mpox

MICROBIOLOGY

• DNA virus and a member of the orthopoxvirus genus of the Poxviridae family, monkeypox is similar to smallpox (variola virus), smallpox vaccine (vaccinia virus), and cowpox virus.
  • In November 2022, the WHO renamed "monkeypox" to "mpox," allowing for a 1-year transition during which both names would be recognized. In 2025, the CDC reverted to monkeypox as its preferred designation.
    • The idea was to reduce the stigma and discrimination associated with the "monkeypox" name and ensure that the infection is not associated much with non-human primates.
  • WHO is using Roman numerals for MPXV variants.
    • The former Congo Basin (Central African) clade is now referred to as Clade I.
      • Has high reported human-to-human transmission rates and mortality (up to 10% historically).
      • It tends to affect children > adults, with higher mortality than Clade II.
        • Recent data suggest < 0.5% for Clade Ib to about 3% for Clade Ia.
    • The former West African clade is Clade II.
      • Clade IIa
        • It causes a mild illness with limited human-to-human transmission and low mortality (~1-3%).
      • Clade IIb refers to variants that circulated during the 2022 global outbreak.
• Although initially named monkeypox, the animal reservoir is believed to be African rodents; however, this has not been fully defined.

CLINICAL

• Previously, an uncommon zoonotic disease spread between infected animals, humans, and contaminated materials.
  • First isolated in 1958, with the first human case in 1970, most human cases are seen in Central and West Africa.
    • Before 2022, cases in the U.S. were predominantly imported or due to contact with animals.
    • Progressively, more cases have been reported annually in Africa (particularly in the DRC and West Africa) since the 1970s.
  • It resembles smallpox but is milder and less transmissible.
  • A large number of cases in Nigeria since 2017 can be traced as the basis of the current WHO global public health emergency.
• Outbreaks in the U.S.
  • 2003: 71 confirmed or suspected cases.
    • The first U.S. outbreak was traced to the importation of Gambian giant rats, squirrels, and dormice, which spread to prairie dogs sold as pets.[32]
      • Eighteen were hospitalized, and no deaths.
  • 2022 outbreak: low-level transmission of Clade II continues worldwide.
    • The U.S. has had the highest number of cases from this outbreak through 2024.
    • Numbers are likely to underestimate actual cases.
      • In the U.S., the majority of cases of clade II are in people who are unvaccinated or have received only one dose of Jynneos.
        • Averaging ~200 cases or fewer per month since 2024.
        • CDC reported statistics: trends and daily cases
    • Spread within social networks implicated, reported in men who have sex with men (MSM), bisexual; few reports in women or children.
    • Deaths are rare in the U.S. and other non-endemic countries during this outbreak. This clade of the mpox virus appears milder than the disease acquired in Africa.
      • The CDC report of deaths in October 2022 found that the majority are Black MSM with advanced HIV, not on ART.
    • 2025: Low levels of Clade II cases continue worldwide.
  • The 2023-24 regional upsurge in the Democratic Republic of the Congo (DRC) is ongoing in 2026. Due to Clade I or Ib, the country has the highest recorded case count, and most provinces have reported cases.
    
    • WHO declared a Public Health Emergency of International Concern in August 2024 based on >15,000 cases and 537 deaths in the DRC. WHO emergency status ended September 2025; however, explicitly stated there is an ongoing public health concern due to ongoing transmission.
      
