Prevalence of Strongyloides sp. and Nippostrongylus sp. in small mammals, Malaysia.

Parasitic nematodes remain important zoonotic pathogens, particularly in tropical regions where human-animal interactions facilitate pathogen transmission. This study investigated the prevalence and genetic characteristics of Strongyloides sp. and Nippostrongylus sp. among non-volant small mammals in Peninsular Malaysia during 2025-2026. A total of 46 small mammals, comprising 28 rats (Rattus spp.) and 18 treeshrews (Tupaia spp.), were screened using PCR targeting the cytochrome c oxidase subunit 1 (COX1) gene. Nippostrongylus sp. was detected in 25.0% (7/28) of rats but was absent in treeshrews. Sequence analysis demonstrated only 93.84% similarity to Nippostrongylus brasiliensis, suggesting the presence of a genetically divergent or potentially novel species. Strongyloides venezuelensis was identified in 14.3% (4/28) of rats and 16.7% (3/18) of treeshrews. Notably, this study documents the first natural detection of S. venezuelensis in Tupaia sp., expanding the known host range of this parasite beyond rodents. Phylogenetic and sequence identity analyses supported the molecular identification of both helminths. These findings highlight the importance of small mammals as potential reservoirs of nematodes in Malaysia and reinforce the need for continuous pathogen surveillance under a One Health framework to better understand parasite diversity, host adaptation, and potential public health risks.