A British tourist in Hong Kong has been struck down with what appears to be mad cow disease.

The 23-year-old man who was visiting Hong Kong is now in hospital and is said to be in a critical condition.

He is being closely monitored and Hong Kong’s Department of Health and the Hospital Authority say as yet the diagnosis has not been confirmed.

The man apparently arrived in Hong Kong in early April and developed dizziness. He appeared mentally deranged and showed other psychiatric symptoms.

He was admitted to Kwong Wah Hospital on April 6.

The man appears to have the clinical features suggesting the variant Creutzfeldt-Jakob Disease (vCJD), commonly known as mad cow disease, believed to be contracted by eating animals infected with mad cow disease, but laboratory tests have so far been negative.

He has since received intestinal surgery and is now critically ill at Prince of Wales Hospital.

Relatives say he has no history of surgery, blood transfusion or blood donation.

Mad cow disease, or bovine spongiform encephalopathy (BSE), is a degenerative nerve disease in cattle.

The human version vCJD is a rare and fatal human neurodegenerative condition.

The hospital has apparently adopted infection control measures.

From October 1996 to November 2002, 129 cases of vCJD have been reported in the United Kingdom (UK), six in France and one each in Canada, Ireland, Italy and the United States of America. Insufficient information is available at present to make any well-founded prediction about the future number of vCJD cases.