Emergency: requires immediate attention
Mpox in Adult
Alerts and Notices
Synopsis
The World Health Organization (WHO) declared mpox (historically, monkeypox) to be a public health emergency of international concern on July 23, 2022. Mpox was declared a public health emergency in the United States on August 4, 2022. The US national public health emergency declaration ended on January 31, 2023.
As of March 29, 2023, the CDC (2022 Outbreak Cases & Data) reported 86 746 confirmed cases of mpox globally in over 100 locations, the vast majority of which did not historically report mpox infections, and more than 30 286 confirmed cases across the United States, including 38 deaths. The 7-day daily average of new cases peaked in August of 2022 and has receded to very low levels as of April 4, 2023. Per CDC modeling analyses, however, most jurisdictions in the United States may be at risk of resurgence or new mpox outbreaks without continued efforts to vaccinate those at risk.
Transmission continues to occur primarily among men who have sex with men (MSM), but any individual who has been in close, personal contact with someone who has mpox – regardless of age, sexual orientation, or gender identity – is at risk for contracting mpox.
Mpox virus infections in children and adolescents younger than 16 years of age have been extremely rare, representing 0.002% of all US cases; none of the cases resulted in critical illness or death. Children aged 0-12 years typically acquired mpox after skin-to-skin contact with an infected household member during caregiving activities, and adolescents aged 13 years and above were most frequently exposed through male-to-male sexual contact.
Domestic animals, pets, and wildlife in close contact with an infected individual may also be at risk for contracting illness.
Immunocompromised patient considerations: Immunocompromised individuals, particularly people with advanced or inadequately treated HIV, are at risk for severe and prolonged illness and even death. An increasing proportion of cases have been identified among Black and Hispanic / Latino individuals, who are disproportionately affected by HIV.
The 2022 outbreak of mpox is unique in several ways.
- Many cases have no clear connection to the larger clusters of cases and no clear history of associated travel.
- In the 2022 outbreak, it appears mpox is spreading through specific social and sexual networks, particularly among persons who identify as gay, bisexual, or MSM, although it is in no way limited to any specific population.
Anyone who has had close physical contact with someone with mpox is at risk of contracting the virus.
Clinical features:
The incubation period of mpox is approximately 12 days (7-14 day range usually, but can be 5-21 days).
The clinical presentation is distinct from prior descriptions of the illness. Notably, anogenital lesions (in some cases painful, in others painless), often without a prodrome, are being observed.
- Many patients have had no associated or preceding febrile illness, fatigue, or other systemic symptoms.
- The eruption that many of these patients develop does not begin on the face, hands, and legs and may not be widespread, nor are the lesions initially numerous. Many patients have presented with a small number of lesions (in some cases 1 or 2) involving the genital or perianal region before the rash spreads to the extremities. These lesions can be, but are not always, quite painful and/or pruritic and may leave scarring.
- The classically described lymphadenopathy associated with mpox does not seem to be a requisite aspect of cases in this outbreak, with some patients having only a single swollen lymph node and some having no lymphadenopathy.
- Some patients present with proctitis or anorectal pain.
- Oropharyngeal symptoms have been reported (including pharyngitis, oral / tonsillar lesions, odynophagia, and epiglottitis) as have conjunctival mucosa lesions.
Transmission:
Human-to-human transmission occurs through close contact, ie, large respiratory droplets, direct contact with skin lesions or bodily fluids, or indirect contact via contaminated clothing or linens. The WHO notes that anyone who has had close physical contact with someone with mpox is at risk of contracting the virus, and there is a high likelihood that further cases with unidentified chains of transmission will be identified. MSM may be at higher risk for infection.
All skin lesions may be infectious. Persons are thought to be infectious starting 1-4 days prior to the onset of symptoms (a UK study of more than 2700 people with confirmed mpox virus between May 6 and August 1, 2022, suggests that presymptomatic transmission [1-4 days before symptoms appear] occurred in around half of all cases [53%]). Patients should be considered to be infectious until crusts have fallen off and the underlying skin re-epithelialized.
