IOWA, USA — Although rarely seen in the United States, concerns have emerged after an Iowa resident died earlier this month from a suspected case of Lassa fever.
The Iowa Department of Health and Human Services and the Centers for Disease Control and Prevention are currently investigating the case, according to a news release.
However, the CDC says the risk to the public is "extremely low."
What is Lassa fever?
The CDC says Lassa fever is a viral disease common in West Africa that is spread to humans through contact with infected rat droppings or urine.
In rare cases, the virus can be transmitted from person to person through direct contact with an infected person's body fluids.
Lassa fever is not spread through casual contact, and a person is not believed to be infectious before symptoms arise, the CDC adds.
What is the mortality rate?
The overall mortality rate of Lassa fever is 1%, according to the Africa Centres for Disease Control and Prevention. In severe cases, where the patient has been hospitalized, the fatality rate is around 15%.
The number of cases in West Africa is estimated between 100,00 to 300,000, with approximately 5,000 deaths. Surveillance for the virus is not consistent, leading to such wide estimates.
What are the symptoms?
About 80% of infected people have mild symptoms or no symptoms and are not diagnosed, according to the CDC.
Lassa fever symptoms for the remaining 20% are typically gradual, beginning with a fever, headache and general weakness. An infected person may begin to develop additional symptoms such as sore throat, nausea, vomiting, cough and chest and muscle pain.
Severe cases can see facial swelling, bleeding, shock and fluid in the lungs.
In fatal cases, death usually occurs within 14 days of symptoms presenting.
How many cases are there in the United States?
If the suspected Iowa case is confirmed by officials, it would be the ninth reported occurrence of travel-associated Lassa fever in the past 55 years. The first documented case was in 1969 in Lassa, Nigeria, where the virus gets its name.