Lassa fever confirmed in traveler returning to Minnesota from West Aftrica
On March 31, 2014, a man returning to Minnesota from West Africa was admitted to a hospital in Minnesota with fever and confusion.
Blood samples submitted to the U.S. Centers for Disease Control and Prevention (CDC) tested positive for Lassa fever on the evening of April 3. Lassa fever is an acute viral disease common in West Africa but rarely seen in the U.S. The last case of Lassa fever in the United States was in 2010 and was travel-related.
The Lassa virus is carried by rodents in West Africa and is transmitted to humans through contact with urine or droppings of infected rodents. Though rare, it can also be transmitted from person to person through direct contact with a sick person’s blood or bodily fluids, through mucous membranes (eyes, nose, or mouth), or through sexual contact.
The virus is not transmitted through casual contact.
The incubation period for Lassa fever is one to three weeks. In West Africa, there are about 100,000 to 300,000 cases of Lassa fever and about 5,000 deaths annually. Eighty percent of human infections don’t show any symptoms. Overall, death is rare in patients who contract Lassa fever, with only 1 percent of all cases resulting in death in areas of West Africa where infection is common.
The Minnesota Department of Health (MDH) is working in close cooperation with the hospital, CDC and others in the investigation. The MDH and CDC are working with the hospital to notify any health care providers or staff who may have had contact with the patient. The general public is not at risk from this case. The Minnesota patient is recovering and is in stable condition.
“The hospital has done an excellent job of caring for the patient and taking all necessary measures to ensure the safety and protection of hospital staff, visitors and patients,” said Dr. Ed Ehlinger, Minnesota Commissioner of Health in a news release.
The ill man flew to Minneapolis-St. Paul on March 31. Promptly after his arrival, the patient was seen by a physician who, given the patient’s travel history and condition, suspected a possible hemorrhagic fever and immediately reported it to MDH.
Since Lassa virus is not spread by casual contact, CDC believes any risk to other airline passengers and crew is extremely low. However, in the interest of protecting passenger health, CDC is working with the airlines to identify passengers and crew who may have had close contact with the ill man during his travel. State and local health departments will reach out to notify these individuals of their possible exposure.
More information about Lassa fever is available on the CDC website at http://www.cdc.gov/vhf/lassa/.