Abstract
BackgroundMalaria still infects many Malawian children, and it is a cause of death in some of them. Regulatory T cells (Tregs) help in negating immune-related pathology, it but can also favor multiplication of malaria parasites. The question remains whether children recovering from uncomplicated malaria (UCM) have higher Tregs and interleukin (IL)-10 levels in convalescence.MethodsWe recruited children between the ages of 6 and 60 months presenting with acute UCM in Blantyre (low transmission area) and Chikwawa (high transmission area). We observed the children after 1 month and 3 months and analyzed their blood samples for parasitemia, lymphocyte subsets, and levels of the cytokines interferon (IFN)-γ, IL-10, and transforming growth factor (TGF)-β. Blood samples from age-matched controls were also analyzed for the same parameters.ResultsCompared with controls, acute UCM was associated with mild lymphopenia, splenomegaly, and high levels of IFN-γ, tumor necrosis factor-α, and IL-10, which normalized in convalescence. In Chikwawa, Treg counts were significantly (P < .0001) higher in convalescence compared with acute disease, whereas in Blantyre, these were as low as in healthy controls both during acute disease and in convalescence. Blantyre had a higher percentage of parasiteamic children (15% versus 12%) in convalescence compared with Chikwawa, but none of these developed symptomatic malaria during the study duration. Concentrations of TGF-β were higher at time points for the study participants and in controls from Blantyre compared with those recruited in Chikwawa.ConclusionsThe high transmission area was associated with high Tregs counts and IL-10 concentrations in convalescence, which could have an effect on parasite clearance. We recommend that children recovering from UCM, especially those from high transmission area, should sleep under insecticide-treated nets, be screened for parasitemia, and a provision of antimalarial prophylaxis should be considered.
Highlights
Malaria still infects many Malawian children, and it is a cause of death in some of them
In Chikwawa, 30 children presenting with acute uncomplicated malaria (UCM) and with a median age of 26.9 months (6.1–51.3) were recruited; 5 withdrew from the study 1 month after recruitment, and 1 additional child withdrew by the second follow-up visit for the same reason as in Blantyre
All UCM participants recruited in Blantyre had positive parasitaemia on the day of recruitment, 4 participants were found to be parasitemic during convalescence by thick and thin malaria slides, whereas in Chikwawa, 3 participants were parasitemic after 3 months convalescence
Summary
Malaria still infects many Malawian children, and it is a cause of death in some of them. The question remains whether children recovering from uncomplicated malaria (UCM) have higher Tregs and interleukin (IL)-10 levels in convalescence. Acute UCM was associated with mild lymphopenia, splenomegaly, and high levels of IFN-γ, tumor necrosis factor-α, and IL-10, which normalized in convalescence. In Chikwawa, Treg counts were significantly (P < .0001) higher in convalescence compared with acute disease, whereas in Blantyre, these were as low as in healthy controls both during acute disease and in convalescence. Blantyre had a higher percentage of parasiteamic children (15% versus 12%) in convalescence compared with Chikwawa, but none of these developed symptomatic malaria during the study duration. Concentrations of TGF-β were higher at time points for the study participants and in controls from Blantyre compared with those recruited in Chikwawa. We recommend that children recovering from UCM, especially those from high transmission area, should sleep under insecticide-treated nets, be screened for parasitemia, and a provision of antimalarial prophylaxis should be considered
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