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Lassa Fever & Key Findings


Recently a study has found that Climate change may aid the spread of Lassa fever, which is endemic to parts of west Africa, to the Central and Eastern parts of the African continent in the next 50 years.


GS II- Health

Dimensions of the article:

  1. Key Findings
  2. What is Lassa fever?
  3. How does it spread?
  4. Symptoms

Key Findings

  • There would be a 600% jump in the number of people exposed to the virus that causes Lassa fever.
  • The number of people at risk of exposure would rise to 453 million by 2050 and 700 million by 2070, up from about 92 million in 2022.
  • An estimated 80% of infections are mild or asymptomatic. But the remaining 20 % can cause haemorrhaging from the mouth and gut, low blood pressure and potential permanent hearing loss.
  • Temperature, rainfall and the presence of pastureland areas are key factors that contributed to the transmission of the Lassa virus.
  • If the virus is successfully introduced and propagated in a new ecologically suitable area, its growth would be limited over the first decades.

What is Lassa fever?

  • The Lassa fever-causing virus is found in West Africa and was first discovered in 1969 in Lassa, Nigeria.
  • The discovery of this disease was made after two nurses died in Nigeria.
  • The death rate associated with this disease is low, at around one per cent.
  • But the death rate is higher for certain individuals, such as pregnant women in their third trimester.
  • According to the European Centre for Disease Prevention and Control, about 80 per cent of the cases are asymptomatic and therefore remain undiagnosed. Some patients may need to be hospitalised and develop severe multi-system disease. Fifteen per cent of the hospitalised patients may die.

How does it spread?

  • The fever is spread by rats and is primarily found in countries in West Africa including Sierra Leone, Liberia, Guinea, and Nigeria where it is endemic.
  • A person can become infected if they come in contact with household items of food that is contaminated with the urine or feces of an infected rat.
  • It can also be spread, though rarely, if a person comes in contact with a sick person’s infected bodily fluids or through mucous membranes such as the eyes, nose or the mouth. Person-to-person transmission is more common in healthcare settings.
  • Even so, people don’t usually become contagious before symptoms appear and cannot transmit the infection through casual contact such as through hugging, shaking hands or sitting near someone who is infected.


  • Mild symptoms include slight fever, fatigue, weakness and headache and more serious symptoms include bleeding, difficulty breathing, vomiting, facial swelling, pain in the chest, back, and abdomen and shock.
  • Symptoms typically appear 1-3 weeks after exposure.
  • Death can occur from two weeks of the onset of symptoms, usually as a result of multi-organ failure.
  • The most common complication associated with the fever is deafness.

-Source: Down to Earth

December 2023