      • Much of the spread appears to be within Congolese households and children, but it has now spread to neighboring countries: Burundi, Kenya, Rwanda and Uganda since 2024-2025.
        • Due to subtype Clade 1b, which emerged in eastern DRC.
    • Travel-related cases have been seen in Europe since the summer of 2024.
      • Current situational awareness of mpox in the U.S. and globally can be found at the CDC and WHO.
    • Clade 1 in the U.S.: patients with a travel history with infection confirmed first in California (2024), Georgia (Jan 2025).
      • The CDC judges the risk of widespread Clade 1 transmission in the U.S. as currently low.
• Transmission
  • The virus may be acquired through contact, including intact skin and mucous membranes, generally close, often skin-to-skin contact, including direct contact with lesions, body fluids, contaminated materials, and respiratory secretions (less common) during prolonged close contact.
    • Animal-to-human transmission is seen following an infected animal bite or scratch, butchering bush meat, direct contact with body fluids or lesions, or contaminated materials.
    • Acquisition by human-to-human is believed to be predominantly through large respiratory droplets among African cases, although they may also be sexually transmitted or through social networks.
      • As a large pox virus, it is not believed to be aerosolizable, but CDC remains recommending respiratory-level PPE.
      • The virus enters the body via broken skin, the respiratory tract or the mucous membranes.
      • Household and nosocomial transmission are described
      • Fomite transmission occurs via contaminated clothing or bed sheets.
    • From acquisition to the first symptoms, the duration may range from 5 to 21 days, with an average of 1 to 2 weeks.
• Human-to-dog transmission has been documented, which is not unexpected since this poxvirus can be spread among mammals, especially small mammals.
  • The virus’s worrisome aspect of entering other animal populations makes control difficult.
• Symptoms: Note that some individuals initially develop a rash, followed by other symptoms, while others experience only a rash.
  • Initial viral prodrome
    • Fever, chills, headache, myalgia, back pain, fatigue
      • Occasionally, a sore throat with lesions on the tongue and oral mucosa
  • Rash phase, typically 1 to 3 days after symptom onset.
    • Viral exanthem, flat/red, becomes nodular, umbilicated, and pox-like with fluid/pus before crusting.
      • Lesions, described as painful, appear in the same stage of development on a single site of the body.
      • Lymphadenopathy often accompanies this phase.
    • For example, in Africa, the rash often begins on the face [Fig. 1], and then spreads [Fig. 2], including the palms [Fig. 3].
      
      • Skin lesions do not develop in all individuals who are infected.
    • Clade II (2022 outbreak - 2026): nodular, pustular, pox-like, and may have eschar, [Fig. 4] and [Fig. 5]
      • Consider all oral, genital and anal (proctitis, too) lesions potentially due to mpox.
        • The rash may appear as pustules, blisters or pimples that may be pruritic or painful.
        • Rectal involvement may cause bloody stools (tenesmus), rectal bleeding, severe rectal pain, and local purulence.
        • Rash onset and evolution are not synchronous; lesions may range from several stages.
          • Lesion(s) may range from a single spot to a grouping to disseminated cutaneous lesions across the body.
            • Lesions may produce pain, which is often pruritic when they are crusted.
          • The rash is not always on the palms or soles.
      • Fever, headache, myalgia, fatigue
      • Lymphadenopathy
      • Respiratory symptoms include dry cough, sore throat and nasal congestion.
  • The illness resolves within 4 weeks.
  • Mortality ranges from 1 to 10% in reported series from Africa (the higher range figure is older data, for Clade I); the 2022 outbreak appears milder, though capable of severe illness, especially in immunocompromised people.
    • Most deaths occur in children or people with HIV.
      • Lessons from the 2022 outbreak showed that most severe outcomes and deaths occur in people with significant immunocompromise, including advanced HIV, and in some settings in children with malnutrition or other comorbid conditions.
    • Risk factors for severe illness appear to be a fever of ≥ 38.3°C and more than 100 skin lesions.
• Differential diagnosis: varicella zoster (primary infection, aka chickenpox), other pox infections (cowpox, orf), smallpox.
  • Consider herpes zoster (shingles), measles, and STIs, i.e., syphilis, HSV, LGV and chancroid.
  • Test for STIs in mpox patients as above, including HIV if not known.
• Diagnosis:
  • Clinical suspicion is necessary; contact the local or state health department for assistance with diagnosis.
  • Real-time PCR of skin lesion material, collect two swabs from each lesion, ideally sampling 2–3 lesions from different body sites or with different appearance.
    • Obtain multiple samples and collect them dry; do not add or store them in viral or universal transport media.
    • CDC guidance for specimen collection
      • Contact the lab for specimen requirements.
      • Wear PPE
      • Skin lesion, pharyngeal and rectal swabs are appropriate.
  • Serology may be helpful if specimens are not available, but PCR is preferred.
    • Submitting specimens to the CDC instructions link.
  • CDC case definitions: (1/30/26)
    • Suspect case
      • New characteristic rash* OR
      • Meets one of the epidemiologic criteria and has a high clinical suspicion for monkeypox
    • Probable case
      • No suspicion of other recent Orthopoxvirus exposure (e.g., Vaccinia virus in ACAM2000 vaccination) AND demonstration of the presence of:
        • Orthopoxvirus DNA by polymerase chain reaction of a clinical specimen OR
        • Orthopoxvirus using immunohistochemical or electron microscopy testing methods OR
        • Demonstration of detectable levels of anti-orthopoxvirus IgM antibody during the period of 4 to 56 days after rash onset
    • Confirmed case: Demonstration of the presence of monkeypox virus (MPXV) DNA by polymerase chain reaction testing or Next-Generation sequencing of a clinical specimen OR Isolation of MPXV in culture from a clinical specimen
    • Epidemiologic criteria Within 21 days of illness onset:
      • Reports having contact with a person or people with a similar appearing rash or who received a diagnosis of confirmed or probable monkeypox OR
        • Had close or intimate in-person contact with individuals in a social network experiencing monkeypox activity, this includes men who have sex with men (MSM) who meet partners through an online website, digital application ("app"), or social event (e.g., a bar or party) OR
        • Traveled outside the US to a country with confirmed cases of monkeypox or where MPXV is endemic OR
        • Had contact with a dead or live wild animal or exotic pet that is an African endemic species or used a product derived from such animals (e.g., game meat, creams, lotions, powders, etc.)
    • Exclusion criteria: A case may be excluded as a suspect, probable, or confirmed case if:
      • An alternative diagnosis can fully explain the illness OR
      • An individual with symptoms consistent with monkeypox does not develop a rash within 5 days of illness onset OR
      • A case where high-quality specimens do not demonstrate the presence of orthopoxvirus, MPXV, OR antibodies to orthopoxvirus
  • CDC definitions for Clade 1 mpox (as of 12/12/25)
    • Suspect case, Clade I
      • Probable or confirmed monkeypox as defined above AND
      • At least one of the Clade I Epidemiologic Criteria (below)
    • Probable case, Clade 1
      
