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Unprotected People Reports: Polio |
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Unvaccinated U.S. Adult Traveling Abroad Contracts Vaccine-Associated Paralytic Polio Through Contact with a Child Vaccinated with OPV |
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| Click here for a fully-formatted PDF version
of this report |
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| The Immunization Action Coalition (IAC)
publishes articles about people who have suffered or died from
vaccine-preventable diseases and periodically devotes an IAC Express issue
to such an article. This is the 82nd in our series. |
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| In February 2006, CDC reported on the first case of paralytic poliomyelitis
identified in the United States since 1999 and the first imported
vaccine-associated paralytic poliomyelitis (VAPP) case ever documented in
the United States. The report describes the occurrence of imported VAPP in
an unvaccinated 22-year-old U.S. woman who traveled abroad, where she was
likely exposed through contact with an infant recently vaccinated with OPV.
This case highlights the previously unrecognized risk for paralytic polio
among unvaccinated persons exposed to OPV during travel abroad. |
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| CDC published "Imported Vaccine-Associated Paralytic Poliomyelitis—United
States, 2005" in the February 3, 2006 issue of MMWR. It was reported by M.
Landaverde, MD, Pan American Health Organization; D. Salas, MD, M. Humberto,
MD, Ministry of Health Costa Rica; K. Howard, R. Walker, MD, St. Joseph's
Hospital and Medical Center, Phoenix; S. Everett, MPH, S. Robyn, Yavapai
County Health Dept, Prescott; L. Erhart, MPH, S. Anderson, MPH, S.
Goodykoontz, Arizona Department of Health Services; M. Pallansch, PhD, J.
Sejvar, MD, Division of Viral and Rickettsial Diseases, National Center for
Infectious Diseases; and K. Kenyan, MPH, J. Alexander, MD, L. Alexander,
MPH, J. Seward, MBBS, Epidemiology and Surveillance Division, National
Immunization Program, CDC. It is reprinted below in its entirety, excluding
references. |
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Paralytic poliomyelitis is rare in the United States because of the success
of universal childhood immunization and the Global Polio Eradication
Initiative. Poliovirus vaccine was introduced in the 1950s. Since then, the
United States has eliminated indigenous wild poliovirus transmission,
controlled imported wild poliovirus cases, and, through a vaccine policy
change (i.e., from live, attenuated oral polio vaccine [OPV] to inactivated
polio vaccine [IPV]), eliminated vaccine-associated paralytic polio (VAPP)
cases. The most recent VAPP case occurred in 1999. The primary risk for
paralytic polio for U.S. residents is through travel to countries where
polio remains endemic or where polio outbreaks are occurring. This report
describes the first known occurrence of imported VAPP in an unvaccinated
U.S. adult who traveled abroad, where she likely was exposed through contact
with an infant recently vaccinated with OPV. This case highlights the
previously unrecognized risk for paralytic polio among unvaccinated persons
exposed to OPV during travel abroad.
In March 2005, an Arizona woman aged 22 years contracted paralytic polio
while traveling in Central and South America. She arrived in Costa Rica on
January 14, 2005, to participate in a university-sponsored study-abroad
program. During her stay with a local family, she visited several tourist
locations along the Pacific coast in Costa Rica, Panama, Nicaragua, and
Guatemala. Her last trip before onset of illness was to an island territory
of Colombia during February 25–28. On March 2, after she returned to the
host family's home, she had fever and general malaise. During the next 24
hours, her symptoms worsened, and she began to have headache and neck and
back pain. On March 6, she experienced acute leg weakness and was
hospitalized locally and soon transferred to a hospital in San Jose, Costa
Rica. On March 9, she was transported by air to Phoenix, Arizona, for
further evaluation.
Upon admission to a hospital in Phoenix, the patient had bilateral areflexic
lower extremity weakness and respiratory failure requiring intubation.
Cerebrospinal fluid (CSF) studies on March 9 revealed lymphocytic
pleocytosis, elevated protein (89 mg/dL), and normal glucose levels (53 mg/dL).
