Lassa fever is an acute viral hemorrhagic illness caused by Lassa virus that affects many countries in West Africa. Lassa virus is transmitted to humans via contact with food or household items contaminated with urine or feces from infected rodents. The number of Lassa virus infections per year in West Africa is estimated at 100,000 to 300,000, with approximately 5,000 deaths. While many of those infected with Lassa virus are asymptomatic, 1 in 5 infections result in severe disease. The more serious symptoms can include hemorrhaging (in gums, eyes, or nose, as examples), respiratory distress, repeated vomiting, facial swelling, pain in the chest, back, and abdomen, and shock. Neurological problems have also been described, including hearing loss, tremors, and encephalitis. The estimated fatality rate for patients hospitalized with severe cases of Lassa fever is 15%. The disease is especially severe late in pregnancy, with maternal death and/or fetal loss occurring in more than 80% of cases during the third trimester.
Lassa fever occurs in all age groups and both sexes. Those at greatest risk are people living in rural areas where infected rodents are usually found, especially in communities with poor sanitation or crowded living conditions. Health workers are at risk if caring for Lassa fever patients if proper infection control methods are not employed. When symptomatic, the onset of disease is usually gradual, starting with fever, general weakness, and malaise. Headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough, and abdominal pain may follow. Because the symptoms of Lassa fever are so non-specific, clinical diagnosis is often difficult, especially early in the course of the disease. Additionally, Lassa fever is difficult to distinguish from other viral hemorrhagic fevers such as Ebola virus, malaria, shigellosis, typhoid fever and yellow fever that are co-endemic in West Africa.
Current standard diagnostics for Lassa virus demand clinical samples be sent to a central laboratory, as they require sophisticated laboratory equipment and highly trained staff. These requirements and the inherent cost associated with such tests, present multiple challenges in resource-poor regions. The our laoratory is focused on making monoclonal antibodies that can be used to detect Lassa virus in a rapid diagnostic assay that is affordable, user friendly and can be performed at the point-of-care while providing results in 15 minutes.
Project Investigator: David P. AuCoin, Ph.D.
Grant support: This study was supported by DTRA contract N00173-16-C-2003, Field-forward diagnostic technologies and tiered evaluation, 2016-2017.