Sequence analysis of the 16s-23s intergenic spacer regions of Flavobacterium columnare

The 16S, 23S, and 5S ribosomal RNA (rRNA) genes are highly conserved sequences in bacteria. For this reason, rRNA genes are often used for phylogenetic classification. On the other hand, the regions between the structural sequences, known as intergenic spacer regions (ITS), are under less evolutionary pressure to be conserved. Because they are not as highly conserved, they can be used to differentiate strains of the same bacterial specie. The purpose of this study was to evaluate the 16S-23S ITS of Flavobacterium columnare, an important pathogen of cultured fish, by comparing the 16S-23S ITS sequences from 70 isolates. We developed two PCR assays that amplify overlapping regions of one large previously identified ITS. The primers targeted the 16S sequence and isoleucine tRNA encoding sequences and the 23S sequence and alanine tRNA encoding sequences. The PCR products were cloned and sequenced. We also targeted I-CeuI restriction fragments from the ATCC type strain that were separated by pulse field gel electrophoresis and analyzed the 16S-23S ITS regions. We found that the genome of this species harbors at least 6 intergenic spacer regions that are very similar and contain the same tRNA encoding sequences. This suggests that earlier studies that used the ITS for distinguishing between strains of Flavobacterium columnare may be comparing sequences from different structural RNA operons and thus have misleading data

CONSUMPTION OF UNREGULATED DRINKING WATER AND HUMAN HEALTH RISK IN RURAL COMMUNTIES

Establishing safe drinking water for rural populations dependent on unregulated water is a global challenge. Despite initiatives to improve access to drinking water, hazards associated with unregulated sources pose a potential risk to human health for rural populations. In the absence of accurate information and monitoring of water quality, consumers form heuristic perceptions of risk associated with their drinking water. Risk perception affects water consumption contributing to uncertainty in risk exposure. Quantifying risk through human health risk assessments (HHRA) has been implemented since the 1940s and advances in risk assessment modeling have created an opportunity to improve HHRA by applying probabilistic Bayesian risk assessment methods. A holistic HHRA integrating risk perception, as it relates to exposure, can quantify uncertainty and provide feedback to improve risk communication and management. The literature lacks a review or summary that characterizes the type and frequency of HHRAs applied to rural populations dependent on unregulated drinking water. The purpose of this thesis is to: (1) summarize studies with HHRA methods applied to unregulated drinking water and rural communities, and describe the characteristics of methods, publications, and current literature gaps; and, (2) characterize and quantify risk perception as it relates to unregulated groundwater wells, and determine the impact of risk perception on human health risk using a holistic HHRA. A systematic scoping review of peer-reviewed literature (Jan 2000 to May 2014) was used to identify studies with HHRAs applied to unregulated or unspecified drinking water. At least one drinking water source was identified as unregulated (21%) or unspecified (79%) in 100 studies, and 7% identified rural communities dependent on unregulated drinking water. No studies integrated non-traditional factors (e.g. risk perception) into a holistic HHRA. HHRAs applied to rural populations dependent on unregulated water are poorly represented in the literature even though almost half of the global population is rural. The scoping review confirmed a lack of HHRA studies addressing unregulated drinking water risks, and the absence of applied methods that facilitated the quantification and integration of non-traditional factors. Based on the review findings, a community-based participatory observational case study and holistic HHRA was applied using arsenic concentrations and survey responses from two communities dependent on unregulated groundwater wells. Risk perception and human health risk was determined using probabilistic (Bayesian) risk assessment methods. Community tap water quality exceeded at least one health standard at a rate of 56% and 65%. Integration of risk perception did not change the overall risk status but lowered the cancer risk for arsenic by 3% for both communities. The probability of exposure to arsenic concentrations over 1:100,000 negligible risk for the two communities was 23% and 22%. There was no correlation between risk perception and drinking water safety in either community. This study achieved a holistic Bayesian risk assessment through the integration of risk perception and provided a probability of risk that can be used to inform risk communication and management specific to the participating communities

