Monkeypox – a quick guide for GPs

Update your knowledge on monkeypox in the UK: how it is spread, its case definitions, signs and symptoms, measures to control transmission, and vaccination
Monkeypox – a quick guide for GPs

This quick guide* covers the key points for GPs on monkeypox, and answers the following questions:

  1. What is monkeypox and how is it spread?
  2. What are the case definitions of monkeypox?
  3. What are the signs and symptoms?
  4. What is the process for diagnostic testing?
  5. What measures should be taken to control transmission?
  6. Is there a recommended vaccination strategy in the UK?
  7. Where can I get the latest updates?

*This quick guide is deliberately concise and readers are strongly recommended to refer to the references listed at the end of the quick guide.

1.  What is monkeypox and how is it spread?1–4

  • Monkeypox is a viral zoonosis (a virus transmitted to humans from animals) with symptoms similar to those seen in the past in smallpox patients, although it is clinically less severe with lower mortality
  • The virus is an enveloped double-stranded DNA virus that belongs to the Orthopoxvirus genus of the Poxviridae family
  • There are 2 clades of monkeypox virus: a Central African clade with a reported mortality of 10% and a West African clade with a 1%-reported mortality
    • In May 2022, the UKSHA (UK Health Security Agency) confirmed that cases identified in the UK were of the West African clade
  • It is important to note that monkeypox does not spread easily between people. Following the coronavirus pandemic, many people will be concerned about this issue
  • 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 transmission can result from:
    • direct contact with monkeypox skin lesions or scabs
    • contact with clothing or linens (such as bedding or towels) used by an infected person
    • coughing or sneezing of an individual with a monkeypox rash

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2.  What are the case definitions of monkeypox?5

Guidance on case definitions has been released to describe the possible, probable and confirmed cases of monkeypox to help inform testing and reporting.

Possible case:

  • A person with a febrile prodrome* compatible with monkeypox infection where there is known prior contact with a confirmed case in the 21 days before symptom onset, or
  • A person with an illness where the clinician has a suspicion of monkeypox – this could include unexplained genital, ano-genital or oral lesion(s) (for example, ulcers, nodules) or proctitis (for example anorectal pain, bleeding)

Probable case:

  • A person with an unexplained rash or lesion(s) on any part of their body (including genital/perianal, oral), or proctitis (for example anorectal pain, bleeding) and who:
    • has an epidemiological link to a confirmed, probable or highly probable case of monkeypox in the 21 days before symptom onset or
    • identifies as a gay, bisexual or other man who has sex with men (GBMSM) or
    • has had one or more new sexual partners in the 21 days before symptom onset or
    • reports a travel history to West or Central Africa in the 21 days before symptom onset or

Confirmed case:

  • A person with a laboratory confirmed monkeypox infection (monkeypox PCR positive)

*Febrile prodrome consists of fever ≥38°C, chills, headache, exhaustion, muscle aches (myalgia), joint pain (arthralgia), backache, and swollen lymph nodes (lymphadenopathy); **Acute illness with fever (>38.5°C), intense headaches, myalgia, arthralgia, back pain, lymphadenopathy.

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3.  What are the signs and symptoms?2,4

25/07/2022 - Please note that the UKSHA is currently updating its guidance (see updated case definitions above)

  • The incubation period is 5 to 21 days, but typically 6 to 16 days following exposure
  • The initial phase of typical clinical illness usually lasts 1 to 5 days:
    • Patients may experience a combination of fever and/or chills, lymphadenopathy, headache, myalgia, backache and exhaustion
    • Lymphadenopathy is a distinctive feature of monkeypox compared with other diseases that may initially appear similar (e.g. chickenpox, measles, smallpox)
    • Fever is present in most, but not all patients
  • A second phase follows with the appearance of a rash, during which time some existing signs and symptoms, including fever, may diminish or disappear
    • The distribution of the rash and the appearance of individual skin eruptions typically change over time: see images below

 Pictures available from UKSHA

  •  Initially, the rash may be maculopapular, typically starting on the face before spreading peripherally, particularly to the palms of the hands and the soles of the feet:
    • It affects the face in 95% of cases and palms of the hands and soles of the feet in 75% of cases
    • Other affected areas include oral mucous membranes (in 70% of cases), genitalia (30%), conjunctivae (20%), as well as the cornea
  • The rash classically evolves into vesicles and then pustules, often with umbilication, which eventually crust and then desquamate during the next 2 to 3 weeks
    • These characteristic pox lesions are typically 0.5 to 1cm diameter and may number from a few to several thousand
  • Localised rashes are seen occasionally, relating to the site of the initial exposure
  • Most patients experience a mild, self-limiting illness, with spontaneous and complete recovery seen within 3 weeks of onset; however, severe illness can occur and sometimes results in death.

