Abstract
BackgroundPolyparasitism is a common condition in humans but its impact on the host immune system and clinical diseases is still poorly understood. There are few studies of the prevalence and the effect of malaria-intestinal parasite co-infections in the immune response to malaria vaccine candidates. The present study determines whether the presence of malaria and intestinal parasites co-infection is associated with impaired IgG responses to Plasmodium vivax AMA-1 and MSP-119 in a rural population of the Brazilian Amazon.MethodsA cross-sectional survey was performed in a rural area of Rondonia State and 279 individuals were included in the present study. At recruitment, whole blood was collected and Plasmodium and intestinal parasites were detected by microscopy and molecular tests. Blood cell count and haemoglobin were also tested and antibody response specific to P. vivax AMA-1 and MSP-119 was measured in plasma by ELISA. The participants were grouped according to their infection status: singly infected with Plasmodium (M); co-infected with Plasmodium and intestinal parasites (CI); singly infected with intestinal parasites (IP) and negative (N) for both malaria and intestinal parasites.ResultsThe prevalence of intestinal parasites was significantly higher in individuals with malaria and protozoan infections were more prevalent. IgG antibodies to PvAMA-1 and/or PvMSP-119 were detected in 74 % of the population. The prevalence of specific IgG was similar for both proteins in all four groups and among the groups the lowest prevalence was in IP group. The cytophilic sub-classes IgG1 and IgG3 were predominant in all groups for PvAMA-1 and IgG1, IgG3 and IgG4 for PvMSP-119. In the case of non-cytophilic antibodies to PvAMA-1, IgG2 was significantly higher in IP and N group when compared to M and CI while IgG4 was higher in IP group.ConclusionsThe presence of intestinal parasites, mainly protozoans, in malaria co-infected individuals does not seem to alter the antibody immune responses to P. vivax AMA-1 and MSP-119. However, IgG response to both AMA1 and MSP1 were lower in individuals with intestinal parasites.
Highlights
Polyparasitism is a common condition in humans but its impact on the host immune system and clinical diseases is still poorly understood
Prevalence of malaria and intestinal parasites Combining the results across all tests (Table 1), 279 individuals were grouped according to their infection status: individuals infected with Plasmodium only (n = 16, M); individuals co-infected with Plasmodium and intestinal parasites (48, CI); individuals infected with intestinal parasites only (98, IP) and individuals negative (117, N)
There was no significant changes in the prevalence and reactivity indices (RI) of antibody to PvAMA-1 (Fig. 4a) and PvMSP-1 (Fig. 4b) in CI and IP groups when individuals infected with H, P and protozoa and helminths (PH) were compared in each
Summary
Polyparasitism is a common condition in humans but its impact on the host immune system and clinical diseases is still poorly understood. There are few studies of the prevalence and the effect of malaria-intestinal parasite co-infections in the immune response to malaria vaccine candidates. The present study determines whether the presence of malaria and intestinal parasites co-infection is associated with impaired IgG responses to Plasmodium vivax AMA-1 and MSP-119 in a rural population of the Brazilian Amazon. It is well known that polyparasitism is a common condition in humans, little is known about the interaction between parasites and its impact on the host immune system and clinical diseases [1]. Little information is available about whether and how co-infections of helminths and malaria parasites can affect specific immune response to malaria parasites and vaccine candidates [20,21,22,23,24,25,26]. Systemic cytokine levels rose with age as well as with infection and exposure to schistosome or had no effect [22, 26]
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