01Approach to the Critical Patient/attcp54

Immediate priorities

›Airway isolation and respiratory threats

›Airborne precautions immediately on suspicion

›Negative-pressure room if available

›N-95 mask for all staff entering room

›Respiratory distress evaluation

›Tachypnea with SpO2 < 94% on room air

›Hypoxia signaling measles pneumonia — most common cause of measles death

›Immunocompromised pattern

›Absent rash does not exclude measles

›Giant-cell pneumonia (Hecht's) risk — often fatal

›If respiratory failure, early intubation planning

›Airborne precautions maintained through intubation

›Apneic oxygenation preferred over BVM to minimize aerosolization

Critical complication triggers

›Encephalitis recognition

›Altered mental status or new seizures

›Incidence approximately 1 per 1,000 cases

›20% mortality, 25% long-term neurologic sequelae

›If encephalitis suspected, emergent CT head then LP

›MRI brain is definitive for ADEM white matter changes

›CSF measles antibody ratio confirms intrathecal synthesis

›Secondary bacterial sepsis

›Persistent high fever after rash onset

›Leukocytosis replacing initial leukopenia

›Toxic appearance

›If septic shock, broad-spectrum antibiotics within 1 hour

›Blood cultures prior to antibiotics when feasible

02History/hx61

Symptom timeline

›Classic prodrome

›Duration 2-4 days before rash

›High fever up to 40.6 C

›Malaise and anorexia

›Three Cs

›Cough

›Coryza (rhinorrhea)

›Conjunctivitis (bilateral, non-purulent)

›Incubation period 10-14 days from exposure

›Range 7-23 days

›Rash onset approximately 14 days post-exposure

Rash characterization

›Maculopapular rash features

›Onset at hairline and face

›Spreads cephalocaudal to trunk then extremities over 3-5 days

›Initially blanching, later brownish with desquamation

›Timing relative to fever

›Rash appears 3-5 days after prodrome onset

›Fever begins to resolve as rash spreads downward

Associated symptoms

›Systemic features

›Photophobia

›Present during conjunctivitis phase

›Worsened by bright examination lighting

›Diarrhea

›Present in 8-10% of cases

›May persist up to 1 month

03Physical Exam/exam60

Vital signs

›Fever and hemodynamic assessment

›Temperature often >= 40 C during prodrome and rash onset

›Fever resolving 2-3 days after rash appearance in uncomplicated disease

›Persistent or recurrent fever signals complication

›Tachycardia commensurate with fever

›Tachycardia disproportionate to fever may indicate pneumonia or sepsis

›Respiratory rate

›>= 30 per minute as severity marker

›SpO2 on room air

HEENT exam

›Oral cavity

›Koplik spots — buccal mucosa opposite lower molars

›Pathognomonic for measles

›Appear 1-2 days before rash; fade after rash onset

›Pharyngeal erythema

›Non-exudative typically

›Eyes

›Bilateral non-purulent conjunctivitis

›Distinguishes measles from bacterial conjunctivitis

›Photophobia assessment

›Corneal exam

›Ulceration in vitamin A-deficient patients

›Slit lamp if keratitis suspected

›Ears

›Otoscopic exam for otitis media

›Complication in 7-9% of cases

›Most common in children under 5 years

04Differential Diagnosis/ddx52

Life-threatening must-not-miss

›Meningococcemia

›ICD-10 A39.2 — cannot miss

›Petechial or purpuric rash — non-blanching

›Rapid hemodynamic deterioration

›Rocky Mountain Spotted Fever

›ICD-10 A77.0

›Rash begins peripherally (wrists, ankles), moves centrally

›Tick exposure history

Viral exanthem mimics

›Rubella (German measles)

›ICD-10 B06.9

›Milder prodrome, no Koplik spots

›Postauricular and suboccipital lymphadenopathy

›Rash duration 3 days vs 5-7 days for measles

›Roseola (HHV-6)

