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Related Subjects: |Fever in a traveller |Malaria Falciparum |Malaria Non Falciparum |Viral Haemorrhagic Fevers (VHF) |Lassa fever |Dengue |Marburg virus disease |AIDS HIV |Yellow fever |Ebola Virus |Leptospirosis | Crimean-Congo haemorrhagic fever |African Trypanosomiasis (Sleeping sickness) |American Trypanosomiasis (Chagas Disease) |Incubation Periods |Notifiable Diseases UK

Asymptomatic or mild febrile illness in approximately 80% of patients. About 100,000 to 300,000 infections of Lassa fever occur annually, with about 5,000 deaths

About

• Animal-borne, or zoonotic, acute viral illness spread by the common African rat.
• Endemic in parts of West Africa including Sierra Leone, Liberia, Guinea and Nigeria
• The first documented case occurred in 1969.
• Lassa fever is named after the town in Nigeria where the first cases occurred.

Aetiology

• single-stranded RNA virus that belongs to the Arenaviridae family of viruses

Clinical

• Onset 1-3 weeks after contact
• Most are mild: fever, general malaise and weakness, and headache.
• Others: severe symptoms including haemorrhaging (in gums, eyes, or nose, as examples), respiratory distress, repeated vomiting, facial swelling, pain in the chest, back, and abdomen, and shock.
• Hearing loss, tremors, and encephalitis. Death due to multi-organ failure.
• The most common complication of Lassa fever is deafness
• Mortality in the third trimester of pregnancy is particularly high

Investigations

• ELISA test for IgM and IgG antibodies as well as Lassa antigen.
• Reverse transcription-polymerase chain reaction (RT-PCR) in early stage of disease.

Management

• Prevent: avoid contact with Mastomys rodents. Rodent proof containers. Controlling their numbers and spread.
• Isolation and precautions: masks, gloves, gowns, and goggles; using infection control measures, such as complete equipment sterilization; and isolating infected patients from contact with unprotected persons until the disease has run its course
• Ribavirin, has been shown to be most effective when given early in the course of the illness.
• Supportive care with fluid and electrolyte balance, oxygenation and blood pressure, as well as treatment of any other complicating infections

References

• Lassa fever: origins, reservoirs, transmission and guidelines