Signs and Symptoms
Signs and symptoms of malaria can be general and non-specific, so it is important for a doctor to take a thorough medical history and for people to tell their doctor if they have traveled to endemic countries, even if they followed preventive measures carefully.
Often, malaria presents as a flu-like illness with fevers, chills, sweats, headaches, aches and malaise. Some people develop gastrointestinal symptoms of nausea, vomiting and diarrhea. Anemia and jaundice can occur. These symptoms can develop as early as 7 days after initial infection or as late as several months after returning to the U.S., but the most typical time is about 14 days after exposure.
Signs and symptoms develop after the parasites emerge from the liver stage and enter red blood cells to multiply, coinciding with the bursting of those red blood cells. The symptoms are cyclic, worsening and then improving every 2-3 days as more red blood cells are infected and burst. An infected person may have an enlarged liver or spleen, but there may be few other signs that can be detected by a physical examination.
Severe malaria, primarily caused by P. falciparum, is life-threatening. It can affect the brain, kidneys and lungs, causing symptoms such as seizures, mental confusion, acute respiratory distress and coma; it can result in multi-organ failure and death. When it affects the brain, it is called cerebral malaria.