6290: Latest Polio Bulletin (fwd)

[Bob Corbett <corbetre@webster.edu>]

From: "Haitian Street Kids, Inc." <haitianstreetkids@rescueteam.com>

Public Health Dispatch: Outbreak of
Poliomyelitis --- Dominican Republic and
Haiti, 2000

[MMWR 49(48):1094,1103, 2000. Centers for Disease Control]



Report

During July 12--November 18, 2000, 19 persons with acute flaccid
paralysis(AFP) were identified in the Dominican Republic, including
six laboratory-confirmed cases with poliovirus type 1 isolates. Of
the 19 case-patients, 16 (84%) were aged 6 years (range: 9
months--21 years).
All case-patients were either unvaccinated (n=14) or inadequately
vaccinated (n=5). In Haiti, a single laboratory-confirmed poliovirus
type 1 case was reported in an inadequately vaccinated child aged 2
years; paralysis onset was August 30. Despite intensive case-finding
activities, no additional cases have
been identified.

The outbreak virus is unusual because it is derived from oral
poliovirus vaccine (OPV) and has 97% genetic similarity to the
parental OPV strain (normally vaccine-derived isolates are >99.5%
similar to the parent strain)and appears to have recovered the
neurovirulence and transmissibility characteristics of wild
poliovirus type 1. In comparison, wild polioviruses normally have
<82% genetic similarity to OPV [1]. The differences in nucleotide
sequences among the outbreak isolates suggest that the virus has
been circulating for approximately 2 years in an area where
vaccination coverage is very low and that the virus had accumulated
genetic changes that restored the essential properties of wild
poliovirus.

The ministries of health of the Dominican Republic and Haiti, with
the assistance of the Pan American Health Organization and CDC, are
investigating the outbreak to determine the extent of spread,
evaluate the reasons for the outbreak, and initiate appropriate
control measures. The Dominican Republic has started a nationwide
mass vaccination campaign with OPV, and three nationwide vaccination
rounds with OPV are planned for
January, February, and March 2001 in Haiti.

Circulation of OPV-derived polioviruses in areas with very low OPV
coverage has been documented in one other setting---type 2
OPV-derived virus circulated in Egypt for an estimated 10 years
(1983--1993) and was associated with >30 reported cases [2].
Vaccination coverage was very low in the affected areas, and
circulation of a vaccine-derived poliovirus stopped when OPV
coverage increased. The key factor in controlling circulating
OPV-derived viruses and wild polioviruses is achieving and
maintaining high vaccination coverage. No evidence for circulation
of OPV-derived virus has been found in areas with high coverage.

Since 1991, no cases of polio attributed to wild poliovirus have
been detected in the Western Hemisphere. The current outbreak
underscores the need for polio-free areas to maintain high coverage
with polio vaccine until global polio eradication has been achieved.
OPV is safe and effective and recommended
for the eradication of polio. All countries should maintain high
quality AFP and poliovirus surveillance and accelerate current
activities to complete the global eradication of wild polioviruses.

Health-care providers should consider polio as a diagnosis in
case-patients with a history of travel to other countries of the
Western Hemisphere from the Dominican Republic and Haiti who present
with AFP usually accompanied by fever. These possible cases should
be investigated properly, including collection of stool samples.
Suspected cases should be reported immediately
to state and local health departments.

Travelers to the Dominican Republic and Haiti who are not vaccinated
adequately should be considered at risk for polio. All travelers
should be vaccinated fully against polio according to national
vaccination policies [3].*

Reported by: Ministry of Health, Pan American Health Organization,
Santo Domingo, Dominican Republic. Ministry of Health, Pan American
Health Organization, Port-au-Prince, Haiti. Caribbean Epidemiology
Center Laboratory, Pan American Health Organization, Trinidad and
Tobago. Div of Vaccines and Immunization, Pan American Health
Organization, Washington, DC. Respiratory and Enteric Viruses Br,
Div of Viral and Rickettsial Diseases, National Center for
Infectious Diseases, and Vaccine Preventable Disease Eradication
Div, National
Immunization Program, CDC.



References

1.Kew OM, Mulders MN, Lipskaya GY, et al. Molecular epidemiology
of polioviruses. Sem Virol 1995;6:401--14.
2.Naguib T, Yang SJ, Pallansch M, Kew O. Prolonged circulation of
Sabin 2-derived polioviruses. In: Program and abstracts of progress
in
polio eradication: vaccination strategies for the end game. Geneva,
Switzerland: International Association for Biologicals, 2000.
3.CDC. Poliomyelitis prevention in the United States: updated
recommendations of the Advisory Committee on Immunization
Practices (ACIP). MMWR 2000;49(no. RR-5).



* Current recommendations for children in the United States include
a 4-dose vaccination series with inactivated poliovirus vaccine
(IPV) at ages 2, 4, 6--18 months, and 4--6 years. Unvaccinated
adults should receive three doses of IPV, the first two doses at
intervals of 4--8 weeks and the third dose 6--12 months after the
second. If three doses cannot be administered within the recommended
intervals before protection is needed, alternative schedules are
proposed. For incompletely vaccinated persons, additional IPV doses
are recommended to complete a series. Booster doses of IPV may be
considered for persons who previously have completed a primary
series of polio vaccination and who may be traveling to areas where
polio is endemic.

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