Sheep Version of Mad Cow Disease in Sludge Spread on Fields

Sheep Version of Mad Cow Disease in Sludge Spread on Fields

December 21, 2000 Natural Life Magazine by Wendy Priesnitz
For five months earlier this year, farmers in the Ottawa area were spreading municipal sludge that was contaminated with the sheep version of so-called Mad Cow Disease (bovine spongiform encephalopathy).

Environmental researcher Maureen Reilly has discovered that between mid-February and July 19, tissues from sheep infected with scrapie were accidentally sent to the Ottawa waste water treatment plant without being adequately treated to kill the infectious agents in the tissue. Then the sludge containing the infectious material was spread on farmland in the Ottawa area as "biosolids" -- the euphanism given to sewage sludge to make it palatable as a fertilizer. Reilly says that the sheep tissues contained scrapie prions (altered proteins), which can remain infectious for several years in the soil.

The discharges occurred while a Canadian Food Inspection Agency (CFIA) animal disease testing laboratory was examining infected and uninfected sheep tissue looking for a way to develop a way to test for scrapie in live animals.

The waste treatment temperature was inadvertently lowered from 134 degrees C to 121 degrees C. CFIA officials say that 121 degrees C is the normal temperature for treating liquid animal waste before it is discharged into sewers, and that more than 99 percent of the scrapie agent is destroyed at that temperature. However, the temperature had been raised as an added precaution during treatment of the waste from post mortems of sheep possibly infected with scrapie

The CFIA says the laboratory has returned to a treatment temperature of 134 degrees C and that "steps have been taken to avoid a repeat of the incident".

The CFIA acknowledged the release of the poorly treated sheep tissue in July and contacted the Ottawa-Carleton wastewater treatment plant. But Reilly says, "I am concerned that...the Laboratory experts, who are most knowledgeable about the survival rates of scrapie infective tissue, were not told that the prion contaminated sludge was spread on agricultural land."

The Ontario Ministry of Environment was also unaware of the situation. A provincial officer from the Ottawa office of the Ministry of the Environment told Reilly that discharges into the sewer system are not counted as spills by the province, and therefore don't need to be reported. Nor have the farmers who received the sludge been notified.

Says Reilly, "Something is very wrong in our disease control mechanisms if this information is not shared among all the relevant regulatory agencies. Public health and agriculture are put at risk by sludge spreading practices. Our public health safeguards are not adequate to protect against the risks that stem from the spreading of sludge that contains disease causing microbes, viruses and parasites."

Scrapie is but is not considered harmful to humans. Health Canada said at the time that there was no human health risk.

The Nobel laureate who discovered prions Professor Stanley Prusiner was quoted last summer as saying he would no longer eat sheep products because of research indicating scrapie as the forward-infectional source of Mad Cow Disease. Recent research has also established scrapie and a form called chronic wasting disease, which occurs in in wild animals, as transmissible to humans.

The U.S. government recently purchased and slaughtered Vermont 350 sheep imported from Europe because they were suspected of having the disease. And Agriculture Canada killed a herd of elk in Saskatchewan. It is feared that the animals were exposed to feed contaminated with Mad Cow Disease.

Scientists believe that eating meat from an animal with mad cow disease causes a variant of Creutzfeldt-Jakob disease (CJD). CJD is a slow-acting virus with a latency period of up to 20 years. It's named after two German neurologists that discovered it in the 1920s. In all the prion diseases, the brain is attacked and turned into the consistency of a sponge. It is always fatal, usually within one year of exhibiting symptoms, and has killed more than 70 people in Europe. Tthe number of cases of the disease is rising at a rate of 30 percent a year.

Although the cattle version of this brain-wasting disorder has yet to show up in the sheep population, the incidence of scrapie is widespread. EU scientists believe sheep could contract the cattle variant, which could spread quickly from flock to flock and need drastic measures to contain.

Wendy Priesnitz is the Editor of Natural Life Magazine and a journalist with 25 years of experience. She is has also authored nine books and is a popular keynote speaker at conferences across North America.

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