Monkeypox

Part of the Communicable Disease Control Manual

Case definition and clinical presentation updated 5 August 2022. Contact definitions and management and general update 18 August 2022. A description of changes can be found at Updates to the Communicable Disease Control Manual.

Contents


Epidemiology in New Zealand

Monkeypox (MPX) is a zoonotic virus (animal-to-human transmission) endemic in parts of Central and West Africa. It is caused by the MPX virus which belongs to the orthopoxvirus genus of the Poxviridae family. MPX can be transmitted human-to-human by close contact with skin lesions, body fluids, respiratory droplets and contaminated materials. There is emerging evidence around presence in semen, but uncertainty about this as a form of transmission.

There are two clades of MPX, the West African clade and Congo Basin (Central African) clade. The case fatality ratio for the West African clade has been documented to be around 1%, whereas for the Congo Basin clade, it may be as high as 10%.

Global outbreak

In the 2022 global outbreak of MPX, the first case was identified in the United Kingdom on 7 May 2022 in a recent traveller from Nigeria. At the time of writing on 8 August 2022, global case numbers were over 28,000 confirmed cases across more than 80 countries.

Most cases within this outbreak are men who have sex with men (MSM) with no travel history to Central or West Africa. All sequenced PCR samples are identified with the less severe West African clade MPX virus.

Clinical presentation

Monkeypox (MPX) classically presents with a prodrome with fever, aches and lymphadenopathy, followed by a characteristic centrifugal rash with the lesions first appearing on the face and moving to distal extremities. The rash also progresses through four stages simultaneously from macules to papules, vesicles then pustules, followed by scabbing.

In the 2022 outbreak, presentations of monkeypox have been atypical:

  • The rash/lesions may be localised to ano-genital skin, or oropharynx or rectal mucosa (proctitis)
  • There may be a solitary lesion
  • The rash/lesions may not necessarily progress through four stages as described above
  • Systemic symptoms may be absent or have developed after the onset of rash.

The clinical presentation is similar to diseases that are more commonly encountered in clinical practice, such as hand foot and mouth disease, varicella zoster, herpes simplex, syphilis and molluscum contagiosum. As a result, more common causes of acute rashes with similar appearances should be considered and excluded where possible. 

However, co-infections have occurred sporadically, and given the evolving epidemiology of monkeypox, patients with a rash suggestive of monkeypox should be considered for testing, even if other conditions are likely.

For more information of the outbreak please refer to:

Case definition

Note: People at increased risk for severe disease include infants and young children, pregnant women, and severely immunocompromised persons.

Clinical and epidemiological criteria

Clinical criteria

A clinically compatible illness characterised by the presence of acute unexplained[1] skin and/or mucosal lesions or proctitis (for example anorectal pain, bleeding)

AND

Epidemiological criteria

At least one of the following:

  • exposure[2] to a confirmed or probable case in the 21 days before symptom onset
  • history of travel to West or Central Africa where MPX is endemic in the 21 days before symptom onset
  • is a priority group for testing.

At this time priority groups for testing include the following:

  • persons who had multiple[3] or anonymous sexual partners in the 21 days before symptom onset
  • gay, bisexual or other men who have sex with men (MSM).

Laboratory test for diagnosis

Laboratory definitive evidence for a confirmed case requires MPX virus detection by NAAT.

Testing should be limited only to patients who meet the clinical and epidemiological criteria. Laboratory confirmation requires the detection of MPX virus nucleic acid by PCR from an appropriate clinical sample. Local laboratories are to test for Varicella (chickenpox, VZV), Herpes simplex (HSV), +/- syphilis if there is capability, prior to referral to a reference laboratory for MPX testing.

In addition to Standard Precautions, Contact and Airborne Precautions should be adhered to for physical examination and collecting samples. A face covering is sufficient for preliminary clinical assessment. This includes the use of eye protection, P2/N95 mask, fluid repellent gown and gloves.

Potential cases are most likely to present to sexual health, primary care or emergency departments, where the treating physician will collect samples. Note that patients should not present to a community collection centre for sampling. Clinicians are advised to follow the most up to date testing advice which can be found on the New Zealand Microbiology Network website.

