Page 30 - ACV Journal DECEMBER 2015
P. 30
News
REMINDER: BEEF BULLS
DAIRY HERDS NEED EBL TESTING
Enzootic Bovine Leukosis (EBL) has been gaining a higher profile of Case-Control Study.” Ed. Craig Meyers.PLoS ONE 10.9 (2015):
late following research in the USA that found an association between e0134304. PMC. Web. 29 Nov. 2015.
the presence of the Bovine Leucosis Virus (BLV) in human mammary
epithelium tissue and a diagnosis of breast cancer. Age, reproductive history, hormones, genetics, and lifestyle are known
risk factors for breast cancer, but the agents that initiate cellular
While BLV is not yet proven to infect humans and is destroyed by changes from normal to malignant are not understood. We previously
pasteurisation, back in 2008 the Australian dairy industry decided detected bovine leukemia virus (BLV), a common oncogenic virus
to eradicate the disease to improve dairy product integrity and of cattle, in the breast epithelium of humans. The objective of this
safeguard future market access. The Dairy EBL Eradication Program study was to determine whether the presence of BLV DNA in human
has been highly successful - the national dairy herd qualified as EBL mammary epithelium is associated with breast cancer.
Free from 31 December 2012 under the OIE rules. Dairy Australia
provides an annual report to OIE demonstrate maintenance of This was a case-control study of archival formalin fixed paraffin embedded
national EBL Freedom to international trading partners. breast tissues from 239 donors, received 2002–2008 from the
Cooperative Human Tissue Network. Case definition as breast cancer
In Australia, the Dairy herd is “free” of EBL but the Beef herd is not. versus normal (women with no history of breast cancer) was established
through medical records and examination of tissues by an anatomical
Cattle vets have a key role in maintaining EBL freedom in Australian pathologist. Breast exposure to BLV was determined by in situ-PCR
dairy herds. The OIE rules for freedom of EBL within the dairy detection of a biomarker, BLV DNA, localized within mammary epithelium.
herds rely on routine surveillance through bulk milk testing and
maintaining a separation between beef and dairy animals The frequency of BLV DNA in mammary epithelium from women with
based on management and biosecurity practices. Beef herds breast cancer (59%) was significantly higher than in normal controls
in Australia still have a low prevalence of EBL and it is important that (29%) (multiply- adjusted odds ratio = 3.07, confidence interval = 1.66–
farmers exclude infected beef bulls from their dairy herds. 5.69, p = .0004, attributable risk = 37%). In women with premalignant
breast changes the frequency of BLV DNA was intermediate (38%)
Dairy Australia is asking farmers thinking of introducing beef bulls or between that of women with breast cancer and normal controls (p for
other beef animals into their herds to ensure that they are trend < .001).
a. coming only from properties free of the disease OR Among the specimens in this study, the presence of amplified BLV
DNA was significantly associated with breast cancer. The odds ratio
b. isolated from dairy stock until tested negative for BLV. A magnitude was comparable to those of well-established breast cancer
blood/milk test for the presence of specific antibodies is a risk factors related to reproductive history, hormones, and lifestyle and
very reliable way to diagnose infection and is available through was exceeded only by risk factors related to genetics (familial breast
the major veterinary diagnostic laboratories. cancer), high dose ionizing radiation, and age. These findings have the
potential for primary and secondary prevention of breast cancer.
The Australian Cattle Veterinarians can greatly assist the dairy
industry by prompting farmers to test beef bulls for BLV if they are
going to be used over dairy herds.
The following is from: Buehring, Gertrude Case et al. “Exposure
to Bovine Leukemia Virus Is Associated with Breast Cancer: A
30 The Australian Cattle Veterinarian | volume 77 | December 2015 www.ava.com.au/cattle
