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Measles Clinical Reference

Measles Clinical Reference

For the most current case counts, exposure sites, and guidance: Michigan.gov/measles.

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RECOGNIZING MEASLES 

What is measles? 

Measles is an acute viral illness caused by a paramyxovirus and one of the most contagious infectious diseases known, with a basic reproduction number (R₀) of 12–18. Transmission is airborne; viable virus can persist in a room for up to two hours after an infected person has left. Susceptible individuals exposed in the same airspace face approximately 90% risk of infection. Measles is not simply a rash illness — it causes significant systemic inflammation and serious complications even in otherwise healthy patients. 

Infectious period and incubation 

  • Infectious period: four days before through four days after rash onset (rash onset = day zero). Because the rash is typically when measles is first suspected, a patient can transmit the virus for up to four days before either they or their provider recognize the illness.
  • Incubation: symptoms typically appear 7–14 days after exposure (range: 7–21 days). 

Clinical presentation

  • Prodrome (days 1–4): high fever (often >104°F), cough, coryza, conjunctivitis (the “3 Cs”). 
  • Koplik spots: small white lesions on the buccal mucosa appearing 1–2 days before rash onset. Pathognomonic when present. 
  • Rash: maculopapular, beginning at the hairline, spreading cephalocaudally over 3–4 days. As the rash progresses, spots may coalesce. The rash is not usually itchy. Fever and rash typically resolve within 7–10 days of prodrome onset. 
Important:  Immunocompromised patients may not develop a rash and can have severe, atypical presentations. Individuals who contract measles after prior exposure to measles antigen — through prior infection or vaccination — may also have a modified, milder presentation than classic measles. Patients who received IG as post-exposure prophylaxis may similarly present atypically. Maintain a high index of suspicion regardless of rash absence. 

Case definitions

Probable

In the absence of a more likely diagnosis, an illness that meets the clinical description with:

  • No epidemiologic linkage to a laboratory-confirmed measles case; and 
  • Noncontributory or no measles laboratory testing. 

Confirmed

An acute febrile rash illness† with: 

  • Isolation of measles virus‡ from a clinical specimen; or 
  • Detection of measles-virus specific nucleic acid‡ from a clinical specimen using polymerase chain reaction; or 
  • IgG seroconversion‡ or a significant rise in measles immunoglobulin G antibody‡ using any evaluated and validated method; or 
  • A positive serologic test for measles immunoglobulin M antibody‡§; or 
  • Direct epidemiologic linkage to a case confirmed by one of the methods above. 

 

† Temperature does not need to reach ≥101°F/38.3°C and rash does not need to last ≥3 days. 
‡ Not explained by MMR vaccination during the previous 6–45 days. 
§ Not otherwise ruled out by other confirmatory testing or more specific measles testing in a public health laboratory. 

MEASLES COMPLICATIONS

High-risk groups

  • Infants and children under 5: account for the majority of measles-related deaths globally. Elevated risk for pneumonia, severe diarrhea, and croup. Infants under 12 months are too young for routine MMR, making community immunity critical. 
  • Adults over 20: higher rates of hepatitis, pneumonia, and encephalitis compared to school-age children; more likely to require hospitalization. 
  • Pregnant patients: associated with preterm labor, low birth weight, spontaneous abortion, and elevated maternal pneumonia risk. MMR is contraindicated in pregnancy. Identify susceptible pregnant patients for postpartum vaccination or IG following exposure. 
  • Immunocompromised individuals: risk of progressive, prolonged, and often fatal measles. Rash may be absent, making diagnosis harder. Cannot receive MMR; depend entirely on community immunity and IG. 
  • Vitamin A-deficient individuals: significantly increased measles severity. Vitamin A may be used as supportive treatment under provider supervision for severe cases. Not a substitute for vaccination and not for prevention. 

