More than 200 people in 27 US states are being tracked for possible rare monkeypox infections, health officials say.
They fear people may have come in to contact with a Texas man who brought the disease in from Nigeria earlier this month.
The man - believed to be the first monkeypox case in the US since 2003 - was taken to hospital but is in a stable condition.
The Centers for Disease Control and Prevention (CDC) says it is concerned passengers who were on board two flights the man made may have been exposed to the disease.
Monkeypox is a rare viral disease from the same family as smallpox, but is much less severe.
Though rare, the disease has been discovered in the US before.
Last month, three cases were identified in the UK?
Monkeypox cases identified in north Wales.
More than 200 contacts sought in US monkeypox case.
More than 200 contacts sought in US monkeypox case1