Clinical Signs

The hallmark of malaria is periodic febrile paroxysms that are usually sudden, with three discernible stages: chills, fever, and sweating. Then, the afebrile patient is exhausted and sleeps. Fever is more severe in naïve patients. Paroxysms may occur every third day (tertian malaria) in P. vivax, P. falciparum and P. ovale infections and every fourth day (quartan) in P. malariae; however, periodicity of fever is not a reliable indicator of species.

P. falciparum is the most deadly because of adherence of parasitized red blood cells to capillary walls. Severe gastrointestinal symptoms, enlarged and tender liver and jaundice may occur. Many patients develop massive splenomegaly (left) (tropical splenomegaly syndrome) after repeated attacks. Traumatic splenic rupture can cause death. Complications are more frequent in those with high levels of parasites, such as immunodeficient or pregnant patients. Cerebral malaria, renal failure and pulmonary edema are often fatal. Patients with cerebral malaria have headache, stiff neck, decreased consciousness, seizures, or focal neurologic signs. Renal involvement can cause glomerulonephritis with proteinuria, hemoglobinuria, oliguria or abnormal urinary sediment. Acute intravascular hemolysis can cause hemoglobinuria, so-called "Blackwater fever", and renal failure. Other complications include severe anemia, hypoglycemia, and disseminated intravascular coagulation. "Algid malaria" describes the clinical findings of clammy skin, cyanosis, and hypotension due to circulatory collapse. P. falciparum infection during pregnancy increases the chance of maternal anemia, spontaneous abortion, stillbirth, prematurity, intrauterine growth retardation and low birth weight.