Complications by severity 

  • Common: otitis media, diarrhea. 
  • Serious: pneumonia (primary viral or secondary bacterial) — leading cause of measles death in children, approximately 1 in 20 cases; hepatitis (more common in adults); croup (more common in young children). 
  • Severe: acute encephalitis (approximately 1 in 1,000 cases; significant risk of permanent neurological sequelae); hospitalization; death.
  • Long-term: subacute sclerosing panencephalitis (SSPE) — rare but uniformly fatal, caused by persistent CNS viral infection, presenting years after acute illness. Immune amnesia — measles depletes previously acquired immunological memory, leaving patients broadly susceptible to other infections for months to years after recovery. 

INFECTION CONTROL

Before the patient arrives 

  • Instruct patients with possible symptoms or exposure to call ahead before presenting.
  • Screen for measles exposure and symptoms at triage.
  • Know your staff’s immunity status in advance — do not wait until an exposure occurs. 

When the patient arrives 

  • Provide a face mask to patients 2 years and older upon arrival. Patients unable to wear a mask should be tented with a blanket or towel.  Immediately move patient and family to an Airborne Infection Isolation Room (AIIR). If unavailable, use a private room with the door closed. In healthcare settings, use a negative pressure room and airborne precautions.
  • No other patients should accompany a child with suspected measles into the isolation area.
  • Patients 2 years and older and their family members should keep masks on throughout the visit if feasible.
  • Only staff with documented evidence of measles immunity should provide care to suspected cases.
  • Follow standard and airborne precautions, including N95 mask for staff. 

After the patient leaves 

  • Do not use the exam room for at least two hours. The standard post-departure contamination window is 2 hours, based on documented airborne persistence of measles virus. However, if your facility can document the air changes per hour (ACH) for the exposure space, CDC's Appendix B Table B.1 allows substitution of a more precise clearance time using a 99.9% removal efficiency standard: at 6 ACH (minimum for standard patient rooms), the window is ~69 minutes; at 12 ACH (minimum for AII rooms), ~35 minutes. Share HVAC documentation with your public health contact — it can meaningfully reduce the scope of the contact investigation. When ACH is unknown, the 2-hour default applies.
Staff immunity during an outbreak:  Birth before 1957 is not sufficient during an active outbreak. All unvaccinated healthcare personnel regardless of birth year should receive two doses of MMR if they lack laboratory evidence of immunity or prior confirmed disease. 

Isolating confirmed or probable cases 

  • Exclude from work, school, childcare, and all public or congregate settings immediately.
  • Cases must be excluded from all public and congregate settings through the end of the fourth day after rash onset. Rash onset is day zero; day four is the last day of required exclusion.
  • At home: case should avoid common areas and wear an N95 when common areas cannot be avoided.
  • If seeking medical care: patient must call ahead so the facility can prepare.
  • Schools, childcare centers, and other congregate settings should have planned spaces to isolate suspected or confirmed cases until departure. Congregate living settings should have planned spaces for quarantine. 

Every office, emergency room, and health system should review their policies and procedures for disease management before an exposure occurs. 


REPORTING

Report immediately — do not wait for lab confirmation.  Measles must be reported within 24 hours of clinical or laboratory diagnosis. A suspected case is sufficient to trigger reporting. 

How to report 

  • Call your local health department first. They will coordinate with MDHHS. 
  • If you cannot reach the LHD: MDHHS Bureau of Infectious Disease Prevention 517-335-8165 | After hours 517-335-9030. 

What to report 

  • Name, date of birth, address, contact information. 
  • Clinical description: symptoms, rash onset date, fever level. 
  • Vaccination history (check MCIR). 
  • Recent travel history (international and domestic). 
  • Known exposures to measles cases.
  • All settings visited during the infectious period (4 days before through 4 days after rash onset): clinic, school, workplace, grocery store, religious gatherings, transportation, etc. 

