A patient dies, and Elan stock takes dive

The patient died after developing a rare brain and spinal cord infection called progressive multifocal leukoencephalopathy. Another case of the disease is suspected.
Tysabri is used to treat multiple sclerosis. It was launched with considerable fanfare in November, and had been expected to reinvigorate Elan’s fortunes. There were hopes that it would become the world’s leading treatment for multiple sclerosis and sales were estimated to exceed $3 billion per year.
Elan’s stock price on the Irish stock market lost 69 percent — or