Viral Disease

Monkeypox Declared a Global Outbreak With Defined Symptoms

In the largest international case series of confirmed monkeypox cases, new symptoms including dermatologic and systemic manifestations have been identified for the virus.1

The researchers—who collaborated across 16 countries—aimed to define transmission, risk factors, clinical presentation, and outcomes of infection as each were previously poorly defined.

Between April 27, 2022, and June 24, 2022, a total of 528 infections, confirmed via polymerase-chain reaction (PRC) tests, were included across 43 sites within the participating countries. Of the total infections, 98% of cases were among men that identified as gay or bisexual, 75% of study participants were White, and 41% had HIV.

Transmission is suspected to be due to sexual activity in 95% of persons. However, researchers were unable to confirm sexual transmission. Of the total participants, sexual history was recorded for 406 persons.

Infected persons presented with rash (95% of people, with 64% having less than 10 lesions), anogenital lesions (73%), and mucosal lesions (41%, with 54 having a single genital lesion). The most common anatomical sites were the anogenital area; the trunk, arms, or lower extremities (55%); the face (25%); and the palms and soles (10%).

The most commonly reported symptoms included fever (62%), lethargy (41%), myalgia (31%), headache (27%), and lymphadenopathy (56%)—clinical symptoms that are similar to sexually transmitted diseases (STIs). The researchers note the similarities as this could lead to misdiagnosis of the infection.

Overall, 13% (n = 70) of people were hospitalized. These patients were hospitalized primarily for pain management. Antiviral treatment was given to 5% of persons.

On July 23, 2022, the World Health Organization (WHO) declared the outbreak of monkeypox cases a public health emergency, giving rise to an international concern.2

“Because viruses know no borders, the world needs to move cohesively and quickly to close knowledge gaps and to contain the outbreak,” the researchers wrote. “Without widely available treatment or prophylaxis, rapid case identification is vital to containment. As is common in clinical medicine, there is a diversity in how illnesses may manifest — and monkeypox is no different.”


—Jessica Ganga



  1. Thornhill JP, Barkati S, Walmsley S, et al. Monkeypox virus infection in humans across 16 countries—April-June 2022. N Engl J Med. Published online July 21, 2022. doi:10.1056/NEJMoa2207323
  2. Multi-country outbreak of monkeypox: external situation report 2. News release. World Health Organization; July 25, 2022. Accessed August 3, 2022.