ABSTRACT
Due to scarcity of human reports, we took advantage of the heaviest infection of M. moniliformis in rats, to describe histopathological and microanatomical valuable useful keys while confronting human occurrences. Samples were obtained from captured rats in Tehran, capital of Iran, during two decades. Tissues sections were performed through hematoxylin and eosin staining to describe histopathological changes in rat's intestines. Totally, nine rats were found infected with M. moniliformis amongst 272 obtained rats. Heavy infection has been distinguished in 2 individuals with parasite burden of 141 and 73 adult worms. Cross sections of worms within the lumen show mucosal thickness, infiltration of eosinophilic leukocyte and increase in goblet cells. Beyond the uncommonness of human infection with M. moniliformis unintended infections should not be ignored. Abundance of rats and roaches as definite and intermediate hosts must be considered particularly in countries with poor hygiene