Prevalence of heterophyid infection in tilapia fish "Orechromas niloticus" with emphasize of cats role as neglected reservoir for zoonotic Heterophyes heterophyes in Egypt.

The current survey was carried out to determine the prevalence of heterophyids infection in tilapia fish "Orechromaus niloticus", and the role of cats "Felis catus" as a reservoir for the zoonotic digenetic trematodes "Heterophyid"-particularly Heterophyes hetrophyes-in Egypt. All over a year, 100 tilapia fish "Orechromas niloticus" were collected randomly from local markets at Alexandria city. Fish specimens were examined for the presence of encysted metacercariae (EMC). Furthermore, specimens of infected fish were experimentally fed to cats as well as rats to detect the adult species and infection ratio, and resulted clinical signs. Results showed that 65% (CI: 55.7-74.3%) of examined fish was infected by one or more of flukes EMC. The highest infection was recorded in summer and spring, followed by autumn then winter. Regarding the identified EMC; Heterophyes spp. was the most common adults (50%). Experimental feeding of EMC to cats and rats resulted in identification of 8 adult flukes namely; H. heterophyes, H. dispar, Haplorchis pumilio, Haplorchis taichiue, Pygidiopsis geneta, Centrocestus cuspidatus, Procerum varium and Prohistomum vivax. Experimentally infected cats were more susceptible to infection compared with rats; also showed more severe clinical and pathological signs than rats. In conclusion, the current work clarifies and highlights a high infection rate of EMC in edible tilapia fish in the study area, also the possible role of cats as a reservoir of the digenetic trematodes particularly the zoonotic H. heterophyes, that necessities planning and application of suitable control measures; and continuous monitoring of fish zoonotic parasites as well as cats and its parasites. © Indian Society for Parasitology 2020.