      • Probable or confirmed monkeypox as defined above AND
      • At least one of the Clade I Epidemiologic Criteria (below) AND
      • Clade II MPXV-negative by polymerase chain reaction testing without Next-Generation sequencing of a clinical specimen to confirm clade
    • Confirmed case, Clade I
      • Demonstration of the presence of clade I MPXV DNA by polymerase chain reaction testing OR Next-Generation sequencing of a clinical specimen
    • Clade I epidemiologic criteria Within 21 days of illness onset:
      • Traveled to an area with evidence of sustained human to human transmission of clade I monkeypox or where clade I MPXV is endemic, OR
      • Reports having contact with person with confirmed, probable or suspect clade I monkeypox, OR
      • Had close or intimate in-person contact with individuals in a social network currently experiencing clade I monkeypox activity, OR
      • Had contact with a dead or live wild animal or exotic pet that is a central African endemic species or used a product derived from such animals (e.g., game meat, creams, lotions, powders, etc.)
      *This interim definition applies to the current situation with Clade I cases globally. If the situation changes, this interim definition will be updated accordingly.
  • The CDC recommends that clinicians collect two specimens from each patient, each from multiple lesions, preferably from different locations on the body and from lesions with varying appearances.

SITES OF INFECTION

• Oral: oral ulceration(s) or pharyngitis.
• Ocular: may threaten vision and suggest rapid treatment initiation, though there is limited data on effectiveness in this situation.
• Cutaneous: Before crusting, macular or papular lesions evolve into nodules, vesicles, or pustules (pox lesions). Lesions often start on the face, mouth, genitals or anus. It may remain limited in a regional area and spread over the body, including palms and soles.
• LN: lymphadenopathy
• Pulmonary: pneumonitis, particularly in severe cases
• Pregnancy: data from DRC[8]
  • Clade I settings suggest that especially early trimester infection correlates with poor outcomes, and should be treated as a very high-risk state in clade I settings.
• Proctitis: may be severe; a frequent reason for hospital admission
• Cardiac: myocarditis, pericarditis, myopericarditis
• CNS: encephalitis, myelitis
  • Lymphocytic pleocytosis in CSF.
  • MRI may have enhancing lesions.