The patient was initially treated for an acute peripheral demyelinating
process, such as Guillain-Barre Syndrome (GBS), with corticosteroids and
plasmapheresis. Electrodiagnostic studies, however, displayed reduced
compound muscle action potentials, normal sensory nerve action potentials,
and widespread denervation, consistent with a severe, asymmetric process
involving anterior horn cells or motor axons. Magnetic resonance imaging of
the cervical and thoracic spine demonstrated signal abnormality in the
anterior cord, indicative of anterior horn-cell involvement. Serologic
results for antibodies specific for West Nile and dengue viruses were
negative. Stool specimens were collected on March 20 and sent to the CDC
polio reference laboratory. The specimens were positive for Sabin-strain
poliovirus types 2 and 3; no other enteroviruses were identified. The
results of serologic tests for all three serotypes were greater than 1:10
for both acute and convalescent specimens. During the course of
hospitalization, the patient recovered respiratory function, was transferred
to a rehabilitation center for physical and occupational therapy, and was
eventually discharged home for outpatient therapy. Sixty days after the
onset of weakness, she had residual weakness in both legs.
The patient had never been vaccinated with either OPV or IPV because of a
religious exemption. The Costa Rican family with whom she lived consisted of
a mother, father, and daughter with no young children. The host family's son
and daughter-in-law lived next door with two children, aged 2 months and 3
years, who visited the host family frequently. The infant received his first
dose of OPV on January 19, 2005, 4 days after the woman arrived to live with
the host family. Vaccination records indicated that both children were up to
date for all other routine vaccinations. The patient had no known or
reported exposure to young children during her 3-day trip to Colombia. She
had no underlying medical or immune-compromising conditions.
Editorial Note
This report describes the first case of paralytic poliomyelitis identified
in the United States since 1999 and the first imported VAPP case ever
documented in the United States. Although the patient initially had a
working diagnosis of an acute peripheral demyelinating process, the clinical
history, physical findings, and laboratory studies are typical for paralytic
polio and inconsistent with GBS, transverse myelitis, or other forms of
acute flaccid paralysis. The patient's only known exposure to OPV was
through contact with the infant grandchild of her host family. The date of
the patient's onset of illness in relation to OPV vaccination and her
presumed contacts with the infant are within the expected ranges for contact
VAPP cases (4–75 days and <30 days, respectively). The poliovirus antibody
titers, uniformly high on both acute and convalescent serum specimens, are
inconclusive. However, the isolation of Sabin-strain polioviruses types 2
and 3 from a stool specimen and absence of isolation or serologic evidence
for infection with another agent known to cause polio-like symptoms (e.g.,
West Nile virus or enterovirus 71) is consistent with VAPP. A panel of polio
experts convened by CDC confirmed this case to be paralytic polio on the
basis of standard clinical evidence, and the case was classified as imported
VAPP with onset of illness within 30 days before entry into the United
States, in accordance with CDC protocol.
Cases of paralytic polio are now rare in the United States because of the
success of the U.S. childhood immunization program and the Global Polio
Eradication Initiative. In the United States, the most recent cases of
paralytic polio caused by indigenous and imported wild polioviruses occurred
in 1979 and 1993, respectively. From the early 1960s, when trivalent OPV
became the vaccine of choice for the childhood immunization program, to the
mid-1990s, approximately eight to 10 VAPP cases occurred annually. Most VAPP
cases occurred in OPV recipients rather than among their contacts. In the
United States in the 1990s, cases of contact VAPP occurred at a rate of one
case per 13 million doses of OPV distributed. To reduce the risk for VAPP,
the United States changed to a sequential IPV/OPV schedule in 1997 and then
to an all-IPV schedule in 2000. This policy change resulted in elimination
of VAPP in the United States, with the most recent case of VAPP, before this
report, occurring in 1999. High coverage rates for poliovirus vaccination
have been maintained among children aged 19–35 months with the transition
from OPV to IPV. In 2004, approximately 92% of children in this age group
received 3 doses of IPV as part of the routine infant and child immunization
schedule. Coverage levels greater than 95% are reached after school entry,
although the majority of states allow philosophical or religious exemptions.