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TESTING & SPECIMENS 

Call before you collect:  Contact MDHHS Division of Immunization at 517-335-8159 or your LHD before submitting specimens. Testing is prioritized for cases with high clinical or epidemiologic suspicion.

Collect both viral specimens (PCR) and serum (IgM) at the same visit to avoid missed opportunities. 

Viral specimens (PCR) — preferred

  • Nasopharyngeal or throat swab, ideally within 3 days of rash onset; no later than 10 days post-rash onset. Submit in viral transport media (VTM).
  • Also collect urine if more than 72 hours have elapsed since rash onset. Urine is most useful between days 5 and 9 after rash onset and should not replace the throat or NP swab — collect both. Do not collect urine if more than 10 days have passed since rash onset.
  • Send to MDHHS Bureau of Laboratories (BOL). Turnaround: 48 hours or less for throat/NP swab; approximately 5 days for urine PCR.

Serum (IgM)

  • Collect between day 3 and day 30 after rash onset (inclusive). IgM collected before day 3 may be falsely negative and should be repeated — see note below.
  • If IgM is negative and was collected fewer than 72 hours after rash onset, repeat using serum collected ≥72 hours after rash onset.
  • Any IgM serum specimens that are pre-approved by MDHHS to be sent to BOL must be frozen at < -20 ⁰C and shipped on dry ice to remain frozen during transport.
  • Shipping to MDHHS BOL
  • Ship overnight delivery. For weekend delivery, specify “Saturday Delivery” and apply a Saturday shipping label — without this, Friday samples arrive Monday and may be untestable.
  • Pre-paid overnight and Saturday delivery labels available from BOL: mdhhslab@michigan.gov.
  • Upper Peninsula providers: the Western Upper Peninsula Health Department Regional Public Health Laboratory (WUP Lab) can provide regional support for measles PCR testing. Contact your Regional Epidemiologist and MDHHS Division of Immunization at 517-335-8159 to arrange.
  • If serum collection is not available in your office, collect the swab (and urine if indicated) for PCR and arrange for the patient to have serum drawn at the nearest laboratory. Call ahead to the receiving laboratory to inquire about their procedures for specimens from patients with potential airborne-transmitted infections — they may require a separate entrance or waiting area.

Interpreting results

  • Negative PCR: does not rule out measles, especially if the swab was collected more than 3 days after rash onset. Consider clinical presentation and epidemiologic factors.
  • Discordant results (e.g., negative PCR + positive IgM): evaluate clinical presentation, epidemiologic risk, and specimen timing. Contact your LHD or MDHHS.
  • False-positive IgM: observed with rubella, roseola, herpesvirus, parvovirus B19, dengue, and elevated rheumatoid factor. Always attempt PCR in parallel.
  • IgG serology: may be helpful in evaluating a suspect case but is not a substitute for PCR and is not sufficient to waive isolation after a known exposure. See Exposure Scenarios.

A positive PCR cannot distinguish vaccine strain from wild-type measles — both return as positive. Measles Virus Analysis (MeVA) genotyping is required to make this distinction: wild-type strains currently circulating in U.S. outbreaks are genotype D8 or B3; the vaccine strain (Edmonston lineage) is genotype A. MDHHS Bureau of Laboratories does not perform MeVA in-house but coordinates testing through the Wisconsin State Public Health Laboratory, with an average turnaround of approximately one week. Contact MDHHS Bureau Infectious Disease Prevention to initiate referral.

Until MeVA confirms a vaccine strain, the child must be managed as potentially infectious with wild-type measles and remain home in isolation. Advise parents that vaccine-related rash occurs in ~5% of MMR recipients (typically 7–12 days post-vaccination) and is a real possibility here — but cannot be assumed without laboratory confirmation in an outbreak context. Isolation is a precaution, not a diagnosis, and will be lifted promptly if MeVA returns genotype A.

PCR may be positive 6-45 days following MMR vaccination, with a median detection time of 11 days.

