Poliomyelitis

Description

Poliomyelitis is an acute viral infection that involves the gastrointestinal tract and occasionally the central nervous system. It is acquired by faecal-oral or oral transmission.

Occurrence

In the pre-vaccine era, infection with poliovirus was common, with epidemics occurring in the summer and fall in temperate areas. The incidence of poliomyelitis declined rapidly after the licensure of inactivated polio vaccine in 1955 and oral polio vaccine in the 1960s. The last cases of indigenously acquired polio in the United States occurred in 1979. Although a polio eradication programme led to elimination of polio in the Western Hemisphere, where the last case associated with wild poliovirus was detected in 1991, outbreaks of vaccine-derived poliovirus type 1 occurred in the Dominican Republic and Haiti in 2000-01, in the Philippines in 2001, and a type 2 outbreak occurred in Madagascar in 2002. During 2003-04, poliomyelitis outbreaks occurred in a number of countries in West and Central Africa, following importation of wild polioviruses types 1 and 3 from Nigeria. In spite of these recent outbreaks, the global polio eradication initiative has reduced the number of reported polio cases worldwide by >99% since the mid-1980s, and worldwide eradication of the disease appears feasible in the future.

Risk for Travellers

Travellers to countries where poliomyelitis cases still occur should be fully immunised. Because of polio eradication efforts, the number of countries where travellers are at risk for polio has decreased dramatically. Most of the world's population resides in areas now considered free of wild poliovirus circulation, including the Western Hemisphere, the Western Pacific Region (which encompasses China), and the European region.

As of September 2004, poliovirus remains endemic in six countries: Afghanistan, India, Pakistan, Nigeria, Niger, and Egypt. During 2003-2004, an epidemic of poliomyelitis spread from Nigeria to a number of countries in sub-Saharan Africa, including Benin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Mali, Togo, Cameroon, Central African Republic, Chad, and the Darfur region of Sudan, as well as Botswana in southern Africa.

Clinical Description

Clinical manifestations of poliovirus infection range from asymptomatic (most of infections) to symptomatic, including acute flaccid paralysis of a single limb to quadriplegia, respiratory failure, and, rarely, death.

Prevention

A person is considered to be fully immunised if he or she has received a primary series of at least three doses of inactivated poliovirus vaccine (IPV), live oral poliovirus (OPV), or four doses of any combination of IPV and OPV. To eliminate the risk of vaccine-associated paralytic poliomyelitis, OPV is no longer recommended for routine immunisation in the United States as of January 1, 2000. OPV is no longer available in this country, although it continues to be used in the majority of countries and for global polio eradication activities.

Infants and Children

Because OPV is no longer recommended for routine immunisation in the United States, all infants and children should receive four doses of IPV at 2, 4, and 6-18 months of age, and 4-6 years of age. If accelerated protection is needed, the minimum interval between doses is 4 weeks, although the preferred interval between the second and third doses is 2 months. The minimum age for IPV administration is 6 weeks. Infants and children who have initiated the poliovirus vaccination series with one or more doses of OPV should receive IPV to complete the series.

Adults

Adults who are travelling to areas where poliomyelitis cases are still occurring and who are unvaccinated, incompletely vaccinated, or whose vaccination status is unknown, should receive IPV. Two doses of IPV should be administered at intervals of 4-8 weeks; a third dose should be administered 6-12 months after the second. If three doses of IPV cannot be administered within the recommended intervals before protection is needed, the following alternatives are recommended:

  • If >8 weeks is available before protection is needed, three doses of IPV should be administered at least 4 weeks apart.
  • If <8 weeks but >4 weeks is available before protection is needed, two doses of IPV should be administered at least 4 weeks apart.
  • If <4 weeks is available before protection is needed, a single dose of IPV is recommended.

The remaining doses of vaccine should be administered later, at the intervals recommended above, if the person remains at increased risk for poliovirus exposure. Adults who are travelling to areas where poliomyelitis cases are occurring and who have received a primary series with either IPV or OPV should receive another dose of IPV before departure. For adults, available data do not indicate the need for more than a single lifetime booster dose with IPV.

Allergy to Vaccine

Minor local reactions (pain and redness) can occur following IPV. No serious adverse reactions to IPV have been documented. IPV should not be administered to persons who have experienced a severe allergic (anaphylactic) reaction after a previous dose of IPV or to streptomycin, polymyxin B, or neomycin. Because IPV contains trace amounts of these three antibiotics, hypersensitivity reactions can occur among persons sensitive to them.

Pregnancy

Although no adverse events of IPV have been documented among pregnant women or their foetuses, vaccination of pregnant women should be avoided on theoretical grounds. However, if a pregnant woman is unvaccinated or incompletely vaccinated and requires immediate protection against polio because of planned travel to a country or area where polio cases are occurring, IPV can be administered as recommended in the adult schedule. Breastfeeding is not a contraindication to immunisation against polio.

Precautions and Contraindications

IPV may be administered to persons with diarrhoea. Minor upper respiratory illnesses with or without fever, mild to moderate local reactions to a previous dose of IPV, current antimicrobial therapy, and the convalescent phase of acute illness are not contraindications for vaccination.

Immunosuppression

IPV may be administered safely to immunodeficient travellers and their household contacts. Although a protective immune response cannot be ensured, IPV may confer some protection to the immunodeficient person. Persons with certain primary immunodeficiency diseases should avoid contact with excreted oral polio vaccine virus (e.g., as may occur with a child vaccinated with OPV within the previous 6 weeks); however, this situation no longer occurs in the United States unless a child receives OPV overseas.

Bibliography
  • CDC. Poliomyelitis. In: Atkinson W, Hamborsky J, Wolfe S, eds. Epidemiology and prevention of vaccine-preventable diseases. 8th ed. Washington, DC: Public Health Foundation; 2004. p. 89-100.
  • CDC. Wild Poliovirus Importations — West and Central Africa, January 2003-March 2004. MMWR Morbid Mortal Wkly Rep. 2004;53;433-5.
  • CDC. Progress toward global eradication of poliomyelitis, January 2003-April 2004. MMWR Morbid Mortal Wkly Rep. 2004;53:532-5.
  • CDC. Poliomyelitis — Madagascar, 2002. MMWR Morbid Mortal Wkly Rep. 2002;51:622.
  • CDC. Acute flaccid paralysis associated with circulating vaccine-derived poliovirus — Philippines, 2001. MMWR Morbid Mortal Wkly Rep. 2001;50:874-5.
  • CDC. Outbreak of poliomyelitis — Dominican Republic and Haiti, 2000-2001. MMWR Morbid Mortal Wkly Rep. 2001;50:855-6.
  • CDC. Poliomyelitis prevention in the United States — updated recommendations of the advisory committee on immunisation practices (ACIP). MMWR Morbid Mortal Wkly Rep. 2000;49(RR-5):1-22.
  • CDC. Poliomyelitis — United States, 1975-1984. MMWR Morbid Mortal Wkly Rep. 1986;35:180-2.
  • World Health Organization. The global poliomyelitis eradication initiative: number of endemic countries at lowest ever. Wkly Epidemiol Rec. 2002;77:414-5.

- Lorraine Alexander, Margaret Watkins, Jim Alexander

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