WHO working with health authorities in European Region after outbreak of Lassa fever in Sierra Leone

WHO/Europe is working closely with partners and health authorities in several Member States following reports of an outbreak of Lassa fever in Sierra Leone.

The International Health Regulations (IHR) National Focal Point of the Netherlands informed WHO of 2 imported cases of Lassa fever. The 2 Dutch doctors had developed symptoms in the days following a surgical procedure in Masanga Hospital in Sierra Leone, and returned to the Netherlands. One of them unfortunately died on the night of 23 November 2019.

Masanga Hospital, located in the Tonkolili District of Sierra Leone, is supported by several nongovernmental organizations. International health workers and researchers from countries including Denmark, the Netherlands and the United Kingdom work alongside the Hospital’s national health workers. Contact tracing and monitoring have been conducted in these and other countries, and in Sierra Leone, as required.

WHO/Europe’s staff coordinated an immediate response with the affected Member States in the European Region. They maintained real-time communication with IHR National Focal Points and other WHO offices as the event unfolded across countries and regions.

Lassa fever is endemic in Sierra Leone, and sporadic cases have been exported to the European Region from other endemic countries including Liberia, Nigeria and Togo. Data from recent imported cases show that secondary transmission of Lassa fever is very rare when standard infection control precautions are observed.

Health staff should consistently implement standard precautions when caring for all patients to prevent infections in health-care settings. They should strictly apply contact precautions, including isolation, when caring for patients suspected or confirmed to have Lassa fever and when handling their clinical specimens or body fluids.

Lassa fever is an acute viral haemorrhagic fever that is transmitted to humans via contact with food or household items contaminated with rodent urine or faeces. Human-to-human infection and laboratory transmission can also occur through direct contact with the blood, urine, faeces or other bodily secretions of a person with Lassa fever. The overall case fatality rate is 1%. It is 15% among patients hospitalized with severe illness.

A more detailed summary of this event, including WHO’s risk assessment and advice, is available via the link below.