Bovine spongiform encephalopathy

VOCABULARY LIST TO TEXT C

Bovine spongiform encephalopathy (BSE) commonly known as mad cow disease is a fatal neurodegenerative disease (encephalopathy) in cattle that causes a spongy degeneration of the brain and spinal cord.

Research indicates that the first probable infections of BSE in cows occurred during the 1970's in the UK. BSE possibly originated as a result of feeding cattle meat-and-bone meal that contained BSE-infected products from a spontaneously occurring case of BSE or scrapie-infected sheep products. There is strong evidence and general agreement that the outbreak and spread of the disease throughout the United Kingdom cattle industry was amplified by feeding prion-infected, bovine meat-and-bone meal to young calves. The disease may be most easily transmitted to humans by eating food contaminated with the brain, spinal cord, or digestive tract of infected carcasses.

Symptoms are not seen immediately in cattle due to the diseases’ extremely long incubation period. Some cattle have been observed to have an abnormal gait, changes in behavior, tremors and hyper-responsiveness to certain stimuli. Hindlimb ataxia affects the animal’s gait and occurs when muscle control is lost. This results in poor balance and coordination. Behavioural changes may include aggression, anxiety relating to certain situations, nervousness, frenzy or an overall change in temperament. Some rare but previously observed symptoms also include persistent pacing, rubbing or licking. Additionally, nonspecific symptoms have also been observed which include weight loss, decreased milk production, lameness, ear infections and teeth grinding due to pain. Once clinical symptoms arise, they typically get worse over the upcoming weeks and months, eventually leading to recumbency, coma and death.

The traditional method of diagnosis relies on histopathological post mortem (necropsy)examination of the medulla oblongata of the brainand other tissues. Immunohistochemistry can be used to demonstrate prion protein accumulation.

Public health control measures, such as surveillance, culling sick animals, or banning specified risk materials, have been introduced in many countries, particularly in those with indigenouscases of confirmed BSE, in order to prevent potentially BSE-infected tissues from entering the human food supply.

Сontrol measures include a program that excludes all animals more than 30 months of age from the human food and animal feed supplies. The program appears to be highly effective.

European Union Commission on Food Safety and Animal Welfare strengthened the European Union's BSE control measures by requiring all member states to remove specified risk materials from animal feed and human food chains. Other control measures include banning the use of mechanically recovered meat from the vertebral column of cattle, sheep, and goats for human food and BSE testing of all cattle more than 30 months of age destined for human consumption.

Notes

European Union Commission on Food Safety and Animal Welfare – КомиссияЕвросоюзапобезопасностипищевыхпродуктовиаттестацииздоровьяживотных

Exercise 18. Look through the text and find information about:

- bovine spongiform encephalopathy causative agent;

- incubation period of bovine spongiform encephalopathy;

- cause of an outbreak in the United Kingdom;

- clinical signs of bovine spongiform encephalopathy;

- prevention of bovine spongiform encephalopathy.