Persistent Infection of Myxobolus cerebralis, the Causative Agent of Salmonid Whirling Disease, in Tubifex tubifex

Abstract

The objective of this study was to quantify and determine the periodicity in the release of the triactinomyxon (TAM) stage of Myxobolus cerebralis, the causative agent of salmonid whirling disease, by its aquatic oligochaete host Tubifex tubifex. For this, 24 individual T. tubifex (infected as a group at 15 C) were examined daily for the release of M. cerebralis TAMs, and the number of waterborne TAMs released by each worm was quantified. The duration of the infection in these worms was also monitored using a polymerase chain reaction (PCR) diagnostic test. TAMs were first released 74 days postexposure (PE) and continued to be released until 132 days PE. During this period, each worm released on average, 1.5 x 10(3) waterborne TAMs 12 times; however, no pattern or periodicity was noted. The results of the PCR diagnostic tests conducted at 5, 7, 9, and 15 mo PE were positive, and the persistent infection was confirmed at 606 days PE (approximately 20 mo) when the remaining worms began releasing TAMs again. Similar results were observed in naturally infected T. tubifex, indicating that these worms remain infected for the duration of their natural lifespan and are capable of shedding viable TAMs, in temporally separate periods. These findings open the possibility of a seasonal periodicity in TAM release by T. tubifex.

Effect of cadmium on the susceptibility of Tubifex tubifex to Myxobolus cerebralis (Myxozoa), the causative agent of whirling disease

“…Following ingestion by the oligochaete, the parasite undergoes development and propagation between the gut epithelial cells (El-Matbouli & Hoffmann 1998). Within several months, numerous triactinomyxon spores (TAMs) are released into the water and subsequently infect the suitable fish host (El-Matbouli et al 1999, Gilbert & Granath 2001, Stevens et al 2001. Infection in T. tubifex may persist for the duration of the worm's lifespan and release of TAMs can occur periodically over the span of at least a few years (Gilbert & Granath 2001).…”

“…Within several months, numerous triactinomyxon spores (TAMs) are released into the water and subsequently infect the suitable fish host (El-Matbouli et al 1999, Gilbert & Granath 2001, Stevens et al 2001. Infection in T. tubifex may persist for the duration of the worm's lifespan and release of TAMs can occur periodically over the span of at least a few years (Gilbert & Granath 2001). Infected worms suffer from suppressed feeding, reduced growth (Stevens et al 2001, Kerans et al 2004, Steinbach Elwell et al 2006, Rasmussen et al 2008) and inhibited reproductive development (Shirakashi & El-Matbouli 2009), though no obvious parasite effects on survival have been shown (Shirakashi & El-Matbouli 2009).…”

Myxobolus marajoensis sp. n. (Myxosporea: Myxobolidae), parasite of the freshwater catfish Rhamdia quelen from the Brazilian Amazon region

“…Some of these species have a considerable impact on fishery productivity by provoking diseases in both the natural environment and the farmed fish (GILBERT & GRANATH, 2001;EIRAS et al, , 2014LOM & DIKOVÁ, 2006).…”

Accelerated deactivation of Myxobolus cerebralis myxospores by susceptible and non-susceptible Tubifex tubifex

“…These research efforts were focused on both aspects of the parasite life cycle. Application of polymerase chain reaction (PCR) technology (Andree et al 1998, Baldwin & Myklebust 2002, Cavender et al 2004) molecular biology (Sturmbauer et al 1999, Beauchamp et al 2001) and other state-of-the-art analytical techniques led to rapid advances and a deeper understanding of the etiology of M. cerebralis in the aquatic oligochaete host T. tubifex (Gilbert & Granath 2001, Beauchamp et al 2002, 2006, Nehring et al 2013. Beauchamp et al (2001) developed mitochondrial 16S ribosomal DNA markers to parse the T. tubifex species-complex into 6 distinct lineages.…”