Key Takeaways
- In 2022, the United States reported 121 confirmed measles cases across 16 jurisdictions, the highest since 2019 elimination declaration.
- Globally, measles caused an estimated 128,000 deaths in 2021, mostly among children under 5 years old.
- Measles incidence in the WHO European Region surged to 90,000 cases in 2018 from under 5,000 in 2016.
- Incubation period for measles is 7-21 days, averaging 10-12 days.
- Prodromal phase of measles lasts 2-4 days with fever up to 104°F (40°C).
- Koplik spots appear 1-2 days before rash in 90% of measles cases.
- MMR vaccine contains live attenuated measles virus (Edmonston-Enders strain).
- Two doses of MMR vaccine provide 97% effectiveness against measles.
- First MMR dose at 12-15 months achieves 93% efficacy.
- Pneumonia complicates 5-10% of measles cases, often fatal in children.
- Encephalitis risk 1 per 1,000 cases, mortality 15%.
- SSPE incidence 1 in 1,000-2,000 in developing countries.
- Global measles mortality 128,000 in 2021, 95% in low-income countries.
- Case-fatality ratio (CFR) 1-5% in developing countries for children under 5.
- Pre-vaccine era US: 400-500 deaths yearly from 3-4 million cases.
Measles outbreaks are resurging globally despite being preventable with vaccination.
Clinical Aspects
- Incubation period for measles is 7-21 days, averaging 10-12 days.
- Prodromal phase of measles lasts 2-4 days with fever up to 104°F (40°C).
- Koplik spots appear 1-2 days before rash in 90% of measles cases.
- Maculopapular rash in measles starts behind ears and spreads cephalocaudally over 3-4 days.
- Cough, coryza, and conjunctivitis (3 Cs) present in 90% of measles patients.
- Measles virus transmission occurs via respiratory droplets, infectious 4 days before to 4 days after rash.
- Secondary attack rate in susceptible household contacts is 85-90%.
- Virus shedding peaks during prodrome, detectable in urine up to 14 days post-rash.
- Encephalitis occurs in 1 in 1,000 measles cases, typically 2-6 days after rash.
- Subacute sclerosing panencephalitis (SSPE) risk is 4-11 per 100,000 cases, latency 7-10 years.
- Otitis media complicates 7-9% of measles cases in children.
- Diarrhea affects up to 8% of measles patients, contributing to dehydration.
- Photophobia and eye pain common due to conjunctivitis in measles prodrome.
- Leukopenia occurs in 60% of measles cases, with lymphopenia predominant.
- Elevated transaminases in 50% of measles patients, indicating liver involvement.
- Thrombocytopenia reported in 15-30% of hospitalized measles cases.
- Measles rash blanches under pressure, fades in 7 days.
- Pathognomonic Koplik spots: 1-3mm white on buccal mucosa opposite molars.
- Fever recurs with rash onset in measles.
- Virus replicates in respiratory epithelium before viremia day 9-11.
- Airborne transmission possible up to 2 hours post-patient departure.
- Diagnosis confirmed by IgM ELISA 72 hours post-rash or PCR.
- Lymphadenopathy less prominent than in rubella.
- Splenomegaly in 50% hospitalized measles children.
- Appendicitis mimic due to mesenteric adenitis in measles.
- Rash spares palms/soles unlike some exanthems.
Clinical Aspects Interpretation
Complications
- Pneumonia complicates 5-10% of measles cases, often fatal in children.
- Encephalitis risk 1 per 1,000 cases, mortality 15%.
- SSPE incidence 1 in 1,000-2,000 in developing countries.
- Diarrhea hospitalization rate 8% in measles outbreaks.
- Blindness from corneal ulceration in 0.1% measles cases in vitamin A deficient areas.
- Myocarditis rare, <1 per 1,000, but reported in measles.
- Thrombocytopenia in 1 per 3,000-4,000 cases, self-limiting.
- Laryngotracheobronchitis in 5% pediatric measles cases.
- Vitamin A supplementation reduces measles mortality by 50% in deficient children.
- Hospitalization rate for measles 20-30% in developed countries.
- Bacterial superinfection causes 60% of measles pneumonia deaths.
- Degenerative CNS disease (SSPE) fatal in 100%, mean survival 1-2 years post-diagnosis.
- Acute cerebellar ataxia in 0.02-0.1% measles cases.
- Acute respiratory distress syndrome (ARDS) in severe measles pneumonia.
- Hemorrhagic measles rash in 5% vitamin A deficient cases.
- Guillain-Barré rare post-measles, <1/million.
- Corneal scarring blindness prevented by vitamin A.
- Reactive thrombocytosis follows thrombocytopenia recovery.
- Aseptic meningitis 0.1 per 1,000 measles cases.
- Secondary bacterial pneumonia: Strep pneumo, H flu common.
- SSPE earlier onset in <2yo at infection: 4-5 years latency.
- Orchitis in 30% post-pubertal males with measles.
- Mastitis in 30% lactating women with measles.
Complications Interpretation
Epidemiology
- In 2022, the United States reported 121 confirmed measles cases across 16 jurisdictions, the highest since 2019 elimination declaration.
- Globally, measles caused an estimated 128,000 deaths in 2021, mostly among children under 5 years old.
- Measles incidence in the WHO European Region surged to 90,000 cases in 2018 from under 5,000 in 2016.
- In 2019, the Democratic Republic of the Congo reported over 250,000 suspected measles cases amid ongoing Ebola response.
- India's measles cases dropped 80% from 2017 to 2022 due to intensified vaccination campaigns.
- In 2023, the UK had 1,603 lab-confirmed measles cases, primarily in London.
