In indigenous populations where soil-transmitted helminths (STH) infections are endemic, STH parasites (i.e., Ascaris lumbricoides, Trichuris trichiura, hookworms) often co-exist and co-evolve with the gut microbiota of their human hosts. The association between STH infections and the gut microbiota of the colonized human hosts has been established, but few studies explored the gut microbiota of the parasites. This preliminary study aimed to characterize the microbiota of the STH parasite for further understanding the STH parasite-host relationship. The gut microbial genomic DNA from four adult A. lumbricoides worms recovered from a six-year-old indigenous Negrito boy living in an STH-endemic village in Perak, Peninsular Malaysia was extracted and sequenced for the V3-V4 region of the 16S rRNA. The microbiota profiles of these worms were characterized and compared with the gut microbiota of their human host, including the profiles from four STH-positive and three STH-negative individuals from the same tribe and village. The gut microbial structure of A. lumbricoides was found to be differed significantly from their human host. The worms contained lower gut bacterial abundance and diversity than human. This difference was evident in the beta diversity analysis which showed a clear separation between the two sample types. While both Firmicutes (52.3%) and Bacteroidetes (36.6%) are the predominant phyla followed by Proteobacteria (7.2%) in the human gut, the microbiota of Ascaris gut is highly dominated by Firmicutes, constituting 84.2% relative abundance (mainly from the genus Clostridium), followed by Proteobacteria (11.1%), Tenericutes (1.8%) and Bacteroidetes (1.5%). The parasites were also found to alter the microbial structure of the human gut following infection based on the relatively higher bacterial abundance in STH-positive versus STH-negative participants. Further studies with a greater number of Ascaris adults and human hosts are needed to confirm the gut microbiota profiles.
Soil-transmitted helminth (STH) parasites, particularly Ascaris lumbricoides and Trichuris trichiura, co-exist and co-evolve with a complex human microbiota within the gut ecosystem. Most research has focused on how parasitic nematodes affect the host gut microbial structure and its consequences. In contrast, studies on the parasites' own associated microbiota remain underexplored. Understanding this gap is crucial, as it adds another layer of complexity to holobiont-holobiont interactions. Driven by the Parasite Microbiome Project, this review summarizes current evidence on Ascaris- and Trichuris-associated microbiomes from both natural and experimental studies, with a focus on their compositions, potential functional roles, challenges, and future directions. Existing findings are largely based on microbiomes associated with the gut of the parasites and are often characterized by transient, host-derived communities acquired through horizontal transmission, which may contribute to parasite survival and host interaction. We therefore emphasize the need to expand investigations to other specific tissues, particularly reproductive organs, as potential sites of a stable and conserved microbiota in STH parasites. Understanding this aspect is essential for advancing our knowledge of parasite-microbiome-host interactions in STH infections and may uncover the potential of microbiome-based therapeutic interventions for STH control and prevention.
There has been an increasing trend in the study of Blastocystis due to its ubiquitous nature, and potential impact on human health. In Malaysia, its prevalence among the undeserved indigenous Orang Asli (OA) population varies widely from 1.7 %- 80.0 %. These huge differences were suggested to be attributed to disparities in living standards, including sanitation and access to treated water status. We investigated the prevalence, risk factors, and subtypes of Blastocystis among the OA Negritos residing in forest periphery villages and the inland jungle settings. A cross-sectional study was conducted involving 259 participants and their stool samples were screened microscopically for intestinal parasites and molecular techniques for Blastocystis. Risk factors including the type of village category and Blastocystis subtypes were identified. Of the 259 participants, 40 (15.4 %) were found to be colonized with Blastocystis. Prevalence was higher in the inland (17/81; 21.0 %) than in forest periphery villages (23/178; 12.9 %), but the difference was not statistically significant (P = 0.096). Among the 40 positive individuals, 31 (77.5 %) were co-infected with soil-transmitted helminths (STH). Multivariate analysis identified the unavailability of a household latrine (P
An undescribed relapsing fever group Borrelia species was detected in a male Haemaphysalis semermis tick infesting a rural cat in an indigenous population in Pahang National Park, Peninsular Malaysia. The 16 S rRNA gene sequence revealed close similarity of this variant to several undescribed Borrelia species and Borrelia theileri, with genetic distances ranging from 0.58 to 0.72%. Furthermore, the flaB, gyrB, and the concatenated 16 S rRNA + flaB + gyrB sequence analyses demonstrated that this variant is distinctly separated from multiple undescribed Borrelia species, Borrelia miyamotoi, and B. theileri, with genetic distances ranging from 3.41 to 7.00%. This study not only reports the first Borrelia found in H. semermis but also suggests that it forms a distinct clade within the relapsing fever group in Peninsular Malaysia.