Case classification

  • Under investigation: A person that has been reported to a Medical Officer of Health but information is not yet available to classify it as confirmed, probable or not a case.
  • Probable: A person who meets the clinical and epidemiological criteria and laboratory confirmation is not possible
  • Confirmed:  A person with laboratory definitive evidence.
  • Not a case: A person that has been investigated and subsequently found not to meet the case definition.

Spread of infection

Reservoir

The natural reservoir of monkeypox virus remains unknown. However, it has been isolated from several African rodents and primates, including the Gambian pouched rat, tree squirrel, rope squirrel and sooty mangabey monkey.

Incubation period

The incubation period is typically 7 to 14 days, with a range of 5 to 21 days. The incubation period may be influenced by the route of transmission, with invasive exposure (e.g. contact with broken skin or mucous membrane) having a shorter incubation period than non-invasive exposure. This is why contacts are asked to monitor for symptoms and take precautions for 21 days from exposure.

Mode of transmission

In Africa, MPX is a zoonosis with transmission typically occurring animal-to-human via rodents.

MPX virus does not spread easily between people, but it can be transmitted person-to-person by close contact (including sexual contact) with skin lesions, body fluids, respiratory droplets (when masks aren’t worn), and contaminated materials such as bedding. There has been evidence that it is present in semen, but it is uncertain whether it can be transmitted this way.

Infectious period

The infectious period begins with the onset of symptoms, either prodromal or rash. Cases remain infectious until the rash has resolved, and all lesions have formed scabs and fallen off, leaving fresh skin underneath. Cases are not considered infectious prior to the onset of symptoms, however some cases may not be aware of their exact symptom onset date as initial symptoms may be both very subtle and/or not visible.

Notification procedure

MPX is a notifiable infectious disease in Schedule 1 of the Health Act 1956 from Thursday 9 June 2022. Health practitioners are required to notify the Medical Officer of Health on suspicion of a case, prior to collection of any samples. Heads of medical laboratories are required to notify the Medical Officer of Health of any NAAT result positive for MPX virus.

In the event of a case under investigation, probable or confirmed detected within New Zealand, Public Health/the Medical Officer of Health must contact the Communicable Diseases team (0800 GET MOH or [email protected]). If a case is notified after usual business hours, a Medical Officer of Health may use their discretion as to when they report the case to the Communicable Diseases team; reporting after usual business hours or awaiting until usual business hours if sufficient information is available ascertain that the risk to public health is low. If after hours, and initial indications suggest risk of potential onward transmission or high-risk factors, then the case should be reported via calling 0800 GET MOH.

One case of MPX identified in New Zealand constitutes an outbreak.

Privacy

Maintaining the privacy of cases and contacts of MPX is especially important given the 2022 outbreak’s disproportionate impact on the MSM community. Those to whom a MPX case or contact status is disclosed may interpret this information as confirmation the case or contact is a man who has sex with men, or otherwise a member of the LGBTIQA+ community. This could endanger the safety of the case or contact, or cause them reputational, emotional, or financial damage.

Disclosing case status to employers or contacts must therefore be carefully thought through, discussed with the case, and weighted proportionally against the risk of transmission. The same is true for disclosure of contact status.

Management of case

Investigation

The interview should include symptom history including onset date, travel history, identification of any high-risk settings, any exposure to a confirmed or probable case, the nature of any contact with a confirmed or probable case, sexual contact, and intimate partners within 21 days of symptom onset, smallpox and monkeypox vaccination status, and other relevant clinical findings to exclude other common causes of rash.[1]

Restriction

When infection is suspected, transmission-based infection prevention and control precautions apply. In addition to Standard Precautions, Contact and Airborne Precautions should be adhered to for clinical assessment and collecting samples. This includes the use of eye protection, P2/N95 mask, fluid repellent gown and gloves.

Probable and confirmed cases will need to isolate until they are no longer infectious which is until their lesions have crusted, the scab has fallen off and a fresh layer of skin has formed underneath (symptoms normally last 14–28 days). 

Further guidance regarding PPE

This means that

  • Cases should sleep in a separate room and limit contact with household members.
  • Cases should wear a mask when in the same room as others and cover skin lesions (where possible).
  • Cases should not share clothing, bedding, towels and unwashed crockery and cutlery.
  • Cases should not go out to public places or venues, or attend places of worship.
  • Cases must avoid physical contact, particularly sexual contact over this period (including kissing, intimate touching).
  • Cases can walk by themselves while keeping a 1 metre distance from others and must wear a mask when leaving the house.
  • Cases should avoid close direct contact with animals, including domestic animals, (such as cats, dogs, mice and other rodents), livestock, and other captive animals, as well as wildlife due to the possibility of human-to-animal transmission.
  • All waste, including medical waste, should be disposed of in a safe manner which is not accessible to rodents and other scavenger animals.

