A man is in stable condition in a Minnesota hospital with Lassa fever after returning from a trip to West Africa, where an outbreak of Ebola virus is now raging.
The Minnesota Department of Health said the man flew to Minneapolis-St. Paul on March 31 and soon after his arrival visited a physician.
Because of his travel history and symptoms, the doctor suspected a possible hemorrhagic fever. The man was admitted to the hospital with fever and confusion and CDC testing confirmed a diagnosis of Lassa fever on April 3, the department and the CDC said in separate statements.
"This imported case is a reminder that we are all connected by international travel," CDC Director Tom Frieden, MD, said in a statement. "A disease anywhere can appear anywhere else in the world within hours."
Lassa fever is rarely seen in the U.S., with only seven cases recorded, the latest in 2010, according to the CDC.
The agency reported that preliminary information suggests the man flew from West Africa to New York City and on to Minneapolis on another flight. The agency did not say where in West Africa the trip started.
The CDC is working with public health officials and airlines to identify anyone who might have had close contact with the infected person, although Lassa fever is not easily spread from human to human.
"Casual contact is not a risk factor for getting Lassa fever," said Barbara Knust, DVM, a CDC epidemiologist in the lab that tested the patient's blood for Lassa virus.
"People will not get this infection just because they were on the same airplane or in the same airport," she said in a statement.
The Lassa virus is carried by rodents and transmitted to humans through contact with urine or droppings, but in some cases people can catch it from another person through direct contact with blood or bodily fluids, the mucous membranes, or sexual contact.
"Given what we know about how Lassa virus is spread to people, the risk to other travelers and members of the public is extremely low," Martin Cetron, MD, of the CDC's Division of Global Migration and Quarantine, said in a statement.
Between 100,000 and 300,000 cases of Lassa fever occur in West Africa each year, with up to 5,000 deaths.
A significant outbreak of Ebola virus -- a different hemorrhagic fever -- is currently affecting Guinea and Liberia in the region.
Although Lassa virus can produce hemorrhagic symptoms, the disease is not related to Ebola, the CDC noted.
The World Health Organization said the Ebola outbreak in Guinea is now at 137 confirmed or suspected cases with 83 deaths, while in neighboring Liberia there have been 14 confirmed or suspected cases with seven deaths.
The current outbreak is caused by a strain of Ebola virus with 98% homology to the Zaire strain, which caused the first recorded outbreaks of the disease, the agency said. This is the first time the disease has been detected in West Africa, aside from a single case reported in Ivory Coast in 1994.