Decades in the past, concern was raised that the milk of dairy cows often incorporates a leukemia-causing virus—more specifically, bovine leukemia virus (BLV), the leading most cancers killer amongst dairy cattle. Most U.S. dairy herds are contaminated with the cancer virus. “Thus the question of whether dairy cows naturally infected with BLV release infectious virus into milk is an important public health consideration” and the subject of my video Is Bovine Leukemia Virus in Milk Infectious?.
Researchers on the University of Pennsylvania decided to put it to the check. And certainly, infectious virus was demonstrated in the milk of 17 of the 24 cows examined, indicating that “humans are often orally exposed to BLV.” Just as a result of we’re exposed to it doesn’t imply it’s causing human illness, although. How do we all know BLV can even infect human cells? We didn’t till 1976 when it was found that BLV can certainly infect human, chimpanzee, and rhesus monkey cells. Nevertheless, that also doesn’t imply BLV necessarily causes cancer in different species.
Researchers can’t lock human infants in a cage and feed them infected milk, however they will cage infant chimpanzees. Chimps Bois and Roger have been fed infected milk, developed leukemia, and died. Until then, we didn’t even know chimps might get leukemia. The undeniable fact that BLV-infected milk appeared to transmit or induce leukemia in our closest dwelling relations definitely did increase the stakes, however human beings are usually not chimpanzees. Yes, our DNA could also be 98 % equivalent, however we might share 60 % of our DNA with a banana. We want human research.
We can’t do interventional trials in this case, because of these pesky Nuremberg rules, but what about observational studies? Do cattle farmers have greater charges of cancer? Apparently so. This discovering led some to recommend that “milk- and egg-borne viruses may be highly important in the pathogenesis [or development] of human leukemia and lymphoma,” but farmers could also be exposed to all types of potential carcinogens, comparable to pesticides. Large animal veterinarians may additionally have more leukemia and lymphoma, however some are also “particularly lax in the use of X-ray protective equipment,” so it didn’t necessarily have anything to do with viruses.
We wanted so-called serology research, testing individuals’s blood for antibodies towards the virus, which would prove human publicity, and we received them. Ten totally different research seemed for BLV antibodies in most cancers sufferers and non-cancer patients, creamery staff versus office staff, veterinarians, unpasteurized milk drinkers, and extra. “Not one of these studies found a single individual with antibodies to BLV…” As a outcome, in 1981, the case was closed: “Therefore, there is strong serological evidence to indicate that BLV is not transmissible to man.” However, the strength of the proof is just as robust as the strength of the check. Chimpanzees Bois and Roger didn’t develop detectable antibodies either, they usually died from BLV.
The checks obtainable a handful of many years in the past have been not likely delicate. “Clearly, the question of whether BLV poses a public health hazard deserves thorough investigation” utilizing extremely sensitive molecular probes. It would take a number of many years for us to get such an examination, and I talk about these landmark findings in my movies The Role of Bovine Leukemia in Breast Cancer and Industry Response to Bovine Leukemia Virus in Breast Cancer.
Thankfully, feline leukemia virus does not look like transmissible. See Pets and Human Lymphoma.
Michael Greger, M.D.
PS: If you haven’t yet, you’ll be able to subscribe to my free videos right here and watch my reside, year-in-review shows: