Mad Cow Disease

Last week, I discussed the One Health Concept, which suggests that the health of humans, livestock, wildlife, and environment are all interconnected. Our food production systems are an important component linking humans, livestock, wildlife, and the environment, and I explained some ways that human food production systems influence pathogen emergence. Today, I’m going to briefly expand on this idea and encourage you to become as informed as possible about how the food that you consume is created, processed, and prepared.

There are MANY humans on the planet. It would be unrealistic to expect that feeding that many people can be accomplished without unintended consequences, such as disease outbreaks and environmental alteration. However, it would be unethical for humans to ignore these negative consequences when they occur. It would also be self-destructive in the long term, because as the One Health Concept explains, human health cannot flourish unless we make sure that our livestock, wildlife, and ecosystems are also flourishing. Therefore, when these problems arise, we should turn to scientists and social scientists for innovations in the ways that we create, process, and prepare our food.

Here’s an example. Bovine spongiform encephalopathy (BSE) is a disease that occurs in cattle around the world. BSE is caused by prions, which are misfolded proteins that cause deterioration of neurological tissues (i.e., the brain). These prions aren’t destroyed by high temperatures, so consumption of infected tissues – even after cooking – can transmit the prions to new hosts. If humans consume the tissues, the disease is called new variant Creutzfeldt-Jakob disease. And if cows consume the tissues, the disease is called bovine spongiform encephalopathy – or, more commonly, mad cow disease.

You might be wondering why cows would ever eat infected cow brains. That seems like a pretty unlikely scenario, because cows are vegetarians. However, cattle farming operations used to include these tissues as meat and bone meal that went into cattle feed. When the transmission route for BSE was discovered, legislation was passed in many countries that prohibited using those high risk tissues as feed for cattle or as food for humans. Additionally, countries have adopted various testing strategies, which at minimum require the removal of any visibly sick animals from the food chain.

In hindsight, feeding cows to other cows on a huge scale seems like a bad idea – if not for ethical reasons, than for pathogen transmission reasons. But of course, you can also see how using those materials in the feed also represented a way to reduce waste products (really important for environmental health) and to cut costs associated with producing beef on such a massive scale. The important thing is that we address the problem to reduce the risks to animal, human, and environmental health. However, while some measures have been taken and BSE incidence is declining, others argue that some practices – such as feeding calves on cow blood as a milk substitute – continue to cause risks to animal and human health. But of course, with money and health on the line, controversy can explode when topics like this hit mainstream media.

So, what are some solutions? Well, that is very complicated and goes far beyond the realm of ecology and into the realm of socioeconomics. In other words, outside my realm of expertise. 😛 But that’s a total cop out, so here is my two cents worth: (1) Transparency in food production systems can reduce the mistrust that citizens feel when problems like this arise (there is no question that things like this will happen). (2) Citizens should be as informed as possible about how their food is grown/raised and processed. This will allow them to vote with their forks, and with many eyes on these complex systems, we will hopefully be more likely to nip problems like this in the bud.

And finally, a sad cartoon of a cow in a straight jacket: