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Post-Polio Health (ISSN 1066-5331)

Vol. 17, No. 4, Fall 2001

Update: Outbreak of Poliomyelitis – Dominican Republic and Haiti, 2000-2001

From July 12, 2000, through September 18, 2001, a total of 21 cases of poliomyelitis (including two fatal cases) were reported from the Caribbean island of Hispaniola, divided between Haiti and the Dominican Republic.1,2

This outbreak was the first in the Americas since 1991 and was associated with the circulation of a type 1 OPV-derived virus, having substitutions affecting 1.8% to 4.1% of nucleotides encoding the major capsid protein (VP1). The circulating vaccine-derived poliovirus associated with the outbreak recovered the capacity to cause paralytic disease and widespread person-to-person transmission and was biologically indistinguishable from type 1 wild poliovirus.

In response to the outbreak, health authorities in both countries conducted house-to-house vaccination with OPV. Three rounds of mass vaccination campaigns were conducted in the Dominican Republic in December 2000, and February and April 2001.

Haiti conducted two rounds of mass vaccination in February and March 2001. However, these campaigns were hampered by logistic difficulties and heavy rains and reached an estimated 40% of the 1.2 million children aged <5 years. During May-July 2001, a door-to-door and school-based campaign among all 2.3 million children aged <10 years was conducted sequentially in all of the country's departments. Preliminary results suggest that 2.4 million OPV doses were administered, and a second door-to-door campaign is underway.

Travelers to the Dominican Republic and Haiti who are not vaccinated adequately are at risk for polio. Travelers should have received poliovirus vaccination according to national vaccination policies3.

References

1. CDC. Outbreak of poliomyelitis – Dominican Republic and Haiti, 2000. MMWR 2000;49: 1094-103.

2. CDC. Outbreak of poliomyelitis –- Dominican Republic and Haiti, 2000-2001. MMWR 2001;50:147-8.

3. CDC. Poliomyelitis prevention in the United States: updated recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2000;49 (no. RR-5).

EXCERPTED FROM: Morbidity and Mortality Weekly Report, October 5, 2001, Vol. 50, No. 39, pp. 855-856.

Acute Flaccid Paralysis Associated with Circulating Vaccine-Derived Poliovirus – Philippines, 2001

Three cases of acute flaccid paralysis (AFP) associated with circulating vaccine-derived poliovirus (cVDPV) isolates were reported in the Philippines during March 15-July 26, 2001.

Following cVDPV outbreaks in the Dominican Republic and Haiti (Hispaniola) during 2000-20011, the global polio laboratory network implemented additional testing requirements for all polioviruses under investigation, prospectively and retrospectively. Both an antigenic-based (ELISA) and a molecular-based test (probe hybridization) are used to determine whether a poliovirus is wild or derived from vaccine (i.e., intratypic differentiation [ITD]). Divergent ITD results (one test showing vaccine-derived and the other wild-type virus) for any poliovirus isolate now require genomic sequencing of the suspect isolates. Retrospective testing of >2,000 vaccine-related isolates from AFP cases globally has revealed no additional cVDPVs, although testing results of other isolates in the laboratory network are pending. The cVDPVs from the Philippines were detected after the implementation of new testing requirements for prospective virus investigations.

Wild poliovirus was last reported in the Philippines in 19932, and national vaccination rounds were last conducted in the Philippines in 1997 followed by sub-national immunization days in 1998 and 1999. Coverage did not extend to the three provinces now reporting cVDPV cases. Routine coverage with 3 OPV doses has been approximately 80% nationwide since the early 1990s; however, coverage gaps are likely, particularly in slum areas.

Travelers to the Philippines should ensure that they are vaccinated appropriately against polio according to national recommendations3.

References

1. CDC update: outbreak of poliomyelitis – Dominican Republic and Haiti, 2000-2001. MMWR 2001;50:855-6.

2. CDC. Progress toward poliomyelitis eradication – Western Pacific Region, January 1, 1996-September 27, 1997. MMWR 1997;46:1113-7.

3. CDC. Poliomyelitis prevention in the United States: updated recommendations of the Advisory Committee on Immunization Practices. MMWR 2000;49 (no. RR-5).

EXCERPTED FROM: Morbidity and Mortality Weekly Report, October 12, 2001, Vol. 50, No. 40, pp. 874-875.