Factors influencing resistance to reinfection with Plasmodium falciparum

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.