People in California, Arizona and Georgia are being monitored for potential infection after previously being on the cruise ship, though none have shown signs of illness so far. It's unclear when those residents were on the ship and when they returned.
"There is no information that the California residents are ill or infected... At this time, the risk to public health in California is low," the California Department of Public Health's Robert Barsanti said in a statement.
So far, three passengers of the cruise ship have died.
The ship, which was off the coast of Africa in Cape Verde, is now en route to the Canary Islands after officials medically evacuated three people, including two in "serious condition."
The trip is expected to take three to four days, the ship's operator, Oceanwide Expeditions, said Wednesday.
Some passengers disembarked the ship before knowledge of the cluster and are back in their home countries. In some cases, authorities are advising those passengers to self-isolate.
The total number of confirmed hantavirus cases aboard a cruise ship has risen to five as global health authorities work to contain a potentially deadly cluster of the disease.
More than 100 passengers remain on the ship, MV Hondius, and the World Health Organization (WHO) is monitoring their health. Officials said that the "overall public health risk remains low" but that there may be some person-to-person spread.
In its first public statement on the outbreak on Wednesday evening, the U.S. Centers for Disease Control and Prevention said, "the risk to the American public is extremely low" and urged Americans aboard the ship to follow the guidance of health officials.
ABC News contributed to this report.