11/14/24, 10\:55 AM MPox (formerly Monkeypox)

MPox (formerly Monkeypox)

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MPox\: Previously known as monkeypox, a rare zoonotic disease caused by the m o n k e y p o x v i r u s (MPV), part of the
Orthopoxvirus genus.
Epidemiology\: Endemic to the Democratic Republic of Congo. Two clades\: Central African (CFR up to 11%) and West African
(CFR \<1%). Outbreaks have occurred outside Africa since 2003, including a signi
2022.
Aetiology\: MPV is a double-stranded DNA virus. It binds to cell surfaces, enters via fusion or endosomal uptake, and
replicates in the cytoplasm.
Transmission\: Zoonotic, mainly from African rodents. Human-to-human transmission through saliva, respiratory excretions,
direct contact with lesions, or vertical transmission.
Risk factors\: Travel to endemic areas, contact with infected individuals/animals, immunocompromised states, and lack of
smallpox vaccination (ceased after smallpox eradication).
Clinical features\: Self-limiting, resolving in 2-4 weeks. Prodromal phase\: fever, headaches, fatigue. Rash appears 1-3 days
later, starting on the face and spreading centrifugally. Lesions progress from macules to papules, vesicles, pustules, ulcers,
and crusts. Lymphadenopathy is a distinguishing feature.
Di
herpes zoster (dermatomal distribution), herpes simplex virus (localized, super
Diagnosis\: PCR testing of swabs from lesion roofs,
cross-reactivity.
Management\: Isolation and supportive care. Antivirals like cidofovir and tecovirimat may be used. Prevention includes
avoiding contact with infected animals, reporting travel-related illnesses, and maintaining hygiene.
Prevention\: Smallpox vaccine (Imvanex) o
Complications\: More severe in unvaccinated individuals. Can include bacterial skin infections, bronchopneumonia,
vomiting, diarrhoea, dehydration, ocular infections, loss of vision, sepsis, congenital MPV, and stillbirth in pregnant women.
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Introduction

MPox (previously known as monkeypox) is a rare zoonotic disease caused by the m o n k e y p o x v i r u s (MPV), which belongs
to the genus Orthopoxvirus, along with v a r i o l a v i r u s , the causative agent of smallpox.
1,2
MPV has emerged as the most important Orthopoxvirus for public health and has caused an ongoing outbreak in the UK,
beginning in May 2022.
3
This article presents a clinical summary of MPV, including its epidemiology, clinical features, and management.

Epidemiology

MPV is endemic to the Democratic Republic of Congo, where the virus was
2
1
There are two clades of the virus\: the Central African (Congo Basin) clade, and the West African clade. The former is more
prone to cause severe disease, with a case-fatality ratio (CFR) of up to 11%, whereas the latter has a CFR of \<1%.
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Since the eradication of smallpox in 1980, MPV has emerged as the most important Orthopoxvirus for public health, and
incidence may be exacerbated by waning immunity following the cessation of smallpox vaccination, which conferred 85%
protection to MPV.
2
Prior to 2003, outbreaks of MPV were limited to Africa, with cases reported in 10 countries. The
Africa occurred in 2003 when a shipment of wild rodents from Ghana is thought to have infected pet prairie dogs in the
USA.
2
Over the following years, cases were reported in Israel, the UK, and Singapore.
4
2022 MPox outbreak
An ongoing outbreak began in the UK following a conth
and
25 th
May, 71 cases were identi
Europe, Australia, and America.
3.5
A notable proportion of cases were identi
to be transmitted through close contact, not sexual transmission.
6
A World Health Organization (WHO) risk assessment has stated that the risk of potential onward spread in the UK is
minimal owing to the rapid public health response including isolation and contact tracing, however, the source of
infection in Nigeria has not been determined, so there remains a risk of further transmission.
7
For the latest information, see the UK Health Security Agency information pages on monkeypox.

Aetiology

The m o n k e y p o x v i r u s ( M P V ) is a double-stranded DNA virus belonging to the genus Orthopoxvirus. This group contains
four other virus species pathogenic to humans, including c o w p o x v i r u s , v a c c i n i a v i r u s , and v a r i o l a v i r u s , the causative agent
of smallpox.
1,2
Pathophysiology8
MPV, and other species of Orthopoxvirus, bind to the cell surface through interaction between their ligands and several
di
Replication occurs in the cytoplasm of cells at the site of infection, where pre-made viral proteins stimulate the expression
of early genes which promote DNA replication, as well as transcription and translation of intermediate and late genes,
which code for structural proteins. Thus, nascent virions are assembled and spread to lymph nodes.
MPV has an incubation period of 7-17 days before the onset of symptoms.
Transmission9
Transmission occurs when the virus gains access through broken skin, the respiratory tract or the mucous membranes.
MPV is zoonotic, and although the host reservoir is still unknown, species of African rodents are implicated.
Animal-human transmission occurs through direct contact with blood, bodily
infected animals.
Human-human transmission is rarer and occurs through saliva and respiratory excretions, direct and indirect contact with
lesion exudate or crust material or vertical transmission via the placenta, or close contact during or after birth.

