Assessing the impact of differences in malaria transmission intensity on clinical and haematological indices in children with malaria

Abstract

BackgroundMalaria control interventions have led to a decline in transmission intensity in many endemic areas, and resulted in elimination in some areas. This decline, however, will lead to delayed acquisition of protective immunity and thus impact disease manifestation and outcomes. Therefore, the variation in clinical and haematological parameters in children with malaria was assessed across three areas in Ghana with varying transmission intensities.MethodsA total of 568 children between the ages of 2 and 14 years with confirmed malaria were recruited in hospitals in three areas with varying transmission intensities (Kintampo > Navrongo > Accra) and a comprehensive analysis of parasitological, clinical, haematological and socio-economic parameters was performed.ResultsAreas of lower malaria transmission tended to have lower disease severity in children with malaria, characterized by lower parasitaemias and higher haemoglobin levels. In addition, total white cell counts and percent lymphocytes decreased with decreasing transmission intensity. The heterozygous sickle haemoglobin genotype was protective against disease severity in Kintampo (P = 0.016), although this was not significant in Accra and Navrongo. Parasitaemia levels were not a significant predictor of haemoglobin level after controlling for age and gender. However, higher haemoglobin levels in children were associated with certain socioeconomic factors, such as having fathers who had any type of employment (P < 0.05) and mothers who were teachers (P < 0.05).ConclusionsThe findings demonstrate significant differences in the haematological presentation and severity of malaria among areas with different transmission intensity in Ghana, indicating that these factors need to be considered in planning the management of the disease as the endemicity is expected to decline after control interventions.

Functional Characterization of Plasmodium falciparum Surface-Related Antigen as a Potential Blood-Stage Vaccine Target

“…As expected, α-EBA-175 (R217) antibodies did not detect native EBA-175 under reduced condition ( Figure 1B, I). The antibodies (α-PfSRA P1, α-PfSRA P2, and α-PfSRA P3) consistently detected multiple processed fragments (17,32, and 58 kDa) of the native PfSRA in ring-stage invasion supernatants ( Figure 1B, II-V) or parasite culture supernatants ( Figure 1C, I-IV) and schizont lysates ( Figure 1D, I-IV).…”

“…Ethical approval was obtained from the ethics committees as documented previously [16,17]. Immunoreactivity screenings of plasma samples were performed by enzyme-linked immunosorbent assay (ELISA) [12] and immuno-dot blotting [18] using the synthetic peptides PfSRA P1 (NNKDNHNKKDTNENC); PfSRA P2 (CENDNDEYGNKNKNS); and PfSRA P3 (CSNNKKKKK NDKKKK).…”

Evaluating antidisease immunity to malaria and implications for vaccine design

“…Thus, we propose that every parasite encounter would, presumably, require a higher parasitaemia (antigen load) to stimulate and activate immune cells. This mechanism may be at play at high exposure levels, as children from these areas often present with higher parasitaemia when sick,58, 61, 96, 133 suggesting that high antigen levels are required to stimulate immune cells to produce proinflammatory cytokines, which cause immunopathology.…”

“…131,132 Thus, we propose that every parasite encounter would, presumably, require a higher parasitaemia (antigen load) to stimulate and activate immune cells. This mechanism may be at play at high exposure levels, as children from these areas often present with higher parasitaemia when sick, 58,61,96,133 suggesting that high antigen levels are required to stimulate immune cells to produce proinflammatory cytokines, which cause immunopathology. A parallel mechanism may involve an increased propensity of immune cells of children who reside in hyperendemic areas to become terminally differentiated, and consequently display exhausted and/or tolerized effector phenotypes.…”

Uncomplicated falciparum malaria among schoolchildren in Bajil district of Hodeidah governorate, west of Yemen: Association with anaemia and underweight

“…This could be partially attributed to the low transmission intensity in the study district compared to the studies in African countries. The impact of transmission intensity on the differences in haematological indices could not be ruled out [63]. The utility of haematological indices as indicators of falciparum malaria should, however, be assessed in symptomatic and complicated infections and those with high parasite densities.…”