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Background: The fraction of persons with influenza virus infection, who do not report any signs or symptoms throughout the course of infection is referred to as the asymptomatic fraction.Methods: We conducted a systematic review and meta-analysis of published estimates of the asymptomatic fraction of influenza virus infections. We found that estimates of the asymptomatic fraction were reported from two different types of studies: first, outbreak investigations with short-term follow-up of potentially exposed persons and virologic confirmation of infections; second, studies conducted across epidemics typically evaluating rates of acute respiratory illness among persons with serologic evidence of infection, in some cases adjusting for background rates of illness from other causes.Results: Most point estimates from studies of outbreak investigations fell in the range 4%-28% with low heterogeneity (I = 0%) with a pooled mean of 16% (95% confidence interval = 13%, 19%). Estimates from the studies conducted across epidemics without adjustment were very heterogeneous (point estimates 0%-100%; I = 97%), while estimates from studies that adjusted for background illnesses were more consistent with point estimates in the range 65%-85% and moderate heterogeneity (I = 58%). Variation in estimates could be partially explained by differences in study design and analysis, and inclusion of mild symptomatic illnesses as asymptomatic in some studies.Conclusions: Estimates of the asymptomatic fraction are affected by the study design, and the definitions of infection and symptomatic illness. Considerable differences between the asymptomatic fraction of infections confirmed by virologic versus serologic testing may indicate fundamental differences in the interpretation of these two indicators. [ABSTRACT FROM AUTHOR]

A modified electrode, based on a hexadecane (C16)-coated glassy-carbon electrode (GCE) has been developed for the determination of parathion. The electrochemical behavior of parathion was investigated by cyclic voltammetry (CV). The peak potential and peak current were found to depend on the supporting electrolyte and the pH of the buffer solution. The reduction currents for parathion were proportional to parathion concentration over the range 8×10–8–2×10–5 mol L–1. The detection limit was 2×10–8 mol L–1 parathion for an accumulation time of 30 s. The effects of organic and inorganic species on the determination of parathion were also studied. A procedure was developed to extract parathion from spiked soil samples using a mixture of dichloromethane and acetone as the extraction solvent. The complete extraction and analytical procedure are simple, inexpensive and rapid. Parathion was determined in a soil sample by use of linear scan voltammetry (LSV). [ABSTRACT FROM AUTHOR]

The Okinawa Trough (OT) is a back-arc basin with a wide distribution of active cold seep systems. However, our understanding of the metabolic function of microbial communities in the cold seep sediments of the OT remains limited. In this study, we investigated the vertical profiles of functional genes involved in methane, nitrogen, and sulphur cycling in the cold seep sediments of the OT. Furthermore, we explored the possible coupling mechanisms between these biogeochemical cycles. The study revealed that the majority of genes associated with the nitrogen and sulphur cycles were most abundant in the surface sediment layers. However, only the key genes responsible for sulphur disproportionation ( sor ), nitrogen fixation ( nifDKH ), and methane metabolism ( mcrABG ) were more prevalent within sulfate-methane transition zone (SMTZ). Significant positive correlations ( P < 0.05) were observed between functional genes involved in sulphur oxidation, thiosulphate disproportionation with denitrification, and dissimilatory nitrate reduction to ammonium (DNRA), as well as between AOM/methanogenesis and nitrogen fixation, and between sulphur disproportionation and AOM. A genome of Filomicrobium (class Alphaproteobacteria) has demonstrated potential in chemoautotrophic activities, particularly in coupling DNRA and denitrification with sulphur oxidation. Additionally, the characterized sulfate reducers such as Syntrophobacterales have been found to be capable of utilizing nitrate as an electron acceptor. The predominant methanogenic/methanotrophic groups in the OT sediments were identified as H 2 -dependent methylotrophic methanogens (Methanomassiliicoccales and Methanofastidiosales) and ANME-1a. This study offered a thorough understanding of microbial ecosystems in the OT cold seep sediments, emphasizing their contribution to nutrient cycling.IMPORTANCEThe Okinawa Trough (OT) is a back-arc basin formed by extension within the continental lithosphere behind the Ryukyu Trench arc system. Cold seeps are widespread in the OT. While some studies have explored microbial communities in OT cold seep sediments, their metabolic potential remains largely unknown. In this study, we used metagenomic analysis to enhance comprehension of the microbial community's role in nutrient cycling and proposed hypotheses on the coupling process and mechanisms involved in biogeochemical cycles. It was revealed that multiple metabolic pathways can be performed by a single organism or microbes that interact with each other to carry out various biogeochemical cycling. This data set provided a genomic road map on microbial nutrient cycling in OT sediment microbial communities., Competing Interests: The authors declare no conflict of interest.