Malaria - Signs and Symptoms

Signs and Symptoms

The signs and symptoms of malaria typically begin 8–25 days following infection; however, symptoms may occur later in those who have taken antimalarial medications as prevention. Initial manifestations of the disease—common to all malaria species—are similar to flu-like symptoms, and can resemble other conditions such as septicemia, gastroenteritis, and viral diseases. The presentation may include headache, fever, shivering, arthralgia (joint pain), vomiting, hemolytic anemia, jaundice, hemoglobinuria, retinal damage, and convulsions. Approximately 30% of people however will no longer have a fever upon presenting to a health care facility. Owing to the non-specific nature of disease presentation, diagnosis of malaria in non-endemic countries requires a high degree of suspicion, which might be elicited by any of the following: recent travel history, splenomegaly (enlarged spleen), fever without localizing signs, thrombocytopenia, and hyperbilirubinemia combined with a normal peripheral blood leukocyte count.

The classic symptom of malaria is paroxysm—a cyclical occurrence of sudden coldness followed by rigor and then fever and sweating, occurring every two days in P. vivax and P. ovale infections, and every three days (tertian fever) for P. malariae. P. falciparum infection can cause recurrent fever every 36–48 hours (quartan fever) or a less pronounced and almost continuous fever.

Severe malaria is usually caused by P. falciparum (often referred to as falciparum malaria). Symptoms of falciparium malaria arise 9–30 days after infection. Splenomegaly, severe headache, hepatomegaly (enlarged liver), hypoglycemia, and hemoglobinuria with renal failure may occur. Renal failure is a feature of blackwater fever, where hemoglobin from lysed red blood cells leaks into the urine. Cerebral malaria is a form of severe malaria that involves encephalopathy specifically related to P. falciparum infection. It is associated with retinal whitening, which may be a useful clinical sign in distinguishing malaria from other causes of fever. Individuals with cerebral malaria frequently exhibit neurological symptoms, including abnormal posturing, nystagmus, conjugate gaze palsy (failure of the eyes to turn together in the same direction), opisthotonus, seizures, or coma.