mNGS and IL-5: potential early diagnostic clues for clonorchiasis before eosinophil rise — a case report

Clonorchiasis, caused by Clonorchis sinensis, often evades early diagnosis in non-endemic regions due to its nonspecific presentation and the delayed appearance of eosinophilia. We report an informative case of a 56-year-old male with acute fever, abdominal pain, and hepatitis, where conventional diagnostics and initial antimicrobial therapy failed. In this case, metagenomic next-generation sequencing (mNGS) of blood identified C. sinensis-specific reads, and cytokine profiling revealed a marked elevation in interleukin-5 (IL-5) before the onset of peripheral eosinophilia. Targeted treatment with praziquantel led to rapid clinical resolution. This case suggests the potential of integrating mNGS and IL-5 monitoring as early diagnostic tools for clonorchiasis, which can allow for intervention prior to classical biomarker emergence.