Release from isolation

Cases can be released from isolation when all lesions have crusted, scabs have fallen off and a fresh layer of skin has formed underneath.

The Medical Officer of Health will advise on release from isolation, which requires confirmation from a clinician that all lesions are healed.

For 12 weeks following release from isolation, the virus may still be present in semen. Therefore, condom use during sexual activity is recommended. This advice will be updated as new evidence becomes available.

Treatment

Most cases are mild and self-limiting with people recovering within two – four weeks. Most cases will not require specific treatment other than supportive management or treatment of complications (e.g., antibiotics for secondary cellulitis).

Advice on clinical management should be sought from an infectious diseases or sexual health physician. Refer to the healthcare pathways for MPX.

The Ministry of Health and PHARMAC are exploring options to secure access to antivirals. In the interim activities should focus on isolation of probable or confirmed cases and contact tracing.

Counselling

Advise the case of the nature of infection and mode of transmission. Educate cases regarding isolation requirements and high-risk people, activities, and settings to avoid while infectious.

Specific support for MSM and others within the rainbow community can be sought from OutLine, the Burnett Foundation, and a full list of support services for rainbow communities can be found on the Rainbow Youth website. Sexual health support and information is available on the Just the Facts website.

Management of contacts

Definition

Contacts can be separated into three groups: high risk close contacts, moderate risk close contacts, and casual contacts. The local Medical Officer of Health (or local public health or sexual health service) will assess contacts and categorise them based on their exposure to the case.

Close contact - high risk

A high-risk close contact is defined as any person with one or more of the following exposures to a probable or confirmed MPX case:

  • Direct physical contact with skin or mucous membranes of a case. (i.e., skin to skin, skin to mucous membranes, mucous membrane to mucous membrane).
  • Direct contact with potentially contaminated materials (bed linens healthcare equipment), crusts from lesions or with bodily fluids from a case

It also includes any household contacts who have had close physical contact with the case or contaminated materials, eg bedding or clothing.

A high-risk healthcare contact is a healthcare worker with one or more of the following exposures without appropriate PPE:

  • Direct physical contact with case, case materials, crusts, or bodily fluids; or
  • Presence in an enclosed room within 1.5 m of a case during aerosol generating procedures
  • Sharps injury from a used needle (including to cleaning or laboratory staff)

Appropriate PPE entails Standard Precautions and Contact and Airborne Precautions. This includes the use of eye protection, P2/N95 mask, fluid repellent gown and gloves.

More guidance on infection prevention and control

Close contact - moderate risk

A moderate-risk close contact is defined as a person with one or more of the following exposures to a probable or confirmed MPX case:

  • Indirect contact in an enclosed poorly ventilated indoor space within 1 meter of a case for more than 3 hours  
  • People sitting either side of a case on an airplane

It also includes household contacts who have not had any direct physical contact but have spent more than three hours with a case.

A moderate-risk healthcare worker is a healthcare worker who has had the following exposure without appropriate PPE:

  • Spillage or leakage of laboratory specimen onto intact skin

Casual contact

A casual contact is defined as a person with one or more of the following exposures, or any unlisted exposure that doesn’t meet the criteria above to a probable or confirmed MPX case:

  • Household members who have not spent time with or had direct physical contact with the case or contaminated materials from the case.
  • Work colleagues in the same workspace as the case.
  • Healthcare workers who were wearing appropriate PPE throughout their interaction with a case.
  • People on an airplane with the case, aside from the people sitting on either side of the case.

Investigation

For identifying potential onward exposures, contact trace from prodrome symptom onset, or 24 hours before rash onset for cases without prodrome. Prioritise contact tracing close contacts and healthcare close contacts, such as recent sexual partners, household contacts, and any healthcare workers not wearing appropriate PPE.

Restriction

No MPX contacts are required to quarantine unless they develop symptoms.

Close Contacts – High risk

Quarantine is not required. Contacts directed to isolate immediately if symptoms develop and contact public health.

