Makindo Medical Notes

Related Subjects: |Herpes Varicella-Zoster (Shingles) Infection |Chickenpox Varicella Infection |Varicella Cerebral Vasculopathy |Herpes Viruses |Herpes Zoster Ophthalmicus (HZO) Shingles |MonkeyPox |Mumps |Measles |Rubella (German Measles) |Epstein-Barr Virus infection

🦠 Monkeypox (Mpox) is a zoonotic viral infection caused by the Monkeypox virus (MPXV). It is endemic in parts of West and Central Africa but outbreaks have occurred worldwide, including in Europe and the UK. Most cases are self-limiting, but severe disease can occur in immunocompromised individuals, children, and pregnant women.

🔬 Pathology

• Caused by the Monkeypox virus, an enveloped double-stranded DNA virus.
• Belongs to the Orthopoxvirus genus (includes Variola – smallpox, Vaccinia, and Cowpox).

📜 History

• First identified in monkeys in 1958 during laboratory outbreaks.
• First human case reported in 1970 in the Democratic Republic of Congo.
• Since 2022, human-to-human transmission (including via close and sexual contact) has led to global outbreaks.

🦠 Spread / Aetiology

• Animal-to-human: bites/scratches, contact with blood or lesions, consumption of undercooked bushmeat.
• Human-to-human:
  • Direct contact with rash, scabs, or body fluids.
  • Contaminated materials (bedding, clothing, towels).
  • Respiratory droplets with prolonged close exposure.
  • Intimate/sexual contact – increasingly recognised in recent outbreaks.
• Reservoir thought to be rodents (rats, squirrels, mice) rather than monkeys.

🩺 Clinical Features

• Prodrome: fever, malaise, myalgia, headache, lymphadenopathy (key feature distinguishing from smallpox).
• Rash: 1–3 days later, starts on face → spreads centrifugally (trunk, limbs, palms/soles, mucous membranes).
• Lesions evolve synchronously: macules → papules → vesicles → pustules → crusts/scabs.
• Duration: 2–4 weeks; usually self-limiting.
• Complications: bacterial superinfection, pneumonia, encephalitis, keratitis, sepsis.

⚖️ Differential Diagnosis

• Chickenpox (varicella) – asynchronous lesions, less lymphadenopathy.
• Measles – rash + Koplik spots, respiratory prodrome.
• HSV/VZV reactivation (shingles).
• Secondary syphilis (palmar/plantar rash).
• Scabies, bacterial impetigo, drug eruptions.

🧪 Investigations

• Swabs from lesions in viral transport medium → PCR (definitive diagnosis).
• Blood tests: HIV status (important for severity risk), syphilis, HSV/varicella as appropriate.
• Always inform laboratory & public health if Mpox suspected (“probable MPX”).
• Contact tracing and case isolation are crucial.

💊 Management

• Infection Control:
  • Isolate suspected/confirmed cases.
  • PPE for staff: FFP2/3 mask, gown, gloves, eye protection.
• Supportive: hydration, analgesia, antipyretics.
• Secondary infections: antibiotics if bacterial superinfection suspected.
• Antivirals & immunotherapy:
  • Tecovirimat (ST-246) – available via specialist centres, recommended for severe disease or immunosuppressed patients.
  • Cidofovir or brincidofovir – less commonly used, reserved cases.
  • Vaccinia Immune Globulin (VIG) – rare, for severe immunodeficiency.
• Vaccination: Modified vaccinia Ankara (MVA-BN, Jynneos/Imvanex) used in ring vaccination strategy for contacts and at-risk groups.
• All cases require infectious disease (ID) input and notification to UKHSA/Public Health.

📊 Prognosis

• Most recover fully within 2–4 weeks.
• Case fatality rates vary by clade: Clade I (Congo Basin) up to 10%; Clade II (West African, recent outbreaks) ~1% or lower.
• Severe disease more likely in children, pregnant women, and immunocompromised patients.

📚 References

• CDC: Monkeypox Clinical Guidance
• UKHSA – Monkeypox Guidance
• Irish Clinical Resource on Mpox