Abstract
Lassa fever (LF) is an acute viral haemorrhagic illness with various non-specific clinical manifestations. Neurological symptoms are rare at the early stage of the disease, but may be seen in late stages, in severely ill patients.The aim of this study was to describe the epidemiological evolution, socio-demographic profiles, clinical characteristics, and outcomes of patients seen during two Lassa fever outbreaks in Ebonyi State, between December 2017 and December 2018. Routinely collected clinical data from all patients admitted to the Virology Centre of the hospital during the period were analysed retrospectively. Out of a total of 83 cases, 70(84.3%) were RT-PCR confirmed while 13 (15.7%) were probable cases. Sixty-nine (83.1%) patients were seen in outbreak 1 of whom 53.6% were urban residents, while 19%, 15%, and 10% were farmers, students and health workers respectively. There were 14 (16.8%) patients, seen in second outbreak with 92.9% rural residents. There were differences in clinical symptoms, signs and laboratory findings between the two outbreaks. The case fatality rates were 29.9% in outbreak 1 and 85.7% for outbreak 2. Neurological features and abnormal laboratory test results were associated with higher mortality rate, seen in outbreak 2. This study revealed significant differences between the two outbreaks. Of particular concern was the higher case fatality during the outbreak 2 which may be from a more virulent strain of the Lassa virus. This has important public health implications and further molecular studies are needed to better define its characteristics.
Highlights
Lassa fever (LF) is a viral haemorrhagic illness caused by Lassa virus (LASV); associated with frequent fatal outcomes, and is endemic in West Africa [1,2,3].LASV is mainly transmitted to humans through exposure to infected rodent urine, faeces, tissue or blood [2] or through direct contact with urine, blood, respiratory secretions or other body fluids of an infected person [4,5]
In two separate outbreaks of LF in Ebonyi State, this study describes 1) the socio-demographic profiles, epidemiological evolution of the outbreaks and case fatality rates, 2) the clinical characteristics, hospital management and outcomes of the confirmed and probable cases and 3) the clinical symptoms significantly associated with mortality in the two outbreaks
The total number of patients diagnosed with LF in the two outbreaks in Ebonyi state from December 2017 to December 2018 was 83; 70 (84.3%) were Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) confirmed and 13 (15.7%) were probable cases but only 64 were treated in the Virology Centre; the other 19 died before treatment at the Centre could be commenced
Summary
Lassa fever (LF) is a viral haemorrhagic illness caused by Lassa virus (LASV); associated with frequent fatal outcomes, and is endemic in West Africa [1,2,3].LASV is mainly transmitted to humans through exposure to infected rodent urine, faeces, tissue or blood [2] or through direct contact with urine, blood, respiratory secretions or other body fluids of an infected person [4,5]. Lassa fever (LF) is a viral haemorrhagic illness caused by Lassa virus (LASV); associated with frequent fatal outcomes, and is endemic in West Africa [1,2,3]. LF symptoms may be mild or asymptomatic in about 80% of cases, but can otherwise cause acute illness [9,10]. Clinical disease usually begins within the first three weeks [11] after exposure with flu-like illness, characterized by a generalized weakness, malaise and fever which may be accompanied by a wide spectrum of non-specific clinical manifestations, at different stages of the disease [12]. Neurological manifestation (Tremors, Seizures, Disorientation, Coma etc) are uncommon in early disease, but may be seen in later stages [4,13,14]. The clinical course of the disease is demonstrated in (S1 Table) [10]
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