DC Health reported the first positive case of orthopox in a resident who recently traveled to Europe, and it sent samples to the Centers for Disease Control and Prevention to test for monkeypox, the agency said Sunday.
The patient is self-isolating and poses no risk to the public, and the agency is monitoring close contacts, she said in a statement.
The orthopox virus family includes monkeypox, DC Health said.
There are currently 25 confirmed cases of monkeypox/orthopoxvirus in the United States as of Friday, according to the latest CDC data.
The first case of monkeypox in the United States this year was reported in Massachusetts.
Monkeypox is a cousin of the smallpox virus and causes similar, but milder, symptoms in humans, according to the CDC.
According to the World Health Organization, the incubation period from the time a person is exposed when the first symptoms appear can range from five to 21 days.
Typically, the illness begins with fever, headache, fatigue, chills, and muscle aches. Unlike smallpox, however, monkeypox also causes swollen lymph nodes.
Chad Murray of ABC News contributed to this report.