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Guidance: Monkeypox - risk assessment and management

Published 26 May 2022
Written by
Dr John Harrison
Senior Medical Officer, National Police Wellbeing Service
Reading time
7 mins

You may have heard of the recent rise in cases of Monkeypox, our Senior Medical Officer, John Harrison has produced this guidance which gives details on the virus and a risk assessment of catching monkeypox

What is Monkeypox?

Monkeypox is a viral zoonosis (a virus transmitted to humans from animals) with symptoms like those seen in the past in smallpox patients, although it is clinically less severe. With the eradication of smallpox in 1980 and subsequent cessation of smallpox vaccination, monkeypox has emerged as the most important orthopoxvirus for public health. Monkeypox primarily occurs in central and west Africa, often in proximity to tropical rainforests, and has been increasingly appearing in urban areas. Animal hosts include a range of rodents and non-human primates[1].

 

Why are we hearing about Monkeypox now?

Human monkeypox was first identified in humans in 1970 in the Democratic Republic of the Congo in a 9-year-old boy in a region where smallpox had been eliminated in 1968. Since then, most cases have been reported from rural, rainforest regions of the Congo Basin, particularly in the Democratic Republic of the Congo and human cases have increasingly been reported from across central and west Africa. In 2003, the first monkeypox outbreak outside of Africa was in the United States of America and was linked to contact with infected pet prairie dogs. These pets had been housed with Gambian pouched rats and dormice that had been imported into the country from Ghana. This outbreak led to over 70 cases of monkeypox in the U.S. Monkeypox has also been reported in travellers from Nigeria to Israel in September 2018, to the United Kingdom in September 2018, December 2019, May 2021 and May 2022, to Singapore in May 2019, and to the United States of America in July and November 2021. From June 8, monkeypox will become a notifiable disease.

The UK Health Security Agency (UKHSA) has reported the total number of cases in the UK (Monday, June 13, 2022) at 470. There are 452 confirmed cases in England, 12 in Scotland, 4 cases have been reported in Wales and 2 in Northern Ireland[2]. The exact details of this recent outbreak are unknown. It has been reported that a notable proportion of cases in the UK have occurred amongst men who have sex with men. However, it should not be assumed that this is only a sexually transmitted disease. A high proportion of England cases were known to be London residents.

 

How is Monkeypox transmitted?

Animal-to-human (zoonotic) transmission can occur from direct contact with the blood, bodily fluids, or cutaneous or mucosal lesions of infected animals. Human-to-human transmission can result from close contact with respiratory secretions, skin lesions of an infected person or recently contaminated objects. Transmission via droplet respiratory particles usually requires prolonged face-to-face contact, which puts health workers, household members and other close contacts of active cases at greater risk. While close physical contact is a well-known risk factor for transmission, it is unclear at this time if monkeypox can be transmitted specifically through sexual transmission routes. Studies are needed to better understand this risk. The chain of transmission in the community seems to be increasing; this may reflect declining immunity in all communities due to cessation of smallpox vaccination. The potential level of transmission is level 2 – within a defined sub-population with a high number of close contacts[3].

 

How do I risk assess the likelihood of catching Monkeypox?

The Center for Disease Control (CDC) in the United States advises that transmission of the virus occurs from contact with an infected animal, human or materials. The virus enters the body through broken skin (even if not visible), respiratory tract or the mucous membrane of the eyes. Human to human transmission is thought to occur via large respiratory droplets[4]. This means that avoidance of prolonged close contact is important. Where this is not possible, use of protective equipment, like that used during the COVID pandemic is advisable. Wearing a surgical mask type IIR will prevent large respiratory droplets entering the respiratory tract when, for example, travelling in a police vehicle, or in the custody environment.

The CDC advises that someone suffering from monkeypox should wear a surgical mask, especially if they have respiratory symptoms. Disposable gloves are required if the person has skin lesions. They should be disposed of carefully, after use. Skin lesions should be covered as far as possible, with long sleeves or trousers. Attention to hand hygiene and cleaning is required. Standard household cleaners / disinfectants may be used.

The latest guidance from the NPCC (Health, Safety and Welfare) was issued on June 9, 2022. It is recommended that, when dealing with a probable case of monkeypox, the following are adhered to:

  • Wear nitrile gloves and an IIR mask when in close proximity to someone believed to be infected
  • Additionally, use eye protection and a gown if possible – especially when dealing with non-compliant people who might spit at officers or staff
  • Use hand sanitizer before and after contact with a member of the public
  • Continue to practice good hygiene including washing clothes with standard detergent if contaminated.

