The epidemiology, symptoms, diagnosis and management of monkeypox virus infections.
Monkeypox is a rare disease that is caused by infection with monkeypox virus.
Monkeypox was first discovered in 1958 when outbreaks of a pox-like disease occurred in monkeys kept for research. The first human case was recorded in 1970 in the Democratic Republic of Congo, and since then the infection has been reported in a number of central and western African countries.
In 2003, monkeypox was recorded in the USA when an outbreak occurred following importation of rodents from Africa. Cases were reported in both humans and pet prairie dogs. All the human infections followed contact with an infected pet and all patients recovered. No other country outside West and Central Africa has reported similar cases or outbreaks.
In 2018 in Africa, monkeypox cases have been reported from Cameroon, the Central African Republic, the Democratic Republic of Congo, Liberia and Nigeria.
On 8 September 2018, an imported case of monkeypox was reported in the UK. A second imported case was reported on 11 September 2018. Further information about these cases and the public health response is available in the Health Protection Report. A third case was reported on 26 September. This person was involved in the care of the case in Blackpool Victoria Hospital before monkeypox was diagnosed.
Monkeypox does not spread easily between people.
Spread of monkeypox may occur when a person comes into close contact with an animal (rodents are believed to be the primary animal reservoir for transmission to humans), human, or materials contaminated with the virus. The virus enters the body through broken skin (even if not visible), the respiratory tract, or the mucous membranes (eyes, nose, or mouth).
Person-to-person spread is very uncommon, but may occur through:
- contact with clothing or linens (such as bedding or towels) used by an infected person
- direct contact with monkeypox skin lesions or scabs
- coughing or sneezing of an individual with a monkeypox rash
The incubation period is the duration/time between contact with the infected person and the time that the first symptoms appear. The incubation period for monkeypox is between 5 and 21 days.
Monkeypox infection is usually a mild self-limiting illness and most people recover within several weeks. However, severe illness can occur in some individuals.
The illness begins with:
- muscle aches
- swollen lymph nodes
Within 1 to 5 days after the appearance of fever, a rash develops, often beginning on the face then spreading to other parts of the body. The rash changes and goes through different stages before finally forming a scab which later falls off.
- areas of erythema and/or skin hyperpigmentation are often seen around discrete lesions
- lesions can vary in size and may be larger than those shown
- lesions of different appearances and stages may be seen at the same point in time.
- detached scabs may be considerably smaller that the original lesion.
Clinical diagnosis of monkeypox can be difficult, and it is often confused with other infections such as chickenpox. A definite diagnosis of monkeypox requires assessment by a health professional and specific testing in a specialist laboratory.
In the UK, the Rare and Imported Pathogens Laboratory (RIPL) at PHE Porton Down is the designated diagnostic laboratory.
Suspected cases should be discussed with the Imported Fever Service prior to submitting samples for laboratory testing.
Treatment for monkeypox is mainly supportive. The illness is usually mild and most of those infected will recover within a few weeks without treatment.
Infection prevention and control
Prevention of transmission of infection by airborne and contact routes is required. Appropriate respiratory isolation is essential for suspected and confirmed cases.
Clinical laboratories should be informed in advance of samples submitted from suspected or confirmed diagnosis of monkeypox, so that they can perform local risk assessments, minimise risk to laboratory workers and, where appropriate, safely perform laboratory tests that are essential to clinical care.
Monkeypox virus is classified as an ACDP Hazard Group 3 pathogen.
Guidance for primary care
Guidance for environmental cleaning and decontamination
See WHO factsheet