History
Elicit any history of travel through, or immigration from, a malarious area. Even a few hours at an airport in an endemic area is significant. Obtain history of blood transfusion, organ transplantation, and (for newborns) malaria in the mother.
Young children manifest this disease in many different ways, but the classic picture of malaria, with periodic fever, shivering, and sweating, is not observed. Malaria can mimic any febrile illness and should be suspected in any febrile child who has recently been in a malarious area. Older children may manifest the classic periodicity of fever with chills and shivering.
After the mosquito bite, children are asymptomatic while the parasites complete the liver cycle and 1 erythrocytic cycle, which takes 8-18 days, depending on the species. Children then become restless, drowsy, apathetic, and anorexic. Older children may report aching body, headache, and nausea.
Fever is usually continuous and may be very high (40°C) from the first day. Many children have only flulike respiratory symptoms at presentation, with mild cough and cold. These symptoms abate in 1-2 days, with or without treatment.
Vomiting is very common in children with malaria and may make oral therapy ineffective. Mild diarrhea is often observed, with dark green mucoid stools. Occasionally, profuse diarrhea with dehydration and circulatory failure is observed.
Seizures are common and may occur at the onset of the disease, even before high fever has set in. Differentiating postictal impairment of consciousness from cerebral malaria is often difficult.
Parasitemia in neonates within 7 days of birth implies transplacental transmission. This congenital malaria is usually associated with placental parasitemia, which sometimes persists even after adequate treatment with antimalarial drugs. Babies have fever, are irritable, refuse feeds, and often develop anemia, jaundice, and hepatosplenomegaly.
Children living in an area where malaria is endemic have frequent infections and develop and maintain partial immunity. These children often develop only a low-grade fever, anemia, poor appetite, and malaise. Tiredness, restlessness, cough, and diarrhea are other symptoms that may occur.
Depending on the species of Plasmodium involved, relapses and recrudescences vary in their effects. P vivax and P ovale both give rise to hypnozoites in the liver. P vivax malaria may relapse for up to 3 years and P ovale for 1-1.5 years. P falciparum and P malariae do not form hypnozoites, so they do not have true relapses. However, the disease recrudesces because of surviving erythrocytic forms.
Although P falciparum can recrudesce for up to 1 year, P malariae may continue to cause clinical malarial attacks even 20 years after the original infection. Only the sporozoites (introduced by the mosquitoes themselves) can penetrate the liver cells. Thus, if malaria is acquired by blood transfusion or transplacentally, no infection of the liver occurs and relapses do not occur.
Physical Examination
Fever can be very high from the first day. Temperatures of 40°C and higher are often observed. Fever is usually continuous or irregular. Classic periodicity may be established after some days. High fever, poor oral intake, and vomiting all contribute to dehydration.
The liver may be slightly tender. Splenomegaly takes many days, especially in the first attack in nonimmune children. In children from an endemic area, severe splenomegaly sometimes occurs.
Prolonged malaria can cause anemia. Also, with heavy parasitemia and large-scale destruction of erythrocytes, mild jaundice may occur. This jaundice subsides with the treatment of malaria.
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The various stages of Plasmodium life cycle are shown. Knowledge of the life cycle of the malarial parasite is essential to understanding the chemotherapy of malaria.
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The various stages of Plasmodium vivax as observed on Giemsa staining of a peripheral blood smear.
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The various stages of Plasmodium falciparum as observed on Giemsa staining of a peripheral blood smear are shown. The presence of more than one parasite in an erythrocyte is unique to this species.
