The Lassa virus spreads through the urine or faeces of infected Mastomys rats. Humans usually become infected by eating or drinking contaminated food or inhaling dust from contaminated droppings or urine. Person to person transmission can occur through exposure to infected blood, tissues and body fluids. The disease does not spread through casual social contact.

High-risk groups

• Residents of or travellers to endemic regions at risk of contact with rats
• Medical and paramedical staff responsible for the care of Lassa patients
• People taking care of sick family members and / or who have been in contact with body fluids or deceased patients

Incubation time

1 to 3 weeks after infection.

Symptoms

• In 80% of cases: none.
• In 20% of cases: mild fever, headache, general malaise. This can progress to more severe symptoms such as haemorrhaging, vomiting, respiratory distress, facial swelling, abdominal and chest pain, shock, resulting in death. 

Treatment

• Intensive supportive care and treatment of any complications
• Administration of antiviral agents such as Ribavirin

Prevention

• Avoiding contact with faeces and urine from rats and other rodents
• Avoiding contact with body fluids of sick people
• In hospital settings: strict quarantine of infected patients and use of protective clothing (mask, gloves, coats, ...)

There is no vaccine against Lassa fever available on the market.

Links

• Complete travel advice for Nigeria
• Centers for Disease Control and Prevention - Lassa fever
• World Health Organization - Lassa fever
• European Centre for Disease Prevention and Control - Lassa fever