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Current Trends Lack of Evidence for Wild Poliovirus Circulation -- United States, 1993

Following the isolation of wild poliovirus type 3 during January-February 1993 among members of a religious community objecting to vaccination in Alberta, Canada, surveillance for poliomyelitis was enhanced among related communities in the United States (1). In addition, during May-July 1993, a series of surveys was conducted in seven states (Iowa, Missouri, New York, Ohio, Pennsylvania, Washington, and Wisconsin) to determine whether wild poliovirus was circulating or had circulated recently among members of these religious communities residing in the states. This report summarizes the results of these surveys.

The isolation of wild poliovirus in Canada and the efforts to enhance surveillance in the United States followed a polio outbreak in the Netherlands during September 1992-February 1993 (2-4). The outbreak was attributed to wild poliovirus type 3 and resulted in 71 cases of polio among members of a religious community objecting to vaccination. A virtually identical genotype of wild poliovirus type 3 was subsequently isolated from stool samples collected from members of related religious groups in Alberta during January- February 1993 (3) and again from samples collected in April 1993; however, this genotype was not isolated from samples collected in June 1993 (P. Duclos, Laboratory Center for Disease Control, Ottawa, Canada, personal communication, November 1994). Based on nucleotide sequence studies, the poliovirus detected in the Netherlands and Canada most likely originated in India (4).

In response to the importation of poliovirus type 3 into the Western Hemisphere, measures taken by state health departments in the United States during April 1993 included 1) intensified efforts to vaccinate persons in religious communities that usually object to vaccination; 2) enhanced surveillance to identify medical conditions possibly caused by poliovirus (i.e., aseptic meningitis and acute paralysis); and 3) the initiation of a series of serologic, stool, and/or environmental surveys in Iowa, Missouri, New York, Ohio, Pennsylvania, Washington, and Wisconsin. The purpose of these surveys was to determine whether poliovirus type 3 was circulating currently or had circulated at any time since 1980 among unvaccinated members of these religious communities.

No cases of aseptic meningitis or acute paralysis have been detected among members of the religious communities since April 1993. Members of these religious communities were enrolled for the serologic, stool, and environmental surveys; poliovirus was not isolated (or detected) in the 122 stool specimens collected from members of 73 families in five states (Iowa, Missouri, Ohio, Pennsylvania, and Washington). A total of 123 serum specimens from persons in four states (Missouri, Ohio, Pennsylvania, and Washington) were tested for neutralizing poliovirus antibody; antibody to poliovirus types 1, 2, or 3 were detected in 40%, 92%, and 26% of specimens, respectively. However, poliovirus type 3 was not detected in any of the 40 children from Ohio and Pennsylvania who were unvaccinated and born after 1979. Based on the serologic surveys, poliovirus type 3 had not circulated in these communities since 1980.

A total of 12 sewage and latrine waste specimens was collected during June and July 1993 from Iowa, Missouri, New York, Pennsylvania, and Wisconsin and was examined by polymerase chain reaction; wild poliovirus was not detected in these samples. Reported by: AM Shemo, MD, S Miller, R Longenecker, A Gray, F Zitnik, R Berman, Pennsylvania Dept of Health. J Bronowski, T Payton, R Genieve, TJ Halpin, MD, State Epidemiologist, Ohio Dept of Health. F James, MD, J Hensley, Whatcom County Health Dept, Bellingham; S LaCroix, State Public Health Laboratory, Washington State Dept of Health. C Friedman, DO, J Hinkle, H Marx, HD Donnell, Jr, MD, State Epidemiologist, Missouri Dept of Health. J Berg, Div of Health, Wisconsin Dept of Health and Social Svcs. J Warming, D Miller, Iowa Dept of Public Health. S Thompson, G Birkhead, MD, D Krohn, New York State Dept of Health. R Berke, MD, M Clark, Chautauqua County Health Dept, Jamestown, New York. M Sobsey, PhD, Environmental Virology Laboratory, Univ of North Carolina, Chapel Hill. Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; National Immunization Program, CDC.

Editorial Note

Editorial Note: Wild poliovirus infection has not been documented among persons in the United States since 1986, when wild poliovirus type 1 was isolated from a person with imported paralytic polio. The last indigenous cases of polio in the United States occurred in 1979 (5), and the last imported case in which wild poliovirus was not isolated was reported in 1993 *.

Polio can be prevented by vaccination. All children and all previously unvaccinated adults should receive a primary series of at least three doses of oral poliovirus vaccine (OPV) or inactivated poliovirus vaccine. For children, the standard recommended 4-dose series of OPV comprises doses at ages 2, 4, and 6 months and 4-6 years (6).

The findings in this report suggest that poliovirus type 3, which caused both the outbreak in the Netherlands during 1992-93 (4) and the "silent" transmission in Canada during 1993 (3), was not imported into the United States. Despite these findings, members of religious groups that object to vaccination and suboptimally vaccinated preschool-aged children who reside in urban areas may be susceptible to polio. If poliovirus is introduced into these unvaccinated groups, the number of persons who are susceptible may support virus circulation. Some members of groups usually opposed to vaccination will accept vaccination if offered.

On September 29, 1994, the International Commission for the Certification of Polio Eradication concluded that wild poliovirus transmission had been interrupted in the Western Hemisphere (7). However, the commission recognized that the region will remain at risk for poliovirus importation until polio is eradicated globally (8). The importations into the Netherlands and Canada underscore the efficiency by which poliovirus can be transported across borders and continents (3,9,10). Unvaccinated persons in groups objecting to vaccination is the primary group in the United States in which transient circulation of imported poliovirus may occur. To ensure that poliovirus transmission cannot be sustained in the United States, poliovirus vaccination coverage should be increased to 90% in all areas.


  1. CDC. Poliomyelitis -- Netherlands, 1992. MMWR 1992;41:775-8.

  2. CDC. Update: poliomyelitis outbreak -- Netherlands, 1992. MMWR 1992;41:917-9.

  3. CDC. Isolation of wild poliovirus type 3 among members of a religious community objecting to vaccination -- Alberta, Canada, 1993. MMWR 1993;42:337-9.

  4. Oostvogel PM, van Wijngaarden JK, van der Avoort HG, et al. Poliomyelitis outbreak in an unvaccinated community in The Netherlands, 1992-93. Lancet 1994;344:665-70.

  5. Strebel PM, Sutter RW, Cochi SL, et al. Epidemiology of poliomyelitis in the United States one decade after the last reported case of indigenous wild virus-associated disease. Clin Infect Dis 1992;14:568-79.

  6. CDC. General recommendations on immunizations: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1994;43(no. RR-1).

  7. CDC. Certification of poliomyelitis eradication -- the Americas, 1994. MMWR 1994;43:720-2.

  8. Pan American Health Organization. Americas certified polio free. EPI Newsletter 1994;16:2-3.

  9. Rico-Hesse R, Pallansch MA, Nottay BK, Kew OM. Geographic distribution of wild poliovirus type 1 genotypes. Virology 1987;160:311-22.

  10. Kew OM, Pallansch MA, Nottay BK, Rico-Hesse R, De L, Yang CF. Genotypic relationship among wild polioviruses from different regions of the world. In: Brinton MA, Heinz FX, eds. New aspects of positive-strand RNA viruses. Washington, DC: American Society for Microbiology 1990;52:357-65.

    • This imported case occurred in a 2-year-old child who had onset of paralysis on December 15, 1993, in Nigeria and was brought for tertiary hospital care to New York 2 weeks later; no poliovirus was isolated from this child.

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