Epidemiology, morphology, and molecular characterization of Stephanurus dentatus (Nematoda: Syngamidae) in wild boars from southwestern South Korea

BACKGROUND: Stephanurus dentatus Diesing, 1839 (Nematoda: Syngamidae), commonly known as the swine kidney worm, parasitizes the renal pelvis, ureters, and perirenal fat of pigs and wild boars, occasionally causing severe pathological effects. Despite reports of low prevalence in domestic pigs in South Korea, no epidemiological data exist for wild boars. This study aimed to investigate the prevalence, morphology, and molecular characteristics of S. dentatus infection in wild boars from the southwestern regions of South Korea. METHODS: A total of 167 wild boars were examined between 2009 and 2019. Kidneys, ureters, and perirenal fat were dissected, and worms were collected for morphological analysis using light and scanning electron microscopy. Molecular identification was conducted via polymerase chain reaction (PCR) and sequencing of the 18S rRNA gene. Phylogenetic analyses were performed to assess taxonomic placement. Morphological identification keys were provided for both the traditional family Syngamidae and the revised family Chabertiidae. RESULTS: Stephanurus dentatus was detected in 38.3% of the examined wild boars (64/167), with a mean intensity of 6.8 worms per infected animal. Morphological analyses of adult worms revealed characteristics consistent with previous descriptions, including the corona radiata, the vulva located posteriorly in females, and a rudimentary copulatory bursa in males. Molecular analyses confirmed 99.7-99.9% identity with reference sequences and supported placement of S. dentatus within the family Chabertiidae. Revised identification keys based on morphology were provided. CONCLUSIONS: This study provides the first epidemiological data on S. dentatus in wild boars in South Korea, demonstrating a substantial prevalence and potential risk for transmission to domestic pigs. Detailed morphological descriptions, identification keys, and molecular analyses presented here contribute valuable information for faunistic, taxonomic, and parasitological studies of S. dentatus.