June 23 (Bloomberg) -- A study of an epidemic caused by cannibalism indicates the human form of mad-cow disease may incubate for more than 50 years before developing into the fatal illness, researchers said in a medical journal.

The findings suggest the eventual size of a variant Creutzfeldt-Jacob disease epidemic may be much bigger than previously thought, U.K. researchers including John Collinge of the University College London wrote in this week's The Lancet.

Bovine Spongiform Encephalopathy, or mad-cow disease, was first found in the U.K. in 1986. Humans catch the disease through meat from cattle that have eaten feed mixed with ground-up parts of infected animals. About 160 U.K. residents have been diagnosed with the disease, with cases also reported in the U.S. and Japan.

``A human BSE epidemic may be multiphasic,'' Collinge said in The Lancet. ``Recent estimates of the size of the variant Creutzfeldt-Jacob disease epidemic based on uniform genetic susceptibility could be substantial underestimations.''

The disease 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.

Cannibalism Disease

The researchers studied kuru, a disease caused by cannibalism that reached epidemic proportions in some areas of Papua New Guinea. The cannibalism, which was a ritual mourning practice, was stopped by Australian authorities in the 1950s. The researchers identified 11 patients with kuru and found that estimated incubations periods were as long as 56 years and may have been seven years longer.

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. The patients identified so far may ``represent a distinct genetic subpopulation with unusually short incubations periods for BSE,'' Collinge said.

Dutch health officials have found a second patient with the human form of the mad-cow disease, the National Institute for Public Health and the Environment said yesterday. At the request of the patient and the patient's family no further information on the case is being released, according to the Bilthoven, Netherlands-based institute's statement.

``The cause of the disease may be linked to consumption of infected beef in the past,'' it said. ``Currently it is safe to consume beef in the Netherlands, because since 2001 possibly infected cows get tested for the disease when being slaughtered.''

Japan will send three teams on June 24 to inspect 35 U.S. meatpacking plants certified to export beef, as part of an agreement under which it will resume U.S. imports. Japan halted imports of U.S. beef on Jan. 20, just weeks after lifting a two- year embargo, after banned cattle material was found in a shipment of veal.

Before the ban Japan was the biggest buyer of U.S. beef, purchasing $1.4 billion out of a total $3.8 billion in exports in 2003. Japan first halted imports in December 2003 after a case of mad-cow disease was found in Washington state.

To contact the reporter on this story: Martijn van der Starre in Amsterdam at vanderstarre@bloomberg.net

Last Updated: June 23, 2006 12:26 EDT