CJD, an incurable degenerative brain disease, is extremely rare under the age of 30, with only four other cases reported in the world to date.
The 16-year-old girl, who is believed to be still alive, is the youngest person to contract the disease in the UK. She is known to have eaten a meat dish containing cow's brain in Cyprus in 1989, although there have been no reported cases of bovine spongiform encephalopathy (BSE) on the island. She also occasionally ate beefburgers and corned beef.
The 18-year-old boy, who died earlier this year, had visited his aunt's cattle farm annually for eight years and drank unpasteurised milk. However, no cases of BSE have been reported in the herd.
Neither of the teenagers had any of the risk factors for CJD. They had not received growth hormone derived from human brain tissue, undergone transplants or tissue grafts, or brain surgery, according to reports in tomorrow's issue of the Lancet.
Professor John Collinge, of St Mary's Hospital, London, says the girl, a Turkish-Cypriot Muslim, developed slurred speech, poor balance, clumsiness, and a frequent need to urinate in August 1994. Within a month, her memory had worsened, she could no longer do arithmetic, had difficulty in speaking and was unsteady on her feet. A brain biopsy in August 1995 confirmed the spongey changes characteristic of CJD.
The boy had a six-month history of memory loss and deteriorating school performance.His condition deteriorated with hallucinations, disorientation, speaking problems, unsteadiness, and he died 9 to 12 months after the onset of symptoms. Analysis of his brain tissue confirmed CJD.
Professor Collinge, who was involved in both cases, says there was no evidence so far that any human case of CJD is related to exposure to BSE but adds: "The extremely young age of onset, and absence of known risk factors, inevitably prompts discussion of a possible link between [the] illness and the recent epidemic of BSE."
He points out that the four cases of CJD in teenagers - from the USA (1978), France (1982), Canada (1988), and Poland (1991) - occurred in countries where BSE had not been reported when the cases were diagnosed. However, he concludes that although the two cases may be "coincidental" and of no particular significance, "they re-emphasise the need for continued epidemiological surveillance of CJD".
The Department of Health confirmed earlier this week that it is investigating a possible fourth case of CJD in a dairy farmer with a BSE-infected herd. Scientists agree that the chance of four cases occurring among dairy farmers is statistically low, but they point out that there has been no increase in CJD among vets or abattoir workers who would also be expected to run an increased risk if BSE had jumped the species barrier. A Government report earlier this month confirmed that the number of CJD cases had doubled between 1985 and 1994, but this may be the result of increased surveillance.Reuse content