Stained prawn disease (SPD) of Pandalus platyceros in British Columbia, Canada, caused by a rickettsial infection

Abstract

Stained prawn disease (SPD) with clinical signs of black discolouration of the cuticula, especially around the edges of body segments, and black stippling on the surface of the hepatopancreas was caused by a rickettsia-like microorganism with a n affinity for fixed phagocytes and haemocytes. This disease was found in prawns from various localities throughout Howe Sound and at one location in the S t r a~t of Georgia, British Columb~a, Canada. The distribution of SPD wlthin Howe Sound has not changed since it was first detected In 1989. However, the prevalence has declined to about 4 % from a record high of about 15% In July 1990 and March 1991 In areas with these high prevalences, an above-average level of mortality, equated to a decline in survival rates from 57 to 15'X,, was detected. These mortalities were not attributable to fishing pressure because the affected area has been closed to fish~ng since November 1988 due to unacceptable levels of dioxin and furan compounds In shellfish tissue samples. Laboratory studies indicated that the SPD agent can be transm~tted horizontally by cannibalism and via the water [exposure to screened (1 mm pore size) effluent from lnfected prawns] and remained infectious for 10 d or more of storage at -lO°C. About 50% of the prawns that fed on infected prawns (both fresh and after being frozen) and 25 % of the prawns exposed to contaminated water became infected. Most mortalities attributable to SPD occurred between 2 and 4 mo after exposure to the etiological agent in the laboratory.

Description of a hepatopancreatic rickettsia-like organism in the redclaw crayfish Cherax quadricarinatus

“…In this report the RLO was observed only in hepatopancreatocytes. This distinct differentiation of tissue tropism is consistent with other crustacean-infecting RLOs (Bower et al 1996). Furthermore, the cytopathology also differed in that the systemic rickettsia-like microcolonies do not usually contain central clear zones as was observed with this hepatopancreatic RLO.…”

“…Basovhilic, Gram-neaative, nucrocolonies of rick- Rickettsia-like organisms (RLO) infect a range of aquahc crustaceans mcludmg amphpods, crabs, prawns and freshwater crayfish (Federici et al 1974, Bonami & Pappalardo 1980, Johnson 1984, Sparks et al 1985, Brock et al 1986, Anderson et al 1987, Krol et al 1991, Ketterer et al 1992, Owens et al 1992, Bower et al 1996. The decapod-infecting RLOs are either confined to the hepatopancreatic tubule epithelium, or are systemic.…”

Rickettsia-like organism associated with tremor disease and mortality of the Chinese mitten crab Eriocheir sinensis

“…As in tremor disease, they mostly infect connective tissues and hemolymph. Unlike the RLO reported by Johnson (1984), Bower et al (1996), Messick (1998), Brett & Prior (1999) and Drobne et al (1999), we did not find RLOs in the epithelium of the hepatopancreas although they were found in the underlying connective tissues. Our cytopathological study revealed that RLOs only infected hemocytes, muscle, and connective tissues but not epithelial cells.…”

Molecular detection methods developed for a systemic rickettsia-like bacterium (RLB) in Penaeus monodon (Decapoda: Crustacea)

“…To survive and reproduce, the rickettsia organism must enter the eucaryotic host cell, multiply within the cell, exit and reestablish this cycle in another cell (Winkler 1990). Rickettsia-like microorganisms infect a wide range of aquatic crustaceans including amphipods, crabs, freshwater crayfish and prawns (Federici et al 1974, Harshbarger et al 1977, Bonami & Pappalardo 1980, Larrson 1982, Johnson 1984, Brock et al 1986, Anderson et al 1987, Krol et al 1991, Frelier et al 1992, Fryer & Lan-nan 1994, Bower et al 1996, Jimenez & Romero 1997, Edgerton & Prior 1999, Wang & Gu 2002.…”