205.1 🎓 醫學生版

205.1.0.1 📌 一頁重點

205.1.0.1.1 Rhinovirus

• #1 cause of common cold (~ 50%)

• 160 serotypes (A, B, C)

• Optimal replication 33°C (nasal passages cooler)
• Self-limited 7-10d
• Asthma + COPD exacerbation trigger
• No vaccine / specific antiviral
• ICAM-1 receptor (majority)

205.1.0.1.2 Seasonal Coronaviruses

• HKU1, OC43 (β-coronavirus — like SARS-CoV-2)
• NL63, 229E (α-coronavirus)
• 10-30% of common colds; some pneumonia in elderly / immunocompromise
• Pre-pandemic, accounted for 15% of common colds
• Cross-reactivity with SARS-CoV-2 antibodies (some prior immunity?)

205.1.0.1.3 Parainfluenza Virus

• 4 serotypes (PIV-1, 2, 3, 4)
• #1 cause of croup (laryngotracheobronchitis) in children (PIV-1 + PIV-2 mostly)
• Inspiratory stridor + barking cough + hoarseness + low-grade fever
• Bronchiolitis + pneumonia (PIV-3)
• Adult: mild URI
• Immunocompromise: severe pneumonia (HSCT)
• Treatment: supportive; nebulized epinephrine + dexamethasone for moderate-severe croup

205.1.0.1.4 Human Metapneumovirus (HMPV)

• Discovered 2001
• Pneumovirus family (like RSV)
• ~ 5-10% pediatric LRTI
• 2024-2025 USA / Asia surge (post-COVID immunity gap effect)
• 中国 2024 December significant HMPV outbreak
• Bronchiolitis, pneumonia, asthma exacerbation
• Severe in elderly + immunocompromise
• No specific antiviral; ribavirin off-label

205.1.0.1.5 Adenovirus (Ch 210 in detail)

• DNA virus, 多 serotypes
• Pediatric URI + LRTI + pharyngitis + GI + conjunctivitis (pink eye)
• Severe in immunocompromise (HSCT, AIDS)
• Treatment: cidofovir + brincidofovir for severe

205.1.0.1.6 Bocavirus (HBoV)

• Parvovirus family
• Co-infection common
• URI + LRTI in children

205.1.0.1.7 Enterovirus D68 (EV-D68)

• 2014 + outbreaks
• Acute flaccid myelitis (AFM) — polio-like paralysis in children
• Severe asthma exacerbation
• Treatment: supportive (no specific antiviral)

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205.1.0.2 1️⃣ Rhinovirus

205.1.0.2.1 Microbiology

• Picornaviridae family
• ssRNA, ~ 7-8 kb
• Capsid VP1-VP4
• 3 species: RV-A, RV-B, RV-C

• 160 serotypes

• ICAM-1 receptor for majority

205.1.0.2.2 Clinical

• Common cold (50%+ of all)
• Nasal congestion, runny nose, sneezing, sore throat, cough
• Low / no fever (usually)
• 7-10d self-limited
• Asthma exacerbation trigger (#1 viral trigger in adults + children)
• COPD exacerbation trigger
• Sinusitis (uncomplicated post-rhinovirus)
• Otitis media in children

205.1.0.2.3 Severe Disease

• Immunocompromise (HSCT) — can be severe
• Pneumonia / LRTI in young infants
• Severe asthma exacerbation

205.1.0.2.4 Diagnosis

• Clinical
• Respiratory PCR panels (BioFire) include — multi-pathogen
• Not necessary for typical mild URI

205.1.0.2.5 Treatment

• Supportive
• No FDA-approved antiviral
• Steroid for asthma exacerbation
• Antibiotic NOT for viral URI (most cold)

205.1.0.2.6 Prevention

• Hand hygiene
• No vaccine (too many serotypes)
• Pre-pandemic mask not standard for common cold

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205.1.0.3 2️⃣ Seasonal Coronaviruses

205.1.0.3.1 Species

• OC43, HKU1 — β-coronavirus (same genus as SARS-CoV-2)
• NL63, 229E — α-coronavirus

205.1.0.3.2 Clinical

• Common cold typically
• Bronchiolitis, pneumonia in some — especially elderly, infants, immunocompromise
• Pre-COVID: 10-30% of upper respiratory infections in adults
• Some immunity to SARS-CoV-2 hypothesized from prior seasonal infections

205.1.0.3.3 Diagnosis

• Multiplex respiratory PCR
• Less clinical decision impact

205.1.0.3.4 Treatment

• Supportive
• No specific antiviral

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205.1.0.4 3️⃣ Parainfluenza (PIV)

