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Monkeypox in Adult
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Monkeypox in Adult

Contributors: Edith Lederman MD, Noah Craft MD, PhD, Paritosh Prasad MD
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Synopsis

Monkeypox is a rare zoonotic Orthopoxvirus infection that is clinically similar to smallpox. Human monkeypox had been limited to the rain forest areas of Central and West Africa (principally the Democratic Republic of the Congo [the former Zaire] and the Republic of the Congo) until June 2003, when cases were first reported in Wisconsin, Illinois, and northwestern Indiana. Infection had not been observed in the Western Hemisphere until this time.

In the United States, cases have been limited to laboratory workers, pet shop workers, and veterinarians, but in Africa the disease affects people who have hunted or eaten squirrels and other infected mammals. Animal species susceptible to monkeypox virus may include nonhuman primates, lagomorphs (rabbits), and some rodents.

The incubation period of monkeypox is approximately 12 days (7-14 day range usually but can be 5-21 days). Monkeypox begins with a prodrome of fever, headache, malaise, backache, lymphadenopathy chills, nonproductive cough, and arthralgias followed 1-10 days later (usually by day 3) by the development of a rash on the face, trunk, and extremities. Some patients also experience myalgias, nausea and vomiting, lethargy, sore throat, dyspnea, and sweats. The clinical presentation is similar to but milder than that of smallpox, with the primary difference being that individuals with monkeypox develop lymphadenopathy whereas those with smallpox do not. Illness typically lasts 2-4 weeks.

Predominant person-to-person transmission and prolonged chains of transmission were suspected in 1996 when 71 cases emerged in Katako-Kombe Health Zone, Kasai-Oriental, and Democratic Republic of the Congo, and again in 2003 in the Likouala region of Republic of the Congo. In order to sustain the disease in the human population, it is believed repeated animal reintroduction of monkeypox virus is needed.

The first documented outbreak of monkeypox in the Western Hemisphere was attributed to a shipment of small mammals from Ghana to the United States in 2003. An infected Gambian giant rat from this shipment infected prairie dogs, which in turn transmitted the disease to humans. The prairie dogs were sold by a Milwaukee animal distributor to 2 pet shops in the Milwaukee area and during a pet "swap meet" (pets for sale or exchange) in northern Wisconsin. Patients from this outbreak reported direct or close contact with prairie dogs, most of which were sick. Illness in the prairie dogs was frequently reported as beginning with a blepharoconjunctivitis that was followed by the appearance of nodular lesions in some cases. Some prairie dogs died from the illness while others reportedly recovered.

Most recently on July 15, 2021, a single case of human monkeypox was confirmed in a US resident who traveled from Nigeria to the United States. No additional cases have been identified from that illness as of early August 2021.

Mortality rates in Africa have ranged from 1% to 10%. In the United States, there have been no fatalities.

Codes

ICD10CM:
B04 – Monkeypox

SNOMEDCT:
359814004 – Monkeypox

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Last Reviewed:08/05/2021
Last Updated:08/05/2021
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Monkeypox in Adult
Monkeypox : Chills, Cough, Fever, Headache, Central Africa, Lymphadenopathy, Umbilicated vesicle, Arthralgia
Clinical image of Monkeypox
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