›ICD-10 B08.20

›Rash appears after fever resolves — opposite pattern to measles

›Primarily children 6-24 months

›Parvovirus B19 (fifth disease)

›ICD-10 B08.3

›Slapped-cheek appearance

›Reticular lace-like rash on extremities

›No conjunctivitis

›Roseola-like drug reaction

›Temporal relationship to new medication

›Eosinophilia possible

›No prodromal three Cs

05Laboratory Tests/lt47

Measles-specific diagnostics

›Measles IgM serology

›Sensitivity 83-98.8%, specificity 93.7-100%

›May be false-negative in first 72 hours after rash onset

›Repeat if initially negative and clinical suspicion remains

›IgG avidity assay

›Distinguishes primary infection from secondary immune response

›Useful in previously vaccinated individuals

›Measles RT-PCR

›Sensitivity 94%, specificity 99%

›Nasopharyngeal or throat swab preferred

›Adding urine PCR improves sensitivity

›Detectable approximately 3 days after rash onset

›Preferred early test when serology may be negative

›Viral genotyping

›Public health laboratory testing for epidemiologic tracking

›Not required for clinical management

›Coordinated through state health department

CBC and inflammatory markers

›Complete blood count

›Leukopenia — especially lymphopenia — characteristic of measles

›Leukocytosis suggests secondary bacterial superinfection

›Thrombocytopenia possible

›Peripheral smear

›Atypical lymphocytes may be present

›CRP and procalcitonin

›Differentiation of viral vs bacterial complications

›Procalcitonin > 0.5 mcg/l suggests bacterial co-infection

06Diagnostic Tests/dt46

Scoring Systems

›CDC clinical case definition

›Generalized maculopapular rash + fever >= 38.3 C + cough, coryza, or conjunctivitis

›Sensitivity 75-90% for clinical diagnosis

›Low positive predictive value in low-incidence settings

›Confirm with laboratory testing in all suspected cases

›Severity stratification

›Uncomplicated: self-limited, resolves within 7 days of rash onset

›Complicated: pneumonia 1-6%, otitis media 7-9%, diarrhea 8-10%, encephalitis 1 per 1,000

›Death: 1-3 per 1,000 in developed countries; higher in resource-limited settings

Scoring Systems (supplemental)

›Immune amnesia assessment

›Measles-induced immunosuppression lasting 2-3 years

›Increased susceptibility to secondary infections

›Counseling and catch-up vaccination planning for household contacts

MRI

›MRI brain indications

›Neurologic symptoms: altered mental status, seizures, focal deficits

›ADEM pattern: T2/FLAIR hyperintensities in white matter

›Bilateral, asymmetric, periventricular or subcortical distribution

›SSPE (subacute sclerosing panencephalitis)

›Late complication years after measles infection

›Cortical and subcortical atrophy on MRI

›Periventricular white matter changes

›MRI spine

›Myelitis pattern in ADEM variant

›T2 signal changes in cord

07Disposition/dispo43

Admission indications

›Inpatient admission criteria

›Respiratory distress, hypoxia, or confirmed pneumonia

›SpO2 < 94% on room air

›Tachypnea with work of breathing

›Neurologic complications

›Encephalitis — ICU level care

›Seizures requiring monitoring

›Severe dehydration or inability to tolerate oral fluids

›IV hydration requirement

›Persistent vomiting

›High-risk patients regardless of apparent severity

›Immunocompromised — ICU or step-down for giant-cell pneumonia risk

›Infants under 12 months with moderate to severe illness

›Pregnant patients with complications

›Vitamin A-deficient with ocular findings

Discharge criteria

›Safe for home criteria

›Clinically stable, tolerating oral fluids, no respiratory distress

›SpO2 >= 94% on room air

›Adequate fever control with antipyretics

›Reliable home isolation capability

›Ability to self-isolate for 4 days after rash onset

›No vulnerable household contacts (unvaccinated, immunocompromised, pregnant, infants < 6 months)

