Evaluation of the diagnostic value of metagenomic next-generation sequencing for zoonotic cestode Spirometra mansoni infection

Metagenomic next-generation sequencing (mNGS) technology offers substantial advantages in parasite detection; however, we still know very little about its diagnostic value for <i>Spirometra mansoni</i> infection. In this study, mNGS technology was used to analyse faecal samples and blood samples from cats infected with <i>S. mansoni</i>, as well as tissue samples and blood samples from mice infected with the plerocercoid larvae of <i>S. mansoni</i>. Moreover, polymerase chain reaction (PCR) was employed to validate the mNGS results. The diagnostic value of mNGS for <i>S. mansoni</i> infection was systematically evaluated. The mNGS results revealed that the read counts of <i>S. mansoni</i> in the cat faeces (CF) samples were 301,497 (CF1), 1,330,549 (CF2), 1,181,162 (CF3), and 0 (CF0), with relative abundances of 3.17%, 16.64%, 13.14%, and 0%, respectively. In the mouse tissue (MT) samples, the read counts of <i>S. mansoni</i> were 10,791 (MT1), 438 (MT2), 3697 (MT3), and 10 (MT0), with relative abundances of 67.21%, 3.65%, 21.12%, and 0.16%, respectively. No sequences of <i>S. mansoni</i> were detected in the cat blood samples or mouse blood samples. The PCR results were consistent with the mNGS results, confirming the accuracy of the mNGS analysis. In addition, during the detection process, the assembly-based analysis did not detect sequences of <i>S. mansoni</i> in all samples. In contrast, the read-based analysis successfully detected the target sequences without fail. Finally, the analysis of microbiota diversity in the definitive host faecal samples revealed that compared with those in the control group, the elevated microbial taxa in the infected group mainly were probiotics, such as <i>Prevotella copri</i> and <i>Bifidobacterium adolescentis</i>. Conversely, the decreased microbial populations were primarily associated with certain diseases, such as <i>Collinsella stercoris</i> and <i>Catenibacterium</i> sp. In this study, the diagnostic value of mNGS for <i>S. mansoni</i> infection was systematically evaluated. These findings establish a foundation for the more precise application of mNGS technology in the detection of <i>S. mansoni</i> and related cestode infections.