Malaria: even more chronic in nature than previously thought; evidence for subpatent parasitaemia detectable by the polymerase chain reaction

• Published in: Transactions of the Royal Society of Tropical Medicine and Hygiene Vol. 90; no. 1; pp. 15 - 19
• Main Authors: Bottius, Emmanuel, Guanzirolli, Antonella, Trape, Jean-François, Rogier, Christophe, Konate, L., Druilhe, Pierre
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01-01-1996; Royal Society of Tropical Medicine and Hygiene; Elsevier
• Subjects: Adolescent; Adult; Aged; Biological and medical sciences; Carrier State - diagnosis; Carrier State - epidemiology; Child; Child, Preschool; Chronic Disease; Human protozoal diseases; Humans; Infant; Infectious diseases; Malaria; Malaria, Falciparum - diagnosis; Malaria, Falciparum - epidemiology; Medical sciences; Middle Aged; Molecular Sequence Data; Parasitemia - diagnosis; Parasitemia - epidemiology; Parasitic diseases; Plasmodium falaparum; Polymerase Chain Reaction; Prevalence; Protozoal diseases; Senegal; Senegal - epidemiology; subpatent parasitaemia; Tropical medicine; Senegal; Africa; Plasmodium falaparum; malaria; subpatent parasitaemia; Senegal; Infection; Human; Polymerase chain reaction; Protozoa; Plasmodium falciparum; Protozoal disease; Malaria; Parasitosis; Technique; Molecular biology; Parasitemia; Sporozoa
• ISSN: 0035-9203; 1878-3503
• DOI: 10.1016/S0035-9203(96)90463-0

In high endemicity areas, malaria is a chronic disease: examination of blood films reveals that up to half of the population, particularly children, harbour parasites at any one given time. The parasitological status of the remainder was addressed using the polymerase chain reaction, a technique 100 to 1000 times more sensitive than microscopy, on a series of samples from Dielmo, a holoendemic area of Senegal. Two-thirds of the microscopically negative individuals were found to harbour subpatent levels of
Plasmodium falciparum, suggesting that more than 90% of the exposed population at any one time, i.e. in a cross-sectional survey, are chronically infected. This also means that the range of parasite loads harboured by humans with various degrees of exposure is remarkably large, probably reflecting a large range of effectiveness of the defence mechanisms against malaria parasites, none of which is fully efficient.