›Reliable follow-up arranged within 48-72 hours

›Primary care or pediatrician confirmation

›Return precautions understood

08Treatment/t63

Airborne isolation

›Infection control measures

›Negative-pressure room placement

›N-95 or higher respirator for all staff

›Duration: 4 days after rash onset (7 days if immunocompromised)

›Contact notification

›Hospital infection control team

›Public health authority

Vitamin A supplementation

›Age-based vitamin A dosing — AAP and WHO recommendation

›Age under 6 months

›50,000 IU orally once daily for 2 consecutive days

›Third dose at 2-4 weeks if clinical vitamin A deficiency signs

›Age 6-11 months

›100,000 IU orally once daily for 2 consecutive days

›Third dose at 2-4 weeks if clinical deficiency

›Age >= 12 months and adults

›200,000 IU orally once daily for 2 consecutive days

›Third dose at 2-4 weeks if xerophthalmia or Bitot spots

›Evidence base

›Reduces measles mortality by 34-50% in children

›Reduces pneumonia severity and duration

›Contraindicated in pregnancy at high doses (teratogenic)

Supportive care

›Hydration

›Oral rehydration solution for mild dehydration

›Small, frequent volumes if oral intake limited by stomatitis

›IV fluid resuscitation for severe dehydration or inability to tolerate PO

›Normal saline or lactated Ringer's bolus 20 ml/kg in children

›Electrolyte replacement for diarrhea losses

›Antipyretics

›Acetaminophen

›Children: 15 mg/kg per dose every 4-6 hours, maximum 75 mg/kg per day

›Adults: 650-1000 mg every 6 hours, maximum 4 g per day

›Ibuprofen

›Children >= 6 months: 10 mg/kg per dose every 6-8 hours

›Adults: 400-600 mg every 6-8 hours

›Aspirin — contraindicated in children (Reye syndrome risk)

Antiviral therapy

›No FDA-approved antiviral exists for measles

›Ribavirin — in vitro activity against measles virus

›Not FDA-approved for measles

›Used off-label in severe cases or immunocompromised patients

›Oral or IV formulation considered in consultation with infectious disease

›Intravenous immunoglobulin (IVIG)

›Post-exposure prophylaxis within 6 days for high-risk contacts

›Ineligible for live vaccine: infants < 6 months, pregnant women, immunocompromised

›Dose: 0.5 ml/kg IM (maximum 15 ml) or 400 mg/kg IV for immunocompromised

Antibiotic therapy

›Antibiotics only for confirmed secondary bacterial infections

›Secondary bacterial pneumonia

›Empiric coverage: amoxicillin-clavulanate or azithromycin in outpatient setting

›Hospitalized: beta-lactam plus macrolide or respiratory fluoroquinolone

›MRSA coverage if severe or risk factors: add vancomycin or linezolid

›Otitis media

›Amoxicillin 80-90 mg/kg per day in children (maximum 3 g per day)

›Amoxicillin-clavulanate if treatment failure at 48-72 hours

›Empiric antibiotics not recommended in uncomplicated measles

›No survival benefit shown without confirmed bacterial co-infection

Post-exposure prophylaxis

›MMR vaccine

›Within 72 hours of exposure for eligible contacts

›Age >= 6 months with no evidence of immunity

›Confers protection or modifies disease severity if exposure confirmed

›Immunoglobulin (IG)

›Within 6 days of exposure for ineligible contacts

›Infants < 6 months: 0.5 ml/kg IM (maximum 15 ml)

›Pregnant women: 0.5 ml/kg IM (maximum 15 ml)

›Immunocompromised: 400 mg/kg IV IVIG

09Special Populations/sp57

Pregnancy

›Maternal and fetal risks

›Spontaneous abortion risk increased

›Premature labor and delivery

›Maternal respiratory complications — pneumonia risk higher

›Fetal measles not documented (virus does not cross placenta reliably)

›Perinatal measles if delivery during viremia

›Neonatal measles if born to infected mother within 10 days

›Management modifications in pregnancy

›Vitamin A supplementation — contraindicated at standard measles doses

›High-dose vitamin A is teratogenic

›Low-dose supplementation (< 10,000 IU/day) considered on infectious disease advice

