Mpox(Monkeypox)

Mpox (previously known as monkeypox) is a zoonotic viral disease caused by the mpox virus1. Though mpox was originally endemic to Africa, in 2022 a significant multi-country mpox outbreak arose in many non-endemic countries, driven by travel and person-to-person transmission. WHO and the United States both recognized the outbreak as a public health emergency. The US public health emergency declaration expired at the end of January 2023, while the WHO emergency declaration ended in May 2023. Case counts have steadily declined worldwide, and new cases in the US are now sporadic and rare2,3. 

Mpox and its causative virus were both originally named monkeypox as the virus was first observed in monkeys. In November 2022 WHO announced adoption of the name “mpox” as a new preferred synonym for monkeypox disease4. Although official efforts to rename the virus are separate and technically still underway, many authorities, including the CDC, are now using the name mpox in reference to both the disease and the virus that causes it.  

Mpox is closely related to smallpox and classically presents with a similar but milder clinical course5. Initial symptoms can include fever, chills, headache, fatigue, joint and muscle pain, and swollen lymph nodes. A characteristic rash typically appears within several days, progressing through several different stages until lesions scab over and fall off. In 2022-2023 outbreak-associated cases, anogenital lesions have been most common, and symptoms other than rash are often very mild or absent altogether6.  

Male to male sexual contact has been the primary mode of disease transmission in 2022-2023 outbreak7. Transmission can occur through direct or indirect contact with mpox lesions, lesion material, respiratory secretions, other bodily fluids, and contaminated materials such as clothing and bedding7. 

Mpox should be suspected in patients with compatible clinical features (especially rash) and risk factors for exposure. Diagnosis is made via laboratory detection of virus DNA from lesion material8. Most patients with mpox have mild, self-limited disease, and can be managed supportively. Several antiviral agents originally developed for the treatment of other viral infections appear effective against mpox and can be considered for certain patients9. Additionally, in the United States, two vaccines are available for mpox pre- and post-exposure prophylaxis10.    There have been relatively few cases of severe disease or death associated with the 2022-2023 mpox outbreak in the United States; most such cases have been in severely immunocompromised individuals, such as those with untreated, advanced HIV infection11.  

Though new mpox cases in the United States have decreased tremendously, the disease has not disappeared altogether, and new cases are still being reported worldwide. Ongoing vigilance is advised. 

1. WHO: Monkeypox Fact Sheet. WHO website. Published May 19, 2022. Accessed August 24, 2023. https://www.who.int/news-room/fact-sheets/detail/monkeypox  

2. WHO: 2022-2023 Mpox (Monkeypox) Outbreak: Global Trends. WHO website. Updated August 23, 2023. Accessed August 24, 2023. https://worldhealthorg.shinyapps.io/mpx_global/

3. CDC: U.S. Mpox Case Trends Reported to CDC. CDC website. Updated August 23, 2023. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/mpox/response/2022/mpx-trends.html

4. WHO: News: WHO Recommends New Name for Monkeypox Disease. WHO website. Published November 28, 2022. Accessed August 24, 2023. https://www.who.int/news/item/28-11-2022-who-recommends-new-name-for-monkeypox-disease

5. Huhn GD et al: Clinical characteristics of human monkeypox, and risk factors for severe disease. Clin Infect Dis. 41(12):1742-51, 2005

6. CDC: Mpox: Healthcare Professionals: Clinical Guidance: Clinical Recognition. CDC website. Updated March 27, 2023. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/monkeypox/clinicians/clinical-recognition.html  

7. CDC: Mpox: Your Health: How It Spreads. CDC website. Updated February 2, 2023. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/monkeypox/if-sick/transmission.html  

8. CDC: Mpox: Healthcare Professionals: Case Definitions for Use in the 2022 Mpox Response. CDC website. Updated July 22, 2022. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/monkeypox/clinicians/case-definition.html  

9. CDC: Mpox: Healthcare Professionals: Clinical Guidance: Clinical Treatment. CDC website. Updated July 10, 2023. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/monkeypox/clinicians/treatment.html  

10. CDC: Mpox: Healthcare Professionals: Monkeypox and Smallpox Vaccine Guidance. CDC website. Reviewed August 2, 2023. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/monkeypox/clinicians/smallpox-vaccine.html  

11. CDC: Mpox: Healthcare Professionals: Clinical Considerations for Treatment and Prophylaxis of Mpox Infection in People Who are Immunocompromised. CDC website. Updated June 26, 2023. Accessed August 24, 2023. https://www.cdc.gov/poxvirus/mpox/clinicians/people-with-HIV.html