Helminth fauna of the monocled cobra ( <i>Naja kaouthia</i> ) from central Thailand: community composition and taxonomic perspectives

Snakes serve as important hosts for parasites at the interface of wildlife, humans and domestic animals. However, their helminth fauna in tropical regions, particularly Thailand, remains poorly documented. This study investigates the helminth fauna, community structure, infection patterns and their co-occurrence dynamics in the monocled cobra (<i>Naja kaouthia</i>) from urbanized areas of central Thailand, based on comprehensive analyses of 34 wild-caught individuals. Using integrated morphological and molecular approaches (e.g. mitochondrial 16S rRNA and <i>COI</i> gene sequencing), 11 helminth species were identified - 9 nematodes (<i>Kalicephalus bungari, Kalicephalus</i> sp. I and II, <i>Paracapillaria najae, Paracapillaria siamensis, Serpentirhabdias orientalis, Strongyloides</i> sp., a filarioid nematode and an unknown encysted nematode), 1 cestode (<i>Duthiersia expansa</i>) and 1 acanthocephalan (<i>Sphaerechinorhynchus</i> sp.) - including 2 newly described species: <i>P. siamensis</i> (infected in gastrointestinal tract) and <i>S. orientalis</i> (in respiratory tract). <i>Serpentirhabdias orientalis</i> and <i>K. bungari</i> were the most prevalent species (75.8%), while encysted nematodes exhibited the highest infection intensities (up to 500 parasites per host). Host-parasite network analysis revealed strong organ tropism in some helminth species (e.g. <i>Paracapillaria</i> spp.) and non-random co-occurrence patterns. Parasite abundance was positively correlated with host body condition, and females harboured greater species richness than males (11 vs. 8 taxa). The absence of trematodes is consistent with the host's terrestrial ecology, while the low prevalence of filarioids (3.0%) suggests limited transmission. These findings underscore the value of integrative taxonomy in revealing hidden parasite diversity and highlight ecological drivers of infection patterns in snakes, with implications for wildlife health and zoonotic risk in human-modified landscapes.