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4.  What is the process for diagnostic testing?6

  • In the first instance, suspected cases must be discussed with local infection clinicians (infectious diseases, microbiology, virology or genitourinary medicine as appropriate)
  • The request form must indicate the risk factors and the reason that monkeypox is suspected
  • Samples should be sent to your normal laboratory for forwarding to the Rare and Imported Pathogens Laboratory (RIPL) for monkeypox testing and for local processing (all other tests).
  • Samples from suspected cases of monkeypox should be sent by Category B transport to:

Rare and Imported Pathogens Laboratory
Manor Farm Road
Porton Down

DX 6930400, Salisbury 92 SP

Contact for RIPL (09:00 to 17:00) is 01980 612 348
It is also possible to email but do not include patient identifiable information.

Monitoring samples from confirmed cases should not be sent to RIPL (see below).

Sampling for monitoring confirmed or highly probable cases

If follow-up testing is required from a confirmed or highly probable case, either because of clinical deterioration or to inform discharge from isolation to an inpatient setting, additional samples should be taken and should include the following:

  • a lesion swab and throat swab in viral transport medium
  • a blood sample in an EDTA tube
  • a urine sample in a universal sterile container

Samples should be sent to by Category B transport to the High Containment Microbiology (HCM) unit at Colindale. Please contact the HCM unit ahead of sending any samples to arrange this testing.

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5.  What measures should be taken to control transmission?3,7, 10

  • Guidance has been published as a consensus by the UK’s four public health agencies – UKHSA, PHS (Public Health Scotland), PHW (Public Health Wales), PHA (Public Health Agency Northern Ireland) – in response to the monkeypox outbreak, setting out measures for HCPs and the general public for managing the disease and preventing further transmission
  • The consensus statement highlights 9 assumptions about the cases identified (since 13 May 2022) in countries that do not have endemic monkeypox, see Box 1.

Box 1. Assumptions about transmission and biology*

1 For individuals with infection who are well, ambulatory, and have either prodrome or rash, the highest risk transmission routes are direct contact, droplet or fomite. Transmission seen so far in this outbreak is consistent with close direct contact
2 There is currently no evidence that individuals are infectious before the onset of the prodromal illness
3 For individuals with infection who have evidence of lower respiratory tract involvement or severe systemic illness requiring hospitalisation, the possibility of airborne transmission has not been excluded
4 It remains important to reduce the risk of fomite transmission. The risk can be substantially reduced by following agreed cleaning methods based on standard cleaning and disinfection, or by washing clothes or domestic equipment with standard detergents and cleaning products. Within healthcare, please refer to local country national infection prevention and control manual / guidance for decontamination
5 Waste management and decontamination practice should follow best practice and be based on all the available evidence on safe handling of all waste in accordance with country specific legislation and regulations
6 The highest risk period for onwards infection is from the onset of the prodrome until the lesions have scabbed over and the scabs have fallen off
7 Deroofing procedures and throat swabs are not considered to be aerosol generating procedures (AGPs) but may cause droplets

There is little available evidence on monkeypox in genital excretions and a precautionary approach for the use of condoms for 12 weeks after infection is recommended10 (this will be updated as evidence emerges), in addition to abstaining from sex while symptomatic including during the prodromal phase and while lesions are present

9 The disease in healthy adults is primarily self-limiting and with a relatively low mortality. There is remaining uncertainty over potentially increased severity in children and in individuals who are highly immunocompromised or pregnant

*Cases identified since 13 May 2022 in countries that do not have endemic monkeypox in animal or human populations

Implications for ambulatory care3

  • For possible, probable or confirmed cases, attending ambulatory healthcare (e.g. general practice) patients should be placed in a single room for assessment, and provided with a fluid resistant surgical mask to wear as appropriate
  • Where possible, pregnant women and severely immunosuppressed individuals should not assess or clinically care for individuals with suspected or confirmed monkeypox; this will be reassessed as evidence emerges
  • Close household and non-household contacts of confirmed cases should be risk assessed. Medium risk (category 2) and high risk (category 3) contacts do not need to isolate, but should avoid sexual or intimate contact with others for 21 days. High risk (category 3) contacts should also avoid contact with children aged under 5 years and individuals who are pregnant or severely immunocompromised, where possible

Please note: implications for community/domestic situations, inpatient healthcare and other residential settings are covered in the consensus statement,3 but outside the remit of this guide.

