Lassa fever is an animal-borne, or zoonotic, acute viral illness. It is endemic in parts of West Africa including Sierra Leone, Liberia, Guinea and Nigeria.SkipdirectlytositecontentSkipdirectlytopageoptionsSkipdirectlytoA-ZlinkSkipdirectlytoA-ZlinkSkipdirectlytoA-ZlinkLassaFeverSectionNavigationCDCHomeFacebookTwitterLinkedInSyndicateLassaFeverFrenchMinusRelatedPagesLassafeverisananimal-borne,orzoonotic,acuteviralillness.ItisendemicinpartsofWestAfricaincludingSierraLeone,Liberia,GuineaandNigeria.Neighboringcountriesarealsoatrisk,astheanimalvectorforLassavirus,the“multimammaterat”(Mastomysnatalensis)isdistributedthroughouttheregion.Theillnesswasdiscoveredin1969andisnamedafterthetowninNigeriawherethefirstcasesoccurred.Anestimated100,000to300,000infectionsofLassafeveroccurannually,withapproximately5,000deaths.SurveillanceforLassafeverisnotstandardized;therefore,theseestimatesarecrude.InsomeareasofSierraLeoneandLiberia,itisknownthat10-16%ofpeopleadmittedtohospitalsannuallyhaveLassafever,demonstratingtheseriousimpactthediseasehasontheregion.TransmissionPeopleareinfectedthroughcontactwithaninfectedrodent...SignsandSymptomsSymptomsofLassafevertypicallyoccur1-3weeksafterexposuretothevirus...RiskofExposurePeopleatgreatestriskarethosewholiveinWestAfrica,anendemicregionforLassafever...DiagnosisTypicallyLassafeverisdiagnosedusingenzyme-linkedimmunosorbentserologicassays(ELISA)...TreatmentRibavirinhasbeenusedwithsuccessinLassafeverpatients...PreventionLassafeverispreventedbyavoidingcontactwithMastomysrodents...OutbreakDistributionMapResourcesWhatyouneedtoknowaboutLassaFeverCdc-pdf[PDF–2pages]Factsheet:LassaFeverCdc-pdf[PDF–3pages]TrainingVideosforLassaFever—EarnContinuingEducationCreditTheEpidemiologyandClinicalPresentationofLassaFever:InformationforMedicalProvidersDiagnosingandTreatingLassaFever:InformationforMedicalProvidersPagelastreviewed:January31,2019Contentsource:CentersforDiseaseControlandPrevention,NationalCenterforEmergingandZoonoticInfectiousDiseases(NCEZID),Divisionof