TREATMENT

FOLLOW UP

• Most severe outcomes and deaths occur in people with significant immunocompromise, including advanced HIV, and in some settings in children with malnutrition or other comorbid conditions.
• If new lesions are forming ≥ 7d of antiviral therapy, consider:
  • Orthopoxvirus PCR testing of new lesions
  • Assess for superinfection (bacterial)
  • Serology to assess IgM response
  • Tecovirimat pharmacokinetic testing
  • Tecovirimat resistance testing
• Sterile abscesses, bacterial superinfection, and bacteremia are seen.
• Isolation practices for confirmed mpox.
  • Isolate at home or another location for the duration of the illness.
  • Isolation ceases when all symptoms have resolved, including all skin lesions that have healed with a fresh layer of skin (not just crusted).
    • The duration ranges from 2 to 4 weeks.
  • While with rash, cover all parts of the skin with clothing, gloves or bandages.
  • Wear a tight-fitting mask, even if you have no fever or respiratory symptoms.
  • Do not share items with others, avoid close contact, and wash hands with alcohol-based sanitizer or soap and water.

OTHER INFORMATION

• The low level of cases continues; we may expect clusters of cases to occur in the U.S. and elsewhere, especially among high-risk individuals who gather for community events.
  
  • Two-dose JYNNEOS vaccination is strongly recommended for all individuals at risk.
  • Those who have received only 1 dose are encouraged to get a second dose for enhanced protection against infection.
  • Two-dose efficacy studies have reported a range of 66-86%. Lower rates were seen among immunocompromised, advanced HIV or 1 dose (51%).
• An increase in mpox cases has been ascribed to the successful eradication of smallpox and the cessation of vaccinia immunization programs.

Basis for recommendation

1. Rao AK, Minhaj FS, Carter RJ, et al. Use of JYNNEOS (Smallpox and Mpox Vaccine, Live, Nonreplicating) for Persons Aged ≥18 Years at Risk for Mpox During an Mpox Outbreak: Recommendations of the Advisory Committee on Immunization Practices - United States, 2023. MMWR Morb Mortal Wkly Rep. 2025;74(22):385-392.  [PMID:40531798]

   Comment: ACIP has now issued formal guidance superseding prior interim recommendations. ACIP recommends immunization for adults at risk. New data over the last couple of years have yielded safety information as well as efficacy data. Moreover, immunization is recommended during clade IIb outbreaks for those at risk. Identified risks have remain unchanged since 2022 recommendations and are 1) MSM who, during the past 6 months, have had or anticipate experiencing at least one of the following: a new diagnosis of one or more sexually transmitted infections, more than one sex partner, sex at a commercial sex venue, or sex in association with a large public event in a geographic area where mpox transmission is occurring; 2) sexual partners of persons who have any of these risk factors; and 3) persons who anticipate experiencing any of these risk factors.
   

2. Dalton AF, Diallo AO, Chard AN, et al. Estimated Effectiveness of JYNNEOS Vaccine in Preventing Mpox: A Multijurisdictional Case-Control Study - United States, August 19, 2022-March 31, 2023. MMWR Morb Mortal Wkly Rep. 2023;72(20):553-558.  [PMID:37200229]

   Comment: More complete data is available, and this is from real-world data for vaccine efficacy which found VE was 75% for one dose and 86% for two doses. This was irrespective of the route of administration or immune status. These data have led to the strong recommendation to recommend a two-dose schedule for risk groups.
   

3. Rao AK, Schrodt CA, Minhaj FS, et al. Interim Clinical Treatment Considerations for Severe Manifestations of Mpox - United States, February 2023. MMWR Morb Mortal Wkly Rep. 2023;72(9):232-243.  [PMID:36862595]

   Comment: Updated guidance based on low levels of evidence for the use of tecovirimat, brincidofovir, cidofovir, trifluridine ophthalmic solution, and vaccinia immune globulin intravenous. As of 2026, tecovirimat given the STOMP and PALM trials should not be used for routine disease in non-severely immunocompromised individuals.
   

