Lassa Fever

Reviewed on 12/2/2022
Lassa Fever
The transmission of Lassa fever from rats to humans occurs through ingestion or inhalation.

Lassa fever is an animal-borne viral illness that spreads through rats. It is an endemic that majorly affects people living in western Africa.

About 300,000 cases of Lassa fever are identified, out of which about 5000 deaths are recorded, yearly. The disease can have mild symptoms but, sometimes, could be life-threatening.

The disease was first identified in a Nigerian town called Lassa. The name was given in 1969 after the death of two nurses in the Nigerian town, of Lassa.

How does Lassa fever transmit?

A multimammate rat type hosts the Lassa virus in its urine or feces. These rats are found in West, Central, and East Africa. They tend to live in houses, usually in the pantry, where food is stored.

The transmission from rats to humans occurs through ingestion or inhalation. These rats shed their feces and urine on objects or foods. The virus usually affects humans by entering the body through open cuts or sores.

Person-to-person transmission can occur via blood feces but not via touch, shaking hands, or hugging. Furthermore, the virus can be spread by sharing needles. A few cases of the virus being transmitted sexually have been reported.

Who are at a high risk of Lassa fever?

The following people are at risk of getting Lassa fever:

  • Visit endemic regions of West, Central, and East Africa
  • Come in contact with the urine or feces of infected rats
  • Eat rats as food
  • Breathe a few airborne particles contaminated with rat's urine or feces

Lassa infection may lead to the following in infected individuals:

  • About 20 percent of the cases of Lassa fever may result in hospitalization
  • Pregnant women with Lassa fever are more likely to have miscarriages, which increases the risk of death in the later stages of pregnancy
  • Most people with Lassa infection may end up with deafness as a complication
  • Death may occur two weeks after the onset of symptoms due to multiorgan failure

What are the signs and symptoms of Lassa fever?

Once infected with the Lassa virus, the person may show the symptoms in one to three weeks. Mostly, the symptoms are mild, and sometimes, they can be severe and life-threatening.

Mild symptoms include:

Severe complications include:

How to diagnose Lassa fever

The symptoms may resemble other hemorrhagic virus infections, such as Ebola virus, malaria, and typhoid, which makes the diagnosis difficult. One of the best methods to diagnose Lassa fever is enzyme-linked immunosorbent serologic assays (ELISA). This test identifies Lassa antigens and immunoglobulin M and immunoglobulin G antibodies.

In the early stages of infection, swab tests may help diagnose the condition.

How to treat Lassa fever

The treatment could be effective in the early stages of infection. Ribavirin, an antiviral, is the most effective drug to treat Lassa viral infection. Ribavirin can be administered orally as a pill or intravenously.

When the symptoms are severe, you may require hospital care and monitoring.

Your healthcare provider helps:

  • Stay hydrated
  • Maintain fluid and electrolyte balance
  • Monitor blood pressure
  • Administer oxygen therapy if required
  • Treat other underlying health issues

How to prevent Lassa virus infection

The infection can be prevented in the following ways:

  • Stay away from rats
  • Wash your hands frequently
  • Keep your surroundings clean
  • Take precautions while caring for sick individuals
  • Foods should be covered properly in tight or rat-proof containers
  • Set up rat traps if you notice any rats around you
  • Do not cook or eat rats

Lassa Fever Symptom


Body temperature measurements are usually measured by temperature devices inserted on or into the rectum, mouth, axilla (under the armpit), skin, or ear (ear thermometers). Some devices (laryngoscopes, bronchoscopes, rectal probes) may have temperature-sensing probes that can record temperature continually. The most common way to measure body temperature was (and still is in many countries) with a mercury thermometer; because of glass breakage and the possibility of subsequent mercury contamination, many developed countries use digital thermometers with disposable probe covers to measure temperature from all of the body sites listed above. Disposable temperature-sensitive strips that measure skin temperature are also used. Oral temperatures are most commonly measured in adults, but rectal temperatures are the most accurate because environmental factors that increase or decrease temperature measurements have the least effect on the rectal area. Rectal temperatures, when compared to oral temperatures taken at the same time, are about 1.8 F (0.6 C) higher. Consequently, an accurate measurement of body temperature (best is rectal core temperature) of 100.4 F (38 C) or above is considered to be a "fever" and the person has a febrile illness.

Reviewed on 12/2/2022
Image Source: iStock image

What Is Lassa Fever?

Lassa Fever.

Viral hemorrhagic fevers.