title: Plasmodium falciparum gametocyte sex ratios in symptomatic children treated with antimalarial drugs.
abstract: The sex ratios of Plasmodium falciparum gametocytes, defined as the proportion of gametocytes in peripheral blood that were male, were evaluated in 1609 children with acute, symptomatic, uncomplicated malaria, pre- and post-treatment with various antimalarial drugs, over an 8-year period (1999-2006) in an endemic area of southwest Nigeria. Gametocyte carriage on presentation was 10% (162 children). In 162 children in whom 5797 gametocytes were sexed on presentation, the weighted mean sex ratio was 0.18 (95% confidence interval 0.13-0.25). Following therapy, in 446 children in whom 38,519 gametocytes were sexed, the weighted mean sex ratio was 0.38 (95% CI 0.33-0.43) on day 3 and 0.70 (95% CI 0.63-0.75) (P<0.000001) by day 7 after therapy commenced. Non-artemisinin monotherapy significantly increased sex ratio producing a male-biased ratio, but artemisinin combination therapy significantly reduced the sex ratio producing a female biased ratio. Pre-treatment sex ratio correlated negatively with haematocrit (r=-0.229, P=0.003) or gametocytaemia (r=-0.435, P<0.0001) but not with other clinical or parasitological parameters. The ratio of the sex-specific half lives male:female, the 'gametocyte maleness index' (GMI), was >1 with non-artemisinin monotherapy but <1 with artesunate and artemisinin-based combinations. In a multiple regression model, anaemia, low gametocytaemia, and enrolment before 2004 were independent predictors of a male-biased sex ratio pre-treatment. A pre-treatment haematocrit <25%, enrolment before 2004 and treatment with non-artemisinin monotherapy were independent predictors of a male-biased sex ratio 7 days postinitiation of therapy. These findings may have implications for malaria management efforts in sub-Saharan Africa.
authors.affiliation: Department of Pharmacology & Therapeutics and Institute for Medical Research and Training, University of Ibadan, Nigeria.
authors.forename: Akintunde
authors.initials: A
authors.lastname: Sowunmi
authors.forename: Sulayman T
authors.initials: ST
authors.lastname: Balogun
authors.forename: Grace O
authors.initials: GO
authors.lastname: Gbotosho
authors.forename: Christian T
authors.initials: CT
authors.lastname: Happi
mesh_terms: D000293:Adolescent; D017954:Africa South of the Sahara; D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000469:parasitology*; D008297:Male; D010963:Plasmodium falciparum / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D012744:Sex Ratio
chemical_list: D000962:Antimalarials