Measles outbreaks in the United States: Public health preparedness, control and response in healthcare settings and
the community
A measles outbreak linked to an importation from Switzerland currently is ongoing in Arizona. The first case, with rash onset on February 12, 2008,
occurred in an adult visitor from Switzerland who was hospitalized with measles
and pneumonia. This hospital admission prompted verification of the measles
immune status of approximately 1800 healthcare personnel and vaccination of
those without evidence of immunity. Through March 31, 2008, nine confirmed
cases have been reported to the Arizona Department of Health Services, and
there are two suspected cases (one in a Colorado resident) and hundreds of
contacts under investigation. The nine case-patients range in age from 10
months to 50 years. All but one were infected in healthcare settings, one of
the five adult case-patients is a healthcare worker, and all cases were
unvaccinated at the time of exposure.
In January and February 2008, San Diego experienced an
outbreak of 11 measles cases, with an additional case-patient who was exposed
in San Diego but became ill in Hawaii. The index case was an unvaccinated child
who had recently traveled to Switzerland, where a measles outbreak is ongoing
(see http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5708a3.htm).
Transmission in this outbreak occurred in a doctor’s office as well as in
community settings. Measles genotype D5 was identified from more than one case
in the San Diego and Arizona outbreaks; this genotype is currently circulating
in Switzerland (see http://www.eurosurveillance.org/edition/v13n08/080221_1.asp).
Confirmed measles cases also have been reported from New York City (involving
genotype D4, which is identical to the genotype responsible for a large ongoing
measles outbreak in Israel; see http://www.eurosurveillance.org/edition/v13n08/080221_3.asp)
and from Virginia (importation from India). In addition, two measles cases
recently confirmed in unvaccinated siblings from Michigan may have resulted
from exposure during a long stop-over in the Atlanta airport.
Although measles is no longer an endemic disease in the United States, it remains endemic in most countries of the world, including some countries in Europe. Large outbreaks currently are occurring in Switzerland and Israel. In the United States from January 1 through March 28, 2008, 24 confirmed cases of
measles resulting from importations from endemic countries have been reported
to the Centers for Disease Control and Prevention (CDC). These cases highlight
the ongoing risk of measles importations, the risk of spread in susceptible
populations, and the need for a prompt and appropriate public health response
to measles cases. Because of the severity of the disease, people with measles
commonly present in physician’s offices or emergency rooms and pose a risk of
transmission to other patients and healthcare personnel in these and in
inpatient hospital settings. Healthcare providers should remain aware that
measles cases may occur in their facility and that transmission risks can be
minimized by ensuring that all healthcare personnel have evidence of measles
immunity and that appropriate infection control practices are followed.
Transmission and case definition
Measles is a highly contagious disease that is
transmitted by respiratory droplets and airborne spread. The disease can
result in severe complications, including pneumonia and encephalitis. The incubation period
for measles ranges from 7 to 18 days. The diagnosis of measles should be
considered in any person with a generalized maculopapular rash lasting ≥ 3 days, a temperature ≥ 101ºF (38.3ºC), and cough, coryza, or conjunctivitis. Immunocompromised
patients may not exhibit rash or may exhibit an atypical rash.
Recommendations
Rapid and aggressive public health action is needed in
response to measles cases. Case investigation and vaccination of household or
other close contacts without evidence of immunity should not be delayed pending
the return of laboratory results. Preparation for other control activities may
need to be initiated before laboratory results are known. Control activities
include isolation of known and suspected case-patients and administration of
vaccine (at any interval following exposure) or immune globulin (within 6 days
of exposure, particularly contacts ≤ 6 months of age, pregnant women, and immunocompromised people, for whom
the risk of complications is highest) to susceptible contacts. For contacts who
remain unvaccinated, control activities include exclusion from day care,
school, or work and voluntary home quarantine from 7 to 21 days following
exposure. Persons who are known contacts of measles
patients and who develop fever and/or rash should be considered suspected
measles case-patients and be appropriately evaluated by a healthcare provider.
If healthcare providers are aware of the need to assess a suspected measles
case, they should schedule the patient at the end of the day after other
patients have left the office and inform clinics or emergency rooms if they are
referring a suspected measles patient for evaluation so that airborne infection
control precautions can be implemented prior to their arrival.
Healthcare providers should maintain vigilance for measles
importations and have a high index of suspicion for measles in persons with a
clinically compatible illness who have traveled abroad or who have been in
contact with travelers. They should assess measles immunity in U.S. residents who travel abroad and vaccinate if necessary. Measles outbreaks are ongoing
in Switzerland and Israel, and measles outbreaks are common throughout Europe. Measles is endemic in many countries, including popular travel destinations, such
as Japan and India. Suspected measles cases should be reported immediately to
the local health department, and serologic and virologic specimens (serum and
throat or nasopharyngeal swabs) should be obtained for measles
virus detection and genotyping. Laboratory testing should be conducted in the
most expeditious manner possible.
