Intestinal Helminths in Laboratory Mice and Rats in Four Research Centers, Tehran, Iran

Mice and rats are the most common laboratory animals used in research centers worldwide [1]. Animal houses that supply mice and rats for experimental researches should have facilities to produce and maintain specific pathogenfree animals under controlled sanitary conditions. However, 95% of laboratory animals are kept in conventional situations that can expose them to various infectious agents including helminth parasites [2, 3]. Moreover, the behavior of the rats and mice supports the quick transmission of pathogens among the colony members in cages. The ease of transmission and direct life cycle along with the resistance of helminths eggs to environmental conditions have led to high prevalence of these parasites in cages environment [4]. From the perspective of safety regulations that should be considered in experimental researches, these pathogens, mainly the zoonotic ones can be regarded harmful for technicians and researchers [5]. According to the literatures, Syphacia obvelata, Syphasia muris, Hymenolepis nana and Aspicularis tetraptera are known as the most prevalent helminths in laboratory animals, of which, only A. tetraptera is not considered zoonotic [6]. Parasitized laboratory animals are not suitable for experiments as their infection may have a negative influence on results. Although most of these infections are subclinical, they are able to affect the animal physiology, leading to changes in immunological and biochemical parameters [7]. In mice during the tissue and luminal phase of H. nana development, Th1-type and Th2 responses are elicited, respectively, with variation of cytokines production during parasite development [8]. The aim of the current survey was to evaluate the present status of helminthic infections in laboratory mice and rats in order to find some measures to control them.