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Factors influencing resistance to reinfection with Plasmodium falciparum
O Domarle1, F Migot-Nabias, J L Mvoukani
1Centre International de Recherches Mécicales de Franceville, Gabon.
Insights
Host factors influence reinfection with Plasmodium falciparum (malaria). Specific antibodies (anti-LSA-J) promote resistance, while others (anti-LSA-Rep) are linked to susceptibility. P. malariae co-infection accelerates P. falciparum reinfection.
Area of Science:
- Immunology
- Infectious Diseases
- Genetics
Background:
- Understanding host factors influencing Plasmodium falciparum reinfection is crucial for malaria control.
- Previous studies suggest a role for immune responses and genetic factors in malaria resistance.
Purpose of the Study:
- To investigate the relationship between host immunologic and genetic factors and resistance to P. falciparum reinfection.
- To identify specific immune markers associated with protection or susceptibility to malaria reinfection.
Main Methods:
- A treatment-reinfection study design was employed with 61 children in Gabon.
- Parasite prevalence was measured, followed by amodiaquine treatment and a 30-week follow-up.
- Blood smears were used to monitor P. falciparum parasite reappearance, assessing delay in reinfection.
Main Results:
- Male sex, normal glucose-6-phosphate dehydrogenase activity, higher interleukin-10 levels, and anti-LSA-Rep antibodies correlated with P. falciparum infection presence.
- Resistance to reinfection was associated with anti-LSA-J antibodies and absence of anti-LSA-Rep antibodies.
- Plasmodium malariae co-infection was linked to more rapid P. falciparum reinfection post-treatment.
Conclusions:
- Host immune responses, specifically antibody profiles against circumsporozoite protein epitopes (LSA-J and LSA-Rep), play a significant role in P. falciparum reinfection.
- Genetic factors like G6PD deficiency and co-infection with other Plasmodium species can modulate malaria infection dynamics.
Abstract:
A treatment-reinfection study design was used to investigate the relationships between host immunologic and/or genetic factors and resistance to reinfection with Plasmodium falciparum. Sixty-one children in Gabon were enrolled in a cross-sectional study to measure the prevalence of each human plasmodial species. All were given amodiaquine for radical cure of parasites, and 40 were subsequently followed-up for 30 weeks. Successive blood smears were examined to measure the delay of reappearance in blood of asexual stages of P. falciparum parasites. Presence of infection during the cross-sectional survey was associated with male sex, non-deficient glucose-6-phosphate dehydrogenase activity, plasma interleukin-10 level, and anti-LSA-Rep antibody concentration. Resistance to reinfection was related to the presence of anti-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.