The onset of illness begins with generic flu-like symptoms; a characteristic high fever (typically 39-40 o C), severe headache, chills, myalgia, prostration, and malaise. For many patients (50-75%) this is followed by rapid debilitation characterized by gastrointestinal symptoms including anorexia, abdominal pain, severe nausea, vomiting, and watery diarrhea. Starting on day four to five patients commonly develop enanthem, dysphasia, and pharyngitis. Additionally, a characteristic maculopapular rash is typically the first distinctive feature indicating a filovirus infection versus influenza or malaria. Other common symptoms include lymphadenopathy, leukopenia, and thrombocytopenia.