Knowledge of the life cycle and transmission is still under investigation, therefore this is a proposed life cycle for B. hominis. The classic form found in human stools is the cyst, which varies tremendously in size from 6 to 40 µm The Number 1. The thick-walled cyst present in the stools The Number 1 is believed to be responsible for external transmission, possibly by the fecal-oral route through ingestion of contaminated water or food The Number 2. The cysts infect epithelial cells of the digestive tract and multiply asexually (The Number 3, The Number 4 ). Vacuolar forms of the parasite give origin to multi vacuolar The Number 5a and ameboid forms The Number 5b. The multi-vacuolar develops into a pre-cyst The Number 6a that gives origin to a thin-walled cyst The Number 7a, thought to be responsible for autoinfection. The ameboid form gives origin to a pre-cyst The Number 6b, which develops into thick-walled cyst by schizogony The Number 7b. The thick-walled cyst is excreted in feces The Number 1.