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Mpox (Monkeypox)

Derm / Viral

Source: IDMP View on spectrum chart →
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Patient
Clinical scenario / source

Annotations only — chart still shows the full chemistry of each drug.

1. Clinical Syndrome

Orthopoxvirus skin and systemic infection. Classical disease: prodrome (fever, lymphadenopathy, myalgia 1–4 d) → centrifugal vesiculopustular rash (face → extremities → palms/soles), all lesions in same stage at one location. 2022+ outbreak features: predominantly MSM sexual transmission with genital, perianal, oral lesions + painful proctitis ± systemic features.

Two clades:

  • Clade I (Central African) — higher mortality (1–10%); ongoing 2024 DRC outbreak with sexual transmission.
  • Clade II (West African) — lower mortality (<0.1%); responsible for 2022 global outbreak.

Excludes: other vesicular rashes (varicella, HSV, herpes zoster, hand-foot-mouth), syphilis (often co-infection — test), molluscum contagiosum (smaller, umbilicated, no fever).

2. Pathogens

Consider the patient: Sexual exposure history, MSM network, immunocompromise (advanced HIV CD4 <200, transplant — severe + prolonged disease), pregnancy / lactation, prior smallpox vaccination (>1980 — partial cross-immunity), prior JYNNEOS vaccination.

Consider the case: Lesion distribution + severity (extensive vs limited), pain control needs (proctitis severe — opioids often needed), co-infection screen (HIV, syphilis, GC, chlamydia at minimum).

Common

    • Mpox Virus (Monkeypox)

      Orthopoxvirus. PCR lesion swab is gold standard. 2022 outbreak primarily clade II via MSM sexual transmission.

3. Empiric Therapy

TierFirst choiceAlternativesDurationComments
Outpatient
  • Supportive care only (most mild cases) — · — · —

    Acetaminophen / NSAIDs for pain; topical analgesics for genital lesions; sitz baths for proctitis; stool softeners; isolation until lesions fully crusted + re-epithelialized.

  • 600 mg · PO BID × 14 d with high-fat meal · PO

    **For severe disease or high-risk hosts** — extensive lesions, severe proctitis, ocular involvement, immunocompromised (HIV CD4 <200, transplant), pediatric, pregnancy. STOMP trial showed limited efficacy in immunocompetent.

Supportive: until lesions fully crusted + re-epithelialized (typically 2–4 weeks). Tecovirimat: 14 days.**Most cases self-limited.** **Pain control is the dominant clinical issue** — proctitis can be severe; opioids often needed. **Isolation precautions** (skin lesions = contact + droplet) until lesions fully resolved. **Sexual contact avoidance** during active lesions; recovered patients counseled re: sexual practices for ~12 weeks (case-by-case).
Admitted to ward
  • 600 mg · PO BID × 14 days with high-fat meal · PO
  • 200 mg IV · q12h × 14 d · IV

    When PO not tolerated.

  • Brincidofovir (CMX001) — · — · PO

    Lipid conjugate of cidofovir; broad DNA virus activity. Used as alternative when tecovirimat unavailable / resistant. Limited availability.

14 days**Hospitalized for severe disease, complications, or immunocompromised.** Pain control with opioids + neuropathic agents; nutritional support if oral lesions limit intake; surgical / urology / ENT / ophthalmology depending on lesion location.

4. Directed Therapy

Most cases are mild + self-limited — supportive care alone.

Tecovirimat indications (CDC):

  • Severe disease (extensive lesions, hemorrhagic, complications)
  • Severe proctitis with significant pain / urinary or fecal retention
  • Ocular involvement
  • Immunocompromised (HIV CD4 <200, transplant, biologics, chemo)
  • Pediatric (≥13 kg)
  • Pregnancy / lactation (with informed consent)
  • Mpox in setting of disrupted skin integrity (eczema, severe dermatitis — "eczema mpox" analog to eczema vaccinatum)

Supportive care priorities:

  • Pain control: scheduled acetaminophen / NSAIDs + opioids for severe lesion pain; topical lidocaine; sitz baths for perineal; stool softeners + viscous lidocaine for proctitis
  • Wound care + hygiene: keep lesions covered; avoid scratching; gentle cleansing
  • Co-infection screening: HIV, syphilis, GC, chlamydia at minimum (sexually transmitted contexts)
  • Bacterial superinfection: monitor — empiric coverage if cellulitic appearance (cephalexin / amox-clav)
  • Isolation: until lesions fully crusted + new intact skin (typically 2–4 weeks)

Adjuncts: tecovirimat under EUA in US. Brincidofovir = alternative DNA polymerase inhibitor (less data, limited availability, hepatotoxicity).

Vaccination prevention:

  • JYNNEOS (modified vaccinia Ankara, replication-deficient): 2-dose series 28 days apart, subQ or ID. Approved for adults ≥18; off-label in pediatrics with risk.
  • Pre-exposure: at-risk MSM + healthcare workers in outbreak settings.
  • Post-exposure: ideally within 4 days of exposure (prevention); 4–14 days may modify disease severity.
  • ACAM2000 (replication-competent) is alternative but more reactogenic; avoid in pregnancy, immunocompromise, atopic dermatitis (eczema vaccinatum risk).

5. Monitoring

Resolution: lesion progression to crusting + re-epithelialization (~2–4 weeks). Persistent / new lesions despite tecovirimat → consider tecovirimat resistance (F13L mutation; brincidofovir alternative).

Pain control + supportive care effectiveness is the main clinical metric.

Toxicity: tecovirimat → headache, nausea (mild). Brincidofovir → hepatotoxicity (more concerning), diarrhea.

Sexual transmission: live virus has been recovered from semen weeks after recovery; CDC recommends condoms × 12 weeks post-recovery; case-by-case counseling.

Pearls

2022 outbreak profile: MSM sexual transmission, genital/perianal/oral lesions, proctitis (often severe). Painful proctitis is the dominant clinical issue — aggressive pain control + symptom management. Most cases mild + self-limited — tecovirimat reserved for severe / high-risk per STOMP 2024. JYNNEOS vaccine prevention is the bigger story than treatment. Always screen for co-infections (HIV, syphilis, GC, chlamydia). Lymphadenopathy is a key distinguishing feature from smallpox (smallpox typically lacks LAD). Eczema mpox (analog to eczema vaccinatum) — severe disseminated disease in atopic dermatitis patients; treat aggressively. No flying or air travel during active lesions per CDC.

References