What Is Monkey Pox and How Is It Defined
Monkey pox is a viral zoonotic disease caused by the monkeypox virus, an orthopoxvirus related to smallpox, with symptoms that include fever, rash, and swollen lymph nodes. The World Health Organization renamed the disease mpox to reduce stigma, and the new terminology is now used in official reports and public health communications WHO mpox naming guidance.
Two distinct clades of the monkeypox virus have been identified, with Clade I historically linked to more severe outcomes and Clade II driving the 2022 global outbreak. Genetic sequencing shows that Clade IIb is the variant responsible for the majority of recent cases outside endemic regions CDC monkeypox clinical overview.
How Monkey Pox Spreads and What the Symptoms Look Like
Transmission occurs through direct contact with infectious rash, scabs, or body fluids, prolonged face-to-face respiratory droplet exposure, and intimate physical contact including sexual activity. The incubation period typically ranges from 5 to 21 days, and individuals are considered contagious from symptom onset until all lesions have fully crusted and a fresh layer of skin has formed WHO outbreak timeline.
Early symptoms often include fever, intense headache, muscle aches, back pain, low energy, and swollen lymph nodes, followed by a rash that evolves from macules to papules, vesicles, pustules, and finally crusts. The rash can appear on the face, palms, soles, mouth, genitals, and anus, and in some recent outbreaks lesions have been localized to the genital or perianal area, sometimes mistaken for sexually transmitted infections CDC clinical signs and symptoms.
Global Case Numbers, Vaccines, and Public Health Response
As of the latest WHO situation reports, confirmed mpox cases have been reported in over 100 countries, with the 2022–2023 multi-country outbreak primarily driven by Clade IIb and sustained human-to-human transmission in networks of close physical contact. The Africa CDC has also reported ongoing Clade I outbreaks in several central and western African countries, prompting heightened surveillance and cross-border coordination WHO mpox emergency declaration.
Two licensed vaccines, ACAM2000 and JYNNEOS (also known as Imvamune or Imvanex), are available for prevention, with JYNNEOS preferred in many national immunization programs due to its safer profile for immunocompromised individuals. Public health authorities have deployed ring vaccination strategies, targeted outreach to affected communities, and enhanced genomic surveillance to track viral evolution and inform travel and public gathering guidance FDA monkeypox vaccine information.