The Centers for Disease Control and Prevention (CDC) issued an alert on Monday after five cases of locally acquired malaria were reported in the US.
Four cases were identified in Florida and one in Texas within the last two months, said the health agency in a release.
It also expressed concern over a potential rise in imported malaria cases associated with increased international travel this summer.
The CDC also highlighted the need to plan for rapid access to IV artesunate, which it said is the first-line treatment for severe malaria in the country.
"Malaria is a medical emergency and should be treated accordingly," said the release.
Suspected malaria patients should be promptly evaluated at a facility capable of delivering rapid diagnosis and treatment within 24 hours of their arrival, it added.
The cases mark the first instances of locally acquired malaria in 20 years.
