Signs and symptoms are variable, but chills followed by fever and sweating constitute the classic malaria paroxysm. The diagnosis should be considered for any person who has been exposed to infection. Complications such as cerebral malaria may occur in Plasmodium falciparum infection. Asymptomatic parasitemia may occur among immune persons.
Demonstration of malaria parasites in blood films
A person's first attack of laboratory-confirmed malaria that occurs in the United States, regardless of whether the person has experienced previous attacks of malaria while outside the country
A subsequent attack experienced by the same person but caused by a different Plasmodium species is counted as an additional case. A repeated attack experienced by the same person and caused by the same species in the United States is not considered an additional case. Blood smears from doubtful cases should be referred to the National Malaria Repository, CDC, for confirmation of the diagnosis. In addition, cases are classified according to the following World Health Organization categories: