MPOX: The Current Outbreak


Mpox (previously known as monkeypox) is an orthopoxvirus (same genus as smallpox) primarily transmitted via direct contact with infectious sores/scabs (and possibly also via bodily fluids.)

Transmission can occur from onset of symptoms until rash has resolved (i.e., scabs have fallen off and skin has healed)

  • Incubation period is generally 1-2 weeks
  • Auto-inoculation may lead to worsening rash

Changing Epidemiology

Mpox was first identified in 1970 in Zaire (now the Democratic Republic of the Congo). There are 2 clades (i.e., group of organisms believed to have evolved from a common ancestor):

  • Central African clade: by far the most common form over first 3 decades; higher mortality [case fatality rate of 10.6% (95% CI: 8.4%-13.3%)]
  • West African clade: responsible for the global outbreak starting in May 2022; lower mortality [case fatality rate of 3.6% (95% CI: 1.7%-6.8%)]
Source: Bunge EM et al. PLoS Negl Trop Dis. 2022

Interestingly, mpox was initially a disease that primarily affected children:

  • In the first 2 decades following its discovery, median age at presentation was 4-5yo for mpox infections. Age at presentation increased to 10yo for 2000-2009 and 21yo for 2010-2019.
  • Regarding age at death in mpox cases, 100% of deaths were in children <10yo in the early years, while for the years 2000–2019, age <10yo accounted for 37.5% of deaths. 

The current outbreak is not the first. Over the past 5 decades, mpox outbreaks have been reported in 10 countries in Africa and 4 countries outside Africa. 

  • Mpox is endemic in 10 countries in Central and Western Africa. 

Regarding the current outbreak, there are over 64,000 confirmed cases of mpox worldwide as of today. 


CDC is tracking symptom frequency as US cases are confirmed.

  • Fever and prodrome (lethargy, myalgia, headache)
  • Rash within 5 days of illness onset (often starts on a mucosal area)
    • Deep-seated and well-circumscribed lesions, often with central umbilication
    • Lesions may progress through sequential stages: macules, papules, vesicles, pustules, and scabs
    • Lesions occur in variable sites, and may be single or multiple
  • Throat/rectal pain (often severe)
  • Lymphadenopathy (most often cervical and/or inguinal)

“Solitary genital skin lesions and lesions involving the palms and soles may easily lead to misdiagnosis as syphilis and other STIs, which may in turn delay detection.”

Thornhill et al, NEJM 2022

Panel A shows the evolution of cutaneous lesions in a person with monkeypox; images a1 and a2 show facial lesions, images b1 through b3 show a penile lesion, and images c1 and c2 show a lesion on the forehead.

Panel B shows oral and perioral lesions: image a, perioral umbilicated lesions; image b, perioral vesicular lesion on day 8, PCR positive; image c, ulcer on the left corner of the mouth on day 7, PCR positive; image d, tongue ulcer; image e, tongue lesion on day 5, PCR positive; and images f, g, and h, pharyngeal lesions on day 0, 3, and 21, respectively, PCR positive on day 0 and 3 and negative on day 21.

Panel C shows perianal, anal, and rectal lesions: image a, anal and perianal lesions on day 6, PCR positive; images b and c, rectal and anal lesions in a single person, PCR positive; image d, perianal ulcers, PCR positive; image e, anal lesions; image f, umbilicated perianal lesion on day 3, PCR positive; image g, umbilicated perianal lesions on day 3, PCR positive; and image h, perianal ulcer on day 2, PCR positive.

Left: Progression of penile lesions and penile oedema. Right: Development of solitary lesion on right upper inner thigh, tracking laterally to outer thigh.

Severe penile complications reported have included penile edema and paraphimosis. Urethral involvement can occur, leading to dysuria, difficulty urinating, or hematuria.

Symmetrical maculopapular rash of the torso, back, and buttocks.

Left: Symmetrical erythematous maculopapular rash on back and upper arms, with areas of confluent erythema. Right: Symmetrical maculopapular rash of the legs following monkeypox infection.

