Mpox clade Ib strain spreads in many countries

• The World Health Organisation (WHO) updated its mpox data dashboard on October 24 stating that community transmission of clade Ib mpox has been reported in the United States, Italy, Spain, Portugal, the Netherlands and Malaysia. 

• Health authorities in Spain, the United States, and the Netherlands reported small numbers of locally-acquired clade Ib mpox cases.

• One imported clade Ib mpox case has been reported from Belgium, in a male with travel history to Malaysia.

• Three additional clade Ib mpox cases without travel history have been reported from Italy and Portugal.

What is mpox?

• Mpox (monkeypox) is an infectious disease caused by the monkeypox virus (MPXV). 

• Mpox virus belongs to the Orthopoxvirus genus in the family Poxviridae. The Orthopoxvirus genus also includes variola virus (which causes smallpox), vaccinia virus (used in the smallpox vaccine), and cowpox virus.

• Mpox has symptoms similar, but less severe, to smallpox. While smallpox was eradicated in 1980, mpox continues to occur in countries of central and west Africa.

• Mpox is zoonosis: a disease that is transmitted from animals to humans.

• Mpox was formerly called monkeypox. Following a series of consultations with global experts, WHO began using “mpox” as a synonym for monkeypox. 

• Monkeypox was first discovered in 1958 when outbreaks of a pox-like disease occurred in monkeys kept for research, hence the name ‘monkeypox’.

• The first human case was recorded in 1970 in the Democratic Republic of the Congo (then known as Zaire), and since then the infection has been reported in a number of central and western African countries. Most cases are reported from Congo and Nigeria. 

• In 2003, monkeypox was recorded in the United States when an outbreak occurred following importation of rodents from Africa. Cases were reported in both humans and pet prairie dogs. All the human infections followed contact with an infected pet and all patients recovered. 

• Mpox is endemic in densely forested regions of West, Central and East Africa, particularly in the northern and central regions of Congo. 

• Mpox outbreaks are caused by different viruses called clades. Clade 1 has been circulating in Congo for years, while clade 2 was responsible for the global outbreak which began in 2022.

• Mpox was declared a public health emergency of international concern (PHEIC) on August 14, 2024.

On September 5, 2025, the World Health Organisation (WHO) chief Tedros Adhanom Ghebreyesus announced that mpox is no longer a PHEIC.

Transmission

• Mpox does not spread easily between people.

• Spread of mpox may occur when a person comes into close contact with an animal (rodents are believed to be the primary animal reservoir for transmission to humans), human, or materials contaminated with the virus. 

• The virus enters the body through broken skin (even if not visible), the respiratory tract, or the mucous membranes (eyes, nose, or mouth).

Person-to-person spread is very uncommon, but may occur through:

• Contact with clothing or linens (such as bedding or towels) used by an infected person.

• Direct contact with mpox skin lesions or scabs.

• Coughing or sneezing of an individual with a mpox rash.

Symptoms

Initial symptoms include fever, headache, muscle aches, backache, swollen lymph nodes, chills and exhaustion. A rash can develop, often beginning on the face, then spreading to other parts of the body. The rash changes and goes through different stages before finally forming a scab, which later falls off.

Treatment

• Detection of viral DNA by polymerase chain reaction (PCR) is the preferred laboratory test for mpox. 

• Mpox, in most cases, is a mild condition which will resolve on its own and have no long-term effects on a person’s health. Most people recover within a few weeks. However, severe illness can occur in some individuals.

• Treatment of mpox patients is supportive dependent on the symptoms. Various compounds that may be effective against mpox virus infection are being developed and tested.

• Prevention and control of human mpox rely on raising awareness in communities and educating health workers to prevent infection and stop transmission.