Livestock as proper reservoirs for zoonotic Blastocystis subtypes in southwestern Iran: A potential threat to public health

Blastocystis sp. is a protozoan parasite commonly found in the gastrointestinal tract of humans and various animals, including livestock. This study aimed to assess the prevalence, subtypes (STs) distribution, and zoonotic transmission potential of Blastocystis sp. in livestock in southwestern Iran. A cross-sectional study was conducted, and fecal samples were collected from cattle and sheep in Shiraz, the capital city of Fars province. Molecular analysis was conducted to amplify a specific fragment from the SSU rRNA gene through PCR and sequencing to detect Blastocystis.sp. and identify the related STs in the livestock population. This study identified a relatively low occurrence of Blastocystis sp. in cattle (8 %; 4/50) and sheep (6 %; 3/50). Nonetheless, different zoonotic STs were found in these animals. In cattle, ST10 accounted for 50 % (2/4), ST1 for 25 % (1/4), and ST3 for 25 % (1/4) of the cases. In sheep, 66.7 % (2/3) and 33.3 % (1/3) of the positive isolates were classified as ST10 and ST3, respectively. Blastocystis sp. was more common in young animals and females, as well as in diarrheal samples (P > 0.05). The findings suggest a significant risk of zoonotic transmission of Blastocystis sp. from livestock to humans in the region. Although this small-scale research was not suitable for firm epidemiological conclusions, it underscores the importance of monitoring and implementing control measures to prevent zoonotic transmission of Blastocystis sp. from livestock to humans in southwestern Iran, highlighting the need for further research to better understand the epidemiology and public health implications of this parasite.