The malaria paroxysm is the defining clinical feature of the disease. However, it is often not present. Fever caused by malaria can have any pattern, and falciparum infections often present with a constant fever. The classic paroxysm typically has three stages, and is preceded in some patients by an initial period of nonspecific symptoms. Those symptoms include fatigue, muscle aches, loss of appetite, headache, and a slight fever of 2-3 day's duration. A paroxysm begins with the "cold" or "chilling" stage lasting 15 minutes to several hours during which the patient feels cold and has shaking chills. The second "hot" stage lasts several hours and coincides with red blood cell rupture and merozoite release. During the second stage temperatures rise to 40°C (104°F) or higher. There is minimal sweating and the patient is at risk of febrile seizures or hyperthermic brain damage. Clinical signs and symptoms include tachycardia, hypotension, cough, headache, backache, nausea, abdominal pain, vomiting, diarrhea, and altered consciousness. Within 2-6 hours, the patient enters the third "sweating" stage of the paroxysm with generalized sweating, resolution of fever, and marked exhaustion, usually giving way to sleep. Paroxysms occur in regular intervals, but take several days to emerge.
Gastrointestinal complaints can be considerable, suggesting a diagnosis of gastroenteritis. Young children and semi-immune individuals may complain of fever and headache as their only symptoms.
Table - I : Selected Characteristics of the Four Species of Human Malaria
Fever periodicity (hours) none 48 48 72
Febrile paroxysm length 16-36 or longer 8-12 8-12 8-10 (hours)
Severity of primary attack severe in mild to mild mild
Drug Resistance ++ + - -
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