209.1 🎓 醫孞生版

209.1.0.1 📌 䞀頁重點

209.1.0.1.1 Measles (Rubeola)
  • ssRNA paramyxovirus, most contagious disease known (R0 12-18)
  • 7-14d incubation
  • 3 C’s prodrome: Cough + Coryza + Conjunctivitis (+ fever + malaise)
  • Koplik spots: bluish-white papules on buccal mucosa — pathognomonic before rash
  • Maculopapular rash starting face/behind ears → spreads down trunk/extremities (cephalocaudal); confluent
  • Complications: pneumonia (#1 cause death), otitis media, diarrhea, croup, subacute sclerosing panencephalitis (SSPE) — late complication 5-15 yr later; immune amnesia (depletes pre-existing immunity to other pathogens)
  • Vaccine: live attenuated MMR — 2-dose schedule (12-15 mo + 4-6 yr); 97% efficacy after 2 doses
  • 2024-2025 outbreaks: USA + Europe + Asia rising due vaccine hesitancy; pediatric deaths reported
  • Treatment: supportive; vitamin A in severe / pediatric (WHO recommendation)
  • 通報 mandatory globally
209.1.0.1.2 Mumps
  • ssRNA paramyxovirus
  • 14-25d incubation
  • Parotitis (uni or bilateral parotid swelling) — main feature; submandibular sometimes
  • Fever, malaise, headache
  • Complications:
    • Orchitis (~ 20% post-pubertal males) — testicular pain + swelling; infertility rare
    • Oophoritis (rare females)
    • Aseptic meningitis (10%)
    • Encephalitis (rare)
    • Hearing loss (rare, sudden, often permanent)
    • Pancreatitis (rare)
  • Treatment: supportive
  • Vaccine: MMR
209.1.0.1.3 Rubella (German Measles)
  • ssRNA togavirus
  • 14-21d incubation
  • Mild illness: fever + posterior cervical / postauricular LAP + 玅疹 maculopapular (pinkish, less confluent than measles)
  • Adults: arthritis common
  • Congenital Rubella Syndrome (CRS): 1st trimester maternal infection → catastrophic fetal:
    • Sensorineural hearing loss (#1)
    • Cataracts, glaucoma
    • Cardiac defects (PDA, pulmonary artery stenosis)
    • Microcephaly + intellectual disability
    • “Blueberry muffin baby” (extramedullary hematopoiesis)
  • Vaccine: MMR
  • Pregnancy + rubella exposure: serology check; CRS prevention via maternal immunization

