Volume 21-16
30 August 1995

Committee to Advise on Tropical Medicine and Travel (CATMAT)*

STATEMENT ON POLIOMYELITIS VACCINATION FOR INTERNATIONAL TRAVELLERS

(Evidence-based medicine recommendations) (1)

The clinical manifestations of poliomyelitis may range from an inapparent infection to severe neurologic involvement with paralysis and death. The ratio of inapparent infection to clinical disease due to polio is estimated to be 60:1 to 1000:1 ^(2,3,4). Polio infection is caused by any of the following three antigenic types of enteroviruses: polioviruses 1, 2 and 3. Fecal-oral is the major route of transmission where sanitation is poor.

In Canada, the last major epidemic occurred in 1959 when 1,887 paralytic cases occurred. Following the introduction of the inactivated polio vaccine (IPV) in 1955, and the oral polio vaccine (OPV) in 1962, the indigenous disease has been virtually eliminated. Rarely, outbreaks have been reported in populations that have declined immunization on religious grounds ^(5,6). From 1980 to 1992, 10 cases of polio were reported in Canada ⁽⁷⁾. Nine of these were felt to be vaccine-related ⁽⁵⁾. Since wild polio viruses no longer circulate in Canada, routine immunization or booster doses of polio vaccine for adults are no longer recommended in Canada, except in special circumstances ⁽⁵⁾.One of these circumstances may be international travel to areas with endemic or epidemic-polio virus activity.

In a recent serologic survey of 233 American international travellers, 12% were found to be lacking antibodies to polio viruses 1 or 3 ⁽⁸⁾. All had antibodies to polio virus 2. All travellers in this survey who had received polio vaccination within the previous 5 years had antibodies to all three types. Only 84% of those who had received a polio booster > 5 years earlier were seropositive to all three types. Although these data may not be generalizable to Canadians, they do suggest that many travellers may not have protective antibodies against the polioviruses.

Because of the small number of polio cases reported in Canada, none of which appear to be travel-related, it will be easier to say who should not be immunized against polio for international travel. This approach will become easier as we move toward the goal of global eradication of polio.

A World Health Organization report on the status of the Expanded Programme on Immunization (EPI) summarizes the incidence of reported cases of polio by world region as of 1992 ⁽⁶⁾. In the Americas, the last case of indigenous polio caused by a wild polio virus was detected in Peru on 23 August, 1991 ⁽⁷⁾. Despite intensive surveillance for cases of flaccid paralysis in the region, no new cases have been detected. Reporting is 100% complete in the region. Forty-two of the 47 countries or regions (89%) have reported no cases of polio for at least 3 years ⁽⁶⁾. When no new cases are reported from a region for 3 years, the region is considered to be free of polio transmission. In October 1994, the World Health Organization reported that poliomyelitis had been eradicated from the Americas ⁽⁹⁾.

Unfortunately, for parts of Africa, the Middle East, and Asia the rates of poliomyelitis continue to range from 1 to 10 cases per 100,000 population (Figure 1). India contributes three of every four reported cases of polio ⁽⁶⁾.

These data do not necessarily translate into a risk of infection or disease for the international traveller. In endemic regions, or in areas experiencing epidemics of polio, a careful pre-travel history of activities that may pose an increased risk of exposure to contaminated water may indicate a need for primary vaccination or for a booster dose for adults. These risk characteristics in a geographic area of polio transmission may include duration of travel, expected exposure to unsafe water, and activities where increased exposure to unsanitary conditions may occur such as back packing, providing international aid or health care, or participating in a cultural exchange program.

Figure 1
Global incidence of poliomyelitis, 1995

RECOMMENDATION 1

Primary immunization of children and, if indicated, primary immunization of adults or a booster dose for adults is recommended in accordance with the recommendations of the National Advisory Committee on Immunization ⁽⁵⁾ [strength of recommendation: category A; quality of evidence: grade III ⁽¹⁾ ] (see also Appendix I).

