On June 11, 2003, Tommy G. Thompson, serving as the U.S. Secretary of Health and Human Services, issued an immediate ban on the importation of prairie dogs along with six species of African rodents. The subsequent day, the Wisconsin Department of Health implemented an emergency order that prohibited the import, sale, and release of prairie dogs and any mammals that had come into contact with them since April 1, 2003. This decisive action followed a report from the Centers for Disease Control and Prevention (CDC) on June 9, which established a link between recent febrile rash illnesses occurring in Illinois, Wisconsin, and Indiana and interactions with infected prairie dogs, thereby indicating the presence of the monkeypox virus. This marked the initial emergence of community-acquired monkeypox in the United States.
Origin of Monkeypox in the United States
The inaugural outbreak of monkeypox outside of Africa transpired in 2003 within the United States, affecting states including Wisconsin, Illinois, Indiana, Missouri, Kansas, and Ohio, with a total of 72 confirmed cases associated with monkeypox Clade 2. The outbreak commenced when prairie dogs, infected by rodents during their transit from Ghana to Texas, transmitted the disease to their new owners. The earliest reported case involved a 3-year-old girl who required hospitalization after being bitten by a prairie dog on May 13. The affected prairie dog exhibited symptoms and succumbed on May 20. On June 2, the girl’s mother began exhibiting illness, and subsequent tests confirmed the presence of an orthopoxvirus. Another case involved a meat inspector who displayed symptoms shortly after sustaining a bite from a prairie dog.
As of June 6, CDC testing had identified monkeypox virus DNA in three additional patients, leading to the identification of 11 confirmed or suspected cases linked to the infected prairie dogs. Ultimately, by July 30, 2003, a total of 72 cases had been documented, with the outbreak reaching its apex between May 29 and June 9, after which no further human cases were reported.
Source of Monkeypox in the United States
The first verified case of monkeypox virus (MPV) in the United States occurred in 2003, with 47 confirmed cases of MPV sickness in six states: Kansas, Ohio, Illinois, Missouri, Indiana, and Wisconsin. The introduction of monkeypox into Wisconsin was traced back to a distributor in Illinois who received a shipment of exotic animals transported into the United States via Texas from Ghana, West Africa, including roughly 800 tiny mammals. CDC laboratory investigations using polymerase chain reaction (PCR) and virus isolation techniques on several species revealed that one Gambian giant rat, three dormice, and two rope squirrels were infected with the monkeypox virus. Evidence of infection was also detected in certain animals that had been isolated from the rest of the consignment upon their arrival in the United States. Upon their arrival in Illinois, the Gambian rats were housed in proximity to the prairie dogs implicated in the outbreak in Wisconsin and other states.
Outbreak of 2021
On November 16, 2021, the CDC and the Maryland Department of Health identified a single case of MPV infection in a person who had just returned from Nigeria to the United States. In July 2021, the CDC documented another monkeypox incidence in Texas, this time involving a Nigerian visitor. It is vital to highlight that MPV does not occur naturally in the United States; nevertheless, incidences have been linked to overseas travel or contact with imported animals from regions where the disease is prevalent. On May 18, 2021, the CDC confirmed a case in Massachusetts with a recent returnee from Canada. Additionally, the CDC reported monkeypox clusters identified in early to mid-May across multiple countries, including occurrences in Europe and North America, where MPV is not typically reported. By June 10, a total of 49 MPV infection cases had been confirmed in the United States.
Outbreak of 2022-23
On May 17, 2022, the United States documented its first case of monkeypox in Massachusetts. By September 23, a total of 24,846 cases had been recorded across all 50 states, the District of Columbia, and Puerto Rico. During the 2022-23 monkeypox outbreak, the United States reported the highest number of cases globally, with California accounting for the majority of cases. Following two cases of monkeypox viral infection in individuals returning from Nigeria to the United States—one in Texas in July 2021 and the other in the Washington, DC area in November 2021—the number of monkeypox cases increased, raising concerns about the possibility of widespread transmission across the United States.
Outbreak of 2024
The first confirmed instance of Clade I monkeypox in the United States was identified in November 2024, following a patient’s travel to an infected region. No additional cases were reported at that time. Clade II monkeypox continues to circulate at low levels. Historically, children have contracted monkeypox in endemic areas of Western and Central Africa, and the elevated number of monkeypox cases documented in this outbreak is likely attributable to transmission within households. Based on current understanding, it is not anticipated that the introduction of monkeypox into the United States would result in a comparable level of risk for children in future occurrences.
Refrences
Philpott, D. (2022). Epidemiologic and clinical characteristics of monkeypox cases—United States, May 17–July 22, 2022. MMWR. Morbidity and Mortality Weekly Report, 71.
Huhn, G. D., Bauer, A. M., Yorita, K., Graham, M. B., Sejvar, J., Likos, A., … & Kuehnert, M. J. (2005). Clinical characteristics of human monkeypox, and risk factors for severe disease. Clinical infectious diseases, 41(12), 1742-1751.
Sale, T. A., Melski, J. W., & Stratman, E. J. (2006). Monkeypox: an epidemiologic and clinical comparison of African and US disease. Journal of the American Academy of Dermatology, 55(3), 478-481.
El Eid, R., Allaw, F., Haddad, S. F., & Kanj, S. S. (2022). Human monkeypox: A review of the literature. PLoS pathogens, 18(9), e1010768.
Mitjà, O., Ogoina, D., Titanji, B. K., Galvan, C., Muyembe, J. J., Marks, M., & Orkin, C. M. (2023). Monkeypox. The Lancet, 401(10370), 60-74.
