Prevalence of strongyloidiasis and schistosomiasis among migrants: a systematic review and meta-analysis

Abstract

Background Global migration from regions where strongyloidiasis and schistosomiasis are endemic to non-endemic countries has increased the potential individual and public health effect of these parasitic diseases. We aimed to estimate the prevalence of these infections among migrants to establish which groups are at highest risk and who could benefit from screening. MethodsWe did a systematic review and meta-analysis of strongyloidiasis and schistosomiasis prevalence among migrants born in endemic countries. Original studies that included data for the prevalence of Strongyloides or Schistosoma antibodies in serum or the prevalence of larvae or eggs in stool or urine samples among migrants originating from countries endemic for these parasites and arriving or living in host countries with low endemicity-specifically the USA, Canada, Australia, New Zealand, Israel, and 23 western European countrieswere eligible for inclusion. Pooled estimates of the prevalence of strongyloidiasis and schistosomiasis by stool or urine microscopy for larvae or eggs or serum antibodies were calculated with a random-effects model. Heterogeneity was explored by stratification by age, region of origin, migrant class, period of study, and type of serological antigen used. Findings 88 studies were included. Pooled strongyloidiasis seroprevalence was 12•2% (95% CI 9•0-15•9%; I² 96%) and stool-based prevalence was 1•8% (1•2-2•6%; 98%). Migrants from east Asia and the Pacific (17•3% [95% CI 4•1-37•0]), sub-Saharan Africa (14•6% [7•1-24•2]), and Latin America and the Caribbean (11•4% [7•8-15•7]) had the highest seroprevalence. Pooled schistosomiasis seroprevalence was 18•4% (95% CI 13•1-24•5; I² 97%) and stool-based prevalence was 0•9% (0•2-1•9; 99%). Sub-Saharan African migrants had the highest seroprevalence (24•1•% [95% CI 16•4-32•7]).Interpretation Strongyloidiasis affects migrants from all global regions, whereas schistosomiasis is focused in specific regions and most common among sub-Saharan African migrants. Serological prevalence estimates were several times higher than stool estimates for both parasites. These data can be used to inform screening decisions for migrants and support the use of serological screening, which is more sensitive and easier than stool testing.

High Prevalence of Strongyloidiasis in Spain: A Hospital-Based Study

“…Our study shows an overall prevalence of almost 10%, which is consistent with other studies conducted among migrant population living in non-endemic areas [17]. This is one of the first studies to evaluate the results of a systematic screening in potentially immunosuppressed patients in which the disease may be more severe.…”

“…The diagnosis of strongyloidiasis in non-endemic areas is currently based on a serological test, which has a considerably higher sensitivity compared with standard fecal techniques [8]. Despite having cross-reactions with other helminthic infections, this is less likely to occur in migrant populations since the possibility of co-infections is lower [16] and it is thus now the current recommended screening technique for these populations [17]. The sensitivity of the serological tests in immunosuppressed individuals seems to be lower [18], but only limited data are available and further prospective studies should better evaluate the accuracy of serological tests in immunosuppressed patients.…”

High Prevalence of Strongyloidiasis in Spain: A Hospital-Based Study

“…Our study shows an overall prevalence of almost 10% which is consistent with other studies conducted in migrant population living in non-endemic areas [17]. This is one of the first studies evaluating the results of a systematic screening in potentially immunosuppressed patients in which the disease may be more severe.…”

“…Based on other seroprevalence studies conducted in non-endemic areas, we estimated a prevalence of S. stercoralis of 11% for our cohort [17]. Based on these data, it was estimated to screen 1700 individuals during 24 months to recruit 150 cases of strongyloidiasis, considering an Alfa error of 5% and a lost to follow-up of 10%.…”

“…The diagnosis of strongyloidiasis in non-endemic areas where re-infection is unlikely is currently based on a serological test which has considerably higher sensitivity compared with standard faecal techniques [8]. Despite having cross-reactions with other helminthic infections, this fact is less likely to occur in migrant populations since the possibility of co-infections is lower [16] and therefore it is nowadays the current recommended screening technique in these populations [17]. The sensitivity of the serological tests in immunosuppressed individuals seems to be lower [18]; but these are limited data and further prospective studies should better evaluate the accuracy of the serological tests in immunosuppressed patients.…”