Basics
Description
- An exanthematous disease that has a relatively predictable course, making clinical diagnosis possible
- Because it is rare, cases are often initially misdiagnosed as a nonspecific viral exanthema, drug eruption, or Kawasaki disease.
- Patients are contagious from 1 to 2 days before onset of symptoms (3 " 5 days before rash) until 5 days after the appearance of the rash. The incubation period is generally 8 " 12 days from exposure to onset of symptoms and ’ Ό14 days until the appearance of rash.
- Types of measles include the following:
- Typical measles (outlined below)
- Modified measles: occurs in children with partial antibody protection (after postexposure administration of immunoglobulin or in infants <9 months old with transplacental antibodies)
- Clinically similar to typical measles but is generally mild
- The patient may be afebrile, and the rash may last only 1 " 2 days.
- Atypical measles: caused by a hypersensitivity reaction to measles infection in those who received killed virus vaccine between 1963 and 1967 and are subsequently exposed to wild-type virus
Epidemiology
- Measles is one of the most highly contagious of all infectious diseases.
- Hospital or clinic waiting rooms (especially pediatric emergency department waiting rooms) have been identified as a major risk, accounting for up to 45% of the known exposures. With adequate immunization (2 doses = 99% effective), measles could be eliminated as a disease.
- Although no longer endemic in the United States, networks of intentionally unvaccinated children have led to several recent U.S. outbreaks originating from measles virus imported from abroad.
- Because 20 million cases of measles occur globally per year (>150,000 deaths), it is critical to maintain high levels of vaccination coverage.
Incidence
- Before the 1963 licensure of vaccine, an estimated 3 " 4 million people acquired measles in the United States each year; by 1983, there were only 0.7 cases per 100,000 population.
- Delays in immunization facilitated large outbreaks in the United States from 1989 to 1991, peaking in 1990 when 27,672 cases were reported, 89 of which were fatal.
- From 2001 to 2012, the median annual number of measles cases reported in United States was 60, peaking in 2011 (22 cases).
- From January to August 2013, 159 U.S. cases were reported, including the largest U.S. outbreak since 1996 (58 cases). The majority of cases occurred in underimmunized individuals and imported from abroad (including U.S. travelers).
General Prevention
- Vaccine recommendations
- Routine vaccination against measles, mumps, and rubella (MMR) for children begins at 12 " 15 months of age, with a second MMR vaccination at age 4 " 6 years.
- With the recent resurgence of measles, aggressive employee immunization programs should be pursued for all health care workers.
- Health care workers born after 1956 who have no documentation of vaccination or evidence of measles immunity should be vaccinated at the time of employment and revaccinated ≥28 days later.
- Infection control measures
- Any inpatient suspected of having measles should be in a negative-pressure respiratory isolation room; health care workers must wear masks, gloves, and gowns (airborne and contact precautions).
- Isolation is required for 4 days after the 1st appearance of the rash; immunocompromised patients require isolation for the course of the illness.
- All suspected cases of measles should be reported immediately to the local health department.
Pathophysiology
Transmission of measles occurs through direct contact with infectious droplets, less commonly by airborne spread.
Etiology
Measles is an RNA virus (paramyxovirus, genus Morbillivirus) with only 1 serotype.
Diagnosis
- The disease involves fever, cough, conjunctivitis, and coryza with an erythematous rash, which has a characteristic progression:
- The rash appears on the face (often the nape of the neck, initially) and abdomen 14 days after exposure. The rash is erythematous and maculopapular and spreads from the head to the feet, often becoming confluent at more proximal sites.
- Pharyngitis, cervical lymphadenopathy, and splenomegaly may accompany the rash.
- Atypical measles
- This group of young adults (2nd and 3rd decades of life) may become quite ill, with sudden onset of fever from 103 ° to 105 °F and headache. The rash, unlike typical measles, appears initially on the distal extremities, progressing cephalad.
- Most patients with atypical measles have pneumonia, often with pleural effusions.
- Diagnosis depends on clinical recognition and by serologic and molecular (RNA) testing.
History
- Case definition from the CDC includes the following:
- Generalized rash lasting ≥3 days
- A temperature of ≥38.3 °C (101 °F)
- Cough, coryza, or conjunctivitis
- Positive testing or epidemiologic linkage to known case
- The mean incubation period is 10 days (range: 8 " 21 days).
- The prodrome of measles lasts 2 " 4 days and begins with symptoms of upper respiratory infection, fever up to 104 °F, malaise, conjunctivitis, photophobia, and increasing cough.
- During the prodrome, Koplik spots (white spots on the buccal mucosa) appear on most people.
- Following this prodrome, the rash appears on the face (often initially at the hairline) and abdomen (14 days after exposure). The rash is erythematous and maculopapular and spreads from the head to the feet.
- After 3 " 4 days, the rash begins to clear, leaving a brownish discoloration and fine scaling.
- Fever usually resolves by the 4th day of rash.
Diagnostic Tests & Interpretation
- When measles is suspected, laboratory confirmation is important.
- The course of typical measles follows a predictable pattern; therefore, laboratory studies to confirm infection in known contacts might not be required.
Lab
- Serum measles-specific IgM titer (simplest)
- Sensitivity may be diminished if assay performed <72 hours from onset of rash; repeat if negative. IgM detectable for at least 1 month from onset of rash
- A comparison of IgG titers obtained during the acute and convalescent stages can be done. Blood samples must be taken at least 7 " 10 days apart.