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6.  Is there a recommended vaccination strategy in the UK?1,8,9

Following the monkeypox outbreak, the UKHSA has published the Monkeypox: vaccination strategy, which is endorsed by the Joint Committee on Vaccination and Immunisation (JCVI). Please note:

  • There is currently no vaccine licensed in the UK for immunisation against monkeypox, but vaccines developed for smallpox are considered to provide cross-protection
  • Smallpox Modified Vaccinia Ankara – Bavarian Nordic (MVA-BN) is distributed under the brand names Imvanex (MHRA-approved in the UK) and Jynneos (FDA-approved in the US)
  • The UKSHA recommends that a selective vaccine strategy should be followed with the aim of interrupting transmission, see below.

Pre-exposure vaccination

Targeted pre-exposure vaccination

  • JCVI proposed that vaccination should be offered as soon as feasible to gay, bisexual and other men who have sex with men (GBMSM) at highest risk due to a large number of contacts
  • These individuals could be identified among those who attend sexual health services, using markers of high-risk behaviour like those used to assess eligibility for HIV pre-exposure prophylaxis (PrEP), but applied regardless of HIV status
  • These risk criteria would include a recent history of multiple partners, participating in group sex, attending sex on premises venues or a proxy marker such as recent bacterial STI (in the past year)
  • In view of the current epidemiology and vaccine supply available, wider vaccination in low risk GBMSM individuals or the general population is not advised at this time.

Occupational vaccination

  • Pre-exposure vaccination should also be prioritised for the following workers at high risk of exposure:
    • staff expected to provide care to monkeypox cases in high consequence infectious disease (HCID) units
    • staff in sexual health clinics designated to assess suspected cases
    • staff in additional hospitals outside HCID units designated to care for monkeypox patients
    • workers in laboratories where pox viruses (such as monkeypox or genetically modified vaccinia) are handled, and others whose work in specialist and reference laboratories
    • staff regularly undertaking environmental decontamination around cases of monkeypox
  • Other healthcare staff should be able to avoid inadvertent exposure by ensuring suspected monkeypox cases are assessed by designated staff, or by wearing appropriate personal protective equipment
  • First doses should be prioritised during this outbreak, with the offer of a second dose for those who continue to be at an increased risk of exposure

Post-exposure vaccination

  • There is limited evidence on the effectiveness of post-exposure vaccination using MVA-BN, and the vaccine should therefore be prioritised for those most likely to benefit (based on timeliness and risk of disease severity)
  • It is recommended that post-exposure vaccination of high-risk community or occupational contacts is offered ideally within 4 days from date of exposure, but may be offered up to 14 days in those at ongoing risk or who are at higher risk of complications of monkeypox
  • Those at higher risk of complications include:
    • children under the age of 10 to 11
    • people who are pregnant
    • individuals with immunosuppression (as defined in the Green Book)
  • This advice is given within the context of the current epidemiological situation in the UK, where disease is typically mild and transmission is predominately occurring within the GBMSM population; it is also given with the consideration that vaccine supply is limited

NB: The UKHSA will evaluate the impact of the vaccination on the outbreak and advice and guidance will be kept under review and is subject to change.

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7.  Where can I get the latest updates on monkeypox?

OnMedica has a page available dedicated to the latest updates as identified by the UKHSA, which you can bookmark for future reference.

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  1. UKSHA and DHSC safety message – Immediate actions in response to cases of monkeypox virus in the UK with no known travel history. OnMedica (accessed 21 June 2022).
  2. Monkeypox fact sheet. World Health Organization (accessed 21 June 2022).
  3. Guidance – Principles for monkeypox control in the UK: 4 nations consensus statement. GOV.UK (accessed 25 July 2022).
  4. Guidance – monkeypox: information for primary care. GOV.UK (accessed 21 June 2022).
  5. Guidance – monkeypox: case definitions. GOV.UK (accessed 25 July 2022).
  6. Monkeypox: diagnostic testing. GOV.UK (accessed 02 August 2022).
  7. New monkeypox guidance for HCPs issued to control transmissions. OnMedica (accessed 21 June 2022.
  8. Monkeypox vaccination recommendations. GOV.UK (accessed 21 June 2022).
  9. Monkeypox outbreak: vaccination strategy. GOV.UK (accessed 21 June 2022).
  10. Monkeypox: semen testing for viral DNA. GOV.UK (accessed 15 July 2022).

Patient information

  • Monkeypox, NHS website (accessed 21 June 2022)
  • Guidance – Monkeypox: infected people who are isolating at home. GOV.UK (accessed 21 June 2022)
  • Guidance – Monkeypox: background information. GOV.UK (accessed 21 June 2022)

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Article first published 23 June 2022.