Plasmodium ovale
P. ovale is similar to P. vivax in many respects, including its selectivity for young, pliable erythrocytes. As a consequence the classical characteristics include:
• The host cell becomes enlarged and distorted, usually in an oval form.
• Schiffner’s dots appear as pale pink granules.
• The infected cell border is commonly fimbriated or ragged
• Mature schizonts contain about 10 merozoites.
P.ovale is distributed primarily in tropical Africa. It is also found in Asia and South America.
Clinical Features
The incubation period for P.ovale is 16-18 days but can be longer. Clinically, ovale malaria resembles vivax malaria with attacks recurring every 48-50 hours. There are however, fewer relapses with P.ovale. Less than 2% of RBCs usually become infected.
Laboratory Diagnosis
Microscopic examination of thick and thin films of blood is the method of choice for confirming the clinical diagnosis of malaria and identifying the specific species responsible for disease.
Malaria parasites in thick and thin blood films are best stained at pH 7.1 – 7.2 using a Romanowsky stain (contains azure dyes and eosin).
The thick film is a concentration method that may be used to detect the presence of organisms. The thin film is most useful for establishing species identification. Serologic procedures are available but they are used primarily for epidemiological surveys or for screening blood donors.
Immunity
There is evidence that antibodies can confer hormonal immunity against malaria infection.
Prevention
• Chemoprophylaxis and prompt diagnosis and treatment.
• Control of mosquito breeding
• Protection of insect bite by screening, netting and protective clothing
• Use of insect repellents.
Treatment
The treatment regimen, including the use of primaquine to prevent relapse from latent liver stages is similar to that used for P.vivax infection.
INSTAGRAM
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