The effect of malaria on the outcome of Lassa Fever

Abstract

Background: Lassa fever (LF) and malaria can co-exist in patients in countries endemic for both infections and thus lead to delay in diagnosis of LF, with consequent adverse effect on outcome. This study was aimed at addressing the paucity of data on the prevalence of malaria as a comorbidity in patients with LF and the effect on outcome. Methods: The clinical presentation and outcome of patients with RT-PCR confirmed LF seen at the Irrua Specialist Teaching Hospital, Nigeria between January 2008 and August 2009 were reviewed. RT-PCR for Lassa virus and blood smear for malaria parasites were done using standard techniques. Treatment was with ribavirin. Results: 102 patients with RT-PCR confirmed LF were managed during the period. 27 (37%) of 73 patients were LF and malaria smear positive while 46 (63%) were LF positive and malaria smear negative; malaria parasite smear was not examined in 29 (28.4%) of the 102 patients. Malaria positive LF patients had a significantly shorter duration of fever (7.6 + 4.93 versus 10.2 + 5.96 days; p 0.1). Overall, patients with CNS manifestations had a significantly higher CFR than those without (54.8% versus 9.4%; p < 0.001), irrespective of the presence or absence of malaria parasites. The mortality rate among patients with severe CNS manifestations (coma and/or seizure) was also significantly higher than among those with milder CNS features (80% versus 31.8%; p < 0.001). Conclusion: There is a high prevalence (37%) of coinfection with malaria in patients with LF, thus emphasizing a high index of suspicion for diagnosis and testing for LF even in the presence of malaria parasitaemia in endemic areas. Our study could not demonstrate a major effect of malaria on outcome. Severe CNSmanifestations such as coma and/or seizures were associated with excess mortality.