Risk factors

Individuals who have travelled to endemic countries and been in contact with infected individuals or animals are at
increased risk of acquisition.
Immunocompromised individuals, such as children and pregnant women often have more severe disease, along with
those with underlying immune de
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People younger than 40-50 may be more susceptible due to the cessation of smallpox vaccination.
7

Clinical features

The disease is often self-limiting, with symptoms usually resolving within 2-4 weeks. The clinical features associated with
MPox infection mirror that of smallpox.
The prodromal phase lasts between 1-4 days and includes fever, headaches and fatigue.
1,2
Importantly, a distinctive feature of MPV infection is maxillary, cervical or inguinal lymphadenopathy (maxillary, cervical or
inguinal), which is absent in similar diseases such as chickenpox, measles, and smallpox.
7
Around 1-3 days following the prodromal phase, a distinctive rash appears, with the number of lesions varying
signi1,2 1
This characteristically appears on the face before taking a centrifugal distribution , with the following body
parts a
9
Face (95%)
Palms of hand and soles of feet (75%)
Genitalia (30%)
Conjunctiva/cornea (20%)
The lesions, shown in Figure 1, develop sequentially from macules to papules and to vesicles (1A) containing clear
10
Vesicles then become well-circumscribed, umbilicated pustules (1B, 1C) before ulcerating (1D) and crusting over (1E, 1F).
The infection can last up to 4 weeks until the lesions desquamate.
1.2
Figure 1. The progression of monkeypox
virus lesions. From A to E\: vesicle,
pustule, umbilicated pustule, ulcerated
pustule, crusting scab formation, partially
removed scab.
10

Di

The WHO recommends suspecting MPox in any person in a non-endemic country with an unexplained acute rash
accompanying either headache, acute onset fever, lymphadenopathy, myalgia, back pain or asthenia if the rash cannot be
explained by more common causes, such as chickenpox, shingles and herpes simplex.
4
Table 1. Di
1,2,11
Di
Smallpox No lymphadenopathy
Varicella-zoster virus (VZV,
chickenpox)
Prolonged febrile prodrome without
lymphadenopathy
Faster progression of rash
Lesions are super
Vesicles distributed mainly on the trunk, in crops
Herpes zoster virus (HZV,
shingles)
Usually dermatomal distribution
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Herpes simplex virus (HSV) Rash is localised and not deep-seated

Diagnosis

Diagnosis of MPV relies on the detection of viral DNA using PCR testing.
4
Samples should be obtained from swabbing the roof,
serology testing are not recommended for the diagnosis of MPV due to their cross-reactivity with other orthopoxviruses.

Management

In the
Antivirals may be used such as cidofovir, a DNA polymerase-inhibitor, and tecovirimat, which inhibits the viral envelope
protein.
11

Prevention

WHO recommends reporting illnesses associated with travel to endemic countries, avoiding contact with infected animals
and avoiding eating or handling bushmeat, as well as using hand hygiene and alcohol-based sanitiser.
4
Prompt contact tracing and surveillance protocols should be employed to curb onward transmission. Health workers
should observe contact and droplet infection control precautions.
12
Although prior smallpox vaccination confers 85% protection against MPox, populations under the age of 50 may no longer
bene
The UK Health Security Agency (UKHSA) is o
diagnosed with MPox to reduce symptomatic infection and severe illness.
3

Complications

Severe complications are more common among unvaccinated (74%) than vaccinated (39.5%) patients; bacterial skin
infections were noted in 19% of unvaccinated MPox patients, and other complications may include bronchopneumonia,
vomiting, diarrhoea, and dehydration.
1,2
Other complications include ocular infections, loss of vision and sepsis in severe cases. Congenital MPV and stillbirth can
occur in pregnant women.

References

McCollum AM, Damon IK. H u m a n m o n k e y p o x . Clinical infectious diseases. 2014 Jan 15;58(2)\:260-7.
Sklenovska N, Van Ranst M. E m e r g e n c e o f m o n k e y p o x a s t h e m o s t i m p o r t a n t o r t h o p o x v i r u s i n f e c t i o n i n h u m a n s . Frontiers
in public health. 2018 Sep 4;6\:241.
UK Health Security Agency. GOV.UK. 2022. M o n k e y p o x c a s e s c o n
2022] Available from\: [LINK]
World Health Organization (21 c o u n t r i e s . Available from\: [LINK]
May 2022). D i s e a s e O u t b r e a k N e w s ; M u l t i-c o u n t r y m o n k e y p o x o u t b r e a k i n n o n-e n d e m i c
GOV.UK. 2022. M o n k e y p o x c a s e s c o n LINK]
Kozlov M. M o n k e y p o x g o e s g l o b a l \: w h y s c i e n t i s t s a r e o n a l e r t . Nature. 2022 May 20. doi\: 10.1038/d41586-022-01421-8. Epub
ahead of print. PMID\: 35595996.
World Health Organization (16 N o r t h e r n I r e l a n d . Available at\: May [LINK]
2022). D i s e a s e O u t b r e a k N e w s ; M o n k e y p o x– U n i t e d K i n gd o m o f G r e a t B r i t a i n a n d
https\://app.geekymedics.com/notebook/2708/ 4/511/14/24, 10\:55 AM MPox (formerly Monkeypox)
Alkhalil A, Hammamieh R, Hardick J, Ichou MA, Jett M, Ibrahim S. Gene expression pro
cells reveals novel interfaces for host-virus interactions. Virology Journal. 2010 Dec;7(1)\:1-9.
World Health Organization (21 May 2022) . D i s e a s e O u t b r e a k N e w s ; M u l t i-c o u n t r y m o n k e y p o x o u t b r e a k i n n o n-e n d e m i c
c o u n t r i e s . Available from\: [LINK]
UK government. Stages of lesion development. License\: [OGL]
BMJ Best Practice. P o x v i r u s i n f e c t i o n ( m o n k e y p o x a n d s m a l l p o x ) – D i LINK]
UK Health Security Agency. GOV.UK. 2022. M o n k e y p o x \: b a c k g r o u n d i n f o r m a t i o n . [Accessed 25 May 2022] Available from\:
[LINK]

Related notes

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Human Immunode

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Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
Diagnosis
Management
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