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CDC reports on measles outbreak in Pennsylvania, Michigan, and Texas during
August-September 2007
CDC published "Multistate Measles Outbreak
Associated with an
International Youth Sporting Event--Pennsylvania, Michigan, and
Texas, August-September 2007" in the February 22 issue of MMWR.
Portions of the article are reprinted below. The CDC website
offers healthcare professionals and the public a wealth of
information about measles disease and vaccine. A link to the
measles web section appears at the end of this IAC Express
article.
Measles, a highly infectious viral illness, is no longer endemic
in the United States because of high coverage rates with an
effective vaccine. However, imported cases continue to cause
illness and outbreaks among susceptible U.S. residents. In
August 2007, a participant in an international youth sporting
event who traveled from Japan to the United States became ill
with measles. Because he traveled while infectious to an event
with thousands of participants and spectators, an outbreak
investigation was conducted in multiple states by state and
local health departments in coordination with CDC, using
standard measles surveillance case definitions and
classifications. This report summarizes the results of that
investigation, which identified six additional measles cases
that were linked epidemiologically to the index case and two
generations of secondary transmission. Viral genotyping
supported a single chain of transmission; six of the seven cases
were linked by genetic sequencing. U.S. organizers of large-scale events attended by international travelers, especially
youths, should consider documentation of adequate participant
vaccination. This outbreak highlights the need to maintain the
highest possible vaccination coverage in the United States,
along with disease surveillance and outbreak-containment
capabilities.
A sporting event held in central Pennsylvania during August 17-26, 2007, included eight U.S. teams and eight international
teams representing Canada, Chinese Taipei, Curacao, Japan,
Netherlands, Mexico, Saudi Arabia, and Venezuela. Combined
participant and spectator attendance for the event was
approximately 265,000. Team members (boys aged 10-13 years) and
coaches resided in the same compound during the event, with a
common area shared by all teams. Access to the compound was
restricted to a small number of officials, corporate sponsors,
and event staff members.
Cases 1 and 2: Pennsylvania, Imported from Japan
A boy aged 12 years on the Japanese team (the index patient),
who had unknown vaccination status, had been exposed to a
sibling with measles-like illness in Japan in late July 2007.
The boy had a sore throat and malaise on August 11 and traveled
to the United States on August 13. The Japanese and Chinese
Taipei teams traveled together by aircraft from Tokyo, Japan, to
Detroit, Michigan, where they cleared immigration and customs,
and then traveled by aircraft to Baltimore, Maryland, where they
chartered a bus to Pennsylvania. On August 14, the patient
visited the event infirmary to be evaluated for his sore throat.
On August 16, he had a measles-compatible rash, cough, Koplik's
spots, fever (102.4 degrees F [39.1 degrees C]), and coryza. The
infectious period for measles extends from 5 days before to 4
days after rash onset. The Pennsylvania Department of Health
(PADOH) was notified, and the patient was isolated. Measles-specific immunoglobulin M (IgM) antibodies were detected in his
serum sample; urine culture yielded measles virus, genotype D5.
PADOH reviewed vaccination records for 481 players, coaches,
translators, and event staff members at the compound; 292 (61%)
either had documentation of 2 doses of measles-containing
vaccine or history of measles disease, or were born before 1957
and were, therefore, considered immune. The remaining 189 (39%)
were offered measles, mumps, and rubella (MMR) vaccine or
serologic testing; 104 chose to be vaccinated, and 85 chose
serologic testing. Sixteen (19%) of those tested lacked evidence
of immunity and subsequently were vaccinated. Public health
staff members and healthcare providers in Pennsylvania were
alerted through the state Health Alert Network, and public
announcements were issued. State health departments in
California, Georgia, and Texas were informed of potential
measles exposures among visiting corporate representatives who
had already attended the event and departed from Pennsylvania.
A second boy aged 12 years with unknown vaccination status who
had direct contact with the index patient only on August 12 in
Japan, arrived in the United States on August 15 to watch the
competition. On August 20, he had a sore throat and fever,
followed by cough and rash on August 23. On August 24,
nasopharyngeal, urine, and blood specimens were collected from
the boy at a local emergency department. He was placed in
isolation in his hotel room. His serum sample was positive for
measles-specific IgM antibodies. Nasopharyngeal culture yielded
measles virus genotype D5. The boy had minimal public
interaction during his infectious period and was deemed not
infectious during his airline travel.
The 29 members of his travel group and all 27 hotel staff
members were interviewed; 38 (68%) persons without adequate
evidence of immunity received MMR vaccine. Guests registered at
the hotel during the boy's infectious period were advised to
contact their physicians and local health departments in the
event of illness. No measles cases were identified among these
groups.