- Ethiopia reported 10,559 measles cases in the first half of 2023 across 147 districts.
- Measles outbreaks in Yemen since 2017 have exceeded 40,000 cases with 700 deaths.
- In 2022, Nigeria confirmed 3,997 measles cases with 44 deaths in 17 states.
- Somalia's 2023 measles outbreak reached 11,580 cases and 163 deaths by July.
- Brazil's measles cases in 2018 totaled 10,322, leading to reintroduction after elimination.
- In 2021, France reported 101 measles cases, up from 12 in 2020.
- Pakistan had over 300 measles deaths in 2023, mostly unvaccinated children.
- The Americas achieved measles elimination in 2016 but saw 23,000 cases in Venezuela by 2019.
- In 2022, Australia reported 20 measles cases linked to international travel.
- Madagascar's 2018-2020 measles outbreak recorded 118,000 cases and 1,400 deaths.
- Measles incidence in unvaccinated US communities reached 1 in 4 infection rate during outbreaks.
- Globally, 83% of children received first measles vaccine dose in 2022, up from 72% in 2000.
- In 2016, 1 in 10 US kindergarteners lacked MMR vaccination documentation.
- Romania reported 14,916 measles cases from 2016-2019 with 64 deaths.
- In 2023, Ohio US outbreak had 85 cases, 36 hospitalized, all unvaccinated.
- Measles R0 (basic reproduction number) averages 12-18 in susceptible populations.
- In 2019, WHO Americas: 8 deaths from Venezuela outbreak.
- Kenya 2023: 13,500 cases, 170 deaths by September.
Epidemiology Interpretation
Mortality and Burden
- Global measles mortality 128,000 in 2021, 95% in low-income countries.
- Case-fatality ratio (CFR) 1-5% in developing countries for children under 5.
- Pre-vaccine era US: 400-500 deaths yearly from 3-4 million cases.
- Measles DALYs: 8.7 million globally in 2019 per IHME.
- Malnutrition increases measles CFR up to 50-fold.
- 2000-2022, vaccination prevented 60% drop in annual deaths from 800k to 128k.
- In 2019 outbreaks, CFR reached 7.3% in DRC.
- Economic burden: US outbreak costs $20k-$100k per case in containment.
- Global under-5 measles deaths: 94% of total in 2021.
- Pre-vaccine Europe: 2.6 million deaths per year estimated.
- HIV co-infection raises measles CFR to 11-33%.
- Vitamin A therapy cuts mortality by 23% overall in trials.
- Annual global cost of measles control: $1.3 billion needed per GAVI.
- In Samoa 2019 outbreak, CFR 0.83% with 83 deaths from 5,700 cases.
- US post-elimination: 1 death in 2015 from 1,282 cases.
- Projected: without action, 10 million cases, 130k deaths in 2023.
- In 2022, Europe had 4 deaths from 1,000+ cases.
- Global economic loss from measles: $10.9 billion 2018-2022.
- CFR <0.1% in vaccinated populations with access to care.
- In 2023 first half, 14 African countries reported 7,521 measles deaths.
- Pre-1963 vaccine: 48,000 hospitalizations yearly US kids.
- 2023 global cases: 10.3 million estimated.
- Yemen 2017-2023: 45,000 cases, 750 deaths.
- Cost per averted death: $30 via vaccination in Africa.
- DRC 2019: 250k cases, 6k deaths, CFR 2.4%.
- Immunodeficiency raises CFR to 30-75%.
- 94% measles deaths in 10 countries 2022.
- US 1989-1991: 123 deaths from 55k cases.
- Lifetime SSPE cost: $2.5M per case US.
- Global 2030 projection: 1.6M deaths without 95% coverage.
- Measles contributes to 1% childhood pneumonia deaths.
Mortality and Burden Interpretation
Vaccination
- MMR vaccine contains live attenuated measles virus (Edmonston-Enders strain).
- Two doses of MMR vaccine provide 97% effectiveness against measles.
- First MMR dose at 12-15 months achieves 93% efficacy.
- Global first-dose measles coverage was 83% in 2022 per WHO/UNICEF estimates.
- Second-dose coverage lagged at 74% globally in 2022.
- Herd immunity threshold for measles is 92-95% population immunity.
- Vaccine-induced immunity lasts decades, with 92% protected 20+ years post-second dose.
- Adverse events post-MMR: fever in 5-15%, rash in 5% within 7-12 days.
- Anaphylaxis after MMR occurs in 1.8 per million doses.
- No link between MMR and autism per 12+ studies involving millions.
- Measles vaccination averted 56 million deaths globally 2000-2022.
- Supplemental immunization activities (SIAs) reached 80% coverage in Africa recently.
- One-dose measles vaccine costs $0.30-$0.50 per child in low-income countries.
- Thimerosal-free measles vaccines recommended since 1999.
- Immune-suppressed individuals contraindicated for live MMR vaccine.
- Pregnancy defer MMR; use immunoglobulin post-exposure if susceptible.
- MMR first dose protects 93%, second boosts to 97%.
- Waning immunity rare; revaccination not routinely needed.
- Outbreak response: single antigen measles vaccine for 6m+ infants.
- US kindergarten MMR coverage 93.5% in 2022-23.
- Supplementary campaigns aim for 95% coverage in 80% districts.
- MR vaccine combo with rubella for gender-neutral delivery.
- Storage: MMR at 2-8°C, 2-year shelf life.
- Post-exposure prophylaxis: MMR within 72h, IG within 6 days.
- IIV contraindicated; use killed vaccine historically risky.
- Global target: 95% two-dose coverage by 2030.
- Febrile seizures post-MMR: 1 per 3,000-4,000 doses.
Vaccination Interpretation
Sources & References
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