In the US, a death from Lassa fever, a virus similar to Ebola, is reported in Iowa

An Iowa person who recently returned to the United States from West Africa has died after contracting Lassa fever, a virus that can cause Ebola-like illness in some patients. State health officials reported the case on Monday.

“I want to reassure Iowans that the risk of transmission in our state is incredibly low. We continue to investigate and monitor this situation and implement necessary public health protocols,” said Robert Kruse, state medical director for the Iowa Department of Health and Human Services, in a statement posted on the department’s website.

The unnamed person was described as a middle-aged person from eastern Iowa. The statement said the person was being cared for at University of Iowa Health Care. It was not stated how long he or she had been in care or whether the person had sought care elsewhere before being admitted to the hospital.

This is important because, although human-to-human transmission of Lassa virus is rare, transmission can occur in healthcare settings, particularly if healthcare workers do not recognize that they are dealing with a patient who has the disease and not taking sufficient medication precautions.

Although there have been previous cases of Lassa fever imported into the United States, they are not common. The statement said there have been eight known imported cases in the last 55 years, including the new one.

There was one case in May 2015 in a New Jersey resident who had traveled to Liberia and another case in a New Jersey resident in 2004. Both individuals died. Minnesota reported one case in 2014; that person recovered.

Lassa fever is endemic in a number of countries in West Africa, including Nigeria, Ghana, Guinea, Sierra Leone and Liberia. In these countries, the virus causes several hundred thousand infections and around 5,000 deaths every year.

The main source of the virus is a rodent called the multimammate rat. People become infected with the virus either by handling or eating infected rodents or by having the rodents in their homes. Food or household items contaminated with urine or feces from infected rodents can transmit the disease.

Although severe Lassa fever causes symptoms similar to Ebola infection, it does not trigger large chains of disease in humans, as can occur in Ebola outbreaks, said Armand Sprecher, a viral hemorrhagic fever expert who works for Doctors Without Borders.

“You don’t see a lot of person-to-person transmission,” Speaker told STAT. “Most people get it from the source, the reservoir.”

According to the World Health Organization, about eight in 10 people who become infected with the virus have no or only mild symptoms, including headaches, fatigue and a mild fever.

According to the Centers for Disease Control and Prevention, symptoms in patients who later develop serious illness may include bleeding, difficulty breathing, vomiting and shock. The WHO estimates that about 15% of people who develop severe Lassa disease die from the disease.

The mortality rate could be much higher in some places, said Robert Garry, a professor at Tulane Medical School in New Orleans who has been studying Lassa fever for several decades. In Sierra Leone, where Garry conducts research, the death rate for severe cases can be as high as 70%, he said. Good supportive care – such as topping up fluids – can increase the chances of survival, he said.

He agreed that most cases involve people infected from an animal source, but said person-to-person transmission can occur, particularly in hospitals. “This is happening in West Africa, even in places where they are very aware of the possibility (of Lassa cases). So if you didn’t expect a disease like this to appear in your hospital, it could happen.”

However, Garry said he doesn't expect any transmission here. “There is little chance of the disease spreading beyond the hospital area. But they have to do the case contact (investigations) and all that to be sure.”

Of the diseases that cause viral hemorrhagic fever — things like Ebola and Marburg fever — Lassa is probably the one most commonly imported into non-endemic countries, Garry said.