Cases 3 and 4: Michigan
In accordance with CDC protocol (CDC, unpublished document,
2008), passenger manifests for the August 13 Tokyo-Detroit and
Detroit-Baltimore flights were obtained to contact persons
seated within one row of the index patient. A woman aged 53
years seated one row in front of the index patient on the
Detroit-Baltimore flight acquired measles (case 3). Although
born in 1954, she recalled no history of measles or receiving
measles-containing vaccine and was administered immunoglobulin
prophylaxis after being identified as a contact. On August 25,
she had fever, cough, and coryza, followed by rash on August 28.
Serum initially was negative for measles IgM and immunoglobulin
G antibodies, but she subsequently seroconverted. Measles viral
RNA, detected in urine by reverse transcription-polymerase chain
reaction (RT-PCR), had an identical sequence to the genotype D5
sequences obtained from the two patients in Pennsylvania.
Case 4 was identified in a U.S.-born man aged 25 years who was
employed as a federal airport officer and had no documented
measles vaccination. The officer and the index patient had been
present in the same Detroit customs area on August 13. On August
23, the officer had wheezing, abdominal pain, and sweating,
followed by rash on August 27. A serum sample obtained August 30
was positive for measles IgM antibodies. Measles virus RNA was
detected by RT-PCR from a throat swab; however, attempts to
amplify the larger region of the N gene necessary for genotyping
were unsuccessful in this case.
A coworker of the officer at the same airport had measles 1
month later. The source of this infection could not be
determined; the coworker's measles might have been linked to
case 4 through an unrecognized chain of transmission (because
the incubation period for measles ranges from 7 to 18 days) or
might have resulted from a separate, unrelated exposure.
Cases 5, 6, and 7: Texas
Case 5 was identified in a U.S.-born man aged 40 years who was
employed as a corporate sales representative and had no
documented measles vaccination. The sales representative had met
the index patient on August 14 in Pennsylvania and had cough,
conjunctivitis, coryza, and fever on August 26. He had rash on
August 28 and was hospitalized the next day with a seizure,
fever of 105.7 degrees F (40.9 degrees C), and pneumonia.
Measles was confirmed by serum IgM antibodies and viral RNA
detected in urine by RT-PCR. He recovered and was discharged
from the hospital after 4 days.
Before his hospitalization, the man had made sales visits to
three Houston-area colleges. Cases 6 and 7 were identified among
male college roommates, aged 18 and 19 years, who had attended
one of the sales events on August 28. Both students were born in
the United States and had received 2 documented doses of MMR
vaccine. They had fever, chills, and myalgia on September 9 and
10, respectively; one had conjunctivitis. Both had rash on
September 11, detectable measles IgM antibodies in serum, and
measles virus RNA by RT-PCR in throat swab specimens. No
additional cases were identified. The genotype D5 sequences
obtained from the three Texas patients were identical to those
of the two patients from Pennsylvania and to one of the two
patients (case 3) from Michigan. On August 30, the outbreak was
reported to the World Health Organization under the revised
International Health Regulations as a public health emergency of
international concern. . . .
Because international events provide opportunities for measles
transmission, organizers of large gatherings attended by
international travelers, especially youths, should consider
documentation of adequate participant vaccination. To prevent
spread of measles, international travelers are encouraged to be
fully vaccinated. MMR vaccine, administered to susceptible
persons within 72 hours of measles exposure, is a recommended
intervention for measles outbreak containment. . . .
The attack rate of measles among susceptible persons has been
documented as >90%. Previous imported measles cases have
demonstrated the potential for larger outbreaks in U.S.
communities with poor vaccination coverage. The small number of
identified cases in this outbreak, despite the large number of
exposed persons, demonstrates the value of maintaining high
measles vaccination coverage in the U.S. population through
adherence to routine vaccination recommendations. This outbreak
also highlights the continuing importance of promoting measles
control and elimination in other countries and sustaining strong
surveillance and response measures in the United States. . . .
To access a web-text (HTML) version of the complete article, go
to: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5707a1.htm
To access a ready-to-print (PDF) version of this issue of MMWR,
go to: http://www.cdc.gov/mmwr/PDF/wk/mm5707.pdf
To receive a FREE electronic subscription to MMWR (which
includes new ACIP statements), go to:
http://www.cdc.gov/mmwr/mmwrsubscribe.html
A CDC web section provides the public with information about
measles disease and vaccine, beliefs and concerns, vaccine
safety, and persons who should not be vaccinated. It provides
healthcare professionals with clinical information,
recommendations, references and resources, provider information
and materials for patients. To access the CDC measles web
section, go to: http://www.cdc.gov/vaccines/vpd-vac/measles
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