.)

Disregard for the importance of this widespread problem is not universal.  Many European countries have conducted programs to eliminate infected herds. For example, in 1996, after thirty years of effort, Finland completely eradicated the infection from its cattle.²  Obviously, the Finns take eating live leukemia viruses seriously. However, in other countries, where the beef and dairy industries make up a large part of the economy, there has been no effort to clean up this cesspool of infection; for example 84% of herds in Argentina and 70% in Canada are found to harbor the bovine leukemia virus.^3-5

The spread of infection in cattle arises from accepted practices in the cattle industry, such as feeding blood from slaughtered cows as a formula and feeding pooled colostrum (early milk) to calves – and the use of syringes, tattooing, and de-horning instruments on multiple animals without proper sterilization between uses.⁶   BLV is also passed directly from mother to calf through her milk.  Most infected cattle do not live long enough to develop actual disease – they remain “healthy” and therefore, are not separated from the herd.  Approximately 1% to 5% of infected cattle do develop leukemia or lymphoma – many of these obviously diseased animals still become part of our food supply.  This virus is easily spread from cow’s milk to other species of animals, and once infected they can become ill with leukemia.  For example, in 1974 it was reported that when 6 infant chimpanzees were fed infected cow’s milk 2 died of leukemia within a year.⁷  So what more evidence could there be that these well-known animal infections are a threat to you and your family (who, by the way, are also animals)?

In the laboratory this virus can infect the cells of many species of animals, including humans.⁸  The bovine leukemia virus has been classified in the same group as the Human T-cell Leukemia/Lymphotropic virus type 1 (HTLV-1), which is known to cause leukemia and lymphomas in humans (Adult T-cell leukemia/lymphoma).⁹  Nationwide and worldwide, leukemia is more common in higher dairy- and beef consuming populations.^10,11  An increased incidence of leukemia has been found among dairy farmers in multiple studies.^12-15  A recent study of Canadian workers found that those individuals working in occupations associated with cattle have approximately twice the risk of developing leukemia and lymphoma.¹⁶

In addition to infecting white blood cells, these viruses also attack other cells in the body, such as cells of the breast and the lymph nodes.  Leukemia viruses infect the cells of a cow’s mammary gland (udder).¹⁷ One recent worrisome study found the virus in the breast tissues of 10 of 23 human breast cancer patients.^18,19 Beef and dairy product consumption in various populations has been found to correlate directly with an increasing incidence of another cancer of the immune system called lymphoma.^20-24

Meat from a thousand beef cattle often makes up a single hamburger patty, because many body parts from many different cows are processed at a single meat packer.  Most milk, cheese, and other dairy products are infected with these viruses, since the milk from many dairy farms is mixed in large vats at the dairy factory before processing and packaging.  Pasteurization of milk kills many types of microorganisms, but it is not foolproof.  There is also concern that pasteurization may break the viruses into fragments that may become even more dangerous.²⁵

If you live in the United States, Canada, Argentina or any other country whose government is indifferent to this problem, you can be pretty sure you will be consuming beef with live whole viruses, and dairy products containing whole viruses or fragments.  Avoiding meat and dairy products is the most effective means to prevent future infection.  You are maybe thinking that the smart move is to switch to chicken and other poultry.  Unfortunately, they are also infected with cancer causing viruses.²⁶  Your only safe choice is a pure vegetarian diet.

Each year about 30,000 new cases of leukemia and 70,000 new cases of lymphoma occur for “unknown reasons” in the USA.  I find it hard to believe that none of these are due to infection with bovine leukemia viruses. Viruses causing leukemia should not surprise people – after all, you take your cat to the veterinarian for feline leukemia virus vaccinations in order to prevent leukemia in your cat.  As always, the burden of proof of safety of a product lies with those selling the food to you and your family.   It has not been proved safe to eat leukemia viruses – and the evidence is even more damning now that we know these viruses infect the vast majority of people who eat meat and milk products.

Don’t despair.  If you live in a country where people follow the Western diet, your risk of developing leukemia or lymphoma each year is only one in 3000.  Plus, these are primarily diseases of children and the elderly, suggesting the strength of our immune system largely determines whether or not we will develop this kind of cancer.  Our diet is the major controllable asset we have for strengthening this defense system.  Even if you are infected with bovine leukemia viruses already, a change to a plant food based diet, like the McDougall diet, will still reduce your risk of developing leukemia. ²⁷ Preventing infections in the first place is the most sensible action parents can take with their children by never feeding these tainted foods – meats and dairy products – to their children. Clearly, there is sufficient evidence to take action; furthermore, there are no negative nutritional consequences from removing these hazardous foods from your diet.

References:

1)  Buehring GC, Philpott SM, Choi KY.  Humans have antibodies reactive with Bovine leukemia virus.  AIDS Res Hum Retroviruses. 2003 Dec;19(12):1105-13.

2)   Nuotio L, Rusanen H, Sihvonen L, Neuvonen E.  Eradication of enzootic bovine leukosis from Finland.  Prev Vet Med. 2003 May 30;59(1-2):43-9.

