SUMMARY:

Mpox is a zoonosis (a disease that is transmitted from animals to humans). However, human-to-human cases have been reported and occur through contact with bodily fluids, lesions on the skin or on internal mucosal surfaces, such as in the mouth or throat, respiratory droplets and contaminated objects.

MPOX: GENERAL CONSIDERATIONS

Signs and Symptoms

• Incubation period: 3 to 17 days
• Prodromal period (initial symptoms)
  • Fever
  • Headache
  • Muscle aches
  • Backache
  • Swollen lymph nodes
  • Chills
  • Exhaustion
  • Note: above symptoms may not occur, or may follow rash development

• Within 1 to 3 days (sometimes longer) following fever
  • Rash beginning on the face then spreading to other parts of the body
  • Lesions often occur in the genital and anorectal areas or in the mouth
  • Rash is not always disseminated across many sites on the body
  • Rash may be confined to only a few lesions or only a single lesion
  • Rash does not always appear on palms and soles
• Lesions
  • Well circumscribed, deep seated, and often develop umbilication (resembles a dot on the top of the lesion)
  • Are of similar size and stage of development on a single site of the body (ex: pustules on face or vesicles on legs)
  • Disseminated rash is centrifugal (more lesions on extremities, face)
  • Described initially as painful, then itchy while healing
• Lesions progression prior to falling off
  • Macules
  • Papules
  • Vesicles
  • Pustules
  • Scabs followed by resolution

• Illness duration
  • 2 to 4 weeks
• Testing
  • Follow CDC guidelines on infection prevention and control guidelines for suspected cases (see primary resources)
  • PCR is the preferred laboratory test for mpox
  • Best diagnostic specimens are directly from the rash
    • Skin | Fluid or crusts | Biopsy where feasible
  • Antigen and antibody detection methods may not be useful as they do not distinguish between orthopoxviruses

Note: After investigating cases of false-positive mpox test results, the CDC now recommends retesting low-risk individuals who test positive with low amounts of virus detected | Consider alternative diagnoses such as hand, foot, and mouth disease; varicella; or molluscum contagiosum

Pregnancy

• Mpox in pregnancy has been associated with
  • Miscarriage
  • Preterm Birth
  • Stillbirth
• Vertical transmission during pregnancy is possible as well as close contact with the newborn following delivery
• It is currently unknown if pregnancy is associated with more severe disease or higher susceptibility to infection
• Treatment should be prioritized for cases identified during pregnancy, recent pregnancy or breastfeeding
• Antenatal monitoring
  • Monitor for severe disease
  • Individualize outpatient vs inpatient care  

Mortality

• In Africa, mpox has been shown to cause death in as many as 1 in 10 persons who contract the disease
• Severity is dependent on health of the individual, the route of exposure, and the strain of the infecting virus

Treatment

• There is no treatment specifically for mpox
• Some drugs developed for smallpox may be used to treat mpox infections due to the genetic similarity between the two viruses
• Antiviral: Tecovirimat (TPOXX)
  • For severe disease: Hemorrhagic | Large number of confluent lesions | Severe necrotizing or obstructing lymphadenopathy | Sepsis | myocarditis | disease requiring hospitalization | Infection of areas at high risk for strictures
  • Consider treatment for patients at high risk for severe disease: Immunocompromised | Pediatric | Pregnant | Breastfeeding | Conditions affecting skin integrity
  • For high-risk patients
• Most patients recover fully within 2 to 4 weeks without treatment
• Patients with mpox should follow CDC guidelines on Isolation
• There are additional therapuetic interventions that can be considered for use if an alternative to tecovirimat is required (refer to CDC links in the ‘Learn More – Primary Sources’ below)

Vaccines

• Recommended for people who have been in contact with someone with mpox
  • Have had multiple sexual partners in the past 2 weeks in an area with known mpox infections
  • Have jobs that may expose them to orthopoxviruses
• The preferred vaccine against mpox is JYNNEOS, a 2-dose vaccine
  • Immune protection is maximized 14 days after the second vaccine dose
• An alternative vaccine to JYNNEOS may be ACAM2000, a single-dose vaccine
  • Immune protection is maximized 4 weeks after dose
  • Has potential for more side effects and adverse events than JYNNEOS

KEY POINTS:

• Diagnostic specifiers include: (Please see CDC Image Gallery in ‘Learn More – Primary Sources’ below for more on lesion identification)
  • Prodromal symptoms may or may not precede rash and can follow rash
• PCR of diagnostic specimen from the rash is the preferred laboratory test for mpox
• Most cases resolve in 2 to 4 weeks without need for treatment
• Some antiviral drugs developed for smallpox, such as tecovirimat (TPOXX), may be used to treat severe mpox infections
• Vaccination is recommended for those exposed to mpox and/or at high risk of contracting mpox
  • The preferred vaccine is JYNNEOS, a 2-dose vaccine
• Physicians and patients should follow CDC guidelines for Infection Prevention
• Evaluate all sexually active adults and adolescents in whom mpox is suspected for HIV and other STIs and provide follow-up as necessary

Learn More – Primary Sources:

General Resources Including Lesion Images

• CDC: Mpox information specifically for healthcare professionals
• CDC (includes IMAGE GALLERY): Clinical Recognition | Mpox
• Tecovirimat Use under Expanded Access to Treat Mpox in the United States, 2022–2023 | NEJM Evidence
• AMA: New CPT Codes for Mpox
• Identifying False-Positive Mpox Results
• CDC: Clinical Considerations for Use of Vaccine for Mpox Prevention in the United States
• SMFM: Mpox Guidance
• Mpox Considerations for People Who Are Pregnant or Breastfeeding