Used for decades for biological warfare, Bacillus anthracis (category A agent) has proven to be highly stable and lethal. Quantitative risk assessment modeling requires descriptive statistics of the limit of detection to assist in defining the exposure. Furthermore, the sensitivities of various detection methods in environmental matrices are vital information for first responders. A literature review of peer-reviewed journal articles related to methods for detection of B. anthracis was undertaken. Articles focused on the development or evaluation of various detection approaches, such as PCR, real-time PCR, immunoassay, etc. Real-time PCR and PCR were the most sensitive methods for the detection of B. anthracis, with median instrument limits of detection of 430 and 440 cells/ml, respectively. There were very few peer-reviewed articles on the detection methods for B. anthracis in the environment. The most sensitive limits of detection for the environmental samples were 0.1 CFU/g for soil using PCR-enzyme-linked immunosorbent assay (ELISA), 17 CFU/liter for air using an ELISA-biochip system, 1 CFU/liter for water using cultivation, and 1 CFU/cm 2 for stainless steel fomites using cultivation. An exponential dose-response model for the inhalation of B. anthracis estimates of risk at concentrations equal to the environmental limit of detection determined the probability of death if untreated to be as high as 0.520. Though more data on the environmental limit of detection would improve the assumptions made for the risk assessment, this study's quantification of the risk posed by current limitations in the knowledge of detection methods should be considered when employing those methods in environmental monitoring and cleanup strategies.
Seventeen Brahman steers were removed from pasture and fed a high grain diet for 8 weeks prior to slaughter. Carotenoid concentrations were determined in samples of serum and subcutaneous fat obtained either from live animals or at slaughter. At slaughter carcass fat colour was assessed according to AUS-MEAT specification. The concentrations of G-carotene in the serum of these animals fell rapidly (over 60%, P lt; 0.001) in the first 2 weeks on the grain diet and then plateaued. There was no change in either the concentrations of carotenoids in subcutaneous fat or in fat colour of these cattle during the whole period of grain feeding. The overall average liveweight gain was 0.59 kg/day. Failure to observe changes in concentrations of carotenoids was unexpected, and may be partly due to the fact that these cattle did not settle to the trial conditions in the feedlot, as indicated by the significantly higher cortisol concentration in their serum compared with the initial slaughter group. The implications of the outcome of this study are discussed.
Four point-of-use disinfection technologies for treating sewage-contaminated well water were compared. Three systems, based on flocculant-disinfectant packets and N-halamine chlorine and bromine contact disinfectants, provided a range of 4.0 to >6.6 log 10 reductions (LR) of naturally occurring fecal indicator and heterotrophic bacteria and a range of 0.9 to >1.9 LR of coliphage.Disasters and flooding can overwhelm sanitation infrastructure, leading to sewage contamination of potable waters. This may be routine during the wet season in many parts of the world and spreads numerous waterborne diseases (21). Pointof-use (POU) water treatment has reduced the incidence of diarrheal disease when used for household drinking water (3,4,6,13) and is now being promoted for disaster relief. While POU systems have recently been reviewed (14), to our knowledge there has been no direct, experimental comparison for treating actual sewage-contaminated waters. In this study, the efficacies of four POU disinfection systems (based on sodium dichloroisocyanurate [NaDCC] tablets, a flocculent-disinfectant powder, and chlorine and bromine contact disinfectant cartridges) in reducing the concentrations of six microbial indicators in well water contaminated with raw sewage were compared.The NaDCC tablets (67 mg; Aquatabs; Medentech, Wexford, Ireland), used for disinfection in low-turbidity water, have shown preliminary efficacy for routine household drinking water treatment (3, 4). The flocculant-disinfectant packet (4 g; PUR; Procter & Gamble Co., Cincinnati, OH) includes Fe 2 (SO 4 ) 3 , bentonite, Na 2 CO 3 , chitosan, polyacrylamide, KMnO 4 , and Ca(OCl) 2 (13). It achieved Ͼ7.3 log 10 reductions (LR) of 24 bacteria species; Ͼ4.6 LR of poliovirus and rotavirus in EPA no. 2 test water (turbidity, Ͼ30 nephelometric turbidity units [NTU]) (15); and reduced diarrheal illness in Guatemala, Liberia, Kenya, and Pakistan (6, 7, 11, 13).HaloPure canisters (Eureka Forbes, Mumbai, India) contain N-halamine polymer disinfectant beads, poly[1,2-dichloro-5-methyl-5-(4Ј-vinylphenyl)hydrantoin] for chlorine canisters, and poly[1,2-dibromo-5-methyl-5-(4Ј-vinylphenyl)hydrantoin] for bromine canisters. Seeded laboratory trials achieved Ͼ6.8 LR for Escherichia coli and Staphylococcus aureus as water was passed through the canisters (2). The Cl-contact (producing residuals ranging from 0 to 0.6 mg/liter) and Br-contact (with residuals of 0.68 to 1.8 mg/liter) disinfectants achieved 2.9 LR and 5.0 LR of the bacteriophage MS2, respectively, and 27.5% and 88.5% reductions of the algal toxin microcystin, respectively (5).Sewage-contaminated water was prepared by mixing 9 liters of potable, nonchlorinated well water (pH 7.8; turbidity, 0.33 NTU; Williamston, MI) with 1 liter of raw sewage (City of East Lansing Wastewater Treatment Plant, MI) with an average pH of 6.6 Ϯ 0.1, a biochemical oxygen demand of 144 Ϯ 36 mg/ liter, a concentration of total suspended solids of 146 Ϯ 31 mg/liter, and a turbidity of 132 Ϯ 12 NTU. Three disinfection trials were conduct...
A pen feeding experiment was conducted in which steers were fed rice straw (0.68% nitrogen, 0.09% sulfur, dry matter basis) with urea alone; urea and molasses, or sodium sulfate; or all three supplements. The role of rice straw as a drought ration, and the effects of the supplements on intake and liveweight, were examined. Urea alone increased roughage organic matter intake by 14% (P=0.07) and total organic matter intake by 16% (P<0.05). Addition of molasses or sodium sulfate or both to the rice straw had no significant effect on intake (P>0.05). A urea supplement reduced liveweight loss from 149 to 86 g/head.d (P<0.05). In general, the small amounts of molasses and sodium sulfate had little effect on liveweight.
The effects of feeding dry season supplements of salt and urea (NaU), salt, urea and sulfur (NaUS) and molasses and urea (MU) on the liveweight of steers grazing native pasture in northern Queensland were studied over four years. Liveweight during the feeding period was improved (P < 0.05) by each supplement in three years out of four, with a mean level of response of 49 g/d. The supplements gave similar results in two years while in one year NaU and MU were better than NaUS (P < 0.05) and in another NaUS was better than NaU (P < 0.05). Compensatory growth by unsupplemented animals after the feeding period eroded liveweight responses to supplements in most cases. Blood sulfate level was not affected by treatment, nor was it related to liveweight in either the feeding or post-feeding periods. Mean levels for unsupplemented animals were 15.8 and 21.2 �g/ml for the feeding and post-feeding periods, respectively. Salivary Na:K ratios exceeded 18:1 throughout the year for unsupplemented and NaUS groups, indicating sodium sufficiency.
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