Lassa fever and what you need to know to stay safe
Picture By Brett Jordan

Lassa fever and what you need to know to stay safe

  • Post published:January 26, 2020
  • Post category:Health / News

What is Lassa fever?

Lassa fever is an animal-borne, or zoonotic, acute viral illness. It is endemic in parts of West Africa including Sierra Leone, Liberia, Guinea and Nigeria. Neighboring countries are also at risk, as the animal vector for Lassa virus, the “multimammate rat” (Mastomys natalensis) is distributed throughout the region. (Centers for Disease and Control Prevention)

Lassa fever, also known as Lassa hemorrhagic fever (LHF) was discovered in Nigeria in the year 1969 and was named after a town (Lassa) in the region. Based on estimations, 400,000 cases are reported per year and about 5,000 deaths per year.

It is a hemorrhagic virus, which means it can cause bleeding, although 8 out of every 10 people with the virus have no symptoms. If it affects the liver, kidneys, or spleen, it can be fatal.

Some facts about Lassa fever

  • Lassa fever is an acute viral haemorrhagic illness of 2-21 days duration that occurs in West Africa.
  • It is most common in Sierra Leone, Liberia, Guinea, and Nigeria.
  • Person-to-person infections and laboratory transmission can also occur, particularly in hospitals lacking adequate infection prevention and control measures.
  • The Lassa virus is transmitted to humans via contact with food or household items contaminated with rodent urine or feces.
  • A large outbreak was reported by the Nigeria Centre for Disease Control that began early in 2018.


The main cause of Lassa virus is a rodent known as the Multimammate Rat of the genus Mastomys


When it is symptomatic, signs generally appear within 6 to 21 days after infection occurs.

An estimated 80 percent of infections do not produce significant symptoms, although there may be a general headache, malaise, and a slight fever.

Lassa fever becomes serious in the remaining 20 percent of cases.

Below is the list of possible symptoms:

  • Headache
  • Bleeding
  • Fever
  • Malaise
  • Vomiting
  • Abdominal Pain
  • Nausea
  • Ringing ear
  • Back pain
  • Chest pain
  • Sore throat
  • Generalized weakness
  • Difficulty in breathing
  • Hepatitis
  • Shock
  • Seizures
  • Tremors

Lassa fever virus can also cause deafness. In around 1 percent of all cases, Lassa fever is fatal, and around 15 to 20 percent of all hospitalizations for the disease will end in death.


  • Lassa fever is most often diagnosed by using enzyme-linked immunosorbent serologic assays (ELISA) that detect IgM and IgG antibodies as well as Lassa antigen.
  • Reverse transcription-polymerase chain reaction (RT-PCR) can be used in the early stage of the disease.

There are diverse and wide means of diagnosis for Lassa fever.


Treatment is made to tackle dehydration and improve symptoms.

However, the antiviral drug ribavirin seems to be an effective treatment for Lassa fever if given early on in the course of clinical illness.

There is no evidence to support the role of ribavirin as a post-exposure prophylactic treatment for Lassa fever.

There is currently no vaccine that protects against Lassa fever, but work on making one is underway


A statement on the World Health Organisation (WHO) official website on the 31st of July, 2017 goes thus, “Prevention of Lassa fever relies on promoting good “community hygiene” to discourage rodents from entering homes. Effective measures include storing grain and other foodstuffs in rodent-proof containers, disposing of garbage far from the home, maintaining clean households and keeping cats.”

Other safety measures include:

  • Washing your hands regularly
  • keeping garbage away from the home
  • avoiding blood and other bodily fluids when caring for sick relatives
  • using protective equipment in a healthcare setting, including masks and eyewear

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