What you need to know after the first US death from Lassa fever

Lassa fever – a potentially fatal virus that causes hemorrhagic fever similar to Ebola – is in the headlines after the first middle-aged person in the U.S. died from the virus, a middle-aged person in Iowa who had visited West Africa.

Rebecca Fischer, an internationally known epidemiologist specializing in tropical diseases at the Texas A&M University School of Public Health, explains what's happening now — and what we need to know for the future.

What's going on in Iowa and should I be worried?

We know from public news reports that the individual was middle-aged, had recently returned to Iowa after a visit to West Africa, and died on October 28 after treatment at a hospital.

The Centers for Disease Control and Prevention (CDC) has said the person was not sick during the trip, so the risk to other passengers is “extremely low.” Government and hospital officials in Iowa also said the risk of transmission was “incredibly low.”

I agree 100 percent with these initial assessments. At this time, given what is known about the spread of the virus, there is no reason to believe that the general public is at risk of contracting Lassa.

What do we know about Lassa fever that makes you and other experts so confident that it is not a major threat in the United States?

Lassa fever is much less fatal than other known viral hemorrhagic fevers such as Ebola or Marburg disease. While some complications such as deafness and kidney failure may occur in extreme cases, most people experience only minor symptoms.

Exposure usually occurs when a person comes into contact with rats carrying the virus or their feces, saliva and other secretions, or with objects contaminated by these secretions. It can also be spread from person to person, but only through contact with an infected person's body fluids, such as blood, urine, saliva and semen.

Rodents are currently not known to carry Lassa virus in the United States. The rat species primarily associated with the Lassa virus is currently only found in West Africa: Nigeria (where the city of Lassa was the first known location of the virus), Sierra Leone, Liberia, Guinea and neighboring countries. Travel-related infections occur in the United States, particularly when travelers from that region have been exposed to rodents or have stayed in villages where Lassa is endemic.

As with Ebola, transmission can occur in certain healthcare settings, but healthcare and laboratory workers can minimize the risk of contracting Lassa by following standard precautions and wearing personal protective equipment.

Importantly, it is believed that Lassa fever is not contagious until symptoms appear – which occurs between two and 21 days after infection – and that it does not spread from one person to another through casual contact such as hugging or shaking hands is transmitted.

How can I tell if I have Lassa fever?

Diagnosing Lassa fever can be difficult because it usually begins with general flu-like symptoms such as weakness, fever, headache, and sore throat.

In severe cases, difficulty breathing, vomiting, swelling of the face, and pain in the chest and back may occur. About one in four patients also suffer from numbness, which subsides after a few months for most people. Others also experience hair loss and difficulty walking during recovery. In severe cases, kidney failure can occur. There is an increased risk for pregnant women and their unborn children.

On the other hand, around 80 percent of those infected show no symptoms at all or only have mild symptoms.

Anyone who fears they may have been exposed to the virus should discuss their concerns with their doctor or health official so appropriate testing can be conducted.

What treatment options are available if I am diagnosed with Lassa fever?

Treatment for Lassa fever is largely supportive, but the antiviral drug ribavirin has also been used, which may be most effective when given soon after symptoms appear. Rest and hydration can also help relieve symptoms. Only about 15 to 20 percent of cases are serious enough to require hospitalization.

A single-dose vaccine for both yellow fever and Lassa fever has been discussed, but this has so far been prohibitively expensive and faces major logistical challenges in getting it to people in West Africa.

How can I prevent myself from getting Lassa fever?

The best tips are to avoid contact with Mastomys Rodents that only occur in West Africa. Closer to home, it is always a good idea to limit exposure to rodents and keep them from entering our homes by storing food in rodent-proof containers and keeping our homes clean. Rodents are not known to carry Lassa virus in the United States, but they transmit several other diseases.

What is the end result?

The bottom line is that public health efforts to prevent the spread of this virus are progressing exactly as they should to contain the virus and ensure that the risk to the public remains low.

The CDC and officials in Iowa are working to determine how the person contracted the virus and to identify anyone the person came into contact with after they showed symptoms. Anyone who has had such contact will be monitored for three weeks and any new developments will be posted on the CDC website.