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Introduction: Influenza B viruses circulate throughout Viet Nam, and their activities vary by region. There have been two antigenically distinct lineages of influenza B viruses co-circulating in the past 20 years; however, only one lineage is selected as a component of contemporary trivalent seasonal influenza vaccines. To improve the understanding of circulating influenza B lineages and influenza vaccine mismatches, we report the virus lineages circulating in northern Viet Nam over an eight-year period (2007-2014). Methods: Lineages of 331 influenza B viruses were characterized by haemagglutination inhibition assay against standard reference ferret (Yamagata) and sheep (Victoria) antisera. Sequence analysis of the haemagglutinin gene was performed in 64 selected influenza B isolates. Results: The proportion of influenza B lineages changed by year. The Yamagata lineage predominated in 2007, 2008 and 2012; the Victoria lineage predominated in 2009-2014 except 2012. The two lineages showed continuous evolution over time. The Northern Hemisphere's influenza vaccine components were mismatched with the predominant circulating viruses in 2007, 2009 and 2014. Discussion: The seasonality of influenza B activity is more variable in tropical and subtropical regions than in temperate zones. Our data showed a common co-circulation of both influenza B lineages in northern Viet Nam, and it was difficult to predict which one was the predominant lineage. Quadrivalent influenza vaccines containing both lineages may improve the effectiveness of influenza vaccine programmes in the future. [ABSTRACT FROM AUTHOR]

Abstract  During an epidemiological survey for Paragonimus and paragonimosis in northern Vietnam, we found extremely large excysted metacercariae (2.50 ± 0.14 mm in length and 0.72 ± 0.08 mm in width; mean ± standard deviation of 20 samples) in mountainous crabs, Potamiscus mieni. Adult worms were successfully obtained by intraperitoneal injection with those large excysted metacercariae in a cat. Morphological and morphometric data of those large excysted metacercariae and the adult worms derived from them are identical to those of Paragonimus proliferus found in Yunnan province, China. However, when second internal transcribed spacer region and cytochrome oxidase subunit 1 gene sequences of those metacercariae and adult worms were compared with those of known Paragonimus spp. deposited in the GenBank, they were almost completely identical to those of Paragonimus hokuoensis metacercariae in China, of which adult worms have never been reported. This is the first record of P. proliferus in Vietnam and the first record from outside of China. Phylogenetic relationship between P. proliferus and P. hokuoensis is discussed. [ABSTRACT FROM AUTHOR]

Abstract: The 900-km-long Red River shear zone (RRSZ) lends a compelling support to the continental extrusion model for the tectonic evolution of southeastern Asia, but has been challenged by many of views, as some new records mainly from northern Vietnam, suspecting the dimensions of RRSZ neither in depth nor in displacement are as large as we expected before. However, compared to the northwestern half of the RRSZ in Yunnan province better studied by many fields, the southeastern half in northern Vietnam is relatively poorly constrained by seismic study, due to insufficient stations and data in the past. This study, using a newly deployed portable broadband seismic network, obtained the first local seismic tomography with a stepwise inversion using P and Pn phases. Surface geology, major structures, and rock properties are well correlated and identified in our model, suggesting the RRSZ is a lithospheric structure at least penetrating to the uppermost mantle with mantle thermal anomalies. In general, the crust of northern Vietnam appears to be weak and sits on a relatively hot uppermost mantle, showing a long and complex thermo tectonic history. A mid-lower crustal segmentation of RRSZ is also proposed to compromise the discrepancies recently observed between Yunnan province and northern Vietnam. [Copyright &y& Elsevier]