Hematologic dysfunction in Lassa fever

Abstract

Lassa fever is widespread in West Africa, where the case fatality is about 16% in hospitalized adult patients. The clinical course is highly variable, with a few patients developing severe disease with bleeding, adult respiratory distress syndrome, encephalopathy and hypovolemic shock. We studied 70 patients admitted with suspected Lassa fever to a hospital in Sierra Leone, West Africa. Fourteen patients classified as having severe Lassa fever on the basis of serum aspartate amino transferase (AST) > 150 IU/L or viremia of > 10^3.6 tissue culture infective dose (TCID) ₅₀/ml were found to have statistically significantly depressed lymphocyte counts when compared with patients with mild Lassa fever (AST 3.6TCID₅₀/ml), (P PPPP=0.0081 for collagen) when compared with patients with mild Lassa fever, and when compared with febrile controls, (P=0.0013 for ADP and P9/L. Though this defect was significantly associated with Lassa fever in the patients studied, platelet dysfunction was also observed in a small number of patients with laboratory confirmed malaria within the febrile control group of patients. In contrast, prothrombin times and partial thromboplastin times in Lassa fever patients were rarely abnormal, and there were no statistically significant differences between Lassa fever patients and febrile controls in coagulation tests or in fibrinogen degradation product levels.