4. O'Shea J, Filardo TD, Morris SB, et al. Interim Guidance for Prevention and Treatment of Monkeypox in Persons with HIV Infection - United States, August 2022. MMWR Morb Mortal Wkly Rep. 2022;71(32):1023-1028.  [PMID:35951495]

   Comment: The guidance is directed explicitly at people with HIV as they are a substantial portion of the current outbreak. The concern is that they may be at increased risk for severe infection, so using tecovirimat is suggested. The cut-off is not known, but some consider CD4 < 350 as a value. They also note early administration of vaccines (≤4 days after exposure) might prevent monkeypox, and later use (5–14 days after exposure) might decrease the severity of monkeypox if infection occurs---although this is unstudied re: MPVX.
   

5. CDC. Caring for Patients with Monkeypox https://www.cdc.gov/monkeypox/hcp/clinical-care/index.html (last updated 1/15/26, accessed 3/23/2026)

   Comment: Treatment should be considered in sensitive anatomical areas with a risk of scarring and those with severe illness. Also, those at high risk of severe mpox infections. Recent trials showing a lack of efficacy of tecovirimat in mild-moderate disease are now incoporated. Combination therapy is often employed in progressive disease in those with advanced immunosuppression. Advice is also given for brincidofovir, VIVIG, and cidofovir. Note: CDC has returned to monkeypox nomenclature in 2025.
   

References

6. Priyamvada L, Minhaj FS, Likafi T, et al. Immunogenicity and safety of MVA-BN vaccine administered 5 years after a two-dose primary series in DR Congo: a prospective cohort study. Lancet Infect Dis. 2026.  [PMID:41819114]

   Comment: In people who had received a 2-dose MVA-BN series 5 years earlier, antibody levels had waned. Still, a booster produced a rapid anamnestic response, including a 93-fold rise in neutralizing antibody titers by day 14 in historically naïve participants, with day-545 titers still >6-fold above baseline. These data support preserved immune memory and give a biological rationale for booster strategies in higher-risk groups.
   

7. Cholli PA, Zucker J, Vigil KJ, et al. Long-Term Mpox Sequelae 11 to 18 Months After Acute Illness : A Cohort Study in Two U.S. Cities. Ann Intern Med. 2026.  [PMID:41554127]

   Comment: A cohort study (n= 154, LAMP study) conducted in Houston and New York City mpox found 58% with at least one persistent issue, with 13% suffering from functional limitations in this time frame. Cited sites with frequency include epithelialized penis, otehr groin/mucosal sites, arms, face & ears, and trunk (ranges 30% to 47%). Small numbers reported anorectal defectation issues (10 pts, 6%) and urinary hesitancy or incontinence (7 pts, 4%).
   

8. Vakaniaki EH, Barhishindi I, Mubiala A, et al. Maternal and neonatal outcomes after infection with monkeypox virus clade I during pregnancy in DR Congo: a pooled, prospective cohort study. Lancet. 2026;407(10525):256-266.  [PMID:41429130]

   Comment: Among 89 pregnant patients with clade I mpox from the DRC, final outcomes were known for 69; adverse outcomes occurred in 51%, including fetal loss in 45%, and first-trimester infection carried the highest risk. Higher lesion viral load, HIV, genital lesions, and direct sexual exposure were also associated with worse outcomes. This is the clearest recent signal that pregnancy, especially early pregnancy, should be treated as a very high-risk state in clade I settings.
   

9. Zucker J, Fischer WA, Zheng L, et al. Tecovirimat for the Treatment of Mpox. N Engl J Med. 2026;394(9):884-895.  [PMID:41740032]

   Comment: This phase 3 RCT of tecovirimat was disappointing, with nearly identical resolution between the treatment arm and placebo (83% vs 84%). No benefits were found either regarding severe pain or viral clearance. Importantly, even with receipt of prior mpox vaccine or HIV status, the active arm did not have better outcomes. Safety was generally good and similar to placebo. This is similar to the PALM007 trial with clade I mpox. One issue is that the dosing may have been too low? This trial does not address whether combination therapy for those with advanced immunosuppression benefits from tecovirimat.
   

