title: Changing malaria epidemiology and diagnostic criteria for Plasmodium falciparum clinical malaria.
abstract: BACKGROUND
  In tropical Africa, where malaria is highly endemic, low grade infections are asymptomatic and the diagnosis of clinical malaria is usually based on parasite density. Here we investigate how changes in malaria control and endemicity modify diagnostic criteria of Plasmodium falciparum attacks.
  
  
  RESULTS
  Parasitological and clinical data from the population of Dielmo, Senegal, monitored during 20 years, are analyzed in a random-effect logistic regression model to investigate the relationship between the level of parasitemia and risk of fever. Between 1990 and 2010, P. falciparum prevalence in asymptomatic persons declined from 85% to 1% in children 0-3 years and from 34% to 2% in adults ≥50 years. Thresholds levels of parasitemia for attributing fever episodes to malaria decreased by steps in relation to control policies. Using baseline threshold during following periods underestimated P. falciparum attacks by 9.8-20.2% in children and 18.9-40.2% in adults. Considering all fever episodes associated with malaria parasites as clinical attacks overestimated P. falciparum attacks by 42.2-68.5% in children and 45.9-211.7% in adults.
  
  
  CONCLUSIONS
  Malaria control modifies in all age-groups the threshold levels of parasitemia to be used for the assessment of malaria morbidity and to guide therapeutic decisions. Even under declining levels of malaria endemicity, the parasite density method must remain the reference method for distinguishing malaria from other causes of fever and assessing trends in the burden of malaria.
authors.affiliation: Institut de Recherche pour le Développement, Laboratoire de Paludologie, UMR 198, BP 1386, Dakar, Senegal.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Roucher
authors.forename: Christophe
authors.initials: C
authors.lastname: Rogier
authors.forename: Fambaye
authors.initials: F
authors.lastname: Dieye-Ba
authors.forename: Cheikh
authors.initials: C
authors.lastname: Sokhna
authors.forename: Adama
authors.initials: A
authors.lastname: Tall
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Trape
mesh_terms: D000293:Adolescent; D000328:Adult; D000962:Antimalarials / Q000627:therapeutic use; D058070:Asymptomatic Diseases; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005334:Fever / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008137:Longitudinal Studies; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology; D008297:Male; D008875:Middle Aged; D018512:Parasitemia / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology; D010963:Plasmodium falciparum / Q000187:drug effects / Q000254:growth & development*; D015995:Prevalence; D012307:Risk Factors; D012675:Senegal / Q000453:epidemiology
chemical_list: D000962:Antimalarials