What is the appropriate workup and management for a patient with suspected measles?

Measles Workup and Management

Immediate Actions Upon Suspicion

Any patient presenting with fever and rash should be immediately isolated with airborne precautions and reported to local/state health authorities without delay, even before laboratory confirmation. 1

Clinical Recognition

• Suspect measles in any patient with febrile illness accompanied by rash. 1
• Clinical case definition requires all three of the following: 1
  • Generalized rash lasting ≥3 days
  • Temperature ≥38.3°C (≥101°F)
  • At least one of: cough, coryza (runny nose), or conjunctivitis
• Koplik spots (pathognomonic enanthem on buccal mucosa) may be present during the prodrome, 2-4 days before rash onset. 2, 3
• The rash characteristically begins on the face and spreads cephalocaudally (head to toe), becoming more confluent as it progresses. 3

Immediate Isolation Protocol

• Place patient in negative-pressure airborne isolation room immediately upon arrival; if unavailable, use a private room with door closed. 4, 5
• Patient must wear a medical mask immediately upon arrival at any healthcare facility. 4, 5
• All staff entering the room must wear N95 respirators (not surgical masks), regardless of immunity status, because measles is airborne. 4, 5
• Only personnel with documented immunity should provide direct patient care. 4, 5
• Maintain isolation for at least 4 days after rash onset, as patients are contagious from 4 days before through 4 days after rash appearance. 4, 5

Laboratory Workup

Primary Diagnostic Testing

Collect blood for measles IgM antibody testing during the first clinical encounter, using a sensitive and specific assay (e.g., direct-capture IgM EIA method). 1

• Timing is critical for interpretation: IgM may not be detectable with less sensitive assays until ≥72 hours after rash onset. 1
• If initial IgM is negative and collected <72 hours after rash onset, obtain a second specimen ≥72 hours after rash onset. 1
• Measles IgM peaks approximately 10 days after rash onset and remains detectable for at least 1 month. 1

Additional Specimen Collection

Collect urine and nasopharyngeal specimens for viral isolation and RT-PCR as close to rash onset as possible, as delay reduces isolation success. 1

• Urine RT-PCR may be more sensitive than nasopharyngeal specimens, especially in previously vaccinated persons who can have negative nasopharyngeal results but positive urine results. 6
• Urine specimens can remain positive up to 24 days after rash onset. 6
• Molecular characterization helps define epidemiologic features and document transmission chains but cannot be used for acute diagnosis. 1

Alternative Serologic Confirmation

• Acute and convalescent serology (significant rise in measles antibody titer) can confirm diagnosis: collect acute specimen within 1-3 days of rash onset and convalescent specimen 2-4 weeks later. 1
• This method has been largely supplanted by single-specimen IgM testing. 1

Laboratory Confirmation Criteria

A confirmed case meets one of the following: 1

• Positive measles IgM antibody
• Significant rise in measles antibody level between acute and convalescent specimens
• Isolation of measles virus from clinical specimen
• Positive RT-PCR for measles virus RNA

Important Testing Caveats

• False-positive IgM results can occur with parvovirus infection (fifth disease), especially when using certain commercial ELISA assays. 1
• Confirmatory testing with direct-capture IgM EIA should be considered when IgM is positive in a patient without identified source or epidemiologic linkage. 1
• Test for rubella if measles serology is negative in a patient with febrile rash illness. 1
• Do not delay reporting, investigation, or control activities while awaiting laboratory results. 1

Essential Treatment

Vitamin A Supplementation (Mortality-Reducing Intervention)

All patients with clinical measles must receive vitamin A supplementation—this is the only evidence-based intervention proven to reduce measles mortality and should never be omitted. 4, 5

• Adults and children ≥12 months: 200,000 IU orally once, provided no vitamin A in the preceding month. 4, 5
• Children <12 months: 100,000 IU orally once. 4, 5
• Second dose on day 2 for complicated measles (pneumonia, otitis media, croup, severe diarrhea, neurological complications). 4, 5
• Extended regimen (day 1, day 2, and 1-4 weeks later) if any eye symptoms of vitamin A deficiency present (xerosis, Bitot spots, keratomalacia, corneal ulceration); use half-dose for infants <12 months. 4, 5

Supportive Care

• Monitor nutritional status and enroll malnourished patients in feeding programs. 4, 5
• Oral rehydration therapy for diarrhea. 4, 5
• Appropriate antibiotics for bacterial superinfections (lower respiratory infections, otitis media). 4, 5
• Treatment is otherwise symptomatic; no specific antiviral therapy is routinely recommended. 7, 3

Public Health Reporting

Report suspected or confirmed measles immediately to local/state health department—measles is reportable in all states and one confirmed case constitutes a public health emergency. 1

• Public health authorities will investigate immediately to classify the case, identify source of exposure, and prevent further spread. 1
• Contact tracing and outbreak control measures should begin immediately, not delayed for laboratory confirmation. 1

Post-Exposure Prophylaxis for Contacts

MMR Vaccine

• Administer MMR within 72 hours of exposure to susceptible contacts to prevent or modify disease. 4, 5
• Healthcare workers without documented immunity must receive first MMR dose immediately after exposure. 4, 5
• Even previously vaccinated individuals may benefit, as vaccine failure occurs in approximately 1% of cases. 4, 6

Immunoglobulin

• Standard dose: 0.25 mL/kg IM (maximum 15 mL) within 6 days of exposure for non-immune contacts. 4, 5
• Pregnant women: 0.25 mL/kg IM (maximum 15 mL) within 6 days of exposure. 4, 5
• Immunocompromised patients: 0.5 mL/kg IM (maximum 15 mL) regardless of prior vaccination status. 4, 5
• Monitor contacts who receive immunoglobulin for 28 days (not 21 days) due to prolonged incubation period. 4, 5

Healthcare Worker Management

• Exposed healthcare workers without documented immunity must be excluded from work from day 5 through day 21 after exposure. 4, 5
• Healthcare workers who develop measles must be excluded until at least 4 days after rash onset. 4, 5
• Documented immunity requires written documentation of 2 doses of MMR vaccine, laboratory evidence of immunity, or birth before 1957. 8

Common Pitfalls to Avoid

• Using surgical masks instead of N95 respirators provides insufficient protection against airborne measles transmission. 4, 5
• Failing to isolate during the pre-rash phase—patients are contagious 4 days before rash appears. 4, 5
• Omitting vitamin A supplementation eliminates the only proven mortality-reducing intervention. 4, 5
• Delaying reporting while awaiting laboratory confirmation—report immediately and begin control measures. 1, 9
• Collecting only nasopharyngeal specimens—urine RT-PCR may be more sensitive, especially in vaccinated persons. 6
• Relying on negative serology if collected <72 hours after rash onset—repeat testing is required. 1