Active monitoring[4] of symptoms is undertaken for 21 days following last exposure to the case. If symptoms develop, isolate immediately and contact Public Health for further advice.

Contacts are directed, for 21 days following their last exposure to the case to:

  • Wear a mask when around others
  • If travelling outside the region/country, to advise public health so their management can be transferred
  • Advise public health if they work in healthcare
  • Avoid high-risk activities including sexual activity, kissing, and other skin-to-skin contact with others

Vaccination may be considered when available.

Close Contact – Moderate Risk

Quarantine is not required. Contacts directed to isolate immediately if symptoms develop and contact public health.

Passive monitoring (self-monitoring)[5] of symptoms for 21 days. If symptoms develop, isolate immediately and contact Public Health for further advice.

Vaccination may be considered for those at higher risk of serious disease when available.

Casual Contact

No quarantine or routine monitoring. No vaccination considered.

Counselling

Advise the contact and/or caregivers of the nature of the disease and symptoms to monitor for.


References and further information

Alakunle E, Moens U, Nchinda G, Okeke MI. 2020. Monkeypox Virus in Nigeria: Infection Biology, Epidemiology, and Evolution. Viruses 12(11): 1257. https://doi.org/10.3390/v12111257

Brown K, Leggat PA. 2016. Human Monkeypox: Current State of Knowledge and Implications for the Future. Tropical Medicine and Infectious Disease 1(1): pps. https://doi.org/10.3390/tropicalmed1010008

Centers for Disease Control and Prevention. 2022. Monkeypox: how it Spreads. Available from https://www.cdc.gov/poxvirus/monkeypox/transmission.html

European Centre for Disease Prevention and Control. 2022. Factsheet for health professionals on monkeypox. Available from https://www.ecdc.europa.eu/en/all-topics-z/monkeypox/factsheet-health-professionals

Miura F, van Ewijk CE, Backer JA, Xiridou M, Franz E, Op de Coul E, et al. 2022. Estimated incubation period for monkeypox cases confirmed in the Netherlands. Eurosurveillance 27(24): 2200448. https://doi.org/10.2807/1560-7917.ES.2022.27.24.2200448

Nolen LD, Osadebe L, Katomba J, Likofata J, Mukadi D, Monroe B, et al. 2016. Extended Human-to-Human Transmission during a Monkeypox Outbreak in the Democratic Republic of the Congo. Emerging Infectious Diseases 22(6): 1014-21. https://doi.org/10.3201%2Feid2206.150579

UK Health Security Agency. 2022. Guidance Principles for monkeypox control in the UK: 4 nations consensus statement. Available from https://www.gov.uk/government/publications/principles-for-monkeypox-control-in-the-uk-4-nations-consensus-statement/principles-for-monkeypox-control-in-the-uk-4-nations-consensus-statement

World Health Organization. 2022. Clinical management and infection prevention and control for monkeypox: Interim rapid response guidance, 10 June 2022. Available from https://www.who.int/publications/i/item/WHO-MPX-Clinical-and-IPC-2022.1

World Health Organization. 2022. Disease Outbreak News; Multi-country outbreak of monkeypox, External situation report #2. Available from https://www.who.int/publications/m/item/multi-country-outbreak-of-monkeypox--external-situation-report--2---25-july-2022

World Health Organization. 2022. Monkeypox. Available from: https://www.who.int/news-room/fact-sheets/detail/monkeypox


Annex

Table 1: Summary of contact tracing definitions

Close contact – high risk of infection

Type of interaction

Examples

Direct physical contact with

  • skin or mucous membranes of a case. (i.e., skin to skin, skin to mucous membranes, mucous membrane to mucous membrane).
  • potentially contaminated materials (bed linens healthcare equipment); crusts from lesions or with bodily fluids from a case

CONTACT NOT WEARING APPROPRIATE PPE

Sexual or intimate contact with or without a condom (including oral, anal, vaginal sex, and kissing).

Dancing (e.g., where skin to skin contact occurs)

Body fluids from case (e.g., saliva) contact with eyes, nose, or mouth of contact

Household contact (higher risk)

CONTACT NOT WEARING APPROPRIATE PPE

Close skin to skin contact (e.g., frequent touching or cuddling, or who have shared bedding, clothing, or towels with a case)

Changing or washing soiled bedding or clothing of a case

Healthcare setting contact (higher risk)

  • Direct physical contact with case, case materials, crusts, or bodily fluids; or
  • Presence in an enclosed room within 1.5 m of a case during aerosol generating procedures
  • Sharps injury from a used needle (including to cleaning or laboratory staff)

CONTACT NOT WEARING APPROPRIATE PPE

Handling soiled bedding or clothing from a case with active lesions (e.g., cleaners, laundry staff)

Presence in the same room when soiled linen has been shaken

Showering a case.

