If you are part of our online community, you know that we recently sold our milk cow “Gretchen!”
Well, during the process, Gretchen’s new mom asked me whether my cows were tested for BLV, or Bovine Leukemia Virus. She is the second person in 4 years to do so. And to be honest, the first time I was asked, I dismissed the question, thinking that the person must have BLV confused with something else. BLV is a disease that I have never tested my cows for, because it is not described in veterinary academic circles as zoonotic (one that transmits from animals to people). Consequently, even if the cows were positive, there was no risk that it would cause disease in people since it was an animal (not human) disease.
Bovine Leukemia Virus is a retrovirus that can infiltrate mammary epithelial cells and white blood cells, particularly the lymphocytes, of cattle. Lymphocytes are necessary to fight infection. When these lymphocytes are infected with the virus, over time they begin to divide prolifically and remain in blood circulation in high numbers. This phase is referred to as persistent lymphocytosis and is associated with a disruption in the immune system, which weakens the animal’s defense against other pathogens. Although this phase is usually stable for several years, persistent lymphocytosis can lead to tumors (lymphosarcoma) in an estimated 5% of infected animals (1).
Because epithelial and white blood cells are shed in milk, those infected with BLV will be consumed in dairy products. If the milk is pasteurized, the viral particles, while inactive, may still cause an immune response in the consumer. However, if the milk (or meat) is consumed raw, there is a higher risk of potential infection and possible disease. I say possible because infection does not always lead to disease! There is currently no vaccine for BLV in cattle, no curative treatment and most recent estimates suggest that 89% of dairy operations and 38% of beef operations had cattle that tested positive for BLV (2). BLV is spread among cows in utero, through the colostrum or by shared equipment that may be contaminated with blood (reused syringes/needles, dehorning or tattooing equipment etc.)
Research being done into the 1980’s concluded that because the virus was not found in circulation in humans, it was therefore not transmissible to man. As testing methods improved over the years, more research led to scientific publications paper in 2016 which confirmed the presence of the virus in tissues of women with breast cancer. Other articles (reference 3 below) are now beginning to study possible routes of transmission.
You can listen to a synopsis by nutritionfacts.org here (copy and paste) https://www.youtube.com/watch?v=ZQEOCDqjdjU
So what does all this mean? Am I going to get breast cancer from eating undercooked meat or drinking milk from BLV positive cows? Since I believe that illness rarely comes from one specific thing but rather a combination of predisposing factors, I would like to say hopefully not!. Still I find it important to be informed about new and emerging diseases and take precautions to avoid necessary risks when I can. I’ll leave you to make your decisions about your own health :)
Maintaining a herd of cows that produce products of the highest and safest quality is and always will be my top priority. As such, I am happy to report that results of recent testing showed that all of our bovines tested negative for Bovine Leukemia Virus.
We will continue to strive for excellence on our farm because anything we can do to ensure you are getting the absolute best products for your body is worth it...because you are worth it!