A Virus Present In Almost Every U.S. Dairy Cow Was Just Strongly Linked To Breast Cancer


A Virus Present In Almost Every U.S. Dairy Cow Was Just Strongly Linked To Breast Cancer

A new study shows that the odds of a woman developing breast cancer are much higher if the bovine leukemia virus (“BLV”) is present in breast tissue. In fact, the research suggests that the odds are far greater than with other common risk factors linked to breast cancer.

BLV infects the blood cells and mammary tissue of beef and dairy cattle causing malignant lymphoma and lymphosarcoma in up to 5% of infected animals. Exposure to BLV is determined by examining the cattle’s milk or serum. If antibodies to BLV are present, than it is likely that the cattle has the virus.

The virus is present in the vast majority of America’s dairy and beef cattle. In fact, a baseline study of the presence of BLV was established during a 1996 study. The results of that study showed that 89% of United States dairy operations had BLV.

The most recent study took place in 2007, where greater than 82% percent of the entire United States dairy herd was tested. The results showed that almost 84% of operations were positive for BLV.

Until recently, it was unsure if BLV could be transmitted to the human population. Professor Gertrude Buehring, a professor of virology at the University of California-Berkeley, and her team showed that BLV can in fact pass to humans. Buehring stated that, “The tests we have now are more sensitive, but it was still hard to overturn the established dogma that BLV was not transmissible to humans. As a result, there has been little incentive for the cattle industry to set up procedures to contain the spread of the virus.”

Taking it a step further, Buehring and her team analyzed the breast tissue from 239 women. The results showed a higher likelihood of the presence of BLV in breast cancer tissue. Further analysis indicated that the odds of having breast cancer if BLV was present was about three times greater than if BLV was absent. 59% of the breast cancer samples had exposure to BLV while only 29% of the tissue samples from women who did not have nor never had breast cancer showed the presence of BLV.

Buehring pointed out that, “This odds ratio is higher than any of the frequently publicized risk factors for breast cancer, such as obesity, alcohol consumption and use of postmenopausal hormones.”

Despite the results, Buehring stressed that, “It is important to note that our results do not prove that the virus causes cancer. However, this is the most important first step. We still need to confirm that the infection with the virus happened before, not after, breast cancer developed, and if so, how.”

Buehring also emphasised that her study did not identify how the virus infected the analyzed breast tissue samples. She proffers that the virus could have been transmitted to the women through the consumption of unpasteurized milk or undercooked meat, or it could have been transmitted by other humans.

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