Mpox is a rare disease similar to smallpox caused by the mpox virus. It’s found mostly in areas of Africa, but has been seen in other regions of the world. It causes flu-like symptoms such as fever and chills, and a rash that can take weeks to clear. There’s no proven treatment for mpox, but it usually goes away on its own.
The mpox virus causes the uncommon condition known as mpox. It causes flu-like symptoms and a rash. It is a member of the orthopoxvirus family, which also includes the more well-known smallpox virus.
When two outbreaks of a disease resembling the pox occurred in populations of monkeys being employed for study, it led to the discovery of mpox in 1958. Although skin-to-skin contact with an infected person can sometimes spread the disease, rodent interaction with sick humans accounts for the majority of its transmission. The mpox virus has two distinct kinds (clades), one of which originated in Central Africa and the other in West Africa. The less dangerous West African clade is the origin of the current global pandemic (2022).
How common is mpox?
Mpox is rare. But the number of cases is increasing in Africa, as well as in regions that haven’t seen these infections before.
Where else is mpox found?
The majority of mpox cases for many years were in Africa. It does, however, occasionally appear in other nations, such as the United States. The United States had the first mpox epidemic outside of Africa in the spring of 2003. Texas received a consignment from Ghana with diseased animals. The virus was transmitted by the sick rodents to domesticated prairie dogs, which ultimately infected 47 people in the Midwest.
Viruses that were formerly mostly restricted to certain regions might more readily spread worldwide as international travel becomes more widespread. A case of mpox was discovered in a resident of the United States who had come to the country from Nigeria in the summer of 2021. Then, epidemics spread beyond of Africa in 2022.
When you come into touch with a person or animal that is infected with the virus, you might develop mpox. Animals can transmit diseases to people by biting or scratching people, or by coming into direct touch with their blood, body fluids, or lesions from an affected animal (sores).
While it is less often, mumps can transmit from person to person. When you come into touch with the sores, scabs, respiratory droplets, or oral secretions of an infected individual, typically through close, personal interactions like hugging, kissing, or intercourse, person-to-person spread (transmission) takes place. Although study is underway, it is unclear if the virus is spread by semen or vaginal secretions.
Moreover, you can get mpox by touching recently contaminated items like the clothing, bedding, and other linens used by an infected person or an infected animal.
After exposure, it may be several days to a few weeks before you develop symptoms. Early signs of mpox include flu-like symptoms, including:
- Muscle aches.
- Swollen lymph nodes.
A rash frequently appears a few days later. The rash initially appears as unpleasant, flat, red pimples. These lumps develop into blisters that ooze pus. The blisters eventually harden over and fall off; the entire process can take two to four weeks. Furthermore, ulcers in the mouth, vagina, or anus are possible.
Not everyone with mpox develops all the symptoms. In fact, in the current (2022) outbreak, many cases aren’t following the usual pattern of symptoms. This atypical presentation includes only a few lesions, no swollen lymph nodes, less fever and other signs of illness. You can have it and not know it. Even if you don’t show many signs of infection, you can spread still spread it to others through prolonged close contact.
Chain reaction with polymerase (PCR)
Depending on the available tests, monkeypox can be diagnosed using culture, polymerase chain reaction (PCR), immunohistochemistry, or electron microscopy.
The ideal sample for PCR testing is skin lesions (roof or fluid from vesicles and pustules and/or dry crusts). Since viremia only lasts a short time, blood PCR is not advised. Both private and governmental health laboratories in the US provide PCR testing services.
Testing should be considered in patients with clinically compatible lesions and an epidemiologic risk factor as well as any patient with a characteristic lesion (deep-seated vesicle or pustule with central umbilication). (See also CDC: Case Definitions for Use in the 2022 Monkeypox Response.)
The majority of monkeypox patients experience a minor, self-limiting illness. For the West African lineage that is causing the current worldwide pandemic, this is especially true. Supportive therapy includes painkillers, fluids, and wound care.
Antiviral therapy should be explored for patients with severe illness, comorbidities, or who are at high risk for severe disease. This includes immunocompromised, pediatric, pregnant, or nursing patients, individuals with active exfoliative skin disorders, patients with hemorrhagic or confluent lesions, mucosal or genital involvement, or any consequences necessitating hospitalization. There is no known, risk-free therapy for the monkeypox virus infection specifically. The following therapies are yet accessible:
- The antiviral drug tecovirimat: Approved by the US Food and Drug Administration [FDA] for the treatment of smallpox—available in oral and IV formulations from the CDC via an Emergency Access Investigational New Drug (IND) protocol for the primary or early empiric treatment of monkeypox in all ages; Approved for smallpox and monkeypox in the European Union
- The antiviral drugs cidofovir or brincidofovir (CMX001)
- Vaccinia immune globulin (IV)
All of these drugs have activity against monkeypox in vitro and in experimental models, but there are few data to guide choice of treatment; a case series of 7 patients reported use of tecovirimat and brincidofovir (1). Tecovirimat is being used in some health care systems in the US in the 2022 outbreak. (See also CDC: Information for Healthcare Providers on Obtaining and Using TPOXX [Tecovirimat] for Treatment of Monkeypox and CDC: Monkeypox: Treatment Information for Healthcare Professionals.)