205.1.0.4.1 Serotypes

• PIV-1, 2, 3, 4
• Paramyxoviridae family
• ssRNA

205.1.0.4.2 Clinical Patterns

205.1.0.4.2.1 Croup (Laryngotracheobronchitis)

• PIV-1 + PIV-2 main causes (also PIV-4)
• 6 mo - 6 yr peak
• “Inspiratory stridor + barking cough + hoarseness + low-grade fever”
• “Steeple sign” on AP neck X-ray (subglottic narrowing)
• Self-limited in most
• Treatment:
  • Mild: humidified air, supportive
  • Moderate: dexamethasone 0.6 mg/kg PO/IM × 1 dose
  • Severe (stridor at rest): nebulized racemic epinephrine + dex
  • Hospitalize if airway compromise

205.1.0.4.2.2 Bronchiolitis + Pneumonia (PIV-3)

• Infants + young children
• Similar to RSV but milder typically

205.1.0.4.2.3 Adult URI

• Mild common cold-like

205.1.0.4.2.4 Immunocompromise

• HSCT severe pneumonia
• High mortality
• DAS181 (fludase) — off-label

205.1.0.4.3 Treatment

• Supportive
• Croup: dex + epinephrine
• No specific antiviral

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205.1.0.5 4️⃣ Human Metapneumovirus (HMPV)

205.1.0.5.1 Discovery + Microbiology

• Discovered 2001 (van den Hoogen, Netherlands)
• Pneumoviridae family (like RSV)
• ssRNA
• 2 main genotypes (A + B)

205.1.0.5.2 Clinical

• Similar to RSV
• Bronchiolitis + pneumonia in infants
• Asthma exacerbation
• Elderly community + nursing home pneumonia
• Immunocompromise — severe

205.1.0.5.3 2024-2025 Surge

• China December 2024 significant outbreak
• USA + Asia 2025 spike
• Post-COVID immunity gap + cyclical
• Pediatric ICU admissions increased

205.1.0.5.4 Diagnosis

• Respiratory PCR panels
• Multiplex molecular testing

205.1.0.5.5 Treatment

• Supportive
• No specific antiviral
• Ribavirin off-label (HSCT severe)
• IVIG sometimes
• Mechanical ventilation as needed

205.1.0.5.6 Vaccine + Future

• MEDI-7510 mAb candidate
• mRNA vaccine candidates (Moderna mRNA-1365)
• Phase 2-3 trials 2024-2025

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205.1.0.6 5️⃣ Enterovirus D68 (EV-D68)

205.1.0.6.1 Background

• Picornavirus
• Occasional outbreaks 2014, 2016, 2018, 2022-2024

205.1.0.6.2 Clinical

• Severe asthma exacerbation (especially children)
• Acute Flaccid Myelitis (AFM) — polio-like paralysis in children
  • 2014 USA cluster
  • Asymmetric limb weakness post-respiratory illness
  • MRI: cervical spinal cord gray matter lesions
  • 通報 CDC
  • Treatment: supportive; IVIG, steroid considered (mixed evidence)
• Bronchiolitis + pneumonia

205.1.0.6.3 Diagnosis

• Respiratory PCR (often missed unless EV-D68 specifically tested)
• CSF PCR (AFM)

205.1.0.6.4 Treatment

• Supportive
• No specific antiviral
• AFM: IVIG, steroid, fluoxetine (debated)

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205.1.0.7 6️⃣ Bocavirus (HBoV)

• Parvovirus family
• Co-infection common
• URI + LRTI in children
• Self-limited
• No specific antiviral

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205.1.0.8 7️⃣ Other Respiratory Viruses

205.1.0.8.1 Coronaviruses (Severe — SARS-CoV-2 in Ch 208)

205.1.0.8.2 Influenza (Ch 206)

205.1.0.8.3 RSV (Ch 207)

205.1.0.8.4 Hantavirus (Pulmonary Syndrome — Ch 219 in actual Harrison)

205.1.0.8.5 Adenovirus (Ch 210)

205.1.0.8.6 Measles (Ch 209)

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205.1.0.9 8️⃣ Treatment Summary

Virus	Treatment
Rhinovirus	Supportive
Seasonal coronavirus	Supportive
Parainfluenza croup	Dex + nebulized epinephrine for moderate-severe
Parainfluenza pneumonia (immunocompromise)	DAS181 off-label, supportive
HMPV	Supportive; ribavirin / IVIG off-label HSCT
Adenovirus (severe immunocompromise)	Cidofovir / brincidofovir
EV-D68	Supportive; IVIG / steroid AFM
Bocavirus	Supportive

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