10. Van Dijck C, Berens-Riha N, Zaeck LM, et al. Long-term consequences of monkeypox virus infection or modified vaccinia virus Ankara vaccination in Belgium (MPX-COHORT and POQS-FU-PLUS): a 24-month prospective and retrospective cohort study. Lancet Infect Dis. 2026;26(2):190-202.  [PMID:41213280]

    Comment: At 8, 16, and 24 months, saliva, anorectal, and available semen PCRs were negative, arguing against prolonged clinically relevant shedding at those late time points. This study also found stronger and more durable immune memory after natural infection than after MVA-BN vaccination; only 4% of vaccinated participants had detectable MPXV neutralizing antibodies at month 8. Clinically, this reinforces the idea that vaccine-induced protection may wane and require boosting in some populations.
    

11. Viguier C, Delobel P, Lescure FX, et al. From neglected to notoriety: a review of Mpox clinical features, virology, epidemiology, treatment and prevention strategies. Eur J Clin Microbiol Infect Dis. 2025;44(11):2569-2596.  [PMID:40928725]

    Comment: Characteristic, comprehensive treatise in this Eur J Clin Micro and ID paper from this group.
    

12. Rohilla S, Gaidhane S, Balaraman AK, et al. Ophthalmic Manifestations of the Mpox Virus: A Systematic Review and Meta-Analysis. J Infect Dis. 2025.  [PMID:39913333]

    Comment: In this review of the literature and meta-analysis, conjunctivitis is the most common ophthalmic complication of Mpox, followed by notable rates for keratitis, eye lesions, and visual impairment. Visual impairment ranged considerably in studies. The treatment effect is not addressed.
    

13. PALM007 Writing Group, Ali R, Alonga J, et al. Tecovirimat for Clade I MPXV Infection in the Democratic Republic of Congo. N Engl J Med. 2025;392(15):1484-1496.  [PMID:40239067]

    Comment: A placebo-controlled randomized controlled trial (RCT) for Clade I disease did not find that tecovirimat led to faster disease resolution in these immunocompetent patients. The mortality rate was lower than usual for clade one disease (1.7%). No safety issues were seen in this trial of 597 patients, with 295 receiving the antiviral.
    

14. Musuka G, Moyo E, Tungwarara N, et al. A critical review of mpox outbreaks, risk factors, and prevention efforts in Africa: lessons learned and evolving practices. IJID Reg. 2024;12:100402.  [PMID:39157420]

    Comment: While most in North America focused on Clade II, Clade I and Ib have been wreaking havoc in the DRC for years, with increasing cases in other African countries. This is an informative perspective on the insufficient efforts to stymie the outbreak.
    

15. Marcus U, Michel J, Lunchenkov N, et al. A seroprevalence study indicates a high proportion of clinically undiagnosed MPXV infections in men who have sex with men in Berlin, Germany. BMC Infect Dis. 2024;24(1):1153.  [PMID:39396951]

    Comment: This study was conducted in Berlin, Germany and found among 1119 MSM participants in 2023 that 70 (7.4%) had clinical mpox diagnosis, however 91 had asymptomatic, mild or unrecognized infection!
    

16. Berry MT, Khan SR, Schlub TE, et al. Predicting vaccine effectiveness for mpox. Nat Commun. 2024;15(1):3856.  [PMID:38719852]

    Comment: Authors argue that delaying a second dose provides more durable immunity, and allows for more first doses to be given in an outbreak situation.
    

17. Leonard CM, Poortinga K, Nguyen E, et al. Mpox Outbreak - Los Angeles County, California, May 4-August 17, 2023. MMWR Morb Mortal Wkly Rep. 2024;73(2):44-48.  [PMID:38236779]

    Comment: Mpox has been identified especially in gay, bisexual and other MSM in the LA County region since spring of 2023. The majority of patients were not immunized, particularly among younger Black, African American, Hispanic, and Latino persons with HIV.
    

