Heavy metacercarial infections of cyprinid fishes in Uji River

Abstract

Between January and April 2000, the cyprinid fishes Zacco platypus and Squalidus chankaensis in Uji River, Kyoto Prefecture showed inactive swimming and hemorrhages on the fins, skin and eyes. No bacterial or viral agents seemed involved in the disease outbreak; however, numerous metacercariae of unidentified trematodes of the family Bucephalidae were found encysted in the fins, skin, musculature and eyes of diseased fish, suggesting these parasitic infections were the etiological agents. The metacercariae comprised two species, designated here as Metacercaria A and Metacercaria B. It is assumed that the infection started with an accidental introduction of infected first intermediate hosts, the freshwater mussel, Limnoperna fortunei , into Uji River, and that Z. platypus and S. chankaensis served as the second intermediate hosts, and the sheatfish Silurus biwaensis as the final host to complete their life cycles. This is the first case of bucephalid infections of freshwater fishes in Japan. The Yodo River system, including Uji River, is the only area in Japan where the bucephalid infections have so far been confirmed. Comments are made on the possible danger of translocation of even a single infected first, second or final host from Uji River to Lake Biwa or other water systems.

Gill histopathology of Maria-da-toca Hypleurochilus fissicornis by metacercariae of Bucephalus margaritae (Digenea: Bucephalidae)

“…Thomson (1983) and Carlton and McGavin (1998) write that parasitic larval phases show chemotaxis by cellular, tissular or systemic host sites for infection, from a specific way. The occurrence of B. margaritae MTC within gill connective tissues-type of H. fissicornis corroborate records concerning to the affinity of this larval stage to the connective tissues from other body regions such as dermal skin layer (Fergusson 1989) and caudal fin rays (Ogawa et al 2004). Olson and Pierce (1997) reported that the affinity to the gill cartilage is characteristic of Heterophyidae.…”

“…Edema, hypertrophy or hyperplasia of the gill epithelium could result in difficulties to gaseous and metabolites exchange with the water due to the higher distances between host blood supply and environment (Evans et al 2005). As also observed by Faliex (1991), Laruelle et al (2002) and Ogawa et al (2004) necrotic features were present in this study and they may represent a response of circulatory disturbs caused by cysts formation. Cysts could modify, through ischemia, the pressure on the PBF afferent and efferent branchial artery and SBF arterioles.…”

“…Encysted MTC of several Digenea species stimulate the local melanocytes in fishes and they are grossly visible due to the dermal melanosis (Ogawa et al 2004). In the present study, the melanosis, properly so called, was not observed as ''black spots'' and the macroscopic aspect of the lesion resembles telangiectasia points as observed by Shoiabi et al (2010).…”

“…They cause severe damage to their host such as fibroblast proliferation (Ogawa et al 2004), inflammatory response, breathing difficulties, necrosis and death (Eiras 1994). The intensity of parasite infection necessary to promote such alterations in one fish is variable according to the parasitic species and its quantity, host dimension and host health condition (Fergusson 1989;Roberts 2001).…”

The fish egg microbiome : diversity and activity against the oomycete pathogen Saprolegnia

“…Wild rainbow trout (Hedrick et al, 1998) Platyhelminths Wild anurans (Brooks et al, 2006) Macroparasites (including Acanthocephala, Annelida, Arthropoda, Cestoda, Monogenea, Nematoda and Trematoda) Amphibians (Koprivnikar et al, 2012) Parabucephalopsis parasiluri and Prosorhynchoides ozakii Fish (Ogawa et al, 2004;Urabe et al, 2007;Ogawa, 2011) Protozoan parasites Ameson, Pleistophora, Psorospermium, Thelohania, Vavraia, Mikrocytos, the Amoebae Paramoeba spp., the flagellates Ichthyobodo spp., the dinoflagellate Hematodinium spp., the ciliates Ichthyophthirius multifilis and Trichodina spp., the Microsporidia Tetramicra brevifilum, the Myxosporeans Tetracapsula bryosalmonae, Mikrocytids Fish, freshwater crayfish, aquatic invertebrates including crabs, lobsters and oysters (Edgerton et al, 2002;Carnegie and Cochennec-Laureau, 2004;Sommerset et al, 2005;Small, 2012;Hartikainen et al, 2014;Powell et al, 2015) Bonamia ostreae…”