Fish Eating Birds Can Spread Bacterial Diseases Between Catfish Ponds

Severe outbreaks of Motile Aeromonad Septicemia disease in commercial catfish aquaculture ponds have been associated with a virulent Aeromonas hydrophila strain (VAh) that is genetically distinct from less virulent strains. We demonstrated that Great Egrets (Arde alba), Double-crested Cormorants (Phalacrocorax auritus), American White Pelicans (Pelecanus erythrorhynchos), and Wood Storks (Mycteria americana) can carry and shed viable VAh after consuming fish infected with Vah. Edwardsiella ictaluri and E. tarda are considered the primary species of Edwardsiella to cause disease outbreaks in North American catfish aquaculture. Genetic analysis has determined that most isolates designated as E. tarda were actually a new species, E. piscicida. There has been an increase in E. piscicida diagnostic cases in recent years possibly due to an increase in hybrid (Channel x blue) catfish production. We conducted a study to determine if Great Egrets (Ardea alba) shed viable E. piscicida when fed catfish infected with the bacteria. Great Egrets fed infected fish shed viable E. piscicida bacteria for multiple days, (Table 1), after last consuming infected fish on day 2 of the study. Great Egrets in the control group did not shed the bacteria. Given that Great Egrets can shed viable E. piscicida after consuming diseased fish, we hypothesize that they could also serve as a reservoir for E. piscicida and could spread the pathogen while predating fish in catfish ponds. Additional research is needed to determine if this shedding could cause disease in these ponds

Potential of Double-crested Cormorants (\u3ci\u3ePhalacrocorax auritus\u3c/i\u3e), American White Pelicans (\u3ci\u3ePelecanus erythrorhynchos\u3c/i\u3e), and Wood Storks (\u3ci\u3eMycteria americana\u3c/i\u3e) to Transmit a Hypervirulent Strain of \u3ci\u3eAeromonas hydrophila\u3c/i\u3e between Channel Catfish Culture Ponds

Aeromonas hydrophila is a Gramnegative bacterium ubiquitous to freshwater and brackish aquatic environments that can cause disease in fish, humans, reptiles, and birds. Recent severe outbreaks of disease in commercial channel catfish (Ictalurus punctatus) aquaculture ponds have been associated with a hypervirulent Aeromonas hydrophila strain (VAH) that is genetically distinct from less virulent strains. The epidemiology of this disease has not been determined. Given that research has shown that Great Egrets (Ardea alba) can shed viable hypervirulent A. hydrophila after consuming diseased fish, we hypothesized that Doublecrested Cormorants (Phalacrocorax auritus), American White Pelicans (Pelecanus erythrorhynchos), and Wood Storks (Mycteria americana) could also serve as a reservoir for VAH and spread the pathogen during predation of fish in uninfected catfish ponds. All three species, when fed VAH-infected catfish, shed viable VAH in their feces, demonstrating their potential to spread VAH

Human Health Risk Assessment Applied to Rural Populations Dependent on Unregulated Drinking Water Sources: A Scoping Review

Safe drinking water is a global challenge for rural populations dependent on unregulated water. A scoping review of research on human health risk assessments (HHRA) applied to this vulnerable population may be used to improve assessments applied by government and researchers. This review aims to summarize and describe the characteristics of HHRA methods, publications, and current literature gaps of HHRA studies on rural populations dependent on unregulated or unspecified drinking water. Peer-reviewed literature was systematically searched (January 2000 to May 2014) and identified at least one drinking water source as unregulated (21%) or unspecified (79%) in 100 studies. Only 7% of reviewed studies identified a rural community dependent on unregulated drinking water. Source water and hazards most frequently cited included groundwater (67%) and chemical water hazards (82%). Most HHRAs (86%) applied deterministic methods with 14% reporting probabilistic and stochastic methods. Publications increased over time with 57% set in Asia, and 47% of studies identified at least one literature gap in the areas of research, risk management, and community exposure. HHRAs applied to rural populations dependent on unregulated water are poorly represented in the literature even though almost half of the global population is rural

Human Health Risk Assessment Applied to Rural Populations Dependent on Unregulated Drinking Water Sources: A Scoping Review

Safe drinking water is a global challenge for rural populations dependent on unregulated water. A scoping review of research on human health risk assessments (HHRA) applied to this vulnerable population may be used to improve assessments applied by government and researchers. This review aims to summarize and describe the characteristics of HHRA methods, publications, and current literature gaps of HHRA studies on rural populations dependent on unregulated or unspecified drinking water. Peer-reviewed literature was systematically searched (January 2000 to May 2014) and identified at least one drinking water source as unregulated (21%) or unspecified (79%) in 100 studies. Only 7% of reviewed studies identified a rural community dependent on unregulated drinking water. Source water and hazards most frequently cited included groundwater (67%) and chemical water hazards (82%). Most HHRAs (86%) applied deterministic methods with 14% reporting probabilistic and stochastic methods. Publications increased over time with 57% set in Asia, and 47% of studies identified at least one literature gap in the areas of research, risk management, and community exposure. HHRAs applied to rural populations dependent on unregulated water are poorly represented in the literature even though almost half of the global population is rural

