Clostrìdìum botulinum - A cause of fish mortality

Clostridium botulinum type E proliferates in dead aquatic animals and sediments and it is distributed by water currents and infected fish. Botulism is a disease with great significance for both aquacultured fish and humans. The existing data about the subject are very few, and the aim of the present paper is to warn fish farmers and pathologists about the possibility of outbreaks in Greece.

Spatial, Temporal, and Matrix Variability of Clostridium botulinum Type E Toxin Gene Distribution at Great Lakes Beaches

ABSTRACTClostridium botulinumtype E toxin is responsible for extensive mortality of birds and fish in the Great Lakes. TheC. botulinum bontEgene that produces the type E toxin was amplified with quantitative PCR from 150 sloughed algal samples (primarilyCladophoraspecies) collected during summer 2012 from 10 Great Lakes beaches in five states; concurrently, 74 sediment and 37 water samples from four sites were also analyzed. ThebontEgene concentration in algae was significantly higher than in water and sediment (P< 0.05), suggesting that algal mats provide a better microenvironment forC. botulinum. ThebontEgene was detected most frequently in algae at Jeorse Park and Portage Lake Front beaches (Lake Michigan) and Bay City State Recreation Area beach on Saginaw Bay (Lake Huron), where 77, 100, and 83% of these algal samples contained thebontEgene, respectively. The highest concentration ofbontEwas detected at Bay City (1.98 × 105gene copies/ml of algae or 5.21 × 106g [dry weight]). This study revealed that thebontEgene is abundant in the Great Lakes but that it has spatial, temporal, and matrix variability. Further, embayed beaches, low wave height, low wind velocity, and greater average water temperature enhance thebontEoccurrence.

Two Novel Toxin Variants Revealed by Whole-Genome Sequencing of 175 Clostridium botulinum Type E Strains

ABSTRACTWe sequenced 175Clostridium botulinumtype E strains isolated from food, clinical, and environmental sources from northern Canada and analyzed their botulinum neurotoxin (bont) coding sequences (CDSs). In addition tobont/E1andbont/E3variant types, neurotoxin sequence analysis identified two novel BoNT type E variants termed E10 and E11. Strains producing type E10 were found along the eastern coastlines of Hudson Bay and the shores of Ungava Bay, while strains producing type E11 were only found in the Koksoak River region of Nunavik. Strains producing BoNT/E3 were widespread throughout northern Canada, with the exception of the coast of eastern Hudson Bay.

Distribution of Clostridium botulinum Type E Strains in Nunavik, Northern Quebec, Canada

ABSTRACTThe distribution and levels ofClostridium botulinumtype E were determined from field sites used by Inuit hunters for butchering seals along the coast of Nunavik. The incidence rates ofC. botulinumtype E in shoreline soil along the coast were 0, 50, and 87.5% among samples tested for the Hudson Strait, Hudson Bay, and Ungava Bay regions, respectively. Spores were detected in seawater or coastal rock surfaces from 17.6% of butchering sites, almost all of which were located in southern Ungava Bay. Concentrations ofC. botulinumtype E along the Ungava Bay coast were significantly higher than on the coasts of Hudson Strait and Hudson Bay, with the highest concentrations (270 to 1,800/kg of sample) found near butchering sites located along the mouths of large rivers. The Koksoak River contained high levels ofC. botulinumtype E, with the highest median concentration (270/kg) found in sediments of the marine portion of the river.C. botulinumtype E was found in the intestinal contents (4.4%) and skins (1.4%) of seals. A high genetic biodiversity ofC. botulinumtype E isolates was observed among the 21 butchering sites and their surroundings along the Nunavik coastline, with 83% of isolates (44/53) yielding distinct pulsed-field gel electrophoresis genotypes. Multiple sources ofC. botulinumtype E may be involved in the contamination of seal meat during butchering in this region, but the risk of contamination appears to be much higher from environmental sources along the shoreline of southern Ungava Bay and the sediments of the Koksoak River.