IAMAT |International Association of Medical Assistance to Travellers| IAMAT |International Association of Medical Assistance to Travellers|

Liberia For Specific Travellers: Lassa Fever

Liberia has confirmed cases of Lassa Fever. The outbreak is still active in Nimba. 

For the latest information on Lassa Fever outbreaks please go to: ProMED-mail. Lassa fever - West Africa (37): Liberia, WHO. ProMED-mail 2018; July 11: 20180711.5898495. <ProMED-mail>. & WHO Weekly Updates on Outbreaks and Other Emergencies. Week 40: 29 September - 05 October 2018. <WHO>. Accessed on October 09, 2018.


Lassa Fever is caused by the Lassa virus belonging to the Arenaviridae family. It is a zoonosis – an animal disease that can spread to humans – transmitted by rats belonging to the Mastomys genus. A person may acquire the virus if they come into contact with the urine and feces of an infected rat. Human to human transmission occurs when a person comes into contact with body fluids such as the blood, urine, and saliva of an infected person. Sexual transmission of the Lassa virus has also been reported. In addition, the virus can spread through unhygienic healthcare settings via improperly sterilized medical instruments, infected blood products, and lack of infection control gear such as masks, gloves, and gowns.


Lassa Fever is present in west Africa. Travellers staying in crowded living areas with poor sanitation conditions are at increased risk. Patients who require medical care in substandard medical facilities and healthcare practitioners working in unhygienic conditions are also at greater risk.


In the majority of cases, the infection is asymptomatic – persons do not exhibit symptoms. Those with symptoms get ill 1 to 3 weeks after contact, starting with flu-like symptoms including fever and general weakness. The illness progresses with a headache, sore throat, cough, muscle, abdominal and chest pain, nausea, vomiting, and diarrhea. More severe symptoms, occurring in 15% to 20% of patients, include facial swelling, uncontrolled bleeding from the mouth, nose, vagina, and gastrointestinal tract. During the later stages, a patient may have convulsions, tremors, disorientation, partial or complete deafness, and may end up in a coma. Lassa Fever can be fatal. Treatment includes supportive care of the symptoms and taking the antiviral drug Ribavirin.

  • Avoid contact with rats.
  • Store food in rodent-proof containers and properly dispose garbage to prevent rodent infestation. 
  • Wash your hands frequently and thoroughly with soap and water. If not available, use an alcohol-based sanitizer. Practice good body hygiene.

There is no preventive medication or vaccine against Lassa Fever.

Lassa virus images, life cycle, and distribution maps
Infection Landscapes

Health risk description last reviewed: September 06, 2016
Country information last updated: October 09, 2018


  • Camerlin AJ, McCormick JB. Lassa Fever. In: McGill, A; Ryan, E; Hill, D; Solomon, T, eds. Hunter's Tropical Medicine and Emerging Infectious Diseases. 9th ed. New York: Saunders Elsevier; 2013: 325-327.
  • Peters CJ, Zaki SR. Overview of Viral Hemorrhagic Fevers. In: Guerrant, R; Walker D; Weller P, eds. Tropical Infectious Diseases. 3rd ed. New York: Saunders Elsevier; 2011: 441-448.
  • Wertheim, Heiman; Horby, Peter; Woodall, John, eds. Atlas of Human Infectious Diseases. Oxford: Wiley-Blackwell; 2012. 273 p.
  • Centers for Disease Control and Prevention: Lassa Fever
  • World Health Organization: Lassa Fever Fact Sheet No. 179

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