Features of Pl. ovale:
(1) It causes relatively mild infections.
(2) It tends to be overshadowed by Pl. falciparum.
(3) Long-term residents in an endemic region develop a degree of immunity.
(4) Many infected patients are asymptomatic most of the time.
Criteria for symptomatic Pl. ovale malaria:
(1) fever (temperature >= 38°C) or fever related symptoms (headache, vomiting, febrile feeling)
(2) > 800 parasites per µL blood
(3) exclusion of other causes of fever (such as Pl. falciparum)
Risk factors for symptomatic Pl. ovale malaria:
(1) sickle cell trait
(2) early childhood (maximum number around 3 to 4 years)
(3) temporary residence in an endemic area
