Short chain nitrocompounds as a treatment of layer hen manure and litter; effects on in vitro survivability of Salmonella,generic E. coli and nitrogen metabolism

The current study was conducted to assess the bactericidal effectiveness of several nitrocompounds against pathogens in layer hen manure and litter. Evidence from an initial study indicated that treatment of layer hen manure with 12 mM nitroethane decreased populations of generic E. coli and total coliforms by 0.7 and 2.2 log₁₀ colony forming units (CFU) g^?1, respectively, after 24 h aerobic incubation at ambient temperature when compared to untreated populations. Salmonella concentrations were unaffected by nitroethane in this study. In a follow-up experiment, treatment of 6-month-old layer hen litter (mixed with 0.4 mL water g^?1) with 44 mM 2-nitroethanol, 2-nitropropanol or ethyl nitroacetate decreased an inoculated Salmonella typhimurium strain from its initial concentration (3 log₁₀ CFU g^?1) by 0.7 to 1.7 log₁₀ CFU g^?1 after 6 h incubation at 37°C in covered containers. After 24 h incubation, populations of the inoculated S. Typhmiurium in litter treated with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate or nitroethane were decreased more than 3.2 log₁₀ CFU g^?1 compared to populations in untreated control litter. Treatment of litter with 44 mM 2-nitroethanol, 2-nitropropanol, ethyl nitroacetate decreased rates of ammonia accumulation more than 70% compared to untreated controls (0.167 µmol mL^?1 h^?1) and loses of uric acid (< 1 µmol mL^?1) were observed only in litter treated with 44 mM 2-nitropropanol, indicating that some of these nitrocompounds may help prevent loss of nitrogen in treated litter. Results warrant further research to determine if these nitrocompounds can be developed into an environmentally sustainable and safe strategy to eliminate pathogens from poultry litter, while preserving its nitrogen content as a nutritionally valuable crude protein source for ruminants.     

A case study of bats and white‐nose syndrome demonstrating how to model population viability with evolutionary effects

Ecological factors generally affect population viability on rapid time scales. Traditional population viability analyses (PVA) therefore focus on alleviating ecological pressures, discounting potential evolutionary impacts on individual phenotypes. Recent studies of evolutionary rescue (ER) focus on cases in which severe, environmentally induced population bottlenecks trigger a rapid evolutionary response that can potentially reverse demographic threats. ER models have focused on shifting genetics and resulting population recovery, but no one has explored how to incorporate those findings into PVA. We integrated ER into PVA to identify the critical decision interval for evolutionary rescue (DIER) under which targeted conservation action should be applied to buffer populations undergoing ER against extinction from stochastic events and to determine the most appropriate vital rate to target to promote population recovery. We applied this model to little brown bats (Myotis lucifugus) affected by white‐nose syndrome (WNS), a fungal disease causing massive declines in several North American bat populations. Under the ER scenario, the model predicted that the DIER period for little brown bats was within 11 years of initial WNS emergence, after which they stabilized at a positive growth rate (λ = 1.05). By comparing our model results with population trajectories of multiple infected hibernacula across the WNS range, we concluded that ER is a potential explanation of observed little brown bat population trajectories across multiple hibernacula within the affected range. Our approach provides a tool that can be used by all managers to provide testable hypotheses regarding the occurrence of ER in declining populations, suggest empirical studies to better parameterize the population genetics and conservation‐relevant vital rates, and identify the DIER period during which management strategies will be most effective for species conservation.     

Fecal contamination in irrigation water and microbial quality of vegetable primary production in urban farms of Metro Manila,Philippines

Microbial contamination of fresh produce can present a severe risk to public health. By conducting a rigorous survey of irrigation waters, the impacts of fecal contamination on the quality of produce could be assessed. In this study, surface waters were observed to be contaminated with Escherichia coli, Salmonella spp., and somatic coliphages. Culture methods show that out of 373 irrigation water, soil, and vegetable samples collected for a 1-year period, 232 (62.20%) were found positive for E. coli, 213 (57.26%) for somatic coliphages, and 2 (0.53%) for Salmonella spp. Out of 190 water samples, 167 (87.9%) were found to have E.coli, 174 (91.6%) have somatic coliphages, and 1 (0.5%) with Salmonella spp. In soil samples, 36 of 91 (39.6%) have E. coli, 31 (34.0%) have somatic coliphages, and none with Salmonella spp. Lastly, out of 92 vegetable samples, 29 (31.5%), 8 (8.7%), and 1 (1.1%) were found to have E. coli, somatic coliphages, and Salmonella spp., respectively. Molecular analysis confirmed the presence of bacterial contaminants. Seasonal weather conditions were noted to have an effect on the presence and number of these fecal indicator organisms. The observed data suggest that contaminated irrigation water may greatly affect the quality of fresh produce from these agricultural operations.     