A Qualitative Study of Interphysician Telephone Consultations: Extending the Opinion Leader Theory

INTRODUCTION: It has been suggested that the use of opinion leaders in the dissemination of information may be an effective method of changing clinical practice. Recent reviews on this topic, however, have found mixed results and have concluded that further research is needed to explore the circumstances that effectively utilize opinion leaders. We studied the interphysician telephone consultation, a situation in medical practice in which we see opinion leaders at work, to generate a grounded theory of opinion leader activity. METHODS: Data were collected and triangulated among 3 sources: documentation of 129 telephone consultations received, 51 hours of field observations of consultants, and in-depth interviews of 12 callers and 12 consultants. Analysis was performed using grounded theory methods. RESULTS: A rich description of the context and mechanisms of opinion leader activity emerged. The results describe that opinion leader activity is effective in an informal context in which the practicing physician initiates the exchange. Valuable elements of opinion leader activity that emerged included the provision of a personal touch, reassurance, and advice that blends clinical experience with published evidence. DISCUSSION: Our results suggest that key to effective opinion leader activity is an informal practitioner-initiated context. Formal didactic sessions led by opinion leaders, therefore, may not be an effective format. In addition to evidence-based medicine, practicing physicians value experience-based medicine and the personal touch and reassurance that contact with an opinion leader can provide. Using opinion leaders as a means of balancing these 2 paradigms may be a useful model for continuing medical education in this domain

A Qualitative Study of Interphysician Telephone Consultations: Extending the Opinion Leader Theory

INTRODUCTION: It has been suggested that the use of opinion leaders in the dissemination of information may be an effective method of changing clinical practice. Recent reviews on this topic, however, have found mixed results and have concluded that further research is needed to explore the circumstances that effectively utilize opinion leaders. We studied the interphysician telephone consultation, a situation in medical practice in which we see opinion leaders at work, to generate a grounded theory of opinion leader activity. METHODS: Data were collected and triangulated among 3 sources: documentation of 129 telephone consultations received, 51 hours of field observations of consultants, and in-depth interviews of 12 callers and 12 consultants. Analysis was performed using grounded theory methods. RESULTS: A rich description of the context and mechanisms of opinion leader activity emerged. The results describe that opinion leader activity is effective in an informal context in which the practicing physician initiates the exchange. Valuable elements of opinion leader activity that emerged included the provision of a personal touch, reassurance, and advice that blends clinical experience with published evidence. DISCUSSION: Our results suggest that key to effective opinion leader activity is an informal practitioner-initiated context. Formal didactic sessions led by opinion leaders, therefore, may not be an effective format. In addition to evidence-based medicine, practicing physicians value experience-based medicine and the personal touch and reassurance that contact with an opinion leader can provide. Using opinion leaders as a means of balancing these 2 paradigms may be a useful model for continuing medical education in this domain

Potential of Double-crested Cormorants (\u3ci\u3ePhalacrocorax auritus\u3c/i\u3e), American White Pelicans (\u3ci\u3ePelecanus erythrorhynchos\u3c/i\u3e), and Wood Storks (\u3ci\u3eMycteria americana\u3c/i\u3e) to Transmit a Hypervirulent Strain of \u3ci\u3eAeromonas hydrophila\u3c/i\u3e between Channel Catfish Culture Ponds

Aeromonas hydrophila is a Gramnegative bacterium ubiquitous to freshwater and brackish aquatic environments that can cause disease in fish, humans, reptiles, and birds. Recent severe outbreaks of disease in commercial channel catfish (Ictalurus punctatus) aquaculture ponds have been associated with a hypervirulent Aeromonas hydrophila strain (VAH) that is genetically distinct from less virulent strains. The epidemiology of this disease has not been determined. Given that research has shown that Great Egrets (Ardea alba) can shed viable hypervirulent A. hydrophila after consuming diseased fish, we hypothesized that Doublecrested Cormorants (Phalacrocorax auritus), American White Pelicans (Pelecanus erythrorhynchos), and Wood Storks (Mycteria americana) could also serve as a reservoir for VAH and spread the pathogen during predation of fish in uninfected catfish ponds. All three species, when fed VAH-infected catfish, shed viable VAH in their feces, demonstrating their potential to spread VAH