Study investigating the clinical manifestations of Rift Valley fever in humans: Systematic review and meta-analysis

Data extraction in this study was aimed at achieving three main purposes: 1) obtain data that describe the characteristics of the included studies, 2) obtain data for assessing the quality of included studies, and 3) obtain data for synthesizing the frequency and duration of clinical manifestations and duration of illness since onset to diagnosis. Information was abstracted on the characteristics of eligible studies including first author’s surname, year of publication, type of article (abstract or full text), list of countries where the study was conducted, information on the study design (cohort, cross sectional/outbreak investigation, intervention studies, case series, reviews); demographics (number of participants that were enrolled, age, sex and nationality); laboratory tests used to confirm diagnosis of RVF (enzyme linked immunosorbent assay or ELISA (IgM & IgG), real-time polymerase chain reaction (rtPCR) or quantitative polymerase chain reaction (qPCR), plaque reduction neutralisation test (PRNT) and focus reduction neutralisation test (FRNT) or other serological and viral antigen tests etc). Data on the number or proportion that had co-infections and type of co-infection such as hepatitis B, malaria, schistosomiasis etcetera were also captured. Rift Valley fever presents among humans in form of clinical syndromes including the general febrile syndrome, hepatic or abdominal syndrome, encephalitis syndrome, visual syndrome and haemorrhagic syndrome. Data was collected on several RVF clinical manifestations in humans for which proportion or description of symptoms was recorded. Data was also extracted on the frequency and levels of each laboratory parameter reported.