About Mpox
Mpox is a rare zoonotic Orthopoxvirus infection that is clinically similar to smallpox.
There are 2 clades of mpox, with differing mortality rates. The Central Africa (Congo Basin) clade is both more contagious and more severe with a reported mortality rate of around 10.6%. The West African clade is thought to be less severe with a mortality rate of about 3.6%.
Historically, mpox begins with a prodrome of fever, headache, malaise, backache, lymphadenopathy, chills, nonproductive cough, and arthralgias followed 1-10 days later (usually by day 3) by the development of a papular, vesicular, then pustular eruption on the face, trunk, and extremities. Some patients also experience myalgias, nausea and vomiting, lethargy, sore throat, dyspnea, and sweats. The clinical presentation is similar to but milder than that of smallpox, with the primary difference being that individuals with mpox develop lymphadenopathy, whereas those with smallpox do not. Illness typically lasts 2-4 weeks. Individuals who received smallpox vaccination were reported to develop milder cases.
Before the 2022 outbreak, cases in the United States were primarily limited to laboratory workers, pet shop workers, and veterinarians. There were 2 US cases in 2021 (July and November), both from travelers returning from Nigeria.
In Africa, the disease affects people who have hunted or eaten squirrels and other infected mammals. Animal species susceptible to mpox virus may include nonhuman primates, lagomorphs (rabbits), and some rodents. Predominant person-to-person transmission and prolonged chains of transmission were suspected in 1996 when 71 cases emerged in Katako-Kombe Health Zone, Kasai-Oriental, and Democratic Republic of the Congo, and again in 2003 in the Likouala region of Republic of the Congo. In order to sustain the disease in the human population, it was believed that repeated animal reintroduction of mpox virus was needed.
The first documented outbreak of mpox in the Western Hemisphere was attributed to a shipment of small mammals from Ghana to the United States in 2003. An infected Gambian giant rat from this shipment infected prairie dogs, which in turn transmitted the disease to humans. The prairie dogs were sold by a Milwaukee animal distributor to 2 pet shops in the Milwaukee area and during a pet "swap meet" (pets for sale or exchange) in northern Wisconsin. Patients from this outbreak reported direct or close contact with prairie dogs, most of which were sick. Illness in the prairie dogs was frequently reported as beginning with a blepharoconjunctivitis that was followed by the appearance of nodular lesions in some cases. Some prairie dogs died from the illness while others reportedly recovered. Lesions in the 2003 US outbreak differed from smallpox lesions in that they were not in the same stage of evolution at the same time. In some patients seen in the United States in 2003, early lesions became ulcerated, especially those at animal bite / scratch sites.
Codes
ICD10CM:B04 – Monkeypox
SNOMEDCT:
359814004 – Monkeypox
Look For
Subscription Required
Diagnostic Pearls
Subscription Required
Differential Diagnosis & Pitfalls
Conditions in the differential diagnosis of genital lesions:- Genital HSV
- Primary syphilis
- Condyloma lata of secondary syphilis
- Chancroid
- Genital aphthous ulcers
- Molluscum contagiosum
- Lymphogranuloma venereum
- Gonorrhea
- Folliculitis
- Varicella zoster (including chickenpox and disseminated zoster)
- Disseminated HSV
- Eczema herpeticum
- Eczema vaccinatum
- Secondary syphilis
- Rickettsialpox
- Tanapox
- Cowpox
- Alaskapox virus
- Orf
- Milker’s nodule
- Deer-associated parapoxvirus infection
- Smallpox has been eradicated but remains a bioterrorism threat.
Best Tests
Subscription Required
Management Pearls
Subscription Required
Therapy
Subscription Required
References
Subscription Required
Last Reviewed:11/02/2022
Last Updated:04/09/2023
Last Updated:04/09/2023
Emergency: requires immediate attention
Patient Information for Mpox in Adult
Overview
Mpox (historically known as monkeypox) is a rare viral infection that is similar in some ways to smallpox but milder.Mpox is very contagious and spreads through close physical contact or contact with fabrics, objects, or surfaces. It can also be spread to and from some animals.
