Mad cow disease, also called bovine spongiform encephalopathy, is a disease found in cattle that causes progressive brain damage in the cattle. It may also affect goats and sheep. New variant CJD, called nvCJD, is a disease that causes the same type of progressive brain damage in humans. NvCJD may actually be the human form of mad cow disease.
Both mad cow disease and nvCJD are believed to be caused by prions. Prions are a modified form of a protein found on normal cell surfaces. Both diseases cause a build up of prions in the brain. The increase in prions causes brain injury and degeneration The same type of prion may cause both mad cow disease and nvCJD.
NvCJD may take 5 to 10 years to develop after a person has been exposed to the BSE prion. It has different symptoms from the classic form of Cretuzfeldt-Jakob disease. Early in the course of the disease, the person may have psychiatric disorders and altered sensations. Later, the person can develop difficulty walking, which is called ataxia. Muscle spasms and dementia show up late in the illness. There may also be visual impairments, paralysis, and sleep disorders.
There is a strong link between mad cow disease and the nvCJD. Most experts believe that this new variant CJD is the human form of mad cow disease. It is believed that the abnormal prion is spread from infected cattle to humans when the person eats meat or beef products. Milk and dairy products from infected cattle don't appear to carry the same risk.
At present, infected cattle are found mostly in Europe, especially in Great Britain. Even there, the risk of getting nvCJD from infected beef is only about 1 case in 10 billion servings of beef. nvCJD has been seen most often in younger people.
Travelers to areas with a high risk for mad cow disease can limit their risk for nvCJD by avoiding beef and beef products. If the person chooses to eat meat, he or she should select solid pieces of muscle meat, such as a steak or roast. Sausage and hamburger should be avoided. Public health measures to test for mad cow disease and eliminate cattle with evidence of BSE are ongoing.
Diagnosis of nvCJD begins with a medical history and physical exam. A recording of brain waves, called an EEG, may show abnormalities. A final diagnosis can be made with a biopsy of the brain. This involves taking a small piece of brain tissue with a special needle. The piece of tissue can then be examined with a microscope.
Mad cow disease causes brain degeneration and death in cattle. NvCJD causes brain degeneration and death in people.
Mad cow disease is highly contagious among cattle. NvCJD does not appear to spread from person to person. However, it may be spread if someone handles brain tissue or other body parts from an infected person.
There is no treatment for nvCJD. Medicines may be used to treat psychiatric problems or to relieve symptoms.
All medicines may have side effects. These may include allergic reactions and stomach upset. Specific side effects depend on the medicines used.
NvCJD causes progressive brain damage and death. The person usually dies within 2 years after symptoms start.
Symptoms and physical exam are followed to see if any new medicines to treat symptoms may be needed. Any new or worsening symptoms should be reported to the doctor.