Zoonoses

Variant Creutzfeldt-Jakob disease

In humans, the most common transmissible spongiform encephalopathy (TSE) is called Creutzfeldt-Jakob disease (CJD). CJD is rare with a worldwide incidence of 1 case per million. Humans who develop this disease will slowly lose the ability to think and to move properly and will suffer from memory loss and progressive brain damage until they can no longer see, speak or feed themselves.

First described in 1996, Variant CJD (vCJD) is similar to CJD as it too is a TSE, yet there are notable differences. First, young people are affected, with an average age of death under 30 years. Second, the disease has a relatively longer duration of illness. Finally, it is strongly linked to exposure, probably through food, to BSE. Other human TSEs have not been linked to food exposure.

The route of transmission of vCJD is not yet fully proven but it is generally accepted that it is transmitted through exposure to food contaminated by BSE.

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Geographic distribution

Variant CJD was first recognized in March 1996.

From October 1996 to November 2002, 129 cases of definite or probable vCJD cases (dead and alive) have been reported from the United Kingdom (UK), plus an additional six cases in France, one in Ireland, one in Italy, one in Canada and one in the United States of America. Three of the French cases as well as the Canadian and United States of America reports are considered to be as a result of exposures in the UK since these people lived in the UK during the BSE epidemic.

Surveillance

The attached excerpt provides WHO recommended standards and strategies for the surveillance, prevention and control of Creutzfeldt-Jakob disease (CJD) and variant CJD (vCJD). This section is part of a larger document entitled "WHO recommended standards and strategies for surveillance, prevention and control of communicable diseases" developed by the WHO Emerging Diseases and Pandemic Response Department (EPR), in collaboration with the Department of Food Safety and Zoonoses (FOS), for major zoonoses involving livestock. Each section, after giving essential information on the main characteristics of the disease and its causative agent(s) and mode of transmission, provides definitions for possible, probable and definite cases of the disease as well as the rational for surveillance and WHO recommended systems for surveillance. Major control and prevention activities in humans and animal hosts are also described. A list of WHO reference materials is provided at the end.

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