- Culture or RNA (RT-PCR) testing of nasopharyngeal, throat, blood, or urine
Differential Diagnosis
With a careful history and physical exam, it is usually possible to diagnose measles. The differential diagnosis includes the following:
- Stevens-Johnson syndrome
- Kawasaki disease
- Other viral exanthem
- Meningococcemia
- Rocky Mountain spotted fever (RMSF)
- Toxic shock syndrome
Treatment
General Measures
- No specific therapy; supportive care
- Ribavirin is active in vitro but not approved by FDA for treatment of measles.
- Vitamin A treatment of children with measles in developing countries has been associated with decreases in both morbidity and mortality.
- The World Health Organization recommends vitamin A for all children with measles worldwide.
- Vitamin A is given once daily for 2 days:
- 200,000 IU for children ≥12 months of age
- 100,000 IU for infants 6 " 11 months of age
- 50,000 IU for infants <6 months of age
- The higher dose may be associated with vomiting and headache for a few hours.
- For children with signs/symptoms of vitamin A deficiency, a 3rd dose at 4 weeks is indicated.
- Vitamin A is available in 50,000 IU/mL injectable solution and may be given orally.
Ongoing Care
Follow-up Recommendations
In uncomplicated measles infection, clinical improvement and fading of rash typically occur on the 3rd or 4th day.
Prognosis
- Mortality in the modern outbreak of 1989 " 1990 occurred in 3 of every 1,000 cases in the United States.
- Case fatality rates are increased in immunocompromised children.
Complications
- Complication rate in 1989 " 1990 outbreaks that occurred throughout the country was 23% and included diarrhea (9%), otitis media (7%), pneumonia (6%), and encephalitis (0.1%):
- Encephalitis, which can lead to permanent neurologic sequelae, occurs in 1 of every 1,000 cases reported in the United States.
- Croup, myocarditis, pericarditis, and disseminated intravascular coagulation (black measles) can also occur.
- In 1990, ’ Ό18 " 20% of patients required hospitalization, many for either dehydration or pneumonia.
- In patients with poor nutrition, most common in developing countries, mortality is higher.
- Subacute sclerosing panencephalitis (SSPE) occurs in 1 per 100,000 children with naturally occurring measles:
- After an incubation period of several years (mean 10.8), a progressive, usually fatal, encephalopathy develops among unvaccinated children.
- Patients with SSPE are not infectious.
Additional Reading
- American Academy of Pediatrics. Measles. In: Pickering LK, Baker CJ, Kimberlin DW, et al, eds. Red Book: 2012 Report of the Committee on Infectious Diseases. 29th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2012:489 " 499.
- Centers for Disease Control and Prevention. Global measles mortality, 2000 " 2008. MMWR Morb Mortal Wkly Rep. 2009;58(47):1321 " 1326. [View Abstract]
- Centers for Disease Control and Prevention. Measles " United States, 2011. MMWR Morb Mortal Wkly Rep. 2012;307(22):2363 " 2365.
- Duke T, Mgone CS. Measles: not just another viral exanthema. Lancet. 2003;361(9359):763 " 773. [View Abstract]
- Farizo KM, Stehr-Green PA, Simpsons DM, et al. Pediatric emergency room visits: a risk factor for acquiring measles. Pediatrics. 1991;87(1):74. [View Abstract]
- Huiming Y, Chaomin W, Meng M. Vitamin A for treating measles in children. Cochrane Database Syst Rev. 2005;(4):CD001479. [View Abstract]
- Mulholland EK, Griffiths UK, Biellik R. Measles in the 21st century. N Engl J Med. 2012;366(19):1755 " 1757. [View Abstract]
- Parker Fiebelkorn A, Redd SB, Gallagher K, et al. Measles in the United States during the postelimination era. J Infect Dis. 2010;202(10):1520 " 1528. [View Abstract]
- Perry RT, Halsey NA. The clinical significance of measles: a review. J Infect Dis. 2004;189(Suppl 1):S4 " S16. [View Abstract]
- Rall GF. Measles virus 1998 " 2002: progress and controversy. Annu Rev Microbiol. 2003;57:343 " 367. [View Abstract]
- Sugerman DE, Barskey AE, Delea MG, et al. Measles outbreak in a highly vaccinated population, San Diego, 2008: role of the intentionally undervaccinated. Pediatrics. 2010;125(4);747 " 755. [View Abstract]
Codes
ICD09
- 055.9 Measles without mention of complication
- 055.2 Postmeasles otitis media
- 055.1 Postmeasles pneumonia
- 055.0 Postmeasles encephalitis
- 055.79 Measles with other specified complications
ICD10
- B05.9 Measles without complication
- B05.3 Measles complicated by otitis media
- B05.2 Measles complicated by pneumonia
- B05.0 Measles complicated by encephalitis
- B05.4 Measles with intestinal complications
SNOMED
- 14189004 Measles (disorder)
- 13420004 Post measles otitis media (disorder)
- 195900001 Measles pneumonia (disorder)
- 111872008 Post measles encephalitis (disorder)
- 240484000 Modified measles (disorder)
- 240483006 Atypical measles (disorder)
- 191727003 Post measles pneumonia (disorder)
- 186562009 Measles with intestinal complications (disorder)
FAQ
- Q: If a health care worker has had a natural measles infection or measles immunization, should one be concerned about infection following exposure?
- A: Those persons born before 1957 who had wild-type measles virus infection are usually immune from reinfection. However, in a report in 1993, 4 health care workers who were previously vaccinated with positive preillness measles antibody levels developed modified measles following exposure to infected patients. Therefore, all health care workers should observe respiratory precautions in caring for patients with measles.
- Q: During an outbreak of measles, should children <12 months of age be vaccinated?
- A: In an outbreak of measles, public health officials may recommend vaccination of infants ages 6 " 11 months with a single-antigen measles vaccine; children initially vaccinated before their 1st birthday should be revaccinated at 12 " 15 months of age. A 2nd dose should be administered during the early school years.