Presence in the same room when a case was undergoing an oropharyngeal procedure such as intubation, bronchoscopy

Close contact – moderate risk of infection

Type of interaction

Examples

Healthcare contact (moderate risk)

CONTACT NOT WEARING APPROPRIATE PPE

Spillage or leakage of laboratory specimen onto intact skin

Household contact (moderate risk)  

CONTACT NOT WEARING A MASK

Individuals who live in the same household and have spent more than 3 hours with a case but have not had any direct physical contact

Indirect contact in an enclosed poorly ventilated indoor space within 1 meter of a case for more than 3 hours  

CONTACT NOT WEARING A MASK

  • People in a workplace or social setting
  • Flight contacts sitting next to a monkeypox case on a plane
  • Sharing a vehicle with a case (e.g., car, taxi)
Casual contact – low risk of infection

Type of interaction

Examples

All other contact with a monkeypox case including the above scenarios where appropriate PPE was used by the contact

Flat mates who spent minimal time together in the same room.

Healthcare workers who had no direct contact and remained more than 1 meter from the case (even if not wearing PPE)

Brief face to face conversations, such as colleagues in the same office

Flight crew; people on flights with a case other than those sitting either side.

Table 2: Summary of contact management

Contact Type

Management Pathway

Close Contact – High Risk

Contacts are told they have had contact with a case, but no identifiable information about a case is disclosed.

Quarantine is not required. Contacts directed to isolate immediately if symptoms develop and contact public health.

Active monitoring of symptoms is undertaken for 21 days following last exposure to the case.

For 21 days following their last exposure to the case, contacts are to:

  • Wear a mask when around others
  • If travelling outside the region/country, to advise public health so their management can be transferred
  • Advise public health if they work in healthcare
  • Avoid high-risk activities including sexual activity, kissing, and other skin-to-skin contact with others

Vaccination may be considered when available.

Close Contact – Moderate Risk

Contacts are told they have had contact with a case, but no identifiable information about a case is disclosed.

Quarantine is not required. Contacts directed to isolate immediately if symptoms develop and contact public health.

Passive monitoring (self-monitoring) of symptoms for 21 days.

Vaccination may be considered for those at higher risk of serious disease when available.

Casual Contact – Low Risk

No quarantine or monitoring required. No vaccination considered. No disclosure of status.


[1] More common causes of acute rashes with similar appearances should be considered and excluded where possible; varicella zoster, herpes simplex, syphilis, molluscum contagiosum.

[2] Exposure: direct physical contact with skin or skin lesions, including sexual contact; or contact with contaminated materials such as clothing, bedding or utensils; or prolonged face-to-face contact, including health care workers without appropriate PPE.

[3] Two or more

[4] Active monitoring for symptoms is when public health officials are responsible for contacting (ie by phone, email, text) periodically to see if a person under monitoring has signs/symptoms. The individual under monitoring must take their temperature daily, watch for signs/symptoms compatible with MPX, and immediately isolate and report to public health officials if they have signs/symptoms. If initial symptoms (other than a rash) they should be quarantined and watched closely over the following seven days. If no rash develops, they can return to temperature monitoring for the remaining days. Completion of monitoring will be based on a high trust model. If a contact reports no presentation of rash for 21 days since last close contact exposure to the case (while infectious), they will be released from follow-up.

[5] Self-monitoring for symptoms may be advised for low-risk contacts. Self-monitoring is when the person being monitored is responsible for taking their temperature once daily and watching for signs/symptoms compatible with MPX. The individual should immediately isolate and report to public health officials if they have such signs/symptoms within 21 days of last exposure. If initial symptoms (other than a rash) they should be quarantined and watched closely over the following seven days. If no rash develops, they can return to temperature monitoring for the remaining days.
Completion of monitoring will be based on a high trust model. If a contact reports no presentation of rash for 21 days since last close contact exposure to the case (while infectious), they will be released from follow-up.

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