Wednesday, November 16, 2005

Waking to a New Flu Threat (and worse)

EVERYONE is wondering whether the bird-flu virus will mutate and cause an outbreak of influenza comparable to the 1918 pandemic, which killed more than 25 million people. But there is an additional possibility - that the bird flu, if it comes, may bring more than influenza.

The influenza pandemic of 1918 was followed by another epidemic. The disease was encephalitis lethargica, or the "sleepy sickness," and like influenza it spread through most of the world. Its symptoms were extraordinarily varied - most commonly there was lethargy, but sometimes there was insomnia, and even frenzy; sometimes there were paralyses, sometimes mental disorders.

It seemed at first as if a dozen different epidemics had sprung up at once, and it was only through the unifying work of a great Austrian doctor, Constantin von Economo, that all these varied symptoms were recognized to be manifestations of a single disease, the one Economo named "encephalitis lethargica."

Of the million or so people who came down with encephalitis lethargica during this period, half a million died in the acute stages of the illness; most of the survivors, people who appeared to have recovered, went on to develop, sometimes decades later, a variety of neurological problems, including a crippling form of parkinsonism.

New York was especially hard-hit by the disease, and as a result it became the world center for encephalitis vaccine trials, all of which failed. In fact, the sickness so exercised the medical community that an estimated 9,000 articles and books were written on it from 1917 to 1939.

But after this it largely vanished from medical consciousness and popular consciousness alike - no cure or causative agent had ever been found and most of the remaining survivors were housed in chronic-care hospitals and forgotten.

In fact, it would take several decades for the disease to become of serious interest again. When the drug L-dopa was introduced in the late 1960's to treat "ordinary" Parkinson's disease, it was also tried with patients who had the far more severe form of post-encephalitic parkinsonism. Many of these patients "awakened" and did spectacularly well for a while, but the effects of L-dopa then faded, and the patients returned to their trance-like states.

The relationship of encephalitis lethargica to the 1918 influenza epidemic is unclear, but we can no longer afford to remain ignorant about it. Economo saw similarities between encephalitis lethargica and a neurological disease - the "nona" - which broke out in Italy just after that country's influenza epidemic of 1889 to 1890. Later research has indeed suggested a recurring association, since the time of Hippocrates, between influenza epidemics and encephalitis-like diseases. In 1982 it was shown that irregularly spaced waves of influenza-pneumonia deaths in Seattle during the early 20th century epidemic were followed approximately one year later by corresponding waves of encephalitis fatalities.

After the arrival of the influenza pandemic via ship passengers in Western Samoa in 1918, fatal cases of encephalitis were reported for several subsequent years. In contrast, American Samoa, which is only 32 miles away, maintained a strict quarantine and avoided the 1918 influenza epidemic. There were no encephalitis lethargica deaths there until 1926, following a later influenza epidemic.

No funds have been allocated to try to better understand this mysterious disease and its relationship to epidemic influenza. Encephalitis lethargica is a particularly insidious disease because it is so variable; any early cases in a new outbreak would almost certainly be misdiagnosed as they were 100 years ago.

It is not unlikely that this disease will return. Perhaps with the imminent influenza epidemic, perhaps not. Regardless, we would do well to re-awaken ourselves to what may be a formidable gathering threat.

Oliver Sacks, a neurologist, is the author of "Awakenings," about encephalitis lethargica patients. Joel A. Vilensky is a professor of anatomy and cell biology at the Indiana University School of Medicine.
LINK

0 Comments:

Post a Comment

Links to this post:

Create a Link

<< Home