Bovine spongiform encephalopathy

The bovine transmissible spongiform encephalopathy (BSE), known as 'mad cow disease'-first noticed in Great Britain in 1986, is similar to scrapie in sheep and Creustfeld Jacob syndrome (CJD) in man, chronic wasting disease of captive mule deer and rocky mountain elk and transmissible encephalopathies in mink. It has been reported from Northern Ireland, the Republic of Ireland, Oman, Switzerland, France, Germany and a few other European countries. There is no report of BSE in India so far although doubtful cases of CJD in human beings have been reported. The causative agent is structurally different from a virus in that it contains protein (PrP) which is a transformed naturally occurring protein constituent of neurons that is encoded by a single chromosomal gene and devoid of nucleic acid. This agent measures 30-50 nm and is extremely resistant to inactivation by heating, UV-irradiation and many chemicals. BSE is classified as Prion disease.

Epidemiology: The disease in cattle occurred as a result of feeding them with ruminant protein supplements in meat and bone-meal derived from scrapie-affected sheep.

Symptoms: It is difficult to diagnose the disease on the basis of clinical signs since such signs are not quite spectacular. Histopathological and histochemical studies, electron microscopy and biochemical analysis for detection of prion protein are presently available for laboratory confirmation of the disease.Prevention, control and treatment: Identification and slaughtering of positive and suspected cases are the only means of control measures available at present