›MMR vaccine contraindicated in pregnancy

›Live attenuated vaccine — teratogenicity risk

›Immunoglobulin IG preferred for post-exposure prophylaxis

›Ribavirin — teratogenic, contraindicated in pregnancy

›Fetal harm documented in animal studies

Geriatric

›Age-related risks

›Adults born before 1957 generally considered immune (endemic exposure era)

›Verify if born 1957-1989: may have received only one MMR dose

›Born 1957-1989 cohort may need second MMR dose documentation review

›Complication risk elevated with age > 20 years

›Pneumonia leading cause of adult measles death

›Hepatitis more common in older adults

›Geriatric management considerations

›Vitamin A supplementation 200,000 IU twice over 2 days if deficient

›Lower risk of toxicity at this dose in adults

10Background/b68

Epidemiology

›Global disease burden

›Estimated 136,000 deaths globally in 2022 — predominantly children under 5

›Resurgence linked to declining vaccination coverage post-COVID-19 pandemic

›WHO and UNICEF estimate 22 million infants missed first MMR dose in 2022

›R0 = 12-18 — among the highest of any infectious disease

›95% population immunity required for herd protection

›Airborne transmission; viable in air up to 2 hours after patient departs room

›United States epidemiology

›Declared eliminated in US in 2000

›Endemic transmission interrupted by vaccination

›Resurgence driven by importations and vaccine hesitancy

›2025-2026 outbreak context

›Largest US outbreak in decades

›CDC HAN advisory issued — healthcare providers on heightened alert

›Transmission parameters

›Contagious from 4 days before to 4 days after rash onset

›Peak viral shedding during prodromal phase

›Virus persists in nasopharynx, blood, and urine

Pathophysiology

›Viral entry and dissemination

›Measles virus (family Paramyxoviridae, genus Morbillivirus)

›Single-stranded negative-sense RNA virus

›Receptor: CD150 (signaling lymphocytic activation molecule, SLAM) on immune cells

›CD46 on epithelial cells for wild-type and vaccine strains

›Primary infection in respiratory epithelium

›Infects alveolar macrophages and dendritic cells

›Spreads via lymphatics to regional lymph nodes

›Primary viremia

›Dissemination to reticuloendothelial system (liver, spleen, lymph nodes)

›Secondary viremia seeds all organs including skin, CNS, lungs

›Immune response and rash pathogenesis

›CD4+ and CD8+ T-cell responses generate rash via immune-mediated mechanism

›Rash absent in T-cell-deficient patients

›Rash appearance correlates with immune activation, not direct viral cytopathicity

›Immune amnesia mechanism

›Measles depletes pre-existing memory B and T lymphocytes

›Immunosuppression lasting 2-3 years

›Increased susceptibility to other infections after measles recovery

›Complications pathophysiology

›Primary measles pneumonia

›Direct viral cytopathic effect in bronchial epithelium and alveoli

›Syncytial giant cells (Warthin-Finkeldey cells) characteristic

›Measles encephalitis (acute)

›Post-infectious immune-mediated ADEM most common

›Direct viral encephalitis less common, more severe

›SSPE (subacute sclerosing panencephalitis)

›Defective measles virus persists in CNS neurons

›Progressive neurodegeneration over months to years

›Incidence approximately 1 per 10,000 measles cases; higher in those infected before age 2

Therapeutic Considerations

›Vitamin A mechanism and evidence

›Reduces measles mortality by 34-50% in children

›Mechanism: restores vitamin A-dependent immune function and epithelial integrity

›WHO recommends for all children with measles in developing and resource-limited settings