18. Hazra A, Zucker J, Bell E, et al. Mpox in people with past infection or a complete vaccination course: a global case series. Lancet Infect Dis. 2024;24(1):57-64.  [PMID:37678309]

    Comment: This report comprises the largest series of people who have reinfection or infection after two doses of JYNNEOS. People who experienced infection after natural immunity (7) had shorter and less severe illnesses. This population was mostly young, gay/bisexual, sexually active men. Typically, fewer lesions were seen, including in the mucosa, with less need for hospitalization or teciviromat.
    

19. Deputy NP, Deckert J, Chard AN, et al. Vaccine Effectiveness of JYNNEOS against Mpox Disease in the United States. N Engl J Med. 2023;388(26):2434-2443.  [PMID:37199451]

    Comment: Case-control data using EHRs found that those without 1 or 2 doses of JYNNEOS were more likely to acquire mpox, suggesting effectiveness.
    

20. Ogoina D, James HI. Mpox among Linked Heterosexual Casual Partners in Bayelsa, Nigeria. N Engl J Med. 2023;388(22):2101-2104.  [PMID:37195934]

    Comment: Without a high index of suspicion, mpox appears likely to go underdiagnosed in the heterosexual population, as this letter reflecting some experience in West Africa suggests.
    

21. Payne AB, Ray LC, Kugeler KJ, et al. Incidence of Monkeypox Among Unvaccinated Persons Compared with Persons Receiving ≥1 JYNNEOS Vaccine Dose - 32 U.S. Jurisdictions, July 31-September 3, 2022. MMWR Morb Mortal Wkly Rep. 2022;71(40):1278-1282.  [PMID:36201401]

    Comment: Most in the US, as of this writing (Oct 2022), had only received one dose of the vaccine due to supply and administration constraints. It appears that one dose does offer some protection based on this observational sample.
    

22. Hagan LM, Beeson A, Hughes S, et al. Monkeypox Case Investigation - Cook County Jail, Chicago, Illinois, July-August 2022. MMWR Morb Mortal Wkly Rep. 2022;71(40):1271-1277.  [PMID:36201399]

    Comment: Close exposure in jail setting to index patient did NOT cause new cases
    

23. Miller MJ, Cash-Goldwasser S, Marx GE, et al. Severe Monkeypox in Hospitalized Patients - United States, August 10-October 10, 2022. MMWR Morb Mortal Wkly Rep. 2022;71(44):1412-1417.  [PMID:36327164]

    Comment: CDC report wherein they offered consultation to 57 severely ill patients who were predominantly Black with AIDS. Among this group, which is a biased sample, nearly one-third (30%) received ICU-level care, and 21% of patients died. Combination therapy was offered, tecovirimat/cidofovir/VIVIG and suggested for those with severe or progressive disease despite initial therapy. Twelve deaths were reported by CDC, which participated in management. The majority were Black men with advanced HIV and had severe disease ascribed to an immunocompromising state. Not all deaths yet directly attributed to a cause, and one was not thought to be related to MPXV. Combination therapy was often employed, with tecovirimat +/- cidofovir and VVIG. Only four patients were on ART.
    

24. Luong Nguyen LB, Ghosn J, Durier C, et al. A prospective national cohort evaluating ring MVA vaccination as post-exposure prophylaxis for monkeypox. Nat Med. 2022.  [PMID:35831633]

    Comment: The authors note in this letter that recent cases in Nigeria (3552) with only one reported fatality, far less than the 1-10% range reported in earlier years. Modified Vaccinia Ankara–Bavarian Nordic (MVA-BN) is a third-generation live vaccine that is non-replicating and reports predominantly African and European experience with PEP, which appears effective.
    

25. Orviz E, Negredo A, Ayerdi O, et al. Monkeypox outbreak in Madrid (Spain): clinical and virological aspects. J Infect. 2022.  [PMID:35830908]

    Comment: Spain has the most reported cases; this experience from Madrid from May to June 2022 is reported for 48 men. The mean age was 35 years, and 87.5% were MSM; lesions appeared in the area where they had sexual intercourse (genital or anal). Sequencing found the isolates consistent with the western African clade, specifically the Nigerian outbreak of 2017-18 that had low mortality.
    