Cutaneous lesions on the nose, hand, and penis over time. On day 17 there were fresh pustular lesions on the hand, a partly scabbed lesion on the face, and fully scabbed lesions on the penis


Current process (time-intensive!) within our hospital system: 

  1. Discuss case with infection control team
  2. Discuss case with RIDOH, who provides testing authorization
  3. Communicate authorization to Lifespan’s microbiology lab, who sends test to ambulatory site
  4. Perform swabs and notify RIDOH for pick-up
  5. Perform contact tracing 

Severe Disease

The most common manifestations of severe disease are severe pain and secondary bacterial infection. 

  • Less common:
    • Poor PO intake / dehydration
    • Acute kidney injury
    • Eye involvement: conjunctivitis, blepharitis, keratitis, loss of vision
  • Rare:
    • Encephalitis
    • Epiglottitis
    • Pneumonitis
    • Myocarditis

Risk factors for severe disease:

  • Immunocompromised state
  • Children <8yo
  • Pregnancy
  • Prior skin disease (e.g., eczema, psoriasis)


  • Symptomatic care for pain:
    • Skin lesions: topical anesthetics (e.g., lidocaine cream)
    • Pharyngitis: saltwater gargles, chlorhexidine mouthwash, viscous lidocaine, and/or magic mouthwash
    • Proctitis: stool softeners, sitz baths
  • Tecoviramat (aka TPOXX)
    • Developed for treatment of smallpox (static not cidal); only available through CDC via local/state DOH
    • Indications: severe disease/pain, eye involvement
    • PO or IV formulations
      • Oral formulation must be taken 30 minutes after a full meal containing moderate/high fat (~25 g of fat)
      • Capsules can be opened and mixed with liquid
    • Generally well-tolerated; ADE include HA and GI upset
  • Trifluridine eye drops for eye involvement (antiviral)
  • Additional considerations for inpatient management


There is currently 1 vaccine with FDA approval: JYNNEOS (2-dose series)

  • Eligibility: after known or presumed exposure to someone with mpox (ideally within 4 days of exposure)
  • Vaccination clinics are available in Rhode Island through RIDOH
  • Note that the ACAM-2000 vaccine is a potential future option for mpox prophylaxis, but at this time is only approved for smallpox

Disease Stigma

How we talk about mpox matters.

Although mpox has thus far predominantly affected MSM, public health experts stress that mpox is relevant to everyone because of its mode of transmission. But public health officials have questioned how to raise awareness about mpox without making the early public health mistakes of the HIV/AIDS crisis when gay and bisexual men were stigmatized and discriminated against. Indeed, mpox shouldn’t share the same fate.

“Targeted health promotion that sensitively supports enhanced testing and education in populations at risk is needed. Involving communities from the outset in shaping the implementation of public health interventions is essential to ensure that they are appropriate and nonstigmatizing and to avoid messaging that will drive the outbreak underground… Although the current outbreak is disproportionately affecting gay or bisexual men and other men who have sex with men, monkeypox is no more a “gay disease” than it is an “African disease.” It can affect anyone.”

Thurman et al, NEJM 2022

CDC guidance on reducing stigma:

  • It’s important to reach any disproportionately affected community with non-alarmist, fact-based messaging about mpox that provides people with tools they can use to protect themselves and others.
  • Messages should be clear, non-judgmental, and avoid stigmatizing any sexual practice or community and ensure content is not homo-/bi-/trans-phobic or heterosexist.
  • When focusing messages to gay, bisexual, and other MSM, use targeted channels that directly reach these audiences, such as specific websites, dating apps, or media programs.

Take-Home Points!

  • Mpox has many potential presentations, including the rash itself
  • Obtaining a testing kit is a time-intensive process—ask for help!
  • System challenges—give feedback!
  • Not everyone needs Tpoxx—consider risk factors for severe disease
  • Vaccination is available for patients and providers
  • Disproportionate demographics—risk factors, messaging

Blog post based on Med-Peds Forum talk by Matt Lorenz, MP Core Faculty

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