Plasmodium falciparum and soil-transmitted helminth co-infections among children in sub-Saharan Africa: a systematic review and meta-analysis

Abstract

BackgroundThe epidemiology of soil-transmitted helminth (STH) and Plasmodium co-infections need better understanding. The findings of the individual studies are inconclusive. A systematic review was conducted to synthesize evidence on the association of STH infection with the prevalence and density of Plasmodium falciparum infection, and its effect on anaemia among children in sub-Saharan Africa (SSA).MethodsRelevant studies published before March 6, 2015 were identified by searching Medline (via Pubmed), Embase, Cochrane Library and CINAHL without any language restriction. Studies on P. falciparum and STH co-infection among children in SSA except for case studies were included in this study. Studies were screened for eligibility and data extracted independently by two authors. The primary outcome assessed was the prevalence of P. falciparum infection and the secondary outcomes included P. falciparum density and prevalence of anaemia. Heterogeneity was assessed using Cochrane Q and Moran’s I2 and publication bias was evaluated using Egger test. A random-effects model was used to estimate the summary odds ratio (OR) and the corresponding 95 % confidence intervals (CI).ResultsOut of 2985 articles screened, 11 articles were included in the systematic review; of these seven were considered in the meta-analysis. Of the 11 studies with 7458 study participants, seven were cross-sectional, one prospective cohort and three were randomized controlled trials. Four studies examined the outcome for hookworms, one for Ascaris lumbricoides and six for pooled (at least one) STH species. Eight studies measured prevalence/incidence of uncomplicated P. falciparum infection, two calculated prevalence of asymptomatic P. falciparum infection, three evaluated P. falciparum density and four considered prevalence of P. falciparum infection related anaemia/mean haemoglobin reduction. The odds of asymptomatic/uncomplicated P. falciparum infection were higher among children infected with STH than those uninfected with intestinal helminths (summary Odds Ratio [OR]: 1.4; 95 % Confidence Interval [CI]: 1.05–1.87; I2 = 36.8 %). Plasmodium falciparum density tended to be higher among children infected with STH than those uninfected with intestinal helminths. However, STH infection was associated with lower odds of P. falciparum infection related anaemia (summary OR: 0.5; 95 % CI: 0.21–0.78; I2 = 43.3 %).ConclusionsThe findings suggest that STH infection may increase susceptibility to asymptomatic/uncomplicated P. falciparum infection but may protect malaria-related anaemia in children. Future studies should investigate the effect of STH infection upon the incidence of severe P. falciparum infection among children in SSA.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1594-2) contains supplementary material, which is available to authorized users.

Malaria Parasitemia in Febrile Patients Mono- and Coinfected with Soil-Transmitted Helminthiasis Attending Sanja Hospital, Northwest Ethiopia

“…This means that hookworm is associated with increased Plasmodium density which suggests a positive association between hookworm infection and occurrence of severe malaria. The finding is in agreement with the previous reports [26,29]. In contrary, A. lumbricoides infection showed less Plasmodium density level than coinfection with hookworm which associated with reducing malaria severity.…”

“…This might be due to the fact that helminths modulate the host immune response both to themselves and to coexisting infections or to the downregulation of the immune system by helminths. Consequently, the Plasmodium parasite could enter into the host and multiply at a faster rate in patients coinfected with STHs [26].…”

Plasmodium falciparum Infection Status among Children with Schistosoma in Sub-Saharan Africa: A Systematic Review and Meta-analysis

“…Therefore, children without S . haematobium infection may have had other helminth infections that could have further confounded the results [46,47]. Moreover, some studies included in this review did not follow WHO criteria to determine classes of intensity of Schistosoma infection.…”

Coinfection of intestinal schistosomiasis and malaria and association with haemoglobin levels and nutritional status in school children in Mara region, Northwestern Tanzania: a cross-sectional exploratory study

“…As a result of geographical overlap between schistosomiasis and malaria, coinfections of these parasites are common which results into various forms of associations, exacerbated health consequences and co-morbidities [ 11 – 15 ]. Evidence from epidemiological studies have indicated that individuals co-infected with more than one parasite species have increased susceptibility to other infections [ 16 – 19 ] and at a risk of developing frequent and more severe disease due to interactions among the infecting parasite species [ 11 , 16 , 17 , 20 – 23 ]. Anaemia and undernutrition are among the most common conditions observed in many field studies in sub-Saharan Africa, Tanzania inclusive, and parasitic infections are among major causes [ 10 , 24 – 31 ].…”