Plasmodium falciparum gametocyte sex ratios in children with acute, symptomatic, uncomplicated infections treated with amodiaquine

Clinical, parasitological and laboratory parameters were evaluated before treatment and during follow-up for 28–42 days, and according to standard methods. Gametocyte sex ratio was defined as the proportion of peripheral gametocytes that are male.

Clinical recovery from illness occurred in all children. Gametocytaemia was detected in 66 patients (11%) before treatment and in another 56 patients (9%) after treatment. Gametocyte densities were significantly higher by days 3–7 following treatment compared with pre-treatment (P < 0.0001). Overall, mean gametocyte sex ratio increased significantly during follow-up and over the study periods from 2000–2006 (P < 0.001 in both cases), but was female-biased at enrolment throughout the study periods. Absence of fever, a haematocrit < 25%, asexual parasitaemia > 20,000/μL, gametocytaemia < 18/μL, and enrolment in 2006 were associated with a male-biased sex ratio pre-treatment. Anaemia and high parasitaemia were independent predictors of gametocyte maleness 7 days post treatment.

Amodiaquine may significantly increase gametocyte carriage, density and sex ratio, and may potentially influence transmission. It is possible that anaemia could have contributed to the increased sex ratio. These findings may have implications for malaria control efforts in Africa.