Mpox is an infectious disease caused by the monkeypox virus (MPXV). There are two known clades of MPXV: clade I, previously called the Congo Basin clade, which includes subclades Ia and the recently identified Ib; and clade II, previously called the West African clade, which includes subclades IIa and IIb. Subclades Ia and Ib have been defined based on the emergence of subclade Ib in the South Kivu province of the Democratic Republic of the Congo, where it has predominantly spread through sexual contact. Subclade Ia is currently considered to encompass all other strains of Clade I that are not Ib.
How does Mpox transmit?
MPXV transmits between humans through close contact with lesions, body fluids, infectious respiratory particles or contaminated materials, or from animals to humans through contact with live animals or consumption of contaminated bushmeat. Transmission through sexual contact has been observed to lead to the appearance sometimes of only genital lesions. Children, pregnant women and people with weak immune systems are at risk of developing complications and dying of Mpox.
What are the symptoms of Mpox?
Mpox causes signs and symptoms which usually begin within a week of exposure but can start one to 21 days later. Symptoms typically last for two to four weeks but may last longer in someone with a weakened immune system. Normally, fever, muscle aches and sore throat appear first, followed by skin and mucosal rash. Lymphadenopathy (swollen lymph nodes) is also a typical feature of mpox, present in most cases.
How is Mpox different from chickenpox, measles, etc?
It is important to distinguish mpox from chickenpox, measles, bacterial skin infections, scabies, herpes, syphilis, other sexually transmissible infections, and medication-associated allergies. Someone with mpox may also concurrently have another sexually transmissible infection such as herpes. Alternatively, a child or adult with suspected mpox may have chickenpox. For these reasons, laboratory testing is important for confirmation of mpox, particularly for the first cases in an outbreak or new geographic area.
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How is it diagnosed?
The primary diagnostic test for MPXV infection is polymerase chain reaction (PCR). The best diagnostic specimens are taken directly from the rash – skin, fluid or crusts – collected by vigorous swabbing. In the absence of skin lesions, testing can be done on oropharyngeal, anal or rectal swabs. However, while a positive result of oropharyngeal, anal or rectal sample confirms mpox, a negative result is not enough to rule out MPXV infection. Testing of blood is not recommended. Serology does not distinguish between different orthopoxviruses and is therefore restricted to reference laboratories where antibody detection methods may be applied for retrospective case classification or in special studies.
How is is treated?
Treatment is based primarily on managing clinical symptoms, ensuring skin care, reducing pain, and preventing and managing complications. Where available through emergency or compassionate use programmes, specific antiviral medications such as tecovirimat can also be used in the treatment of mpox, particularly for severe cases or individuals at higher risk of complications.
Three vaccines are currently available for use to prevent mpox in different countries (MVA-BN, LC16-KMB, and OrthopoxVac – the latter not yet commercialized). WHO recommends use of MVA-BN or LC16 vaccines when the others are not available.
Vaccination is recommended by WHO for individuals at high risk of exposure.
