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More than 200 people in 27 states are being monitored for possible exposure to monkeypox after they had contact with an individual who contracted the disease in Nigeria before traveling to the United States this month, according to the Centers for Disease Control and Prevention. To date, no additional cases have been detected.

State and local health authorities are working with the CDC to identify and assess the individuals, and follow up with them daily until late this month, said Andrea McCollum, who leads the poxvirus epidemiology unit at the agency’s National Center for Emerging and Zoonotic Infectious Diseases.


“It is a lot of people,” McCollum acknowledged.

The efforts stem from the discovery that a U.S. resident infected with monkeypox traveled from Lagos, Nigeria, on an overnight flight to Atlanta that arrived on July 9; the person then traveled the same day to Dallas. On July 15, the individual sought care at a Dallas hospital emergency room, where the diagnosis of monkeypox was made.

The people being monitored include a number who sat within 6 feet of the infected individual on the Lagos to Atlanta flight; others who used the mid-cabin bathroom on that flight; airline workers who cleaned the bathroom after the flight; flight attendants; and some family members who had contact with the individual in Dallas.


Passengers on the Atlanta-Dallas flight with indirect contact — in other words, those sitting near the infected person — were deemed to have had too short an exposure to be at risk, said McCollum.

“We define indirect contact as being within 6 feet of the patient in the absence of an N-95 or any filtering respirator for greater than or equal to three hours,” she said.

Monkeypox is caused by a virus that is related to smallpox, the only human virus to have been eradicated. It causes less severe illness than smallpox, but is still quite dangerous. The CDC said that the fatality rate for the strain of monkeypox seen in the Dallas case is about 10%.

Monkeypox is rarely seen in people. There was a large outbreak in the U.S. in 2003, when a shipment of animals from Ghana contained several rodents and other small mammals that were infected with the virus; 47 confirmed and probable cases were reported in five states. The outbreak was the first time human cases of monkeypox were reported outside of Africa.

In the past few years, Nigeria has seen an uptick of monkeypox cases and seven exported cases have now been detected: four in the United Kingdom and one apiece in Singapore, Israel, and the United States. In one of the importation events in the U.K., a local health care worker was infected after having unprotected contact with the patient.

The original source or sources of the monkeypox virus have not been identified, though cases have been linked to the handling of bushmeat and the trade of exotic small mammals, McCollum said.

The disease triggers fever, chills, swollen glands, and a characteristic rash that is disseminated across the body, including on the palms of hands and the soles of feet.

The virus spreads through a variety of ways: inhalation of respiratory droplets from infected people or contact with their lesions or bodily fluids. The virus can also be transmitted by having contact with bed linens or other items that have been used by an infected person, McCollum said.

The incubation period for monkeypox — the time from exposure to symptoms — can be anywhere from three to 17 days, though the CDC has asked state and local health authorities to monitor the identified people for 21 days, a period that ends on July 30. Most people who contract monkeypox do so within five to 13 days, which means if additional cases are found, they will likely start to show symptoms soon. “We’re in the time frame where we certainly want to closely monitor people,” McCollum said.

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