209.1.0.2 1⃣ Measles

209.1.0.2.1 Virology
  • ssRNA paramyxovirus
  • Surface proteins: H (hemagglutinin), F (fusion)
  • CD150/SLAM receptor on lymphoid cells; nectin-4 on epithelial
  • R0 = 12-18 (one of most contagious diseases known)
209.1.0.2.2 Transmission
  • Airborne respiratory droplet + aerosol — virus stable in air ~ 2 hr
  • Highly contagious even brief contact in same room hours later
  • 4 days before to 4 days after rash onset = contagious
209.1.0.2.3 Clinical
209.1.0.2.3.1 Incubation (10-14 days)
209.1.0.2.3.2 Prodrome (3-5 days)
  • “3 C’s”: Cough, Coryza, Conjunctivitis
  • Fever (rising to 39-40°C)
  • Malaise
  • Koplik spots: bluish-white papules on buccal mucosa opposite molars — pathognomonic, appear 1-2 days before rash, fade as rash appears
209.1.0.2.3.3 Rash (4-7 days)
  • Maculopapular, blanching
  • Starts face + behind ears → spreads cephalocaudally to trunk + extremities
  • Confluent (becomes blotchy)
  • 3-5 days fading order similar to onset
  • Brown / coppery hyperpigmentation as fades
209.1.0.2.3.4 Recovery
  • 7-10 days
  • Cough may persist
209.1.0.2.4 Complications
209.1.0.2.4.1 Pneumonia (Major Death Cause)
  • Most common cause of measles death
  • Primary viral pneumonia (giant cell pneumonia in immunocompromise)
  • Secondary bacterial (S. aureus, S. pneumoniae)
209.1.0.2.4.2 Otitis Media
  • ~ 10% children; can lead to hearing loss
209.1.0.2.4.3 Diarrhea + Dehydration
  • Major in developing countries
209.1.0.2.4.4 Croup
  • Subglottic edema
209.1.0.2.4.5 CNS
  • Acute encephalomyelitis (1 in 1000) — post-infectious
  • SSPE (Subacute Sclerosing Panencephalitis):
    • 5-15 years post-infection (latent CNS infection)
    • Progressive cognitive decline, myoclonic seizures, motor deterioration
    • Fatal in years
    • Risk: measles before age 2
    • No effective treatment
  • ADEM
209.1.0.2.4.6 Immune Amnesia
  • Measles wipes out pre-existing immunity to other pathogens (Mina et al. Science 2019)
  • Lymphocyte memory depletion + reformation needed
  • Increased susceptibility to other infections 2-3 years post-measles
  • Major argument for vaccination
209.1.0.2.4.7 Pregnancy
  • Increased severity in pregnancy
  • Preterm labor
  • Fetal loss
209.1.0.2.5 Diagnosis
  • Clinical in classic presentation (4 days post-rash + 3 C’s + Koplik / rash pattern)
  • Measles IgM serology (acute)
  • PCR of nasopharyngeal swab or oral fluid (sensitive)
  • Multiplex respiratory PCR panels include
  • Public Health 通報 immediately
209.1.0.2.6 Treatment
  • Supportive: hydration, antipyretic, isolation
  • Vitamin A for severe / pediatric (WHO recommendation):
    • 200,000 IU PO × 1 dose, repeat 24 hr
    • Reduces mortality
    • 100,000 IU for 6-11 mo
    • 50,000 IU for < 6 mo
  • Treat secondary bacterial infections
  • Ribavirin off-label for severe / immunocompromise
  • Hospitalization for severe / complications
209.1.0.2.7 Vaccine (MMR)
  • Live attenuated Edmonston-derived strain
  • 2-dose schedule: 12-15 mo + 4-6 yr
  • 97% efficacy after 2 doses
  • Side effects: mild fever, rash, lymphadenopathy 1-2 weeks post-vaccination
  • Contraindications: pregnancy, severe immunocompromise, severe egg/neomycin allergy (rare)
209.1.0.2.8 Post-Exposure Prophylaxis
  • MMR vaccine within 72 hr of exposure for susceptibles
  • Measles IG (IM or IV) within 6 days for high-risk (pregnant, immunocompromise, infants)
209.1.0.2.9 2024-2025 Outbreaks
  • USA: > 270 cases by mid-2024 (continuing); pediatric deaths reported (Florida, Texas)
  • Europe: > 30,000 cases 2023; UK, Germany, Romania
  • Asia: pockets in vaccine-resistant communities
  • Drivers: vaccine hesitancy, immigration without immunization records, religious / philosophical exemptions
  • 反 vaccine misinformation (Wakefield 1998 fraudulent autism link — debunked but legacy effect)

209.1.0.3 2⃣ Mumps

209.1.0.3.1 Virology
  • ssRNA paramyxovirus
  • Different antigens than measles
  • 1 serotype
209.1.0.3.2 Transmission
  • Respiratory droplet
  • Less contagious than measles
  • Vaccine-modified disease milder
209.1.0.3.3 Clinical
209.1.0.3.3.1 Prodrome
  • Fever, malaise, headache 1-2 days
209.1.0.3.3.2 Parotitis
  • Uni or bilateral parotid swelling — main feature
  • Earache, pain with chewing
  • Submandibular gland sometimes
  • Self-limited 7-10 days
209.1.0.3.3.3 Complications
  • Orchitis (~ 20% post-pubertal males):
    • 4-8 days after parotitis
    • Testicular pain + swelling
    • Usually unilateral; bilateral less common
    • Infertility rare even bilateral
    • Self-limited 1-2 weeks
  • Oophoritis (rare females)
  • Aseptic meningitis (10% — usually mild, headache + photophobia)
  • Encephalitis (rare, < 0.1%)
  • Sensorineural hearing loss (rare, often permanent, unilateral most)
  • Pancreatitis (rare)
  • Mastitis (rare)
  • Thyroiditis (rare)
209.1.0.3.4 Diagnosis
  • Clinical (parotitis + appropriate epidemiology)
  • Serology IgM
  • PCR (saliva or oral swab)
  • Salivary amylase elevation common
209.1.0.3.5 Treatment
  • Supportive
  • Ice packs for parotid + scrotum
  • Analgesic
  • Bed rest
209.1.0.3.6 Vaccine (MMR)
  • Live attenuated Jeryl Lynn strain
  • 2-dose schedule with measles
  • Efficacy 88% after 2 doses (lower than measles)
  • Outbreaks in vaccinated communities (waning immunity) — booster ACIP for outbreak
209.1.0.3.7 Outbreaks
  • College outbreaks (close contact, waning vaccine)
  • Religious / vaccine-resistant communities
  • 通報

