Pig farming's influence on human gut microbiota has been observed previously, but its pervasiveness is unclear. We therefore aimed at studying whether pig farming influenced human gut microbiota composition in Thailand and whether poultry farming did too. We collected human stool samples (71 pig farmers, 131 chicken farmers, 55 non-farmers) for 16S rRNA sequencing and performed subsequent DADA2 analyses of amplicon sequence variants. We found that Alpha diversity values were highest among chicken farmers. Relative abundances of Prevotellaceae were significantly higher among pig farmers than among chicken farmers and non-farmers (p < 0.001). Beta diversity plots revealed different clustering according to occupation. The presence or absence of antimicrobial-resistant Escherichia coli was not associated with changes in gut microbiota composition. In conclusion, occupation was the strongest factor influencing gut microbiota composition in Thailand. We hypothesize that Prevotellaceae amplicon sequence variants are transmitted from pigs to pig farmers.