Mortality curves of blind cave crayfish (Orconectes australis australis) exposed to chlorinated stream water

Chlorinated stream water toxicity was tested on the blind cave crayfish Orconectes australis australis from Merrybranch Cave, White County, Tennessee. An undisturbed natural cavern, Merry-branch was formed between two strata of sandstone having a mean elevation of 354 meters (MSL). Test water was collected from a subterranian stream in the cave supporting the hypogean crayfish population, and transported to the laboratory. No chlorinity was detected in the underground stream water.In the laboratory, cave water was chlorinated with sodium hypechlorus solution at various concentrations of total residual chlorine, combined residual, and free chlorine content as measured by Standard Methods titration procedure. Thirty-six crayfish, six crayfish per test solution, were subjected to a three day acclimation period at chlorine concentrations ranging from 0.21–1.50 mg./l. total residual chlorine, 0.20–0.30 mg./l. combined residual chlorine, and 0.01–1.20 mg./l. free chlorine; and then subjected t0 a 24 hour time-to-death (hourly) bioassay at the following chlorine water dilutions (mg./l.): (1) 7.45 total residual, 0.45 combined residual, and 7.00 free, (2) 3.39 total residual, 0.39 combined residual, and 3.00 free, (3) 2.85 total residual, 0.35 combined residual, and 2.50 free, (4) 2.30 total residual, 0.30 combined residual, and 2.00 free, (5) t.96 total residual, 0.21 combined residual, and 1.75 free, and (6) control. Fluctuations within these concentrations ranged from ± 0.20 free chlorine. All test solutions and a control were delivered by an Esvelt serial diluter. In addition, a 24 hour time-to-death (hourly) bioassay was conducted at the same dilutions 0n crayfish not acclimated to chlorine.These test demonstrated that crayfish mortalities generally increased with increasing concentrations of chlorine in both bio-assays, while acclimated crayfish tended to be more tolerant than non-acclimated ones.Funds for this research were provided by the Aquatic Ecology Fund, Biology Dept., Tennessee Technological University     

Advances in the development of Salmonella-based vaccine strategies for protection against Salmonellosis in humans

Salmonella spp. are important human pathogens globally causing millions of cases of typhoid fever and non-typhoidal salmonellosis annually. There are only a few vaccines licensed for use in humans which all target Salmonella enterica serovar Typhi. Vaccine development is hampered by antigenic diversity between the thousands of serovars capable of causing infection in humans. However, a number of attenuated candidate vaccine strains are currently being developed. As facultative intracellular pathogens with multiple systems for transporting effector proteins to host cells, attenuated Salmonella strains can also serve as ideal tools for the delivery of foreign antigens to create multivalent live carrier vaccines for simultaneous immunization against several unrelated pathogens. Further, the ease with which Salmonella can be genetically modified and the extensive knowledge of the virulence mechanisms of this pathogen means that this bacterium has often served as a model organism to test new approaches. In this review we focus on (1) recent advances in live attenuated Salmonella vaccine development, (2) improvements in expression of foreign antigens in carrier vaccines and (3) adaptation of attenuated strains as sources of purified antigens and vesicles that can be used for subunit and conjugate vaccines or together with attenuated vaccine strains in heterologous prime-boosting immunization strategies. These advances have led to the development of new vaccines against Salmonella which have or will soon be tested in clinical trials.     

Benefits of swimming pools in two remote Aboriginal communities in Western Australia: intervention study

Objective To determine the health impact of swimming pools built with the aim of improving quality of life and reducing high rates of pyoderma and otitis media.Design Intervention study assessing prevalence of ear disease and skin infections before and at six monthly intervals after opening of swimming pools.Setting Two remote Aboriginal communities in Western Australia.Participants 84 boys and 78 girls aged < 17 years.Main outcome measures Changes in prevalence and severity of pyoderma and perforation of tympanic membranes with or without otorrhoea over 18 months after opening of pools.Results In community A, 61 children were seen before the pool was opened, and 41, 46, and 33 children were seen at the second, third, and fourth surveys. Equivalent figures for community B were 60, 35, 39, and 45. Prevalence of pyoderma declined significantly from 62% to 18% in community A and from 70% to 20% in community B during the 18 months after the pools opened. Over the same period, prevalence of severe pyoderma fell from 30% to 15% in community A and from 48% to 0% in community B. Prevalence of perforations of the tympanic membrane fell from 32% in both communities to 13% in community A and 18% in community B. School attendance improved in community A.Conclusion Swimming pools in remote communities were associated with reduction in prevalence of pyoderma and tympanic membrane perforations, which could result in long term benefits through reduction in chronic disease burden and improved educational and social outcomes.