Milk from a mad cow can contain risky prion proteins,
indicating that drinking tainted milk might be a way for the mad cow
disease to transmit from a mad cow to humans, according to a new study.
Scientists believe that prions are responsible for
transmissible spongiform encephalopathies (TSE) or brain wasting diseases after accumulation in the central nervous system in animals and humans.
Early studies have proved that body fluids such as the blood
may carry the infectious proteins. It has been reported that some people who
received blood transfusion developed a human version of mad cow disease.
But it is unknown whether milk could carry prions until the
The government officials often say that the nervous systems including
the spiral bones but not other parts may carry infectious agents. Body fluids such as the blood have
been rarely mentioned as a possible vehicle of the infectious agents.
In the current study, Nicola Franscini and colleagues at Case
Western University School of Medicine and other institutions were able to detect
prion protein (PrPC)-the precursor of prions (PrPSc)-in milk from humans, cows,
sheep, and goats.
The detection was made possible using a sensitive methodology
the researchers have recently developed.
Franscini and colleagues also detected PrPC in homogenized and pasteurized
They said prions are heat-resistant and even ultrahigh temperature
treatment only partially diminishes endogenous PrPC concentration.
Prions are known to persist in all types of harsh environment, according to the United States Department of Agriculture.
The results of the study indicate that drinking milk from a
cow infected with mad cow disease may transmit the disease to the consumers
although it has not been evaluated how serious the risk might be.
The researcher write in their report that “The low
concentration of the proteinaceous agent in body fluids and its long incubation
time complicate epidemiologic analysis and estimation of spreading and thus the
risk of human infection.”
Source: Franscini N, Gedaily AE, Matthey U, Franitza S, Sy
M, et al. (2006) Prion Protein in Milk. PLoS ONE 1(1): e71.