Lassa feverICD-11 Subcategory

A disease endemic in large parts of sub-Saharan Western Africa caused by infection with Lassa virus. Infection is mild or asymptomatic in most cases, but can cause severe illness or death. After a prodromal period of 7-10 days (sometimes longer), initial symptoms/signs include fever, malaise, headache, sore throat, vomiting, abdominal pain, and diarrhea. Subsequently, patients develop high fever, extreme lethargy, edema of head/neck, encephalopathy, pleural effusion, and ascites. Bleeding into the skin, mucosae and underlying tissues occurs in the severest cases. Deafness occurs in many patients, and the disease is often particularly severe in pregnancy. The overall lethality can reach 15% even among hospitalized patients receiving supportive care. Transmission occurs by inhalation, consumption, or direct contact with excretions and bodily fluids from infected rodents. Diagnosis occurs by identification of Lassa virus in blood samples by molecular or serologic methods.