encephalitis lethargica: Sleepiness in China Caused by Flu

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A Surge of Sleepiness in China Appears to Have Been Caused by Flu

By DONALD G. McNEIL Jr.

Cases of narcolepsy — a condition that causes sufferers to fall asleep without

warning — tripled in China after the 2009 swine flu pandemic, according to a

study released Monday. But the surge appeared to be an annual late spring event

caused by the flu itself, not by China's swine flu vaccination campaign.

The issue is important, explained Dr. Emmanuel Mignot, a Stanford University

narcolepsy specialist who works in China and is an author of the study, because

a " double-boosted " swine flu vaccine used in Europe apparently caused narcolepsy

in some Swedish and Finnish children.

Narcolepsy and a related but even rarer illness, cataplexy — a tendency to

collapse when swept by strong emotions — are caused by the death of brain cells

that secrete hypocretin, which regulates sleep. Those cells, Dr. Mignot

explained, are probably killed by autoimmune reactions that stem from winter

infections like flu and strep throat.

For several years after the 1918 Spanish flu pandemic, medical authorities

described a seasonal somnolence they called " encephalitis lethargica. "

In the study, published in ls of Neurology, scientists from Stanford and

Beijing University People's Hospital looked at 154 new narcolepsy diagnoses —

mostly in children — after the 2009 pandemic. Spring onsets were seven times as

common as winter ones. But only 6 percent had had flu shots.

" Our paper shows that to be sick with the flu itself can trigger narcolepsy, "

Dr. Mignot said. " So maybe regular flu vaccines can protect against it. "

http://www.nytimes.com/2011/08/23/health/23global.html