Despite high vaccination coverage, another OPV-associated risk was
identified recently in the United States. In September 2005, an
unvaccinated, immunocompromised infant was found to be infected with a
vaccine-derived poliovirus, presumably originating outside the United States
in a country that uses OPV. Upon further investigation, four other children
in two other families in the same small, rural community were found to be
asymptomatic carriers of the virus. No cases of paralysis have been
associated with circulation of this virus in the community.
The Global Polio Eradication Initiative has successfully reduced the burden
of paralytic polio globally and the threat of imported polio in the United
States. In 1988, when the initiative began, 125 countries reported cases of
paralytic polio. At the end of 2004, six countries had endemic polio
(Afghanistan, Egypt, India, Niger, Nigeria, and Pakistan) and transmission
had been reestablished in six countries (Burkina Faso, Central African
Republic, Chad, Côte d'Ivoire, Mali, and Sudan). The Americas were certified
polio free in 1994, with the most recent reported case occurring in Peru in
1991.
For protection against polio, all infants and children in the United States,
regardless of travel status, should receive 4 doses of IPV at ages 2, 4, and
6–18 months and 4–6 years. If accelerated protection is needed, the minimum
interval between doses is 4 weeks, although the preferred interval between
the second and third dose is 2 months. The minimum age for IPV
administration is 6 weeks. Infants and children who have begun receiving the
poliovirus vaccination series with 1 or more doses of OPV should receive IPV
to complete the series.
Because of the minimal risk for exposure to polioviruses and because most
adults are immune as a result of vaccination during childhood, routine
poliovirus vaccination of adults (i.e., persons aged >18 years) residing in
the United States is recommended only for certain adult groups who are at
increased risk for exposure to polioviruses. Adults who are traveling to
areas where polio is still epidemic or endemic 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
3 doses of IPV cannot be administered within the recommended intervals
before protection is needed, the following alternatives are recommended:
- If more than 8 weeks are available
before protection is needed, 3 doses of IPV should be administered at
least 4 weeks apart.
- If fewer than 8 weeks but more than 4
weeks are available before protection is needed, 2 doses of IPV should
be administered at least 4 weeks apart.
- If fewer than 4 weeks are available
before protection is needed, a single dose of IPV is recommended.
Adults who are traveling to areas where polio
cases are occurring and who have received a primary series with either IPV
or OPV should receive another dose of IPV before departure. According to
available data, adults do not need more than a single lifetime booster dose
with IPV.
In 2004, approximately 25 million U.S. residents traveled abroad to OPV-using
countries in Central and South America, Asia, Africa, and Europe. Before the
case described in this report, the risk for VAPP in an unvaccinated traveler
to an OPV-using country with no wild poliovirus transmission was considered
negligible. However, this case indicates that the risk for VAPP, although
low, is not zero. Overall, the risk for paralytic disease in a traveler is
much greater in a polio-endemic country or outbreak country (e.g., Nigeria)
than in an OPV-using country that is free from wild poliovirus, although
this increase in risk is difficult to quantify.
Polio among travelers is preventable. Travelers to countries where polio is
endemic or where outbreaks are occurring should be made aware of the risk
for acquiring paralytic polio in those countries and be vaccinated in
accordance with current recommendations. Healthcare providers assessing
vaccine needs for unvaccinated adults traveling to countries that use OPV
should be aware of the risk that OPV might pose to such travelers and should
consider offering them polio vaccination. At least 4–6 weeks before
departure, international travelers should contact travel medicine providers
to obtain vaccinations and prophylactic medications. Providers should assess
the need for itinerary-specific vaccines and ensure that travelers are up to
date on all routine vaccinations, including polio vaccination. Information
on vaccination requirements for international travelers is available from
the CDC publication, Health Information for International Travel, 2005--2006
(http://www.cdc.gov/travel/yb/index.htm)
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| 2/6/06 • REPORT #82 |
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| Disclaimer: The Immunization Action Coalition (IAC) publishes
Unprotected People Reports for the purpose of making them available
for our readers' review. We have not verified the content of this
report. |
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