Impact of fish infected with encysted metacercariae on the public health, at Cairo District, Egypt

Abstract

Examination of 452 fresh and brackish water fish, from Cairo district, Egypt, representing Clarias gariepinus, Lebeo noliticus and Mugil cephalus, revealed the occurrence of nine species of encysted metacercariae in Cl. gariepinus, belonging to family Heterophyidae, two unidentified digenean metacercariae in L. niloticus and two unidentified digenean metacercariae in M. cephalus. The relationship between parasite prevalence and fish species, seasonal prevalence and fish weight was investigated. The highest rate of infection (73.68%) was recorded in autumn, in Cl. gariepinus, while the lowest (54.05%) was observed in summer. Whereas, in M. cephalus and L. noliticus, the highest prevalence of infection (56.67 and 26.09%, respectively), was recorded, in spring. But, in M. cephalus the lowest infection rate (25.82%) was detected in winter, while in L. niloticus (12.50%), it was recorded in autumn. The intensity of infection in Cl. gariepinus increased with fish weight till 150g while, it decreased in fish weighing more than 200g. Similarly, in M. cephalus, the infection rate increased with increase of fish weight till 100g, but was lower in larger fish. In L. niloticus, there was no relationship between rate of infection and fish weight; the highest intensity of infection was recorded in fish weighing 100-150g. The identification of metacercariae was assessed by feeding experimentally two dogs with flesh of Cl. gariepinus, containing encysted metacercariae and the recovery of flukes from their intestines. The impact of infection of humans and animals is discussed.

Keywords: Trematodes, prevalence of infection, Heterophyidae, Heterophyes heterophyes, Pygidiopsis genata, fish, Clarias gariepinus, Lebeo niloticus, Mugil cephalus.