Also called
- rubeola
Geographic distribution
- endemic and epidemic in Europe, Africa, and Asia (except South Korea)
- no longer endemic in Americas
Incidence/prevalence
- USA
- no sustained epidemic since elimination in 2000
- 170 cases reported from 17 states and Washington, DC, from January 2015 to February 2015
- 644 cases reported from 27 states in 2014
- sustained outbreaks reported from measles-endemic regions
- Europe (23,000 cases from January 2014 to March 2015)
- Democratic Republic of Congo (89,108 cases in 2013)
- China (107,024 cases in 2014)
Risk factors
- living in or travel to endemic and epidemic regions
- sporadic epidemics in Americas likely due to
- importation from endemic countries
- lack of vaccination (88% to 91% of patients acquiring measles in recent epidemics in USA not adequately vaccinated)
Pathogen
- measles virus
- member of Paramyxoviridae family, morbillivirus genus
- enveloped, single-stranded, RNA virus
- 19 genotypes
Transmission
- person-to-person via large respiratory droplets (less commonly via small aerosol particles)
- infectious from about four days before to four days after rash onset
- attack rate
- high among children aged younger than 12 months in developing countries
- secondary attack rate greater than 90% among unvaccinated persons
- incubation period
- 10 to 12 days to fever onset
- 14 days (range seven to 18 days) to rash onset
- it typically occurs among patients without prior vaccination
Immune response
- cellular (viral clearance typical by day 20)
- humoral
- IgM appears with rash, followed by sustained production of IgG
- provides lifelong immunity
- infants protected by passive transfer of maternal antibodies
Clinical presentation
- prodrome about 10 to 12 days after infection
- lasts two to four days with symptoms including
- fever (may be 103°F to 105°F [39°C to 41°C])
- cough
- coryza
- conjunctivitis
- Koplik spots
- small blue-white lesions on bright red background of buccal mucosa
- may appear one to two days either before or after rash onset
- pathognomonic for measles
- lasts two to four days with symptoms including
- maculopapular rash arises about two to four days after fever onset
- spreads from face and head to trunk and extremities
- may become confluent on upper body
- fine desquamation may occur in areas that are severely affected
- typically resolves after three to six days
- in infants, may have
- anorexia
- diarrhea
- lymphadenopathy
- rare presentations include
- pneumonia
- encephalitis (0.1% to 0.3%)
- secondary infections at time of presentation may include
- otitis media
- pneumonia
History
- Making the diagnosis
- diagnosis usually clinical
- report suspected cases to state or local health department
- most common confirmatory diagnostic testing includes
- serum antibody testing (IgM preferred)
- PCR (oropharyngeal, nasal, or nasopharyngeal swabs)
- viral isolation not routinely performed for diagnosis, but may be useful for surveillance
- biopsy and pathology only if there are complications