›AAP recommends for all hospitalized children with measles in US

›Contraindications

›Pregnancy — teratogenic at high doses

›Pre-existing hypervitaminosis A

›No approved antiviral — management is supportive

›Ribavirin off-label use in severe or immunocompromised cases

›Limited human evidence; in vitro activity demonstrated

›Case reports suggest possible benefit in life-threatening disease

›IVIG — passive immunity for post-exposure prophylaxis

›Does not treat established measles but may attenuate severity

›Vaccination as definitive prevention

›Two-dose MMR confers > 97% protection

›First dose 93% effective; second dose raises protection to 97%

›Live attenuated vaccine — contraindicated in pregnancy and significantly immunocompromised

›Post-exposure MMR within 72 hours may prevent disease in exposed contacts

›Evidence: ACEP Level B recommendation equivalent class for post-exposure use

11Patient Discharge Instructions/pdi39

copy discharge instructions

›Isolation instructions

›Remain home and avoid contact with others for 4 days after rash onset

›Do not go to school, work, childcare, or public spaces

›Avoid contact with unvaccinated individuals, pregnant women, infants, and immunocompromised persons

›Notify anyone who may have been exposed

›Especially unvaccinated contacts, pregnant women, and immunocompromised individuals

›Contact local public health department if advised

›Expected course

›Fever typically resolves 2-3 days after rash onset

›Rash fades over 5-7 days in order of appearance (face first)

›Full recovery in uncomplicated cases within 7-10 days

›Cough and fatigue may persist 1-2 weeks after rash resolves

›Normal part of viral recovery

›Medications and home care

›Acetaminophen or ibuprofen as directed for fever and discomfort

›Do not give aspirin to children — risk of Reye syndrome

›Vitamin A as prescribed — complete full course

›Increase fluids: water, oral rehydration solution, broth

›Small, frequent sips if mouth sores limit swallowing

›Household contact protection

›Household contacts without evidence of immunity should contact their doctor

›MMR vaccine within 72 hours of exposure if eligible

›Immunoglobulin injection within 6 days if not eligible for vaccine

›Immune amnesia counseling

›Increased susceptibility to other infections for up to 2-3 years after measles

›Ensure all routine vaccinations are up to date at follow-up visit

›Return to emergency department immediately for

12References/r29

Guidelines and key sources

›Do LAH, Mulholland K. Measles 2025. New England Journal of Medicine. 2025

›Comprehensive review of clinical features, management, and current outbreak context

›Source for complication rates, contagiousness parameters, vitamin A evidence

›Strebel PM, Orenstein WA. Measles. New England Journal of Medicine. 2019

›Epidemiology, vaccination science, post-exposure prophylaxis protocols

›Risk factor analysis including vaccine timing and immunocompromised populations

›Goodson JL, Filardo TD. Measles (Rubeola). CDC Yellow Book. 2025

›Travel medicine and clinical management framework

›Post-exposure prophylaxis guidance for travelers and healthcare settings

›Stoneman EK. Measles. Journal of the American Medical Association. 2025

›JAMA clinical update — current US outbreak context and management pearls

›Hübschen JM, Gouandjika-Vasilache I, Dina J. Measles. Lancet. 2022

›Global burden, laboratory diagnostics, genotyping for public health

›Lumbar puncture and CSF diagnostics for encephalitis

›Alves Graber EM et al. An Update and Review of Measles for Emergency Physicians. Journal of Emergency Medicine. 2020

›Emergency department-focused clinical review

›Diagnostic approach, isolation protocols, and disposition criteria

Laboratory and diagnostic references

›Miller JM et al. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update. IDSA and ASM. Clinical Infectious Diseases. 2024

›PCR and serology performance characteristics for measles diagnosis

›Preferred specimen types and testing sequence

›Kaur A et al. Acute Management of Measles: A Systematic Review of Therapeutic Strategies. Antiviral Research. 2026

›Systematic review of ribavirin and supportive care evidence

›Off-label antiviral options in severe and immunocompromised disease

›CDC Health Advisory HAN00522. Expanding Measles Outbreak in the United States. 2025

›Current outbreak epidemiology and guidance for the 2025 travel season

›Provider alert recommendations for heightened clinical suspicion

Evidence & Review

Evidence & Review