During influenza season: All influenza-like illnesses are not due to influenza: Dengue mimicking influenza

Background During influenza season, many patients present to the emergency department (ED) for evaluation with influenza-like illnesses (ILIs). ILIs are commonly due to influenza A or B, but other infections may mimic influenza in their clinical presentation. With the high volume of ILIs presenting to the ED during influenza season, the ED physician should be alert to other infections masquerading as influenza. Case Report We report an interesting case of a 31-year-old female who presented with an ILI during influenza season. She had recently been in contact with multiple people with influenza. Her nonspecific laboratory tests done in the ED were consistent with influenza, except for a highly elevated serum ferritin level. The serum ferritin level was the key finding that led to the correct diagnosis of dengue fever, which she acquired during a recent trip to Haiti. Why Should an Emergency Physician Be Aware of This? During influenza season, facing high patient volumes of ILIs in the ED, the ED physician needs to be aware of clinical features in ILIs that may suggest a mimic of influenza.