The Threat of Disease Increases as Species Move Toward Extinction

At local scales, infectious disease is a common driver of population declines, but globally it is an infrequent contributor to species extinction and endangerment. For species at risk of extinction from disease important questions remain unanswered, including when does disease become a threat to species and does it co‐occur, predictably, with other threats? Using newly compiled data from the International Union for Conservation of Nature (IUCN) Red List, we examined the relative role and co‐occurrence of threats associated with amphibians, birds, and mammals at 6 levels of extinction risk (i.e., Red List status categories: least concern, near threatened, vulnerable, endangered, critically endangered, and extinct in the wild/extinct). We tested the null hypothesis that the proportion of species threatened by disease is the same in all 6 Red List status categories. Our approach revealed a new method for determining when disease most frequently threatens species at risk of extinction. The proportion of species threatened by disease varied significantly between IUCN status categories and linearly increased for amphibians, birds, and all species combined as these taxa move from move from least concern to critically endangered. Disease was infrequently the single contributing threat. However, when a species was negatively affected by a major threat other than disease (e.g., invasive species, land‐use change) that species was more likely to be simultaneously threatened by disease than species that had no other threats. Potential drivers of these trends include ecological factors, clustering of phylogenetically related species in Red List status categories, discovery bias among species at greater risk of extinction, and availability of data. We echo earlier calls for baseline data on the presence of parasites and pathogens in species when they show the first signs of extinction risk and arguably before. La Amenaza de Enfermedades Incrementa a Medida que las Especies se Aproximan a la Extinción     

F-RNA噬菌体及其作为水中肠道病毒指示物的研究进展

城市污水的再生利用是缓解水资源紧张、减少水污染和改善生态环境的有效途径。污水及其回用水中的肠道病毒对人体健康的风险日益受到关注。直接检测水中肠道病毒的操作复杂、安全性差、时间长、需要专门的技术和设备，因此需要寻找合适的指示生物，以实现对水中肠道病毒的及时检测和风险评价。F-RNA噬菌体是通过性菌毛感染雄性大肠杆菌的一类RNA细菌病毒，在污水中普遍存在，在大小、形态结构及对环境条件和水处理过程的抗性与肠道病毒相似，被认为是水中肠道病毒的合适的指示生物。文章介绍了F-RNA噬菌体在环境及污水中的分布、存活和去除特性、检测方法及作为水中肠道病毒指示生物的研究进展。     

Assessment of risk from long term exposure to waterborne pathogens

Disease due to waterborne pathogens, whether in outbreak or endemic form, continues to be a problem in both the developing and the developed world. Control of waterborne disease requires accurate assessment of the pathogen dose-response relation and of likely patterns of exposure. Heretofore, risk assessment of pathogen exposure has been done on the basis of several standard biologically plausible dose-response models. In this paper, the problem of estimating the long-term risk from waterborne pathogens is put into a rigorous mathematical and statistical framework. The implications of the biologic assumptions embedded in the dose-response models (e.g., heterogeneity in susceptibility) are fully considered, as are the likely patterns of long-term exposure (e.g., temporal correlations within individuals and heterogeneity of mean exposures). Two types of long-term risk are described, risk per person-time and risk per individual where the latter is the risk of infection at least once. The effects on these risks of heterogeneity in individuals susceptibilities and mean exposures and of temporal correlations of exposures are described, both theoretically and empirically using a sample of experimental data sets. Because different models with equal plausibility may give very different results in the low-dose range but fit the experimental data equally well, we apply the model uncertainty algorithm of Buckland et al. (1997) on example data sets. Finally, the computational aspects of the general problem, which are often challenging, are discussed along with the conditions under which simplifying approximations may be utilized.     

越冬期淡水白鲳发病之病原细菌的研究

从越冬期淡水白鲳病鱼的肝脏内分离纯化到一细菌菌株ＣＢＺＨＧ４,用ｎ（ｃｅｌｌ＝１０＾５～１０＾６ｍＬ＾－１的菌液浓度在腹腔注射试验鱼后４８ｈ内全部死亡,证实为病原菌。ＣＢＺＨＧ４经ＡＰＩ ２０ＮＥ系统鉴定为嗜水性气单胞菌（Ａｅｒｏｍｏｎａｓ ｈｙｄｒｏｐｈｉｌａ）,对卡那霉素多种抗生素和呋喃类药物敏感,对青霉素类、先锋霉素等抗生素、磺胺类药物和０／１２９不敏感。表２参２