Molecular Detection of Sarcocystis suihominis and Sarcocystis miescheriana in Wild Boars Hunted for Human Consumption in Poland Highlights a Potential Risk for the Consumer

Abstract

Introduction: Wild boars and domestic pigs can act as intermediate hosts for two Sarcocystis species: Sarcocystis miescheriana and the zoonotic Sarcocystis suihominis. Humans become infected with S. suihominis by eating raw or undercooked meat. Herein we investigated the occurrence of Sarcocystis spp. in wild boars hunted for human consumption in Poland. Methods: Diaphragms were collected from 241 wild boars during two hunting seasons; a multiplex-PCR protocol targeting the mtDNA cox1 gene of S. miescheriana and S. suihominis was applied; diaphragm samples testing positive for S. suihominis under- went sarcocysts isolation and molecular characterization. Results: Out of 241 wild boars, 216 (90%) revealed the presence of S. miescheriana DNA, including eight (3.3%) co-infected with S. suihominis. The diaphragms of three wild boars testing positive for S. suihominis and S. miescheriana were further processed, yielding 37 sarcocysts. Two out of 37 isolated sarcocysts tested positive for S. suihominis and were further molecularly charac- terized, showing 98.9%–100% identity on the 18S rRNA gene and 98.7% identity on the cox1 mtDNA gene with S. suihominis. Thirteen of the remaining sarcocysts were molecularly characterized, leading to the identification of S. miescheriana in 12 cysts; one out of the 13 sarcocysts yielded a 1053 bp cox1 mtDNA sequence and a 923 bp 18S rDNA sequence showing < 89.1% and 95.6% homology, respectively, with any known Sarcocystis species. Conclusions: This is the first study identifying Sarcocystis spp. circulating in wild boars intended for human consumption in Poland, revealing a non-negligible rate of infection with the zoonotic S. suihominis, a high rate of infection with S. miescheriana and the presence of a putative new Sarcocystis sp. Our study highlights that the risk for the consumers of undercooked wild boar meat cannot be excluded.