Schistosoma haematobium effects on Plasmodium falciparum infection modified by soil-transmitted helminths in school-age children living in rural areas of Gabon

Abstract

BackgroundMalaria burden remains high in the sub-Saharan region where helminths are prevalent and where children are often infected with both types of parasites. Although the effect of helminths on malaria infection is evident, the impact of these co-infections is not clearly elucidated yet and the scarce findings are conflicting. In this study, we investigated the effect of schistosomiasis, considering soil-transmitted helminths (STH), on prevalence and incidence of Plasmodium falciparum infection.MethodologyThis longitudinal survey was conducted in school-age children living in two rural communities in the vicinity of Lambaréné, Gabon. Thick blood smear light microscopy, urine filtration and the Kato-Katz technique were performed to detect malaria parasites, S. haematobium eggs and, STH eggs, respectively. P. falciparum carriage was assessed at inclusion, and incidence of malaria and time to the first malaria event were recorded in correlation with Schistosoma carriage status. Stratified multivariate analysis using generalized linear model was used to assess the risk of plasmodium infection considering interaction with STH, and survival analysis to assess time to malaria.Main findingsThe overall prevalence on subject enrolment was 30%, 23% and 9% for S. haematobium, P. falciparum infections and co-infection with both parasites, respectively. Our results showed that schistosomiasis in children tends to increase the risk of plasmodium infection but a combined effect with Trichuris trichiura or hookworm infection clearly increase the risk (aOR = 3.9 [95%CI: 1.7–9.2]). The incidence of malaria over time was 0.51[95%CI: 0.45–0.57] per person-year and was higher in the Schistosoma-infected group compared to the non-infected group (0.61 vs 0.43, p = 0.02), with a significant delay of time-to first-malaria event only in children aged from 6 to 10-years-old infected with Schistosoma haematobium.ConclusionsOur results suggest that STH enhance the risk for P. falciparum infection in schistosomiasis-positive children, and when infected, that schistosomiasis enhances susceptibility to developing malaria in young children but not in older children.

Schistosoma haematobium infection modulates Plasmodium falciparum parasite density and antimalarial antibody responses

“…However, they have generated contradictory findings. Lower parasite densities (PD) and a lower incidence of Pf infection or malaria‐related complications in children infected by Sh have been reported, whilst other studies have reported an increased risk of Pf infections or higher PD associated with Sh or S mansoni coinfections . The lack of an association between Schistosoma infection and the risk of Pf infection has also been reported in Kenya, Ethiopia and Uganda .…”

“…Lower parasite densities (PD) and a lower incidence of Pf infection or malaria-related complications in children infected by Sh have been reported, [3][4][5][6][7] whilst other studies have reported an increased risk of Pf infections or higher PD associated with Sh or S mansoni coinfections. [8][9][10][11][12] The lack of an association between Schistosoma infection and the risk of Pf infection has also been reported in Kenya, Ethiopia and Uganda. 13,14 Differences in parasite exposure and related anti-parasitic immunity, study population and design, as well as the sensitivity of diagnostic tools could partly explain these discordant observations.…”

“…In our study, the effect of Sh infection on Pf PD seemed to be independent of the intensity of Sh infection because no difference in Pf PD was observed when Sh infection was dichotomized into low, moderate or heavy Sh intensity.Another study conducted in Mali indicated that Sh infection was associated with lower Pf PD and a reduced risk of progression to symptomatic disease in long-term Pf asymptomatic carriers 7. However, others found that Sh infection increases the risk of Pf infection and the prevalence of Pf parasites in Sh-infected children 8. The risk ofPf infection was clearly increased when Sh infection was combined Frequencies of B cells, eosinophils and neutrophils according to the Sh and Pf infection status.…”

Intestinal parasitic infection among household contacts of primary cases, a comparative cross-sectional study

“…Soil-transmitted helminths infection (Ascaris Lumbricoides, Trichuris trichiura, and Hookworm) alone affects 1.5 billion people worldwide [7]. Sub-Saharan Africa bears the highest-burden for both helminths infection and other intestinal parasitic infections [8].…”

Focused Assessment with Sonography for Urinary Schistosomiasis (FASUS)—pilot evaluation of a simple point-of-care ultrasound protocol and short training program for detecting urinary tract morbidity in highly endemic settings

“…This study was conducted at the Centre de Recherches Médicales de Lambaréné (CERMEL) located in the semi-rural setting of Lambaréné, Gabon, where UGS is highly prevalent. [14][15][16][17][18][19] It was part of a larger study, which additionally assessed epidemiological aspects as well as immunological and metabolomic aspects of UGS; these will be reported separately. Procedures relevant for the pilot assessment of the POCUS protocol were: (1) development of a POCUS scan protocol; (2) the training of two operators; (3) evaluation of the diagnostic accuracy of POCUS operators, using remote expert image review as a reference; and (4) comparing the ultrasound findings with parasitology test results.…”