Eutrophication and Bacterial Pathogens as Risk Factors for Avian Botulism Outbreaks in Wetlands Receiving Effluents from Urban Wastewater Treatment Plants

Abstract

b; Regional Centre for Water Studies (CREA), UCLM, Ciudad Real, Spain c Due to the scarcity of water resources in the "Mancha Húmeda" Biosphere Reserve, the use of treated wastewater has been proposed as a solution for the conservation of natural threatened floodplain wetlands. In addition, wastewater treatment plants of many villages pour their effluent into nearby natural lakes. We hypothesized that certain avian pathogens present in wastewater may cause avian mortalities which would trigger avian botulism outbreaks. With the aim of testing our hypothesis, 24 locations distributed in three wetlands, two that receive wastewater effluents and one serving as a control, were monitored during a year. Sediment, water, water bird feces, and invertebrates were collected for the detection of putative avian pathogenic Escherichia coli (APEC), Salmonella spp., Clostridium perfringens type A, and Clostridium botulinum type C/D. Also, water and sediment physicochemical properties were determined. Overall, APEC, C. perfringens, and C. botulinum were significantly more prevalent in samples belonging to the wetlands which receive wastewater. The occurrence of a botulism outbreak in one of the studied wetlands coincided with high water temperatures and sediment 5-day biochemical oxygen demand (BOD 5 ), a decrease in water redox potential, chlorophyll a, and sulfate levels, and an increase in water inorganic carbon levels. The presence of C. botulinum in bird feces before the onset of the outbreak indicates that carrier birds exist and highlights the risk of botulinum toxin production in their carcasses if they die by other causes such as bacterial diseases, which are more probable in wastewater wetlands.

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

“…In addition, both the Jeorse and Portage beaches have river outfalls. Our hypothesis is further supported by a study in Spain, which found that wastewater treatment plant effluent was a good source for types C and D and other avian pathogens (44). Other than Bay City, Jeorse also has very high C. botulinum detections and concentrations.…”

“…Tobico Marsh is a bird sanctuary that ultimately drains over the beach at Bay City (43). A study in Spain found that feces of water birds contained C. botulinum types C and D, and wetlands provide a good environment for type C and D proliferation (44). Bird fecal matter of Tobico Marsh may contain C. botulinum type E, and it is vital to conduct further studies to detect bontE in fecal matter and potential delivery to Saginaw Bay.…”

Studies on avian pathogenic Escherichia coli in commercial broiler chicken in South East Queensland

“…A number of studies showed that APEC is found in the surrounding environment around farms (Anza et al, 2014;Cortes et al, 2010;Sola-Gines et al, 2015). The reported overlap between APEC strains isolated from farm workers clothes, hands and boots, and poultry farms, suggest that people may act as a significant vehicle for the introduction and spread of APEC and other pathogens to the poultry farms from the external environment (Belanger et al, 2011;Cho et al, 2012;Johnson et al, 2008b;Lynne et al, 2012;Zhu Ge et al, 2014).…”

“…The reported overlap between APEC strains isolated from farm workers clothes, hands and boots, and poultry farms, suggest that people may act as a significant vehicle for the introduction and spread of APEC and other pathogens to the poultry farms from the external environment (Belanger et al, 2011;Cho et al, 2012;Johnson et al, 2008b;Lynne et al, 2012;Zhu Ge et al, 2014). Movement of staff and visitors between sheds that potentially harbour APEC and/or other pathogens may also pose a source of infection (Anza et al, 2014).…”

“…A distance greater than 20 m between the car park and the shed which can relate to overall design of the farm and human movement, a lack of shower facilities and/or people not showering prior to entering the sheds were risk factors for increased incidence of APEC carriage. It has been highlighted previously that APEC might be common in the surrounding farm environments (Guenther et al, 2011) and that people entering poultry sheds can introduce APEC from the external environment (Anza et al, 2014). Further studies, which investigate the importance and benefits of spatial containment (i.e.…”