SCIENCE / MEDICINE : Polio Looks to Be on the Way Out

International health officials predicted last week that they probably will succeed in eliminating polio from the Western Hemisphere by the end of this year, a major step in a campaign to eradicate the crippling disease from the globe by the year 2000. Polio, or poliomyelitis, caused by a virus in contaminated water and food, produced tens of thousands of cases of paralysis annually in the United States until the first effective vaccine was introduced in 1954.

So far this year, despite intensive case-tracking efforts, only three confirmed cases of polio caused by the natural virus have been found in the Americas, compared with 45 by this time last year, said Ciro de Quadros, regional adviser to the Expanded Program of Immunization for the Pan American Health Organization. Rare cases of paralytic polio also occur in recipients of the live-virus vaccine.

Because of successful vaccination programs, polio cases in the Western Hemisphere have been declining steeply over the last decade, from about 6,000 annually in the late 1970s to 132 last year.

Polio is a far bigger problem in the Eastern Hemisphere, causing more than 200,000 cases of paralysis annually.