Explained | What is mad cow disease and how can it be prevented?

Brazil, the world’s largest exporter of beef, has decided to halt exports of the same to China starting February 23. This decision comes after a case of mad cow disease was reported in the country’s northern state of Para.

The suspension, which is expected to be temporary, was announced since the two countries have an animal health pact between them.

Minister Carlos Favaro said regarding the situation, "All measures are being taken immediately at each stage of the investigation and the matter is being handled with total transparency to guarantee Brazilian and global consumers the recognized quality of our meat.”

What is mad cow disease?

Officially known as bovine spongiform encephalopathy (BSE), mad cow disease is a “transmissible, neurodegenerative, fatal brain disease of cattle”, according to the World Health Organization. The incurable disease first came into the news in 1986 in England after an unknown neurological ailment began affecting cows.

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The agent that causes this disease is highly resistant to freezing or heating, even at temperatures at which milk is pasteurised and sterilised, the WHO says.

The ailment is colloquially known as mad cow disease because the affected animal loses coordination and can also be violent and nervous.

Incubation period and symptoms

The incubation period for BSE is pretty long — around four to six years — and within this period there is no symptom that could prompt a preventive cure.

Even after the onset of the disease, the only symptoms are the animal’s loss of coordination and its violent behaviour. There is no way in which the disease can be clinically detected in a live animal. Only after its death, scientists can confirm whether it was afflicted with the disease by checking its brain tissues under a microscope. The brain tissues of a cow that has died of BSE will have a spongy appearance.

Prevention

The only way to prevent this disease is by not feeding animal-derived food to cattle. In some countries, parts of a cow like the brain, spinal cord and some other parts of the slaughtered animal are disposed off with special care in order to prevent the spread of BSE.