According to the World Health Organisation, here are some key facts to know about Lassa fever:
- It is an acute viral haemorrhagic illness of 2-21 days’ duration.
- Though first described in the 1950s, the virus causing the disease was not identified until 1969. The virus is a single-stranded RNA virus belonging to the virus family, Arenaviridae.
- It is known to be endemic in West Africa, particularly in countries such as Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone and Nigeria.
- About 80 per cent of people who become infected with the virus have no symptoms. One in 5 infections results in severe disease, where the virus affects several organs such as the liver, spleen and kidneys.
- The onset of the disease, when it is symptomatic, is usually gradual, starting with fever, general weakness and malaise. After a few days, headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhoea, cough, and abdominal pain may follow. In severe cases, facial swelling, fluid in the lung cavity, bleeding from the mouth, nose, vagina or gastrointestinal tract and low blood pressure may develop.
- Protein may be noted in the urine. Shock, seizures, tremor, disorientation, and coma may be seen in the later stages. Deafness occurs in 25 per cent of patients who survive the disease. In half of these cases, hearing returns partially after 1–3 months. Transient hair loss and gait disturbance may occur during recovery.
- Death usually occurs within 14 days of onset in fatal cases. The disease is especially severe late in pregnancy, with maternal death and/or foetal loss occurring in more than 80 per cent of cases during the third trimester.
- The Lassa virus is transmitted to humans via contact with food or household items contaminated with rats’ urine or faeces.
- Person-to-person infections and laboratory transmission can also occur, particularly in hospitals lacking adequate infection prevention and control measures.
- Lassa fever occurs in all age groups and both sexes. Persons at greatest risk are those living in rural areas where 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 in the absence of proper barrier nursing and infection prevention and control practices.
- Early supportive care with rehydration and symptomatic treatment improves survival.
11 facts you need to know about Lassa fever