Mpox: 42,000 cases, 1,100 deaths, why new ‘clade' is a cause of concern
More contagious Clade Ib a cause of concern, mpox cases seen in 120 countries
The World Health Organisation (WHO) has sounded off concern on a resurgence of Mpox.
As of October 17, 2024, latest data from the agency stated that the death toll from mpox has risen to 1,100 people, with 42,000 lab-confirmed cases globally.
Deployment of approved mpox vaccines has been found wanting, and the WHO has appealed for funding support to ramp up production of approved shots, especially in high-risk countries.
• It is a viral illness caused by the monkeypox virus, a species of the genus Orthopoxvirus.
• It 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 DR Congo (DRC).
• Since then the infection has been reported in a number of African countries.
If it’s not a new virus, why is it a cause of concern?
Prior to 2022, most cases were reported from the DR Congo, Nigeria and about a dozen other African countries.
In 2003, mpox was recorded in the US when an outbreak occurred following the importation of rodents from Africa that also infected pet prairie dogs.
What are the symptoms of mpox infection?
Common symptoms of mpox are a skin rash or mucosal lesions which can last 2–4 weeks accompanied by fever, headache, muscle aches, back pain, low energy, and swollen lymph nodes.
How does mpox spread?
Mpox can be transmitted to humans through physical contact with someone who is infectious, with contaminated materials, or with infected animals.
The virus spreads through close contact, causing flu-like symptoms and pus-filled lesions.
How is mpox infection confirmed?
Laboratory confirmation of mpox is done by testing skin lesion material by polymerase chain reaction (PCR).
How is mpox treated?
- Currently, mpox is treated with supportive care.
- The goal of treating mpox is to take care of the rash, manage pain and prevent complications.
- Early and supportive care is important to help manage symptoms and avoid further problems.
- If you're very sick, your provider might prescribe antiviral drugs like cidofovir or tecovirimat.
- These drugs are approved to treat other viral infections (like smallpox), but researchers need to learn more about how well they work for mpox.
Source: Cleveland Clinic
Are there mpox vaccines available?
There are vaccines and therapeutics developed for smallpox approved in some countries and can be used for mpox in some circumstances.
How can mpox be prevented?
Mpox can be prevented by avoiding physical contact with someone who has mpox.
Do people infected with mpox recover?
Yes, most human infections followed contact with an infected pet or person recover.
However, people with severe mpox may require hospitalisation, supportive care and antiviral medicines to reduce the severity of lesions and shorten time to recovery.
What is the mpox fatality rate?
According to available data cited by the WHO, between 0.1 per cent and 10 per cent of people with mpox have died.
What are the known mpox genetic groups?
There are 2 major genetic groups (clades) of mpox virus MPXV:
- Clade I (formerly known as Central African or Congo basin clade)
- Clade II (formerly known as West African clade).
Clade I is split into:
- Clade Ia
- Clade Ib
Clade II is split into:
- Clade IIa
- Clade IIb
Clade II also has subgroup clusters, called "lineages".
The majority of the cases seen in the outbreak in 2022 were from clade IIb, lineage B.1.
• A clade, or monophyletic group, refers to a collection of organisms that includes a common ancestor and all its descendants, representing a continuous line of evolutionary descent.
• In phylogenetics, clades are easily identified using a phylogenetic tree, as they form distinct branches that trace this unbroken lineage.
• Phylogenetics is the study of the evolutionary relationships among biological species or entities based on their genetic or physical characteristics.
• It uses data such as DNA, RNA, and protein sequences to reconstruct evolutionary trees, known as "phylogenetic trees".
• These trees illustrate the ancestry of species and how they are related, showing how they diverged from common ancestors over time.
In August, the Department of Health in Victoria, Australia reported an "ongoing outbreak of mpox in Victoria and other Australian jurisdictions", mostly impacting gay, bisexual, and other men who have sex with men. This outbreak is caused by Clade IIb of the virus.
Meanwhile, the more contagious clade 1b is also making waves.
Why is the current outbreak considered a “new threat”?
The new outbreak is driven by a more contagious variant of the mpox virus, known as clade 1b.
This variant has spread rapidly in the DR Congo and neighbouring countries, with children being particularly affected. Sweden and Germany have both confirmed Clade 1b cases.
Is Clade IIb also a cause of concern?
In 2022–2023, a global outbreak of mpox was caused by the clade IIb strain.
A team led by Dr. Fabio Scarpa, a post-doctoral researcher at the Department of Biomedical Sciences, University of Sassari, Italy, published in August 2024 edition of the journal Microorganisms an “Update of the Genetic Variability of Monkeypox Virus Clade IIb Lineage B.1”
The researchers reported that their analyses indicate a slow rate of evolution of the virus, noting a generally stable viral population size of Clade IIb.
“In general, the data indicate that the MPXV outbreak is primarily localised within a few consistent geographic clusters. The virus’s evolution is relatively slow, as indicated by its stable genetic variability, and Clade IIb lineage B.1 does not currently show signs of rapid genetic changes or population growth.”
However, the team issued a warning against complacency: “The current low level of genetic diversity should not lead to complacency. Ongoing genomic surveillance is essential for effective outbreak management and understanding.
They also urged continued vigilance in order to detect any new variants that might influence the outbreak’s trajectory.
Why was mpox declared a public health emergency of international concern (PHEIC)?
The WHO determined that the upsurge of mpox constitutes a public health emergency of international concern (PHEIC) under the International Health Regulations (IHR).
The declaration came following the advice of an IHR Emergency Committee of independent experts who met earlier to review data presented by experts from WHO and mpox affected countries.
WHO Regional Director for Africa Dr Matshidiso Moeti said: “Significant efforts are already underway in close collaboration with communities and governments, with our country teams working on the frontlines to help reinforce measures to curb mpox.
(1) MVA-BN (Modified Vaccinia Ankara - Bavarian Nordic), or
(2) LC16 (made by Japan’s KM Biologics).
These are the two approved vaccines for people at risk during an mpox outbreak.
A third one, ACAM2000 (Emergent Biosolutions/Sanofi Pasteur) may also be used for certain people based on an individual assessment when other vaccines are not available.
(Source: WHO)
Vaccine access for lower-income countries which have not yet issued their own national regulatory approval will be accelerated after the WHO triggered the process for “Emergency Use Listing” (EUL) for mpox vaccines. EUL also enables partners including Gavi and UNICEF to procure vaccines for distribution.
How much is needed to speed up mpox vaccine production and distribution?
WHO anticipates an immediate funding requirement of an initial $ 15 million to support surveillance, preparedness and response activities.
The agency said it is working with countries and vaccine manufacturers on potential vaccine donations, and coordinating with partners through the interim Medical Countermeasures Network to facilitate equitable access to vaccines, therapeutics, diagnostics and other tools.
To allow for an immediate scale up, WHO has released $1.45 million from the WHO Contingency Fund for Emergencies and may need to release more in the coming days.
WHO has appealed to donors to fund the full extent of needs of the mpox response.