Direct transmission of the haemoflagellate Cryptobia salmositica among Pacific salmon (Oncorhynchus spp.)

Abstract

BOWER, S. M., and L. MARGOLIS. 1983. Direct transmission of the haemoflagellate Cryptobia salmositica among Pacific salmon (Oncorhynchus spp.). Can. J. Zool. 61: 1242-1250.Laboratory-reared juvenile Oncorhynchus nerka were marked, inoculated with Cryptobia (= Trypanoplasma) salmositica, and held in tanks with equal numbers of untreated fish. About 85% (1 16 of 137) of the untreated fish (held in freshwater or seawater) exposed by brief out-of-water contact with heavily infected fish in a dipnet became infected. Without out-of-water contact, only 4% (3 of 85) of the untreated fish held in the same tanks as inoculated fish became infected. The flagellates were shown to escape from the coelom to the body surface of infected fish via ruptured areas in the region of the abdominal pores. The escaped flagellates were similar in morphology to those in the blood and were equally sensitive to lysis in water but the mucus from the fish provided the flagellates with short-term protection. Supportive evidence that direct transmission may occur in the field was obtained when juvenile Oncorhynchus kisutch held in seminatural rearing channels in a hatchery showed an increase in the prevalence of infection after they were moved to an adjacent channel. Leech vectors (Piscicola salmositica) were not observed to account for the increase in the number of infected fish, and the prevalence of infection remained low in fish that were not moved. Indirect versus direct life history is currently the only criterion used in distinguishing Trypanoplasma (parasitic in blood and other fluids of fish) from Cryptobia (parasitic in molluscs and externally on fish). The evidence of direct transmission in a blood f o m demonstrates that this criterion is not reliable. The genus Trypanoplasma Laveran and Mesnil, 1901 is therefore considered to be a junior synonym of the genus Cryptobia Leidy, 1846. BOWER, S. M., et L. MARGOLIS. 1983. Direct transmission of the haemoflagellate Cryptobia salmositica among Pacific salmon (Oncorhynchus spp.). Can. J. Zool. 61: 1242-1250.Des Oncorhynchus nerka immatures ClevCs en laboratoire ont 6tC marquCs, puis ont r e p une injection de Cryptobia (= Trypanoplasma) salmositica avant d'ttre placCs dans des aquariums avec des nombres Cgaux de poissons sains. Environ 85% (1 16 de 137) des poissons sains (gardCs en eau douce ou en eau salCe) exposCs, par de brefs contacts hors de l'eau dans un filet, a la prCsence de poissons trks infect& ont contract6 l'infection. Sans ce contact hors de l'eau, seulement 4% (3 de 85) des poissons sains gardCs en aquarium avec des poissons infectCs ont contract6 l'infection. C'est par des zones endommagdes dans la rCgion des pores abdominaux que les flagellCs quittent le caelome du poisson infect6 pour en atteindre la surface. Les flagellCs ainsi libirks sont morphologiquement semblables a ceux du sang et sont aussi sensibles a la lyse dans l'eau, mais le mucus produit par le poisson assure aux flagellks une protection a court teme. 11 semble que le parasite puisse ttre transmis directement...

Purified metallo-protease from the pathogenic haemoflagellate Cryptobia salmositica and its in vitro proteolytic activities

“…gills, mucous membranes, connective tissue, blood vessels) before it has access to the blood of fish. Our current hypothesis is that the secreted metallo-protease contributes to the formation of lesions in infected fish which include blisters on the body surface, as was shown by Bower & Margolis (1983). Parasites released onto the body surface are carried in mucous strands via the water to other fish, and infections result when they penetrate the mucous membrane in the oral cavity or gills (Woo & Wehnert 1983).…”

“…The parasite is normally transmitted by the blood sucking leech Pisciola salmositica (see Woo 1978), but it is also transmitted directly between fish (Bower & Margolis 1983, Woo & Wehnert 1983. However, the mechanism for the direct transmission is unknown.…”

Phylogeny of the bodonid flagellates (Kinetoplastida) based on small-subunit rRNA gene sequences.

“…Lom, 1976 ;Becker, 1977 ;Brugerolle et al, 1979), while deemed insufficient by others (e.g. Bower & Margolis, 1983 ;Woo, 1994). Recently described differences in the kDNA structure between T. borreli Yasuhira & Simpson, 1996) and C. helicis , along with the 18S and 28S rRNA data are considered by us as substantial.…”

Phylogeny of the kinetoplastida: taxonomic problems and insights into the evolution of parasitism

“…Another discrepancy is that the subdivision of the suborder Bodonina onto two families, Bodonidae and Cryptobiidae (Vickerman 1976(Vickerman , 1978, as both members mingle with each other on the tree. A separation of the fish parasites onto the genera Cryptobia and Trypanoplasma, supported by some researchers (Lom 1976, Becker 1977, Brugerolle et al 1979, and challenged by the others (Bower & Margolis 1983, Woo 1994, is also not supported.…”