From
Infections in Medicine^®

Pediatric Bulletin
Poliomyelitis Eradication: Still a Challenge

Benjamin Estrada, MD, University of South Alabama, Mobile.

[Infect Med 18(2):77-78, 2001. © 2001 Cliggott Publishing Co., Division of SCP/Cliggott Communications, Inc.]

During the last 4 decades, there has been significant progress toward the eradication of poliomyelitis. The first inactivated poliovirus vaccine was introduced shortly after epidemic poliomyelitis reached its peak in the United States during the 1950s. The subsequent development of oral poliovirus vaccine (OPV) containing attenuated virus had a significant impact on public health worldwide. Combined efforts of the World Health Organization (WHO) and the ministries of health of many countries have led to massive immunization campaigns that have been successful in significantly decreasing the global prevalence of this disease.

One of the WHO's top priorities was the worldwide eradication of this infection by the year 2000. Although substantial progress toward this goal has been made, poliomyelitis remains endemic in some countries. A geographic area of concern is the eastern Mediterranean region, which includes Pakistan and Afghanistan. Sixty percent of all acute flaccid paralysis cases reported to the WHO in 1999 occurred in Pakistan.^[1] Poliomyelitis continues to be endemic in some areas in West Africa; this is evidenced by a recently reported outbreak in Cape Verde that included 33 cases, some of which had associated mortality.^[2] In addition, vaccine coverage remains low in central Africa -- only 40% in 1999.^[3]

In 1991, the Western Hemisphere had been declared free of poliomyelitis. However, the Pan-American Health Organization (PAHO) recently reported a poliomyelitis outbreak in Haiti and the Dominican Republic. Six virologically confirmed cases of poliomyelitis have occurred in the Dominican Republic since July 12, 2000, and 16 additional persons have manifested symptoms of this disease. One case has been virologically confirmed in Haiti. According to the CDC, the age range of persons with reported cases has been 9 months to 21 years, with most cases in children younger than 6 years. All patients were either inadequately vaccinated or unvaccinated. The governments of both countries have continued active surveillance in search of additional cases. According to the PAHO, the virus isolated in this outbreak is 97% similar to the Sabin type 1 virus contained in poliovirus vaccine and probably originated from it. This is now a wild virus, believed to have been in circulation for about 2 years. Previous experience has shown that prolonged circulation of OPV virus in areas with low coverage may trigger disease outbreaks. Efforts to complete mass immunization campaigns are under way in both countries.^[4,5]

The outbreak in the Dominican Republic and Haiti comes as a surprise, since this area of the world had been certified as being free of poliomyelitis for several years. The importance of continuous surveillance and high immunization coverage needs to be emphasized until global eradication is achieved, even in those countries where transmission is considered less likely. Children traveling to areas where poliomyelitis is endemic or to countries where recent outbreaks have been reported should be current on their poliovirus immunization according to the schedule recommended by the American Academy of Pediatrics.^[6] Most persons older than 18 years in the United States who have not been vaccinated or whose immunization status is unknown should receive inactivated poliovirus vaccine. The recommended immunization schedule for adults includes administration of the first 2 doses 1 to 2 months apart and a third dose 6 to 12 months after the second.^[7]

References

1. Centers for Disease Control and Prevention. Progress toward poliomyelitis eradication -- Pakistan, 1999-June 2000. MMWR. 2000;49(33):758-762.
2. Centers for Disease Control and Prevention. Public health dispatch: outbreak of poliomyelitis -- Cape Verde, 2000. MMWR. 2000;49(47):1070.
3. Centers for Disease Control and Prevention. Progress toward poliomyelitis eradication -- African Region, 1999-2000. MMWR. 2000;49(20):445-449.
4. Centers for Disease Control and Prevention. Public health dispatch: outbreak of poliomyelitis -- Dominican Republic and Haiti, 2000. MMWR. 2000;49(48): 1094,1103.
5. Pan-American Health Organization. Outbreak of poliomyelitis in Dominican Republic and Haiti: low vaccination coverage with oral polio vaccine allows sabin-derived vaccine virus to circulate. Available at: http://www.paho.org/english/dpi/press_001202.htm.
6. Committee on Infectious Diseases, American Academy of Pediatrics. Poliovirus infections. Red Book 2000. 25th ed. 2000:465-470.
7. Centers for Disease Control and Prevention. Poliomyelitis -- health information for international travel, 1999-2000. Available at: http://www.cdc.gov/travel/diseases/polio.htm.

Dr Estrada is assistant professor of pediatrics, division of pediatric infectious diseases, University of South Alabama, Mobile.