Mpox infection leads to an itchy and often painful rash. Patients may or may not experience fever, headache, backache or other body aches, and/or swollen glands, before or after the rash. Mucous membrane inflammation such as pharyngitis and/or proctitis can occur. The rash may start on the genitals or anus or be on the face, mouth, trunk, hands or feet, or arms or legs. There may be just a few sores or many.
Persons are thought to be infectious starting 1-4 days prior to the onset of symptoms. Illness usually lasts 2-4 weeks. Patients are considered infectious until the crusts have fallen off the rash.
Who’s At Risk
The 2022 outbreak has mostly affected gay men, bisexual men, and men who have sex with men, but cases in women and children have occurred as well. There does not need to be sexual exposure, although the majority of cases in the current outbreak have been in close-knit sexual networks. Anyone in contact with mpox rash, scabs, or body fluids from a person with mpox or who touches contaminated objects or fabrics can get mpox.Before the 2022 outbreak, most cases occurred in certain African countries and could be spread by travel. The 2022 outbreak has spread to over 90 countries including those in Europe, North America, and South America.
Signs & Symptoms
Signs and symptoms appear around 7-14 days after exposure to the mpox virus.Mpox infection causes an itchy rash that starts in the genital or anal region and spreads to the legs. Alternatively, the rash may start on the face or hands. The rash can be painful and leave scars.
In addition:
- Inflammation of the lining of the rectum (proctitis) may occur with anogenital exposure. Similarly, inflammation of the throat tissues can occur with pharyngeal exposure.
- Some people run a fever and feel fatigued, but many infected people never run a fever.
- Some patients have a headache, muscle aches, and/or nausea.
- Some patients have swollen lymph nodes.
- Some patients develop a rash inside their mouths.
Self-Care Guidelines
Persons are thought to be infectious starting 1-4 days prior to the onset of symptoms. People are considered infectious until their lesions have crusted and the crusts have fallen off the rash.If you think you may have mpox, contact your health care provider.
You should isolate, wear a mask when with others, and cover any skin lesions. Do not pick or scratch the rash or shave in the affected area as this may spread the virus, causing more sores to develop. Wash your hands often. If you have sores on your hands, wash gently and wear gloves when handling common objects or surfaces.
Eat healthy foods, stay hydrated, and get plenty of rest.
Over-the-counter and self-care options for fever, pain, and/or itch:
- Ibuprofen (Advil, Motrin) or acetaminophen (Tylenol)
- Topical gels containing benzocaine and/or lidocaine
- Oral antihistamines (eg, Benadryl)
- Topical creams such as calamine lotion or petroleum jelly
- Warm oatmeal baths
- For oral rash, salt-water rinses and/or antiseptic mouthwashes (eg, chlorhexidine mouthwash)
- For anogenital rashes, a sitz bath
When to Seek Medical Care
If you think you may have mpox, contact a primary health care provider as soon as possible. In the meantime, avoid close physical contact with others.Genital mpox can be mistaken for a sexually transmitted infection (STI) such as herpes or syphilis. Your doctor may run tests to rule out common STIs.
Treatments
Smallpox vaccination can prevent mpox. The US Center for Disease Control and Prevention (CDC) recommends that patients exposed to mpox should be vaccinated within 4 days of the exposure to prevent onset of disease. If the vaccine is given between 4 and 14 days after the date of exposure, then vaccination may reduce symptoms.Your doctor may prescribe antiviral medication, especially if you are immunocompromised.
Your doctor may prescribe stronger pain medications than over-the-counter ibuprofen or acetaminophen.
For painful oral rash, your doctor may prescribe a special mouthwash or recommend viscous lidocaine.
For painful anogenital rash, your doctor may prescribe medication to add to your sitz bath.
Emergency: requires immediate attention
Mpox in Adult