Mad Cow Disease

Description

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Context

Brazil has halted its beef exports to China after a case of mad cow disease was confirmed in the northern state of Para.

What is Mad Cow Disease?

Mad cow disease is also known as bovine spongiform encephalopathy (BSE).
It is a transmissible, slowly progressive, degenerative, and fatal disease which affects the central nervous system of adult cattle.
The infectious agent that causes mad cow disease is an abnormal version of a protein normally found on cell surfaces, called a prion, research has shown. When this protein gets altered, it destroys the nervous system tissue- the brain and spinal cord. Although, the reason for the same is still unknown.

In a nutshell,

Mad Cow disease is not caused by bacteria, and is not treated with antibiotics. Rather, it is thought to be caused by abnormal prions, which are misfolded proteins concentrated in nervous system parts, particularly the brain, spinal cord, and nerve endings.

Symptoms

Symptoms include abnormal behavior, trouble walking, and weight loss.
Later in the course of the disease the cow becomes unable to function normally.
There is conflicting information around the time between infection and onset of symptoms. In 2002, the WHO suggested it to be approximately four to five years. Time from onset of symptoms to death is generally weeks to months.

Transmission

People cannot get mad cow disease. But in rare cases they may get a human form of mad cow disease called variant Creutzfeldt-Jakob disease (vCJD), which is fatal. Over time, vCJD destroys the brain and spinal cord.

Treatment

There is no treatment for BSE and no vaccine to prevent it. Currently, there is no reliable way to test for BSE in a live cow. After a cow dies, scientists can tell if it had BSE by looking at its brain tissue under a microscope and seeing the spongy appearance.