Recommended Usage

Infants and Children: immunization against poliomyelitis may be undertaken with IPV or OPV. The recommended schedule is to immunize at 2, 4, 6 (omit this dose if OPV is used exclusively) and again at 18 months of age, with a booster at 4 to 6 years and 14 to 16 years (omit this dose if OPV is used exclusively). Following primary immunization, the only indication for revaccination is a one-time booster as an adult, at least 10 years after primary immunization, for travellers to foreign countries where poliomyelitis is endemic.

For children < 7 years, but not immunized in infancy: immunization against poliomyelitis may be undertaken with IPV or OPV. The recommended schedule is as follows: first visit, 2 months later, 2 months following the second dose (omit this dose if OPV is used exclusively), 6 to 12 months later, at 4 to 6 years (omit this dose if the previous doses given after the fourth birthday) and 14 to 16 years (omit this dose if OPV is used exclusively) and, if required, every 10 years thereafter.

Routine immunization schedule for children > 7 years, or for adults, not immunized in infancy: immunization against poliomyelitis may be undertaken with IPV or OPV. Caution is advised in using OPV in a previously unimmunized adult, or in an individual who may expose an unimmunized adult to the vaccine strain, due to the risk of vaccine-associated disease. The vaccine is given at the first visit, 2 months later, 6 to 12 months later and, if required, every 10 years thereafter.

RECOMMENDATION 2

Booster immunization against polio is not required for travel to the Americas ⁽⁶⁾ (strength of recommendation: category E; quality of evidence: grade II).

RECOMMENDATION 3

International travellers to other polio-endemic or epidemic regions of the world should be considered for a primary series or booster vaccination, depending upon an evaluation of their risk of exposure to the virus ^(6,8) (strength of recommendation: category A; quality of evidence: grade II).

Appendix 1

References

1. MacPherson DW. Evidence-based medicine. CCDR 1994;20: 145-47.

2. Centers for Disease Control. Neurotropic diseases surveillance: poliomyelitis summary, 1974-1976. CDC, Atlanta, 1977.

3. Nathanson N, Martin JR. The epidemiology of poliomyelitis. Enigmas surrounding its appearance, periodicity, and disappearance. Am J Epidemiol 1979;110:672-92.

4. Melnick JL, Ledinko N. Social serology: antibody levels in a normal young population during an epidemic of poliomyelitis. Am J Hyg 1951;54:354-82.

5. National Advisory Committee on Immunization. Canadian immunization guide. 4th ed. Ottawa, Ont: Health Canada, 1993 (Supply and Services Canada, Cat. No. H49-8/1993E).

6. Expanded programme on immunization: poliomyelitis in 1992. Wkly Epidemiol Rec 1993;68:225-30.

7. Expanded programme on immunization: update: eradication of paralytic poliomyelitis in the Americas. Wkly Epidemiol Rec 1992;67:325-26.

8. Hilton E, Singer C, Kozarsky P et al. Status of immunity to tetanus, measles, mumps, rubella and polio among U.S. travelers. Ann Intern Med 1991;115:32-3.

9. Expanded programme on immunization: certification of poliomyelitis eradication - the Americas, 1994. Wkly Epidemiol Rec 1994;69:293-95.

* Members: Dr. S. Dumas; Dr. G. Horsman (ACE); Dr. J.S. Keystone; Dr. D. Lawee; Dr. J.D. MacLean; Dr. D.W. MacPherson (Chairman); Dr. J. Robert; Dr. R. Saginur; Dr. D. Scheifele (NACI); Mrs. R. Wilson (CUSO).

Ex-Officio Members: Dr. P. Percheson (HPB); Dr. E. Gadd (HPB); Dr. S. Mohanna (MSB); Dr. R. Nowak (DND); Dr. M. Tipple (CDC); Dr. C.W.L. Jeanes (Secretary); Dr. J.S. Spika (LCDC); Ms. S. Ladouceur (Advisory Committee Secretariat Officer); Dr. J. Losos (LCDC).

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