Lassa fever

Overview

This is a tropical infectious disease caused by the Lassa virus. It presents with a constantly high fever, accompanied by headaches, a sore throat and muscle pain as well as a skin rash. In severe cases bleeding occurs, various organs can suffer damage, and the disease can be fatal. Obtaining medical advice for travellers before leaving on a trip is a good idea.

Symptoms

• Incubation period: 6-21 days

Mild progression

• Flu-like symptoms, slow onset
  • Exhaustion
  • Fever (permanently high)
  • Headaches and sore throat
  • Swollen neck lymph nodes
  • Joint and muscle pain
  • Skin rash
  • Nausea, vomiting
  • Diarrhoea
  • Burning eyes (conjunctivitis)

Complications/severe progression

In particular in the case of a weakened immune system or pregnancy

• Oedema (collection of fluid)
• Cerebral inflammation/meningitis
  • Cramps
  • Loss of hearing, right through to permanent deafness
• Kidney and liver damage
• Pneumonia
• Haemorrhage (bleeding), coagulation disorders
  • External and internal bleeding
  • Red dots on skin (petechiae)
  • Blood loss, possibly cardiovascular collapse
• Can cause death (multiple organ failure)

Causes and treatment

Cause

• Pathogen: Lassa virus
• Transmission
  • Rodents: contact, excretions, contaminated food, infected dust
  • Human-to-human: droplet/wound infection, secretions, sexual intercourse

Further treatment by your doctor / in hospital

Possible tests

• Physical examination
• Examination of blood, urine or tissue samples in high-security laboratories

Possible therapies

• Isolation (risk of contagion)
  • Persons you've been in contact with also have to be examined and isolated, if necessary
• Treatment of symptoms
  • Medication (fever/painkillers)
  • Control coagulation
  • Replace lost fluids
• Antiviral medication (ribavirin)
  • Only for severe cases
  • Viral suppression
  • This can have severe side-effects

What can I do myself?

• Don’t travel if you're pregnant (severe disease course)
• Medical advice for travellers before every trip to the tropics
  • No vaccination available
• Rodents
  • Avoid contact with mice and other rodents
  • Dispose of food suspected to have been contaminated by rodents
• Regularly sanitise your hands

When to see a doctor?

• Fever during or up to three weeks after returning from a trip to the tropics or subtropics
• Bleeding into the skin
• Feeling of being very unwell

Further information

Ostschweizer Infostelle für Reisemedizin (Eastern Switzerland Information Centre for Travel Medicine)
www.osir.ch

Swiss Tropical and Public Health Institute (Schweizerisches Tropen- und Public Health-Institut)
www.swisstph.ch/en/

FDFA (travel links)
www.eda.admin.ch/eda/en

Synonyms

Lassa fever, Lassa fever and Lassa haemorrhagic fever, Lassa haemorrhagic fever