Measles

Key Features

Essentials of Diagnosis

• Exposure 7–18 days before onset of prodrome in an unvaccinated patient

• Prodrome:

  • Fever

  • Coryza

  • Cough

  • Conjunctivitis

  • Malaise

  • Irritability

  • Photophobia

  • Koplik spots

• Rash

  • Brick red, irregular, maculopapular

  • Appears 3–4 days after onset of prodrome

  • Begins on the face and proceeds "downward and outward," affecting the palms and soles last

• Leukopenia

General Considerations

• Transmitted by inhalation of infective droplets

• Highly contagious

• Communicability is greatest during the preeruptive and catarrhal stages, continuing for 4 days after the appearance of rash

• Illness confers permanent immunity

Demographics

• For 2020, the WHO European Region reported a total of 12,205 measles cases in Europe

• This is compared to 104,554 cases and 42 deaths in 2019

• The 2019 outbreak of measles in the US was associated with 268 cases between January 1, 2019 and March 14, 2019 in 15 states

• The highest recent number of cases in the US was 667 persons in 2014 in 27 states followed by 372 cases in 2018

• Globally, measles continues to affect large numbers, with WHO estimating 7 million infections for 2016, the year with most recently compiled data

• Because of the COVID-19 pandemic, over 22 million infants did not receive their first dose of the measles vaccine in 2020, the largest deficit in 2 decades, which increases the likelihood of major outbreaks

Clinical Findings

Symptoms and Signs

• Prodromal phase

  • Fever

  • Malaise may be marked

  • Coryza (nasal obstruction, sneezing, and sore throat)

  • Persistent and nonproductive cough

  • Conjunctivitis manifests as redness, swelling, discharge, and photophobia

• These symptoms intensify over 2–4 days before onset of the rash and peak on the first day of the rash

• Characteristic measles rash appears on the face and behind the ears

  • Initial lesions are pinhead-sized papules that coalesce to form a brick red, irregular, blotchy maculopapular rash

  • Spreads to the trunk and extremities, including the palms and soles

  • Lasts for 3–7 days and fades in the same manner it appeared

• Koplik spots

  • Small, irregular, and red with whitish center on the mucous membranes

  • Appear about 2 days before the rash and last 1–4 days as tiny "table salt crystals" on the palatal or buccal mucosa opposite the molars or on vaginal membranes

• Other findings

  • Pharyngeal erythema

  • Tonsillar yellowish exudate

  • Coating of the tongue in the center with a red tip and margins

  • Moderate generalized lymphadenopathy

  • Splenomegaly

Differential Diagnosis

• Kawasaki disease

• May be mistaken for other exanthematous infections

Diagnosis

• Koplik spots are pathognomonic

• Leukopenia usually present unless secondary bacterial complications exist

• Thrombocytopenia is common

• Proteinuria is often observed

• Real-time reverse transcriptase-polymerase chain reaction (RT-PCR), available from the CDC and some public health ...