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Recognizing Measles

Measles Complications

Infection Control

 

PEP Guidance

Routine Vaccination

Vaccination Clinical Scenarios

Treatment

Vaccine Safety

 

References

MDHHS Communication Approach

Contacts

PEP GUIDANCE

Any person exposed to measles who cannot demonstrate presumptive evidence of immunity should be offered PEP. Contact your LHD immediately — they can assist with eligibility assessment and contraindication review.

MMR vaccine

  • For individuals 6 months and older who lack presumptive evidence of immunity and have no contraindications to MMR.
  • Must be given within 72 hours of first exposure. Calculate from the exact time of exposure, not just the calendar date.
    • Example: exposure April 1 at 11 a.m. → MMR deadline April 4 at 11 a.m.; IG deadline April 7 at 11 a.m.
  • For persons who previously received only one MMR dose: administering a second dose within 72 hours of exposure may also prevent measles disease, though evidence is more limited than for unvaccinated individuals.
  • Effectiveness depends on the timing of vaccination and the nature of the exposure.
  • PEP with MMR does not prevent or alter the clinical severity of mumps or rubella. However, if the exposed person does not have evidence of mumps or rubella immunity, they should still be vaccinated, as not all exposures result in measles infection.
  • Preferred over IG in most situations when timing allows.

Immunoglobulin (IG)

  • Must be given within 6 days of first exposure.
  • Reserved for those who cannot receive MMR: infants under 6 months, pregnant patients without evidence of immunity, and severely immunocompromised individuals. Not recommended for individuals with isolated IgA deficiency or with thrombocytopenia or coagulation disorders contraindicating intramuscular injections.
Critical:  Do NOT administer MMR and IG simultaneously — this invalidates the vaccine. After IG, delay MMR for a minimum of 6 months (IMIG) or 8 months (IVIG).

Why the 72-hour MMR window exists

After exposure, measles virus begins replicating in the respiratory mucosa and regional lymph nodes. A healthy immune system can mount a vaccine-induced response faster than wild-type measles completes its incubation — but only if the vaccine is given early enough. Beyond approximately 72 hours, viral replication has progressed to a point the vaccine response cannot outpace. IG works differently — passive preformed antibodies directly neutralize circulating virus — which is why its window extends to 6 days.

Does receiving IG eliminate the need to isolate?

No. IG modifies illness but does not prevent infection. A person who receives IG may still become infected, may present atypically (no rash, mild fever), and may still be infectious to others. Modified cases are often not recognized as measles. Exposed individuals who received IG must still be excluded for the full 21 days after exposure (extended to 28 days if IG was received).

After PEP: monitoring

  • All exposed contacts should be monitored for 21 days after last exposure (28 days if IG was received).
  • Contacts who receive their first MMR dose within 72 hours of first exposure may not require exclusion from public settings — but this is an LHD determination, not a provider determination. Contact your LHD, who will assess the exposure setting and risk of transmission to others before deciding whether exclusion is needed.
  • Instruct all contacts to report symptom onset immediately and isolate pending testing.

Sourcing IG

  • Every practice should have a plan for locating IG before it is needed. Work with your local health system and IG manufacturers.
  • If difficulty procuring IG, contact your LHD — MDHHS is working with local health departments on IG availability and distribution.

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ROUTINE VACCINATION

Standard MMR schedule

  • Children: first dose at 12–15 months; second dose at 4–6 years. Minimum interval between doses: 28 days.
  • Adolescents: two doses through age 18. Catch up as soon as possible if doses are missing.
  • Adults (19+): one or two doses depending on risk factors, unless other presumptive evidence of immunity exists. Two doses especially important for: healthcare personnel; international travelers; post-secondary students; close contacts of immunocompromised individuals; and people with HIV who are not severely immunosuppressed. A very small proportion of adults (less than 5%) may have received killed (inactivated) measles vaccine from 1963 through 1967; these adults may need one dose (low risk) or two doses (high risk). Measles-Mumps-Rubella (MMR) Vaccine - RECOMMENDATIONS SUMMARY

Presumptive evidence of immunity

A person is considered immune if they have at least one of: written documentation of adequate vaccination; laboratory evidence of immunity; laboratory confirmation of prior measles; or birth before 1957 (general public only — see note below for healthcare personnel).

