TABLE 17.1.

Essential Features of the Plasmodia Routinely Infecting Humans

	P. falciparum	P. vivax	P. malariae	P. ovale	P. knowlesi
Relative abundance	Very common	Very common	Rare	Rare	Rare
Natural host	Human	Human	Human	Human	Macaques
Other hosts	•Some African apes	•Some African apes •New World monkeys	•Some New World monkeys	•Some African apes	•Gibbons •Leaf monkeys •Others
Incubation period	7–14 days	10–20 days	15–30 days	11–16 days	9–12 days
Blood schizogonic cycle	48 hours (tertian)	48 hours (tertian)	36 hours (quartan)	48 hours (tertian)	24 hours (quotidian)
Latent hepatic stage	No	Yes	No	Yes	No
Geographic distribution	Subtropical and tropical Americas, Africa, Asia	Temperate, subtropical, and tropical Americas, Africa, Asia	Subtropical and tropical Americas, Africa, Asia	Subtropical and tropical Africa and Asia	Tropical Southeast Asia
Parasitemia	>100,000/µL dangerous	Does not correlate with clinical threat	Almost never high	Almost never high	>50,000/µL dangerous
RBC infected	Any	Youngest reticulocytes	Older erythrocytes	Reticulocytes	Any
Organs infected	Vascular sinuses	Vascular sinuses, spleen, and marrow	Vascular sinuses and unknown	Vascular sinuses and unknown	Vascular sinuses
Salient syndromes in severe disease	•Seizuresa •Coma •AKIb •Jaundice/hepatic dysfunctionb •ARDSb •Anemiaa •Shock •Metabolic acidosis	•Platelets <50,000/µL •Shock •Jaundice/hepatic dysfunction •Severe anemia •Metabolic acidosis •AKI •Coma •Abnormal bleeding •ARDS •Splenic infarction/rupture	•Rare case reports of AKI and ARDS	•ARDS •Anemia	•ARDS •Jaundice/hepatic dysfunction •AKI •Shock •Metabolic acidosis
Drug resistance problems	•Chloroquine (universal) •Artemisinin (Southeast Asia)	•Chloroquine (Southeast Asia) •Primaquine (Southeast Asia)	One report of chloroquine resistance in southern Sumatra, Indonesia	Unknown	None
Dormancy	Rare	Latent hypnozoites, about 1 month up to 4 years	As long as several decades, mechanism unknown	Latent hypnozoites, but durations unknown	None known

AKI, Acute kidney infection; ARDS, acute respiratory distress syndrome; RBC, red blood cell.

^aMore common in children.

^bMore common in adults.