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Prevalence and Subtype Distribution of Blastocystis sp. in Senegalese School Children
Salma Khaled1, Nausicaa Gantois1, Amadou Tidjani Ly2
1Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Centre d'Infection et d'Immunité de Lille, University of Lille, CNRS, Inserm, CHU Lille, F-59000 Lille, France.
Insights
This study reveals a high prevalence of Blastocystis (80.4%) in Senegalese children, with subtype 2 being most common. Findings highlight varied subtype distribution and potential transmission routes in Africa.
Area of Science:
- Medical Parasitology
- Infectious Diseases Epidemiology
- Molecular Biology
Background:
- Blastocystis sp. is a common enteric protozoan with significant, yet understudied, impacts on human health.
- Data on Blastocystis sp. prevalence and subtype distribution in Africa are notably scarce.
Purpose of the Study:
- To conduct the first large-scale, multicenter epidemiological survey of Blastocystis sp. in Senegal.
- To determine the prevalence and subtype distribution of Blastocystis sp. infections in healthy school children.
Main Methods:
- Real-time polymerase chain reaction (PCR) was used to detect Blastocystis sp. in 731 stool samples from 10 villages.
- Positive samples underwent subtyping to identify different Blastocystis sp. subtypes (STs).
- Intra-subtype genetic polymorphisms were analyzed.
Main Results:
- Overall Blastocystis sp. prevalence was high at 80.4%, with significant village-to-village variation (51.7%–100%).
- Subtype 2 (ST2) was predominant in single infections, followed by ST1, ST3, ST7, ST10, and ST14 (ST10 and ST14 reported in humans for the first time).
- Mixed infections occurred in 23% of positive individuals, and significant intra-subtype genetic diversity was observed, particularly for ST1, ST2, and ST3.
Conclusions:
- The study establishes a high prevalence and diverse subtype landscape of Blastocystis sp. in northwestern Senegal.
- Variations in ST and genotype distribution suggest multiple transmission sources, including human-to-human, zoonotic, and waterborne routes.
- Further research is needed to understand the public health implications of Blastocystis sp. in the region.
Abstract:
Blastocystis sp. is an enteric protozoan that frequently colonizes humans and many animals. Despite impacting on human health, data on the prevalence and subtype (ST) distribution of Blastocystis sp. remain sparse in Africa. Accordingly, we performed the first multicenter and largest epidemiological survey ever conducted on Blastocystis sp. for this continent. A total of 731 stool samples collected from healthy school children living in 10 villages of the northwestern region of Senegal were tested for the presence of Blastocystis sp. by real-time polymerase chain reaction followed by subtyping of positive samples. Considerable variation in prevalence between villages (51.7 to 100%) was evident with the overall prevalence being 80.4%. Mixed infections were identified in 23% of positive individuals. Among 453 school children with a single infection, ST2 was predominant, followed by ST1, ST3, ST7, ST10, and ST14; this is the first report of ST10 and ST14 in humans. Genetic polymorphisms were evident at the intra-ST level with the identification of numerous ST1 to ST3 genotypes. ST1 showed the greatest intra-ST diversity followed by ST2 and ST3. The prevalence and distribution of STs and genotypes varied among target villages, pointing to several potential infection sources, including human-to-human, zoonotic, and waterborne transmission.
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