There are two forms of monkeypox: a milder west African strain and a more severe central African, or Congo, strain. The current outbreak in the UK is said to be the west African strain[5].  The incubation period (interval from infection to onset of symptoms) of monkeypox is usually from 6 to 13 days but can range from 5 to 21 days.

The infection can be divided into two periods:

  • the invasion period (lasts between 0–5 days) characterized by fever, intense headache, lymphadenopathy (swelling of the lymph nodes), back pain, myalgia (muscle aches) and intense asthenia (lack of energy). Lymphadenopathy is a distinctive feature of monkeypox compared to other diseases that may initially appear similar (chickenpox, measles, smallpox)
  • the skin eruption usually begins within 1–3 days of appearance of fever. The rash tends to be more concentrated on the face and extremities rather than on the trunk. (A chickenpox rash typically concentrates on the trunk and face, whereas in smallpox and monkeypox the extremities are involved. These are all vesicular rashes. A measles rash usually begins as flat red spots at the hairline and then spreads downwards to the neck, trunk, arms, legs and feet.) It affects the face (in 95% of cases), and palms of the hands and soles of the feet (in 75% of cases). Also affected are oral mucous membranes (in 70% of cases), genitalia (30%), and conjunctivae (20%), as well as the cornea. The rash evolves sequentially from macules (lesions with a flat base) to papules (slightly raised firm lesions), vesicles (lesions filled with clear fluid), pustules (lesions filled with yellowish fluid), and crusts which dry up and fall off. The number of lesions varies from a few to several thousand. In severe cases, lesions can coalesce until large sections of skin fall off.

Someone with chickenpox (varicella) is said to be infectious 1 – 2 days before the onset of the rash; smallpox becomes infectious once fever develops. It might be assumed, therefore, that the risk of infection from monkeypox begins before the onset of the rash.

UKHSA health protection teams are contacting people considered to be high-risk contacts of confirmed cases and are advising those who have been risk assessed and remain well to isolate at home for up to 21 days.

Despite further cases being detected, the risk to the UK population remains low.

 

How serious is infection with Monkeypox?

Monkeypox is usually a self-limited disease with the symptoms lasting from two to four weeks. Severe cases occur more commonly among children and are related to the extent of virus exposure, patient health status and nature of complications. Underlying immune deficiencies may lead to worse outcomes. As with COVID, therefore, it is important to avoid exposing vulnerable people to the risk of transmission of the virus. Complications of monkeypox can include secondary infections, bronchopneumonia, sepsis, encephalitis, and infection of the cornea with ensuing loss of vision.

 

Diagnosis and treatment

A history of prolonged close contact with an infected person, or contact with infected material, leads to laboratory testing. Polymerase chain reaction (PCR) is the preferred laboratory test given its accuracy and sensitivity. For this, diagnostic samples for monkeypox are collected by healthcare workers from skin lesions.  Serology and antigen detection methods are not recommended.

Clinical care for monkeypox is aimed at alleviating symptoms, managing complications and preventing long-term complications. Patients should be offered fluids and food to maintain adequate nutritional status. Secondary bacterial infections should be treated as indicated. 

UKHSA has purchased supplies of a safe smallpox vaccine (called Imvanex, supplied by Bavarian Nordic) and this is being offered to identified close contacts of someone diagnosed with monkeypox to reduce the risk of symptomatic infection and severe illness.

 


[1] Monkeypox. World Health Organisation. https://www.who.int/news-room/fact-sheets/detail/monkeypox

 

 

[2] Monkeypox cases confirmed in England – latest updates. https://www.gov.uk/government/news/monkeypox-cases-confirmed-in-england-latest-updates

 

 

[3] Investigation into monkeypox outbreak in England: technical briefing 1. UKHSA. June 10 2022. https://www.gov.uk/government/publications/monkey-pox-outbreak-technical-briefings/investigation-into-monkeypox-outbreak-in-england-technical-briefing-1

 

 

[4] Monkeypox Transmission. CDC. https://www.cdc.gov/poxvirus/monkeypox/transmission.html

[5] What is monkeypox and should you be worried? The Guardian. May 23, 2022. https://www.theguardian.com/world/2022/may/23/what-is-monkeypox-source-cases-infections-spread-experts