Lincolnshire Post-Polio Library - A Service of The Lincolnshire Post-Polio Network
Post-Polio Syndrome: Pathophysiology and Clinical Management
Anne Carrington Gawne and Lauro S. Halstead

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III. EPIDEMIOLOGY.

During the epidemics in the U.S. from 1952 to 1954, the incidence of new cases was approximately 15/100,000, as Figure 1 demonstrates.[10] The incidence peaked in 1952 with over 57,879 new cases reported in the U.S. After the Salk vaccine was introduced in 1955 and the Sabine vaccine in 1961 the incidence dropped to 0.04/100,000 by 1963. The last confirmed case of paralytic polio from domestic wild virus in the U.S. occurred in 1979.[10] Paralytic polio is now a rare complication of the current Sabin (oral) vaccination. In the U.S. between 1961 and 1964, there was an incidence of paralysis in 4.9/10 million doses compared with an incidence of 0.23/10 million in 1989, as Figure 2 shows.[10] The greatest risk is from the initial immunization (1/700,000).[11]

Figure 1.
FIGURE 1. Reported rates per 100,000 persons of poliomyelitis and of death from poliomyetitis, United States, 1932 to 1989. (IPV = inactivated polio vaccine; OPV = oral polio vaccine.)

A survey by the National Center for Health Statistics in 1987 found there were more than 640,000 survivors of paralytic polio.[12] Thus, despite the virtual elimination of new cases, paralytic polio remains one of the most prevalent neuromuscular diseases in this country. While PPS is more common in those who have experienced moderate to severe paralysis,13 population-based surveys show that as many as 64% of polio survivors develop new symptoms.[2] If these samples are representative of a typical distribution, then it can be estimated that over 409,000 people may experience the late effects of polio. While some of this population has died since the original survey, there has also been an unknown and largely unexpected increase in the number of polio survivors in the U.S. resulting from the influx of affected immigrants, refugees, and illegal aliens from Southeast Asia and Latin America. In 1991, the World Health Organization (WHO) estimated that 85% of children world-wide received three doses of the TOPV vaccine, a significant increase over the percentage in 1971 (15%), largely due to the effort WHO put into their vaccination campaign.[14] While no cases of wild polio infection occurred in the Americas in 1993, WHO estimates that 96,500 new cases occurred in the developing world; in particular Africa, Asia, and India, due to inadequate immunization.[15]

Figure 2
FIGURE 2. Reported cases of paralytic poliomyelitis (total and vaccine-associated per 10 million doses of Sabin vaccine), U.S., 1960 to 1989.

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