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. they therefore list it for urgent research and development to develop new diagnostic tests, vaccines, and medicines. in 2007, siga technologies, studied a medication in guinea pig with lassa fever. work on a vaccine is continuing, with multiple approaches showing positive results in animal trials.