Twenty to thirty cases had been described in Europe, as being caused by importation through infected individuals. These cases found outside of West Africa were found to have a high fatality risk because of the delay of diagnosis and treatment due to being unaware of the risk associated with the symptoms. Imported cases have not manifested in larger epidemics outside of Africa due to a lack of human to human transmission in hospital settings. An exception had occurred in 2003 when a healthcare worker became infected before the person showed clear symptoms. Nigeria
2018 outbreak
An outbreak of Lassa fever occurred in Nigeria during 2018 and spread to 18 of the countrys states; it was the largest outbreak of Lassa recorded. On 25 February 2018, there were 1081 suspected cases and 90 reported deaths; 317 of the cases and 72 deaths were confirmed as Lassa which increased to a total of 431 reported cases in 2018. 2019 outbreak
The total cases in Nigeria in 2019 was 810 with 167 deaths, the largest case fatality rate(23.3%) until then. 2020 outbreak
The epidemic started from the second week of the January.
By the tenth week the total number of cases has risen to 855 and deaths to 144, the case fatality rate of 16.8%.2021 Outbreak
On the 8th of December 2021, the Nigeria Centre for Disease Control (NCDC) was notified of the death of two persons from Lassa fever.2022 Outbreak
The epidemic took a new form, from 3 to 30 January 2022, 211 laboratory confirmed Lassa fever cases including 40 deaths (case fatality ratio: 19%) have been cumulatively reported in 14 of the 36 Nigerian states and the Federal Capital Territory across the country. In total from January until March, 132 deaths have been reported with a case fatality rate (CFR) of 19.1% which is lower than the CFR for the same period in 2021 (21.0%). Liberia
Lassa fever is endemic in Liberia. From 1 January 2017 through 23 January 2018, 91 suspected cases were reported from six counties: Bong, Grand Bassa, Grand Kru, Lofa, Margibi, and Nimba. Thirty-three of these cases were laboratory confirmed, including 15 deaths (case fatality rate for confirmed cases = 45.4%).In February 2020, a total of 24 confirmed cases with nine associated deaths has been reported from nine health districts in six counties. Grand Bossa and Bong counties account for 20 of the confirmed cases. History
The disease was identified in Nigeria in 1969. It is named after the town of Lassa, where it was discovered.A prominent expert in the disease, Aniru Conteh, died from the disease. Research
The Lassa virus is one of several viruses identified by WHO as a likely cause of a future epidemic.