BEIJING, June 23 (Xinhuanet) -- The number of people infected with mad cow disease could be far higher than thought because of a longer incubation period, British scientists said in this week's the Lancet.

    Reporting in the Lancet, a medical journal, researchers believed the time between infection with mad cow disease, or bovine spongiform encephalopathy (BSE), and developing the human form of mad cow disease, or variant Creutzfeldt-Jakob disease (vCJD), may exceed 50 years.

    Therefore, recent estimates of the size of vCJD epidemic "based on uniform genetic susceptibility could be substantial underestimations," the researchers wrote in the Lancet, suggesting that more vCJD patients could emerge in the coming decades.

    BSE is caused by abnormal prions, a type of protein that damages the patient's central nervous system. The prions unfold in the brain, creating vast dead spots.

    The team from University College London used a disease called kuru, caused by cannibalism among tribes in East Indonesia before the 1950s, to analyse and predict the potential incubation period of BSE prions.

    They found that the last case of kuru, the only currently epidemic human prion, occurred in 1996, 50 years after authorities last prevented tribesmen from eating their dead relatives as a mark of respect.

    However, the incubation period for BSE prions in humans may be even longer because infection between species typically takes longer than within species, the researchers wrote. Enditem