Clade I Monkeypox Outbreaks

Outbreak overview

In the United States

• The risk posed by the clade I monkeypox outbreak to most people within the United States remains low. The risk to men who have sex with men is low to moderate.
• Clade I cases in the United States have increased in frequency since March 2026.
• As of September 2026, there have been more than 80 clade I monkeypox cases reported in at least 22 states.
• The majority of these cases are among gay, bisexual, or other men who have sex with men. Many of these cases:
  • Had recently traveled from areas associated with the outbreak in Central and Eastern Africa;
  • Reported sexual contact during travel to parts of Western Europe where newer outbreaks are being reported; OR
  • Reported sexual contact with people who had traveled from these areas.
• Since August 2026, an increasing proportion of clade I cases in the United States have been reported in individuals with no recent international travel or known links to people who had recently traveled.
  • Cases with presumed domestic transmission have been reported in more than 10 jurisdictions, indicating a likely transition to sustained clade Ib transmission in the United States.
• CDC expects to see additional cases of both travel-related and domestically acquired cases of clade Ib occurring across the United States.

In Central and Eastern Africa

• Clade Ia monkeypox outbreaks began impacting western areas of the Democratic Republic of the Congo (DRC) in 2024.
  • Available data indicate that clade Ia monkeypox has spread through sexual contact, regular household contact, and encounters with infected dead or live wild animals.
• Clade Ib monkeypox cases initially impacted eastern areas of DRC in late 2023.
  • This subclade has driven much of the spread throughout Central and Eastern Africa and most travel-associated cases to other parts of the world.
  • Available data indicate that these cases at first spread through heterosexual intimate or sexual contact between adults, then spread likely occurred within households, including to children.
    
• The disease spread in 2024 and 2025 to neighboring countries of DRC, only some of which are endemic for the virus that causes monkeypox, and sustained local spread occurred.
  

Outside Central and Eastern Africa

• Several countries in other parts of Africa, Asia, Europe, North America, and South America, as well as Australia, have confirmed clade I monkeypox cases mostly in travelers who'd recently been in areas with clade I outbreaks.
  • To date, there have been more than 300 clade Ib cases in high-income countries, and no deaths have been reported.
• Several countries in Western Europe are reporting clade Ib monkeypox cases among individuals who had no documented history of international travel.
  • These cases were likely related to intimate or sexual exposure among men who have sex with men.
  • We expect additional cases in Europe and the United States.
• For data since January 1, 2024, see 2022-24 Monkeypox (Monkeypox) Outbreak: Global Trends (shinyapps.io).
  • Confirmed cases include those that are laboratory confirmed as monkeypox virus and may include cases only confirmed as orthopoxvirus. These data are provided for situational awareness and are subject to change.

Clade I monkeypox and children

Early in the Central and Eastern African outbreak that began in 2024, a high proportion of suspected cases in some areas were reported in children younger than 15 years of age. Historically, cases of monkeypox in children where monkeypox occurs regularly often happen after contact with wild animals that carry the disease. People then can spread the disease to close contacts, including in their households. The number of children with suspected monkeypox in this outbreak is probably due to spread within and between close households, the large number of younger people in affected countries, misdiagnosis of other diseases (such as measles), poor sanitary conditions, limited access to health services, and a high level of food insecurity and malnutrition.

Based on what we know today, we don't expect to see the same sort of pattern in the United States for several reasons, including smaller household sizes, access to cleaning and disinfecting products, and improved access to medical care, equipment, and information about preventing spread while caring for patients.

Notably, there are no consistent reports of schools as drivers of monkeypox transmission during any recent outbreaks.

If cases of clade I monkeypox do happen in children the United States, CDC has clinical and public health guidance for reporting, testing, and effective case management.

What CDC is doing

• CDC has been supporting DRC monkeypox research and response for more than 20 years.
• CDC and other U.S. government agencies have continued working in-country with partners in affected areas on disease surveillance, building local laboratory capacity, strengthening public health and laboratory workforce capacity, case investigation, case management, infection prevention and control, border health, and risk communication and community engagement.
• In the United States, CDC monitors both clade II and clade I monkeypox cases across the United States and follows surveillance reports to monitor for any changes in demographics, disease severity, or case counts by jurisdiction.
• CDC also performs surveillance testing to identify monkeypox clade for specimens sent to CDC's poxvirus laboratory.

Resources