Exposure history and case-fatality rate among patients with laboratory-confirmed Lassa fever cases, Nigeria, January 1–May 6, 2018. A) Proportion of persons reporting Lassa fever exposure risks for all case-patients, HCWs, and non–HCWs. To assess differences in exposure risks between HCWs and non–HCWs, p values were calculated by using the χ2 test and adjusted by the Bonferroni correction. B) The case-fatality rate for case-patients who did or did not receive ribavirin. C) An investigation of the case-fatality rate in patients who survived >7 days after symptom onset. For panels B and C, p values were calculated by using binomial logistic regression analysis adjusted for age and sex and applying the Bonferroni correction. HCW, healthcare worker.