26. Aden TA, Blevins P, York SW, et al. Rapid Diagnostic Testing for Response to the Monkeypox Outbreak - Laboratory Response Network, United States, May 17-June 30, 2022. MMWR Morb Mortal Wkly Rep. 2022;71(28):904-907.  [PMID:35834423]

    Comment: During the first month and a half of the US monkeypox outbreak, the CDC evaluated 2009 specimens from their external lab network on suspicion of monkeypox. The CDC found that 36% were positive for non-variola Orthopoxvirus. All of those sequenced to date were from the West African clade, similar to findings from patients in Spain and the UK.
    

27. Seang S, Burrel S, Todesco E, et al. Evidence of human-to-dog transmission of monkeypox virus. Lancet. 2022.  [PMID:35963267]

    Comment: In a brief report from Paris, two men with MPXV had subsequent skin lesions in their Italian greyhound PCR positive for MPXV. This canine isolate had 100% homology with one of the patients. The men did sleep with their dog. Worrisome, this is the first report ever in the medical history of viral transmission to a dog. It is not absolutely certain that the dog didn’t harbor the virus first, but it seems unlikely.
    

28. Philpott D, Hughes CM, Alroy KA, et al. Epidemiologic and Clinical Characteristics of Monkeypox Cases - United States, May 17-July 22, 2022. MMWR Morb Mortal Wkly Rep. 2022;71(32):1018-1022.  [PMID:35951487]

    Comment: Early US experience n = 1195. Median age 35, men 98.7%, 94% with MSM in the prior 3 weeks, 41% w/ HIV. Rash in 100% with genitals the most common site (46%). Fever in 63%, lymphadenopathy in 59%.
    

29. Grosenbach DW, Honeychurch K, Rose EA, et al. Oral Tecovirimat for the Treatment of Smallpox. N Engl J Med. 2018;379(1):44-53.  [PMID:29972742]

    Comment: Animal model data lead to approval of the drug for smallpox since human data is impossible.
    

30. Huhn GD, Bauer AM, Yorita K, et al. Clinical characteristics of human monkeypox, and risk factors for severe disease. Clin Infect Dis. 2005;41(12):1742-51.  [PMID:16288398]

    Comment: Risk factors for severe disease appeared to be two: fever ≥ 38.3°C and > 100 lesions.
    

31. Learned LA, Reynolds MG, Wassa DW, et al. Extended interhuman transmission of monkeypox in a hospital community in the Republic of the Congo, 2003. Am J Trop Med Hyg. 2005;73(2):428-34.  [PMID:16103616]

    Comment: Six cases among those in this pediatric outbreak had an extended chain of transmission among humans. Authors aptly noted the potential for more concerning and widespread transmission among humans in future if cases are not contained early in an outbreak.
    

32. Centers for Disease Control and Prevention (CDC). Update: multistate outbreak of monkeypox--Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin, 2003. MMWR Morb Mortal Wkly Rep. 2003;52(27):642-6.  [PMID:12855947]

    Comment: The report describes 71 cases, 35 lab-confirmed and 36 suspected cases, with the majority exposed to prairie dogs. Use of smallpox vaccine included pre-exposure administration to 3 veterinarians, 2 lab workers, and two healthcare workers and post-exposure to 23 individuals. All 35 confirmed cases traced back to prairie dogs housed, at an Illinois animal distributor, with Gambian giant rats and dormice that originated from Ghana.
    Rating: Important
    

Media

Monkeypox

Pox lesions on a child from a 1997 outbreak in the DRC.

Source:

CDC/ Brian W.J. Mahy, BSc, MA, PhD, ScD, DSc

Monkeypox

A child with numerous lesions on the face, from a 1997 outbreak in DRC.

Source: World Health Organization (WHO)/ Brian W.J. Mahy, BSc, MA, PhD, ScD, DSc

Monkeypox palms

Palms with maculopapular skin lesions appearing similar to smallpox but due to monkeypox (from 1997 DRC outbreak).

Source: CDC/ Brian W.J. Mahy, BSc, MA, PhD, ScD, DSc

Monkeypox lesions 2022

UK Health Security Agency

Monkeypox lesions

Source: NHS England High Consequence Infectious Diseases Network