Healthcare personnel: During an active measles outbreak, birth before 1957 is not sufficient. All unvaccinated healthcare personnel regardless of birth year should receive two doses of MMR if they lack laboratory evidence of immunity or prior confirmed disease.

How long until the vaccine is effective?

Approximately 2–3 weeks for full protective immunity. For international travelers, confirm vaccination status and vaccinate at least two weeks before departure. If departure is imminent and the patient is not immune, vaccinate anyway — partial lead time still provides meaningful protection.

Contraindications to MMR

  • Severe allergic reaction after a previous dose of MMR or to any vaccine component.
  • Severe immunodeficiency (hematologic or solid tumors, chemotherapy, congenital immunodeficiency, long-term immunosuppressive therapy, or HIV with severe immunosuppression).
  • Family history of altered immunocompetence unless verified as immunocompetent.
  • Pregnancy (or planning to become pregnant in the next 4 weeks).

Precautions (not absolute contraindications)*

  • Moderate or severe acute illness with or without fever.
  • Recent (≤11 months) receipt of antibody-containing blood product.
  • History of thrombocytopenic purpura or thrombocytopenia.

Need for tuberculin skin testing or IGRA testing.

*A vaccination might be indicated in the presence of a precaution if the benefit of protection from the vaccine outweighs the risk of an adverse reaction.

No documentation of vaccination

Do not check a titer. Vaccinate according to current recommendations. Verbal reports of vaccination without written documentation are not acceptable as presumptive evidence of immunity. If a patient is unsure of their immunity or vaccination status, the best defense against measles is vaccination — it is safe to vaccinate even if the patient may already be immune.

If your office is unable to administer additional MMR vaccines, direct patients to their local health department for vaccination.

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Vaccination Clinical Scenarios

  • Two valid MMR doses with negative, equivocal, or low-level titer

    • The provider who ordered the titer should review and interpret the result. 
    • A person with two documented, appropriately timed MMR doses and negative, equivocal, or low-level serologic results does not need an additional MMR dose. 
    • Exception: women of childbearing age with a negative rubella titer after two doses of a rubella-containing vaccine should receive a third and final MMR dose (not during pregnancy). 
    On routine serologic testing:  Routine serologic testing is not recommended for individuals with two documented valid MMR doses. If a titer is obtained, results should not be used to determine the need for additional vaccination. A negative serologic result does not override documented vaccination history.

  • Adult vaccination by risk factors

    • No  doses needed: born before 1957 (except healthcare personnel during an outbreak); born 1957 or later, low risk, with at least one documented dose of live measles vaccine; laboratory evidence of immunity or prior confirmed measles.
    • One  dose needed: born 1957 or later, low risk (not a healthcare worker, international traveler, or post-secondary student), no documented vaccination, no laboratory evidence of immunity.
    • Two doses needed: healthcare personnel without prior documented live measles vaccination and no lab evidence of immunity; international travelers born 1957 or later; and post-secondary students. A very small proportion of adults (less than 5%) may have received killed (inactivated) measles vaccine from 1963 through 1967; these adults may need one dose (low risk) or two doses (high risk).   
    • Providers have clinical discretion to offer up to two MMR doses to patients who request vaccination, provided there are no contraindications. 

TREATMENT

There is no antiviral treatment for measles. Management is supportive. Antibiotics do not treat or prevent measles and should not be used unless a secondary bacterial infection (such as bacterial pneumonia or otitis media) is identified.

