Strongyloidiasis in Africa: Systematic Review and Meta-Analysis on Prevalence, Diagnostic Methods, and Study Settings

Abstract

Background. Strongyloidiasis is an intestinal parasitic infection mainly caused by Strongyloides stercoralis. Although it is a predominant parasite in tropics and subtropics where sanitation and hygiene are poorly practiced, the true prevalence of strongyloidiasis is not known due to low-sensitivity diagnostic methods. Objective. This systematic review and meta-analysis is aimed at determining the pooled prevalence of strongyloidiasis in African countries, stratified by diagnostic methods, study settings, and patients. Methods. Cross-sectional studies on strongyloidiasis published in African countries from the year 2008 up to 2018 in PubMed and Google Scholar databases and which reported at least one Strongyloides spp. infection were included. Identification and screening of eligible articles were also done. Articles whose focus was on strongyloidiasis in animals, soil, and foreigners infected by Strongyloides spp. in Africa were excluded. The random effects model was used to calculate the pooled prevalence of strongyloidiasis across African countries as well as by diagnostic methods and study settings. The heterogeneity between studies was also computed. Result. A total of 82 studies were included. The overall pooled prevalence of strongyloidiasis was 2.7%. By individual techniques, the pooled prevalence of strongyloidiasis was 0.4%, 1.0%, 3.4%, 9.3%, 9.6%, and 19.4% by the respective direct saline microscopy, Kato-Katz, formol ether concentration, polymerase chain reaction, Baermann concentration, and culture diagnostic techniques. The prevalence rates of strongyloidiasis among rural community, school, and health institution studies were 6.8%, 6.4%, and 0.9%, respectively. The variation on the effect size comparing African countries, diagnostic methods, study settings, and patients was significant ( P ≤ 0.001 ). Conclusions. This review shows that strongyloidiasis is overlooked and its prevalence is estimated to be low in Africa due to the use of diagnostic methods with low sensitivity. Therefore, there is a need for using a combination of appropriate diagnostic methods to approach the actual strongyloidiasis rates in Africa.

Prevalence and risk factors of strongyloidiasis among schoolchildren in Sabach Sanjal and Upper Badibou districts in the North Bank East Region of The Gambia

“…Another study revealed that larva output in faecal specimens ranged from 0.003 larvae per gram to 151.2 larvae per gram ( Khieu et al, 2013 ). However, the use of a Kato-Katz technique only in this study is a limitation and cannot efficiently detect all S. stercoralis infection ( Machicado et al, 2012 ; Hailu et al, 2020 ; WHO, 2020 ). Thus, the result of our study should be interpreted cautiously.…”

“…On the other hand, a prevalence of 24.4% among schoolchildren in Cambodia was obtained using combined two methods, Baermann and Koga agar plate culture techniques ( Khieu et al, 2013 ). Additionally, a recent systematic review of 82 studies in Africa found Kato-Katz to be a less popular tool for diagnosis of S. stercoralis with just 2 of these studies utilising the technique for detection of S. stercoralis ( Hailu et al, 2020 ). The study also found that Kato-Katz detected S. stercoralis larvae in only 8 out of 810 participants ( Hailu et al, 2020 ).…”

“…Additionally, a recent systematic review of 82 studies in Africa found Kato-Katz to be a less popular tool for diagnosis of S. stercoralis with just 2 of these studies utilising the technique for detection of S. stercoralis ( Hailu et al, 2020 ). The study also found that Kato-Katz detected S. stercoralis larvae in only 8 out of 810 participants ( Hailu et al, 2020 ). These are further evidence that S. stercoralis is not an ideal method for diagnosis of S. stercoralis .…”

“…Kato-Katz technique is recommended for field estimation of STHs infection and schistosomiasis because it provides a standardised reading, glycerin enhances microscopy and the microscopists can be easily trained ( Katz et al, 1972 ). On the other hand, Kato-Katz technique was found not suitable for S. stercoralis ( Machicado et al, 2012 ; Hailu et al, 2020 ; WHO, 2020 ); however, during the field estimation, some of S. stercoralis may be recovered by this technique. The prevalence of strongyloidiasis by Kato-Katz method among preschool and schoolchildren was reported at 4% in Ethiopia ( Amare et al, 2021 ), 2.1% in Madagascar ( Hakami et al, 2019 ), 2.2% in Zanzibar ( Knopp et al, 2008a ), 9.7% in the Eastern Caribbean Sea ( Kurup and Hunjan, 2010 ), 5.8% in Ethiopia ( Legesse and Erko, 2004 ), 0.2% in Angola ( Mirante et al, 2016 ) and 2.7% in Thailand ( Sedionoto et al, 2019 ).…”

Endemic parasitic infections in donors and recipients of stem cell and solid organ transplants: focus on strongyloidiasis and Chagas disease

“…Studies on the global prevalence of S. stercoralis reported different results [51,52] and it was recently estimated at 8.1% of the population, corresponding to 613.9 million people [53]. It is widely distributed around the globe with higher prevalence in tropical and subtropical regions, particularly Latin America [54], South East Asia, Sub-Saharan Africa [55], southern United States and the Appalachian region [56]. Risk is higher in rural populations with poor sanitation and low socio-economic status [57] as well as in migrants and refugees from endemic areas [58][59][60] Travelers staying for prolonged periods in endemic regions are also at risk [61].…”