The clinical symptoms of malaria are fever, chills, headache, myalgias, and fatigue. Some people also experience vomiting, nausea, and diarrhea. The symptoms are seen 10 days to 4 weeks after the infection, “although a person may feel ill as early as 7 days or as late as 1 year after infection,” the US CDC says. If left untreated, it progresses to a serious condition where the patient experiences changes in mental state, seizures, renal failure, acute respiratory distress syndrome, and even coma.