No new cases of monkeypox have been identified among the people monitored for possible exposure after they came into contact with an infected person last month, the Centers for Disease Control and Prevention said Monday.
Health officials had been monitoring more than 200 people in 23 states and territories, as well as other countries, most of whom flew on one of the two flights the person took to travel from Lagos, Nigeria, to Dallas on July 8 and 9.
The monitoring period for more than three-fourths of the contacts — including all the people on the flights — ended on July 30, with no infections detected, a CDC spokesperson said. The agency is still monitoring some others, but they are considered to be “very low risk,” the spokesperson said.
The person infected with monkeypox — a U.S. resident — traveled from Lagos to Atlanta, arriving July 9, and then continued on to Dallas. The individual was diagnosed with monkeypox on July 15 after seeking care at a Dallas emergency room.
Monkeypox is caused by a virus that is related to smallpox. The virus causes less severe illness than smallpox, but the CDC had said that the fatality rate for the strain in the Dallas case is about 10%.
Monkeypox is considered a rare infection, though in the past few years Nigeria has seen an increase of cases. It causes fever, chills, swollen glands, and a widespread rash.
The people from the flights who were being monitored included people who sat within 6 feet of the person on the Lagos to Atlanta flight; those who used the same bathroom on the flight and workers who cleaned the bathroom; and flight attendants. People on the Atlanta-Dallas flight who sat close to the person were not considered at risk because the exposure time was too short.
Some family members who had been in contact with the person upon arrival in Dallas were also under monitoring.
The incubation period for monkeypox — how long it takes after exposure for symptoms to develop if an infection occurred — is from three to 17 days. The CDC asked state and local health authorities to monitor people for 21 days in this case.