Preventing transmission in healthcare settings
To prevent transmission of measles in healthcare settings,
airborne infection control precautions (available at http://www.cdc.gov/ncidod/dhqp/gl_isolation.html)
should be followed stringently. Suspected measles patients (i.e., persons with
febrile rash illness) should be removed from emergency department and clinic waiting
areas as soon as they are identified, placed in a private room with the door
closed, and asked to wear a surgical mask, if tolerated. In hospital settings,
patients with suspected measles should be placed immediately in an airborne
infection (negative-pressure) isolation room if one is available and, if
possible, should not be sent to other parts of the hospital for examination or
testing purposes.
All healthcare personnel should have documented evidence of
measles immunity on file at their work location. Having high levels of measles
immunity among healthcare personnel and such documentation on file minimizes
the work needed in response to measles exposures, which cannot be anticipated.
Recent measles exposures in hospital settings in three states necessitated
verifying records of measles immunity for hundreds or thousands of hospital
staff, drawing blood samples for serologic evidence of immunity when
documentation was not on file at the work site, and vaccinating personnel
without evidence of immunity.
Recommendations for vaccination
Measles is preventable by vaccination. MMR
vaccine is routinely recommended for all children at 12–15 months of age, with
a second dose recommended at age 4–6 years. Two doses of MMR vaccine are
recommended for all school students and for the following groups of persons
without evidence of measles immunity: students in post–high school educational
facilities, healthcare personnel, and international travelers who are ≥ 12 months of age. Other adults without evidence of measles immunity should
routinely receive one dose of MMR vaccine. To
prevent acquiring measles during travel, U.S. residents aged ≥ 6 months traveling
abroad should be vaccinated or have documentation of measles immunity before
travel. Infants 6–11 months of age should receive one dose of monovalent
measles vaccine (or MMR vaccine if monovalent vaccine is not available) prior
to travel.
During a measles outbreak, additional vaccine recommendations
should be considered: 1) children ≥ 12 months of age should receive their first dose of MMR vaccine as soon
after their first birthday as possible and their second dose 4 weeks later, 2)
healthcare facilities should strongly consider recommending one dose of MMR
vaccine to unvaccinated healthcare personnel born before 1957 who do not have
serologic evidence of immunity or physician documentation of measles disease,
and 3) one dose of measles or MMR vaccine should be considered for infants ≥ 6 months of age.
Further information on measles and measles vaccine is
available at state health departments’ websites and at http://www.cdc.gov/vaccines/vpd-vac/measles/default.htm.
Additional Sources of Information
The Centers for Disease Control and Prevention maintains a website with
many informative articles and references on measles and the MMR vaccine.
Several links are listed below.
CDC. Measles, Mumps, and
Rubella—Vaccine use and strategies for elimination of measles, rubella, and
congenital rubella syndrome and control of mumps: recommendations of the
Advisory Committee on Immunization Practices (ACIP). MMWR 1998:4(No RR-8);1–57.
Immunization of
Health-Care Workers, Recommendations of the Advisory Committee on Immunization
Practices (ACIP) and the Hospital Infection Control Practices Advisory
Committee (HICPAC). MMWR 1997:46 (RR-18):1–42.
CDC. Outbreak of measles—San Diego, California, January–February 2008. MMWR 2008;57(08):203–6.
CDC. Multistate measles outbreak
associated with an international youth sporting event—Pennsylvania, Michigan, and Texas, August–September 2007. MMWR 2008;57(07):169–73.
CDC.
Progress in reducing global measles deaths, 1999--2004. MMWR 2006;55(09):247–9.
CDC. Import-associated
measles outbreak—Indiana, May–June 2005. MMWR 2005;54(42):1073–5.
CDC. Preventable measles
among U.S. residents, 2001–2004. MMWR 2005;54(33):817–20.
CDC. Progress in
reducing measles mortality—worldwide, 1999–2003. MMWR 2005;54(08):200–3.
CDC. Brief
Report: Imported measles case associated with nonmedical vaccine exemption—Iowa, March 2004. MMWR 2004;53(11):244–6.
CDC. Manual for the surveillance of vaccine-preventable
diseases.
Guideline for Isolation Precautions: Preventing Transmission of
Infectious Agents in Healthcare Settings 2007.
Measles: General Information, provides background and incidence
information and links to other information, including laboratory tools.
MMR Vaccine Information Statement .
MMR Vaccine Questions and Answers for
Clinicians.
Vaccines and Preventable Diseases: Measles Disease
In-Short, provides
general information about measles, including a description of the disease,
information about symptoms, complications, transmission, and the vaccine and
who needs it.
Vaccines and Preventable Diseases: Measles Vaccination,
provides general
information about the disease, vaccination information, beliefs and concerns,
vaccine safety, and who should not be vaccinated. It also contains more
specific information for clinicians, including technical information,
recommendations, references and resources, provider education, and materials
for patients.
Travelers’
Health,
including information for specific groups and settings.
Travelers’ Health: Yellow Book, CDC health information for
international travel 2008.