A treatment-reinfection study design was used to investigate the relationsh
ips between host immunologic and/or genetic factors and resistance to reinf
ection with Plasmodium falciparum. Sixty-one children in Gabon were enrolle
d in a cross-sectional study to measure the prevalence of each human plasmo
dial species. All were given amodiaquine for radical cure of parasites, and
40 were subsequently followed-up for 30 weeks. Successive blood smears wer
e examined to measure the delay of reappearance in blood of asexual stages
of P. falciparum parasites. Presence of infection during the cross-sectiona
l survey was associated with male sex, non-deficient glucose-6-phosphate de
hydrogenase activity, plasma interleukin-10 level, and anti-LSA-Rep antibod
y concentration. Resistance to reinfection was related to the presence of a
nti-LSA-J antibodies, and the absence of anti-LSA-Rep antibodies. Moreover,
P. malariae-infected subjects were usually co-infected with P. falciparum,
and were also more rapidly reinfected with P. falciparum after treatment,
compared with those without P. malariae infection.