Comments
INITIAL SYMPTOMS:
Headache, fatigue, and myalgias followed by fever; "Febrile paroxysms at regular intervals are unusual and suggest infection with P. vivax or P. ovale." [Harrison, p. 764] Rash or lymphadenopathy suggests another cause of the fever. [Cecil]
FINDINGS:
Anopheline mosquitoes bite at night and release sporozoites into the blood. The sporozoites infect human hepatocytes. One to three weeks later, the hepatocytes release merozoites into the blood. Malarial paroxysms are associated with the invasion and rupture of red blood cells by these merozoites. Paroxysms are marked by fever, chills, headache, and nausea followed by profuse sweating. Other findings that may occur in all forms of malaria are anemia, jaundice, splenomegaly, and hepatomegaly. For P. vivax and P. ovale, infected hepatocytes can rest in a latent stage for 2-3 years. [Merck Manual, p. 1381-90] In one series of 160 patients in a travel clinic, symptoms were as follows: fever (100%), headache (100%), weakness/fatigue (94%), night sweats (91%), arthralgias (59%), myalgias (56%), diarrhea (13%), and abdominal pain (8%). The classic paroxysm lasts several hours and includes chills followed by high fever, then profuse sweating, and finally extreme fatigue and sleep. [PPID, p. 3072, 3081] As a general rule, uncomplicated malaria does not cause lymphadenopathy, pharyngitis, rash, or pulmonary consolidation. [Cohen, p. 1164; PPID, p. 3081]
SEVERE FALCIPARUM INFECTIONS:
The WHO criteria for severe malaria are any one of the following: cerebral malaria, respiratory distress, prostration, hyperparasitemia, severe anemia, hypoglycemia, jaundice, renal insufficiency, hemoglobinuria, shock, cessation of eating and drinking, repeated vomiting, and hyperpyrexia. P. falciparum can cause pulmonary edema and ARDS by sequestering in the tiny veins and capillaries of the lungs. Therefore, dyspnea is a finding in severe malaria. The urine may have the dark color of hemoglobinuria (black water fever) rather than the red color of hematuria. [PPID, p. 3075, 3082] Patients with P. falciparum malaria usually present within 4-6 weeks of their return from an endemic area. The fever pattern in falciparum malaria is "hectic." Cough and dyspnea are present in fewer than 20% of patients. Splenomegaly is present in about 25% of cases. Even less common are jaundice, abdominal pain, and hepatomegaly. Urticarial rash is rare. The WBC count is usually normal or slightly low (high in 5% of cases). Kidney function tests are usually normal at the time of presentation in the clinic. [ID, p. 2295] Inadequately treated patients with falciparum malaria may develop severe malaria: acute encephalopathy and coma, convulsions, renal failure, jaundice, pulmonary edema, bleeding diathesis, and shock. The other three malarias do not usually cause life-threatening disease. [CCDM, p. 372] Symptoms of cerebral malaria include deviated eyes, salivation, irregular breathing, opisthotonus, seizures, and coma. Complications, more common in children, include paralysis, aphasia, cerebellar ataxia, and cortical blindness. [Cohen, Ch. 111] Thrombocytopenia is commonly seen in malaria. [Wallach, p. 616] Secondary pneumonia is a complication. Less than 5% of patients with severe malaria have bleeding complications including hematemesis. [Guerrant, p. 671, 656]
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