3)  Sargeant JM. Associations between farm management practices, productivity, and bovine leukemia virus infection in Ontario dairy herds.  Prev Vet Med. 1997 Aug;31(3-4):211-21.

4)  VanLeeuwen JA,.  Seroprevalence of infection with Mycobacterium avium subspecies paratuberculosis, bovine leukemia virus, and bovine viral diarrhea virus in maritime Canada dairy cattle.  Can Vet J. 2001 Mar;42(3):193-8.

5)  Trono KG. Seroprevalence of bovine leukemia virus in dairy cattle in Argentina: comparison of sensitivity and specificity of different detection methods. Vet Microbiol. 2001 Nov 26;83(3):235-48. 

6)  Gonda M.  Bovine immunodeficiency virus.  AIDS. 1992 Aug;6(8):759-76 

7)  McClure HM, Keeling ME, Custer RP, Marshak RR, Abt DA, Ferrer JF. Erythroleukemia in two infant chimpanzees fed milk from cows naturally infected with the bovine C-type virus.  Cancer Res. 1974 Oct;34(10):2745-57.

8)  Graves DC, Ferrer JF.   In vitro transmission and propagation of the bovine leukemia virus in monolayer cell cultures.  Cancer Res. 1976 Nov;36(11 Pt 1):4152-9.

9)  Johnson J. Molecular biology and pathogenesis of the human T-cell leukaemia/lymphotropic virus Type-1 (HTLV-1). Int J Exp Pathol. 2001 Jun;82(3):135-47.

10)  Hursting SD.  Diet and human leukemia: an analysis of international data.  Prev Med. 1993 May;22(3):409-22.

11)  Howell MA.  Factor analysis of international cancer mortality data and per capita food consumption.  Br J Cancer. 1974 Apr;29(4):328-36.

12)  Kristensen P.  Incidence and risk factors of cancer among men and women in Norwegian agriculture.  Scand J Work Environ Health. 1996 Feb;22(1):14-26.

13)  Reif J.  Cancer risks in New Zealand farmers.  Int J Epidemiol. 1989 Dec;18(4):768-74. 

14)  Blair A.  Leukemia cell types and agricultural practices in Nebraska.  Arch Environ Health. 1985 Jul-Aug;40(4):211-4. 

15)  Donham KJ.  Epidemiologic relationships of the bovine population and human leukemia in Iowa. Am J Epidemiol. 1980 Jul;112(1):80-92. 

16)  Fritschi L, Johnson KC, Kliewer EV, Fry R; Canadian Cancer Registries Epidemiology Research Group.  Animal-related occupations and the risk of leukemia, myeloma, and non-Hodgkin's lymphoma in Canada.  Cancer Causes Control. 2002 Aug;13(6):563-71. 

17)  Buehring GC, Kramme PM, Schultz RD.  Evidence for bovine leukemia virus in mammary epithelial cells of infected cows. Lab Invest. 1994 Sep;71(3):359-65.

18)  GC Buehring, KY Choi and HM Jensen.  Bovine leukemia virus in human breast tissues. Breast Cancer Res 2001, 3(Suppl 1):A14

19)   Buehring GC   Evidence of bovine leukemia virus in human mammary epithelial cells Semin Cell Dev Biol  199735: 27A; Abstract V-1001. 

20)  Sarasua S, Savitz DA.  Cured and broiled meat consumption in relation to childhood cancer: Denver, Colorado (United States). Cancer Causes Control. 1994 Mar;5(2):141-8. 

21)  Zhang S, Hunter DJ, Rosner BA, Colditz GA, Fuchs CS, Speizer FE, Willett WC.  Dietary fat and protein in relation to risk of non-Hodgkin's lymphoma among women.  J Natl Cancer Inst. 1999 Oct 20;91(20):1751-8.

22)  Fritschi L, Johnson KC, Kliewer EV, Fry R; Canadian Cancer Registries Epidemiology Research Group.  Animal-related occupations and the risk of leukemia, myeloma, and non-Hodgkin's lymphoma in Canada. Cancer Causes Control. 2002 Aug;13(6):563-71. 

23) Chiu BC.  Diet and risk of non-Hodgkin lymphoma in older women.  JAMA. 1996 May 1;275(17):1315-21.

24)   Cunningham AS. Lymphomas and animal-protein consumption. Lancet. 1976 Nov 27;2(7996):1184-6. 

25)  Ferrer JF.  Milk of dairy cows frequently contains a leukemogenic virus.  Science. 1981 Aug 28;213(4511):1014-6. 

26)  Johnson ES. Poultry oncogenic retroviruses and humans. Cancer Detect Prev. 1994;18(1):9-30..

27)  Zhang SM, Hunter DJ, Rosner BA, Giovannucci EL, Colditz GA, Speizer FE, Willett WC.  Intakes of fruits, vegetables, and related nutrients and the risk of non-Hodgkin's lymphoma among women. Cancer Epidemiol Biomarkers Prev. 2000 May;9(5):477-85.

2004 John McDougall All Rights Reserved