title: Patterns of malaria indices across three consecutive seasons in children in a highly endemic area of West Africa: a three times-repeated cross-sectional study.
abstract: OBJECTIVE
  To study the manifestations of Plasmodium infection, and its relations with the malaria disease, especially when comparing dry and rainy seasons in a hyperendemic area of West Africa.
  
  
  METHODS
  The study was carried out in an area where malaria transmission is high, showing important seasonal variations. One thousand children, representing the total child population (1-12 year old), were observed transversally at the end of three consecutive seasons (dry/rainy/dry). The usual indicators, such as parasite density, splenomegaly, anaemia, or febrile disease were recorded and analysed.
  
  
  RESULTS
  The prevalence of Plasmodium falciparum was high in all age groups and seasons, constantly around 60%. The high transmission season (rainy) showed higher rates of anaemia and spleen enlargement and, in the youngest children only, higher parasite densities. There were also differences between the two dry seasons: in the first one, there was a higher rate of fever than in the second one (p < 0.001). Low parasite density (<2,000 p/μl) was never associated with fever during any season, raising some concern with regard to the usefulness of parasite detection. The possible origins of fever are discussed, together with the potential usefulness of analyzing these indices on a population sample, at a time when fever incidence rises and malaria is one potential cause among others. The distinction to be made between the Plasmodium infection and the malaria disease is highlighted.
  
  
  CONCLUSIONS
  These data confirm previous hypotheses of a strong difference in malaria infection and disease between dry and rainy seasons. The most relevant seasonal indicator was not mainly parasite rate and density but anaemia, spleen enlargement, prevalence and possible origin of fever.
  
  
  CONCLUSIONS
  In any situation (i.e. fever or not) and especially during the dry season, one must consider that detection of parasites in the blood is only evidence of a Plasmodium infection and not necessarily of a malaria disease. In such a situation, it seems suitable to obtain, through national malaria teams, a well-defined situation of transmission and prevalence of Plasmodium infection following zones and seasons, in order to adapt control strategies. For researchers, a systematic management of data separately for dry and rainy season appears mandatory.
authors.forename: Denis-Luc
authors.initials: DL
authors.lastname: Ardiet
authors.forename: Bertrand
authors.initials: B
authors.lastname: Graz
authors.forename: Thomas
authors.initials: T
authors.lastname: Szeless
authors.forename: Anne
authors.initials: A
authors.lastname: Mauris
authors.forename: Jacques
authors.initials: J
authors.lastname: Falquet
authors.forename: Ogobara K
authors.initials: OK
authors.lastname: Doumbo
authors.forename: Amagana
authors.initials: A
authors.lastname: Dolo
authors.forename: Ousmane
authors.initials: O
authors.lastname: Guindo
authors.forename: Mahamadou S
authors.initials: MS
authors.lastname: Sissoko
authors.forename: Moussa
authors.initials: M
authors.lastname: Konaré
authors.forename: Sandrine
authors.initials: S
authors.lastname: Motamed
authors.affiliation: IMSP: Institut de Médecine Sociale et Préventive (currently Institut de santé globale), CMU, rue Michel Servet 1, Genève 4 CH-1211, Switzerland. Andre.Rougemont@unige.ch.
authors.forename: André C
authors.initials: AC
authors.lastname: Rougemont
mesh_terms: D000354:Africa, Western / Q000453:epidemiology; D000740:Anemia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D019353:Endemic Diseases; D005260:Female; D005334:Fever / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D016778:Malaria, Falciparum / Q000453:epidemiology*; D008297:Male; D059208:Parasite Load; D015995:Prevalence; D012621:Seasons; D013163:Splenomegaly / Q000453:epidemiology