209.1.0.4 3⃣ Rubella (German Measles)

209.1.0.4.1 Virology
  • ssRNA togavirus (not paramyxovirus)
  • 1 serotype
  • Less contagious than measles
209.1.0.4.2 Transmission
  • Respiratory droplet
  • Vertical (placental — major concern)
209.1.0.4.3 Clinical (Postnatal Acquired)
  • Mild illness usually
  • 14-21d incubation
  • Pink maculopapular rash (less confluent than measles)
  • Posterior cervical + postauricular LAP characteristic
  • Low-grade fever
  • Adults: arthritis common (hands, wrists, knees), joint swelling
  • 3-5 day duration
  • “3-day measles” historical name
209.1.0.4.4 Congenital Rubella Syndrome (CRS)
  • 1st trimester maternal infection = highest fetal risk (50%+ severely affected)
  • Decreasing risk with later trimester
  • Catastrophic fetal:
    • Sensorineural hearing loss (#1, often only abnormality)
    • Cataracts, glaucoma
    • Cardiac defects (patent ductus arteriosus PDA, pulmonary artery stenosis)
    • Microcephaly + intellectual disability
    • “Blueberry muffin baby” — purple papules of extramedullary hematopoiesis
    • Hepatosplenomegaly
    • Thrombocytopenia
  • Excess mortality first year
  • Vaccinate before pregnancy if non-immune
  • Rubella serology routine prenatal in many countries
209.1.0.4.5 Diagnosis
  • Clinical + serology IgM
  • PCR (nasopharyngeal, urine)
  • Fetal: amniocentesis PCR + maternal serology
209.1.0.4.6 Treatment
  • Supportive
  • No specific antiviral
  • Termination counseling for CRS if 1st trimester
209.1.0.4.7 Vaccine (MMR)
  • Live attenuated RA 27/3 strain
  • 2-dose schedule
  • Universal childhood vaccination
  • Pregnancy contraindicated (live)
  • Theoretical risk but no documented CRS from inadvertent vaccination
209.1.0.4.8 Eradication Progress
  • Americas region: measles + rubella + CRS eliminated 2015 (WHO declared)
  • Re-introductions occur from imported cases
  • Goal: global eradication

209.1.0.5 4⃣ MMR Vaccine Composite

209.1.0.5.1 Components
  • M (Measles): Edmonston-derived
  • M (Mumps): Jeryl Lynn
  • R (Rubella): RA 27/3
209.1.0.5.2 Schedule
  • First dose 12-15 mo
  • Second dose 4-6 yr (before school entry)
  • Adults non-immune: 1-2 doses depending history
209.1.0.5.3 MMRV (Measles, Mumps, Rubella, Varicella)
  • ProQuad combination
  • Slightly higher febrile seizure rate at first dose vs MMR + Varicella separate
  • 4-6 yr second dose preferred MMRV
209.1.0.5.4 Efficacy
  • Measles: 97% after 2 doses
  • Mumps: 88% after 2 doses
  • Rubella: 97% after 2 doses
209.1.0.5.5 Contraindications
  • Pregnancy (live virus)
  • Severe immunocompromise (HIV CD4 < 200 — but consider in HIV stable + CD4 ≥ 200)
  • Severe egg/neomycin allergy (rare)
  • Recent IVIG (within 3-11 months — live vaccine response blunted)
209.1.0.5.6 Post-Vaccination Reactions
  • Mild fever
  • Rash 6-12 days post-vaccination
  • Lymphadenopathy
  • Arthralgia (rubella component, adults)
  • Rare anaphylaxis
209.1.0.5.7 Why Annual Booster Not Needed
  • Long-lasting immunity (durable from childhood vaccination)
  • Re-exposure-based boosting in community
  • Some waning (esp. mumps) — outbreak boosters in young adults considered