Mad Cow Precautions Continue to be Justified

The extreme reaction of the Japanese government this summer to the discovery of a human vCJD case, in a person who visited the United Kingdom, albeit briefly, showed the strong desire of governments to minimize the risk of infection, particularly infection of national blood supplies.


Between what seems like a steady drumbeat of new countries and parts of the world revealing the presence of human or animal TSEs, we at COTT are reminded of one of the fundamental rules in science: in the face of uncertainty, do not presume to be too restrictive.

In 1999 essentially all donor deferrals were dropped concerning individuals and families with diagnosed or symptomatic classical CJD, as it was not proven to be cattle-related, remained a disease of older age groups, and was not found in blood.

Statistics from the UK CJD Surveillance Unit show a “bell curve” for the rise and fall of bovine disease, peaking in about 1985, and of human vCJD there as well, peaking about ten years later. However, the “tail” of that curve cannot be correctly perceived due to the multi-year process of case investigation. Some experts also note that it won’t go to zero since some infection continues to be found.

Families of classical CJD victims, the disease widely held to be a background-level concern, with a incidence rate of 1:1,000,000, now feel more strongly than even a few years ago that change is occurring, that the background level is rising. UK data shows an increase in the trendline of such cases, from 40 deaths per year in 1992 to 60 in 2004, a 50% rise in just over a decade.

To those who would say it is time to relax the CJD-related geographic donor deferral requirements of recent years, we at COTT say, it’s too soon. We point to the scientific principle above, we point to the troubling variations in cases of related diseases, in humans and in animals, we point to the lack of conclusive evidence regarding the transmission of vCJD to man, and we point, as other countries have with increasing urgency of late, to the importance of a pristine blood supply.

The two published studies of blood transmissibility of prion disease came out only in the last two years, causing rethinking of many of our protections to date, and the Hunter study on transmission from asymptomatic animals completed the alarm. Two years well after the peak of the UK vCJD curve, and almost twenty after the discovery of the prion. We obviously are still learning, have not taken the measure of this agent yet at all, and are likely to be dealt more surprises in the next five years. It would be very shortsighted to assume we knew everything about this threat and relax our guard anytime soon.

The large-scale USDA program to not find BSE cases in US cattle, and its refusal to permit tracing of infected meat when one does pop up, serve their intended purpose of maintaining complacency in the population, reinforcing as with many other things American the perceived differences of the USA from the rest of the developed world. Although it will be a bitter pill to swallow, we at COTT would hope that public pressure will force USDA to a more stringent screening, and the number of cases found will more realistically rise into the range of 20-40. At those numbers, we will not need to plead as loudly for actions to protect blood; all will respond.

VOL. 12 NUMBER 2 Originally published on 10-24-2005

The Food Chain

The Food Chain from the Slaughterhouse to the Infusion Needle: The confirmation of the transmission of Mad Cow disease (CJD and variant CJD) to humans is now accepted based on events in Great Britain. Given that we have now transitioned from the “hypothetical” dangers
of Mad Cow transmission from cattle to humans to the reality of TSE (transmissible spongiform encephalopathy) transmissibility, it is imperative that the connection between food and blood be prioritized by those tasked with the regulation of America’s blood supply. At the ground floor is the reality that those who consume beef products also donate blood. The importance of that basic reality falls squarely on the shoulders of the Food & Drug Administration. With that in mind, the relationship between the regulation of the blood supply and the regulatory tracking of America’s cattle herds must be elevated to a much more integrated and comprehensive threshold. We also must be concerned about our deer herds and those that hunt and consume deer meat. These animals are also showing TSE and there is concern and those that hunt and consume them. While persons involved in public health cannot be expected to learn the specifics of agricultural animal management, some familiarization with these events is warranted.

Starting from the bottom or end result of the chain, for a person to receive the infectious agent for the disease from blood, it (the agent) must be:

  • Present in donated blood (and, for plasma product users, not sufficiently removed in fractionation;
  • Present in the donor’s bloodstream via consumption of infected food;
  • Present in the food – beef cattle – through horizontal contagion from others, linking eventually back to the United Kingdom.

This last gives most people pause – the US stopped importing British beef years and years ago. But the Canada link was responsible for the first US case found. The second case was all ours. It’s here. And if our sampling system caught two, a fuller test might catch hundreds …

Most countries protect their populations from this disease by thorough testing of all or most cattle before slaughter. Usually this means testing only those older than 30 months, the time when detectable symptoms begin to appear. Determining the age of cattle in slaughter is based on presence of certain molars, not an ironclad system.

However the US doesn’t test all cattle over 30 months. We test less than one percent of them, plus any other beef cow which cannot walk or otherwise shows possible symptoms of BSE.

Instead, the US requires slaughterhouses to make extensive changes in the process, to assure that all cerebral and spinal materials are removed, so that theoretically even infected cattle can be processed into meat and sold in US stores but the meat will not be infectious.

This is similar to cutting the bad part out of an apple, or tearing the mold off the corner of a piece of bread, and consuming the remainder with no concern. Except for two things: 1) discovery, research on and handling of prions is so new it may be naïve to conclude which parts are infectious and which aren’t, and 2) the age determination and the removal of the potentially infectious material are performed by low wage employees, often with minimal training.

Oversight of these functions by USDA has been the linchpin in holding public confidence in the USDA plan to successfully protect our health. However, its efficacy is not widely reported, but anecdotal evidence abounds of its shoddy implementation. As one brief example, workers assigned to mark cattle when the indicated molars are found miss many so the packages coming out of the other end of the plant are wrongly labeled “USDA Inspected and Passed” and taken to market.

A few other examples of in-plant procedural inadequacies that allow risk materials to pass into the food chain:

Requirements [Inspectors]:

Check every carcass for age

Requirements [Other Staff/Vets]:

Verify on paper and spot checks

Document violations of USDA rendering requirements

Provide line inspections when vacancies due to illness, etc.

Actual Procedure [Inspectors]:

Not trained or told to check every carcass

Actual Procedure [Other Staff/Vets]:

Not trained or told how to verify.

Spot checks as seldom as once a day.

Not allowed to record frequency of spot checks.

Only permitted if seen in person. For others, take word of employees over inspectors.

Not permitted to record violations observed when filling in for line staff.

Source: Public Citizen

So USDA inspectors are tightly constrained, subsidiary to slaughterhouse employees versus in a regulatory role over them, and, essentially, complicit in permitting much potentially infectious material to pass. There is no post-production test for presence of this material before packaging.

When you put into your arm weekly or monthly the distillation of the blood of tens of thousands of donors, you go to extreme lengths to advocate for its purity. USDA does not.

VOL. 12 NUMBER 1 Originally published on 10-24-2005