Supportive care

  • Bed rest and adequate fluid intake.
  • Antipyretics and analgesics for fever and headache.
  • Monitor for and treat complications as they arise: otitis media, pneumonia, encephalitis, and dehydration are the most common requiring active management.

Vitamin A 

Vitamin A does not prevent measles — only the MMR vaccine prevents measles. Do not recommend vitamin A for prevention, and do not recommend high-dose supplementation, as it can cause serious toxicity including nausea, vomiting, headache, fatigue, joint and bone pain, blurry vision, skin and hair problems, increased intracranial pressure, liver damage, confusion, and coma. In pregnancy, vitamin A toxicity can cause birth defects.

Vitamin A may be useful as a supplemental treatment once someone has a measles infection, particularly for severe cases or those with documented low vitamin A levels. Consistent with AAP guidance, vitamin A may be administered to hospitalized infants and children with measles as part of supportive management. It should be given only under provider supervision. Most people get enough vitamin A through diet — carrots, bell peppers, fish, broccoli, yogurt, and chicken are good sources. Supplementation should not be recommended routinely. 

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COUNSELING PATIENTS ON VACCINE SAFETY

Does the MMR vaccine cause autism? 

No. There is no scientific evidence that any vaccine, including MMR, causes autism. In 1998, researcher Andrew Wakefield published a report in The Lancet suggesting a possible link between MMR and autism based on eight children. Subsequent studies comparing hundreds of thousands of vaccinated and unvaccinated children found no difference in autism rates. The original paper was retracted, and Wakefield lost his medical license. As immunization rates dropped in response to the unfounded concerns, outbreaks of measles and mumps led to hospitalizations and deaths that could have been prevented.

Healthcare providers are among the most trusted sources of health information. Your recommendation to vaccinate matters. For resources to help address vaccine hesitancy, see the References section. 

How to talk to patients about vaccination

  • Becoming a Trusted Messenger (training course): voicesforvaccines.org/course/becoming-trusted-messengers/
  • Vaccinations Are Safe: Explaining Why — vaccineinformation.org
  • Are Vaccines Safe? — vaccinateyourfamily.org 

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References

Clinical resources 

Local Health Department Resources

Michigan-specific resources 

Vaccine safety resources for patient counseling 

COMMUNICATIONS APPROACH

How guidance updates will reach you 

  • Michigan.gov/measles: the authoritative real-time reference for the Michigan outbreak. Updated as new information becomes available. Includes current case counts by county, active exposure sites, jurisdiction-specific guidance, and early MMR recommendation sunset dates. 
  • Michigan Health Alert Network (MIHAN): primary push notification mechanism for providers. Register at Health Alert Network. HANs are sent by email and/or text when guidance changes significantly or urgent clinical action is needed. 
  • Provider bulletins: issued to providers as significant guidance changes occur. 

Wastewater monitoring 

MDHHS monitors approximately 30 wastewater treatment plants statewide for wild-type measles virus. A positive signal indicates viral genetic material in a sewershed and warrants increased clinical awareness. It does not identify cases, indicate outbreak scale, or independently trigger exclusion or PEP decisions. A negative result does not rule out measles activity. LHDs will communicate locally when relevant signals are detected. 

Contacts

MDHHS Reporting and Guidance

Bureau of Infectious Disease Prevention: 517-335-8159

After-Hours On-Call: 517-335-9030

Bureau of Laboratories: MDHHSLAB@michigan.gov

Case Counts & Exposure Sites: Michigan.gov/measles

Register for MIHAN Alerts: Health Alert Network

Local Health Department (LHD) Directory 

Contact your local health department for jurisdiction-specific guidance, contact tracing coordination, and case reporting. Michigan LHD directory: Local Health Department Maps 

Or accessed at Michigan.gov/mdhhs (search “local health departments”). 

MDHHS and local health departments are actively engaged to support frontline providers. Do not hesitate to call — timely reporting and communication is essential to limiting spread.