What are the diagnostic and treatment protocols for a patient suspected of having measles?

Measles Examination: Diagnostic and Treatment Protocols

Immediate Actions Upon Suspected Measles

When a patient with suspected measles presents, immediately isolate them in an airborne-infection isolation room (negative pressure) and have them wear a medical mask while awaiting laboratory confirmation. 1

Clinical Recognition

A clinical case of measles requires all three of the following features: 1

• Generalized rash lasting ≥3 days
• Temperature ≥38.3°C (≥101°F)
• At least one of: cough, coryza (runny nose), or conjunctivitis

Additional diagnostic clues include: 2, 3, 4

• Prodrome of high fever with cough/coryza/conjunctivitis 2-4 days before rash
• Koplik spots (pathognomonic white spots on buccal mucosa)
• Erythematous maculopapular rash beginning on face and spreading cephalocaudally
• History of measles exposure

Diagnostic Testing Protocol

The CDC recommends serum measles-specific IgM antibody testing as the first-line diagnostic test, using a sensitive and specific assay such as the direct-capture IgM EIA method. 1, 5

Specimen Collection Timing

• Collect blood for IgM testing during the first clinical encounter 1
• Critical timing consideration: IgM may not be detectable until ≥72 hours after rash onset with some assays 1, 5
• If initial IgM is negative and collected within 72 hours of rash onset, obtain a second specimen at least 72 hours after rash onset 1, 5
• Measles IgM peaks at approximately 10 days after rash onset and remains detectable for at least 1 month 1
• IgM seropositivity rate is 92-100% when collected 6-14 days after symptom onset 5

Additional Diagnostic Testing

In addition to serology, collect specimens for viral isolation and genetic characterization as close to rash onset as possible: 1

• Urine specimen
• Nasopharyngeal mucus specimen
• Contact local/state health department for shipping instructions 1

Alternative Diagnostic Criteria

Laboratory confirmation can also be achieved by: 1

• Significant rise (4-fold or greater) in measles antibody titer between acute (1-3 days after rash) and convalescent (2-4 weeks later) serum specimens 1, 3
• Isolation of measles virus from clinical specimen 1, 3
• Detection of measles virus RNA by reverse transcriptase-PCR 3

False Positive/Negative Considerations

Important caveats about IgM testing: 1, 5

• False-positive results can occur with parvovirus infection (fifth disease), other viral infections, or rheumatoid factor positivity
• Confirmatory testing with direct-capture IgM EIA should be considered when IgM is positive but patient has no identified exposure source or epidemiologic linkage
• False-negative results occur if specimen collected too early (<72 hours after rash onset)

Infection Control Measures

Immediate Isolation Protocol

All staff entering the room must use N95 respirators or equivalent respiratory protection, regardless of immunity status, as there is a ~1% vaccine failure rate. 1, 2

Specific isolation requirements: 1

• Place patient in airborne-infection isolation room (negative pressure) immediately
• If unavailable, use private room with closed door
• Patient must wear medical mask
• Only staff with presumptive immunity should enter if possible
• All staff must use N95 respirators

Infectious Period

Patients with measles are infectious from 4 days before rash onset through 4 days after rash onset. 1

• Healthcare personnel with measles must be excluded from work until ≥4 days following rash onset 1

Management of Exposed Contacts

Healthcare Personnel Exposure Protocol

For healthcare workers without evidence of immunity exposed to measles: 1

• Offer MMR vaccine immediately (effective if given within 72 hours of exposure)
• Exclude from work days 5-21 following exposure
• Those who decline vaccination should be excluded days 5-21 after first exposure through day 21 after last exposure, even if given immune globulin

For healthcare workers with 1 documented vaccine dose: 1

• May remain at work
• Should receive second dose

Post-Exposure Prophylaxis for Contacts

Contacts without presumptive immunity should receive one of the following: 1

• MMR vaccine within 72 hours of exposure (preferred for most)
• Intramuscular immune globulin 0.25 mL/kg (40 mg IgG/kg) for nonimmunocompromised persons
• Quarantine until 21 days after exposure

Special consideration for infants <12 months: 1

• Passive immunization with immune globulin may be preferred, especially for household contacts
• If vaccinated at 6-11 months during outbreak, must be revaccinated at 12-15 months and again before school entry

If immune globulin is administered, observe for signs/symptoms for 28 days after exposure (not 21 days) because immune globulin may prolong the incubation period. 1

Treatment

Treatment for measles is primarily supportive, as there is no specific antiviral therapy for uncomplicated cases. 2, 3

More aggressive management is required for: 2

• Pregnant patients
• Immunocompromised patients
• Unvaccinated patients

Treatment options for high-risk patients may include: 2

• Measles vaccine (post-exposure prophylaxis)
• Intravenous immunoglobulin
• Vitamin A supplementation
• Ribavirin (in severe cases)

Reporting Requirements

Immediately report suspected cases to local or state health department—do not wait for laboratory confirmation before reporting or implementing control measures. 1, 5

• One confirmed measles case constitutes an urgent public health situation requiring immediate investigation 1
• Rapid reporting enables contact tracing and outbreak control 5