Past observational data from Africa suggests that the smallpox vaccine is at least 85% effective in preventing monkeypox, because monkeypox virus is closely related to the virus that causes smallpox (1). However, previous smallpox vaccination does not always provide lifelong immunity but likely reduces illness severity. Two smallpox vaccines may be used for the prevention of monkeypox disease: JYNNEOS and ACAM2000 (see CDC: Monkeypox and Smallpox Vaccine Guidance).
The JYNNEOS vaccine is a live but weakened (attenuated) vaccinia virus that does not reproduce in the person who receives it. It is indicated for the prevention of monkeypox (and smallpox) in adults 18 years of age and older who are at high risk of monkeypox (or smallpox). JYNNEOS may also be offered to people at high risk of social exposure to monkeypox in the setting of local outbreaks (see CDC: Monkeypox Vaccination Basics; Who Should Get Vaccinated?). The vaccine is given as a series of 2 injections under the skin given 4 weeks apart. Vaccination with JYNNEOS may be an alternative for people who cannot receive ACAM2000, such as those who have a weakened immune system (see below list). However, people who have a weakened immune system may have a diminished response to the JYNNEOS vaccine. Limited data on the effectiveness of the JYNNEOS vaccine in the current outbreak are becoming available. Across 32 US jurisdictions, among males aged 18 to 49 years eligible for JYNNEOS vaccination, monkeypox incidence was 14 times as high among unvaccinated males compared with those who had received a first vaccine dose ≥ 14 days earlier (see CDC: Rates of Monkeypox Cases by Vaccination Status).
The ACAM2000 vaccine contains live vaccinia virus, which is related to the smallpox virus and provides cross-immunity to the monkeypox and smallpox viruses. It is indicated for people who are at high risk of monkeypox (or smallpox). ACAM2000 is given by rapidly jabbing a small area 15 times with a specially designed needle that has been dipped in the vaccine. This is considered one dose. Then the vaccine site is covered with a dressing to prevent the vaccina virus from spreading to other body sites or to other people. Vaccination is considered successful if a small blister develops about 7 days later. If it does not appear, people are given another dose.
Vaccination with ACAM2000 is dangerous and not recommended for some people, especially those with the following risk factors:
- Weakened immune system (such as those who have AIDS or who take medications that suppress the immune system)
- Skin disorders (particularly atopic dermatitis [eczema])
- Eye inflammation
- Heart condition
- Age under 1 year
The Advisory Committee on Immunization Practices (ACIP) recommends that people at risk of occupational exposure to orthopoxviruses receive either the JYNNEOS or ACAM2000 vaccine to protect against infection (see CDC: Monkeypox and Smallpox Vaccine Guidance and CDC: Monkeypox/Vaccines).
Non-hospitalized patients with monkeypox should
- Isolate at home until the lesions have resolved and scabs have fallen off and a fresh layer of intact skin has formed
- Avoid direct physical contact with other people and animals
- Not share potentially contaminated items, such as bed linens, towels, clothing, drinking glasses, or eating utensils, and should clean and disinfect commonly touched surfaces and items
- Wear a mask if close contact with others in the home is necessary
Infection control measures in the hospital include having patients in a private room with the door closed. Special air handling is not required unless procedures likely to spread infectious oral secretions are performed (eg, intubation, extubation). Activities that may result in dried materials being distributed in the air or on surfaces (eg, use of fans, shaking of dirty linens) should be avoided. Appropriate personal protective equipment (PPE) includes gown, gloves, N95 level mask (or equivalent), and eye protection. EPA-registered hospital-grade disinfectants with an emerging viral pathogen claim should be used for standard disinfection. For patients with the West African clade, waste may be handled according to usual guidelines for infectious medical waste. For patients with the Congo Basin clade, medical waste is classified as Category A under the US Department of Transportation (DOT) Hazardous Materials Regulations and should be managed accordingly (see CDC: Infection Prevention and Control of Monkeypox in Healthcare Settings).
All healthcare personnel caring for patients with monkeypox should monitor for symptoms at least twice daily for 21 days from their last encounter. People with high-risk exposures (see CDC: Monitoring People Who Have Been Exposed) should be offered postexposure prophylaxis via vaccination with JYNNEOS or ACAM2000. Vaccination should ideally occur within 4 days of exposure but can be effective up to 14 days after exposure (see CDC: Monkeypox and Smallpox Vaccine Guidance).