Test Developed for 'Mad Cow'-Related Disease

Test Developed for 'Mad Cow'-Related Disease

July 20, 2001 Reuters by Emma Hitt

NEW YORK (Reuters Health) - British researchers have developed a test for variant Creutzfeldt-Jakob disease (news - web sites) (vCJD), the fatal illness that has been linked with consumption of cattle infected with bovine spongiform encephalopathy, commonly known as ``mad cow'' disease.

Investigators have also found evidence of the disease in tissue other than the brain, indicating that it may be possible to spread the disease through surgical procedures and blood donations.

vCJD is an invariably fatal disorder in which the brain steadily degenerates. It strikes people under 40. In the beginning, patients often exhibit personality changes, depression and withdrawal. Then reasoning skills and motor coordination begin to deteriorate. Within about a year, the person dies.

Malformed proteins called prions are believed to be responsible for vCJD.

According to the US Centers for Disease Control and Prevention (news - web sites), through the end of last year, 87 definite or probable cases of vCJD had occurred in the UK, representing almost all known cases worldwide. But the possibility that large numbers of apparently healthy people might be incubating the disease has raised concerns about transmission through surgical procedures and blood and organ donations.

The new test may be able to prevent the spread of vCJD through blood and organ donations and help estimate the number of people who have been exposed to or infected with the disease, the researchers report in the July 21st issue of The Lancet.

The test, developed by Dr. John Collinge of the Imperial College in London and colleagues, is capable of detecting protein from the infective agent of vCJD in tissues outside the brain, where it is present in 100-fold lower concentrations than in brain tissue.

To develop the test, the scientists took tissue from four patients who had died from vCJD and used specific antibodies that could detect the vCJD protein in tonsil, spleen and lymph nodes.

Collinge suggests that tonsil tissue would be the tissue of choice for diagnosis and screening for vCJD in the population.

In the same issue of the journal, Dr. Moira E. Bruce of the Institute for Animal Health, Edinburgh, Scotland, and colleagues, demonstrated the presence of vCJD in spleen and tonsil by injecting mice with diluted tissue samples from two patients with the disease. In most cases, the mice developed the disease when they were injected with the infected tissue.

``This is the first direct demonstration that the infective agent (of vCJD) is present outside the brain in patients with vCJD,'' Bruce told Reuters Health. ``No infective agent was detected in blood samples from vCJD patients, but this does not rule out the possibility that very low levels of infectivity might be present in blood,'' she said.

This study finding confirms that there may be a risk of contamination of surgical instruments from tissues such as spleen and tonsil of vCJD patients, Bruce concludes.

``The primary use of an early diagnostic test would probably be to prevent transmission (through blood donations, for example) and to achieve a better understanding of the prevalence of the exposed and infected population in the UK,'' said editorialist Dr. David C. Bolton, with the New York State Institute for Basic Research in Mental Retardation and Developmental Disabilities, Staten Island.

Bolton told Reuters Health that there is no treatment for vCJD. But he noted that ``some groups are working on identifying and developing compounds that might slow the progression of the disease by slowing the conversion of the cellular prion protein to the disease-related form.''

SOURCE: The Lancet 2001;358:164-165, 171-180, 208-209.

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