116 research outputs found
Travel-associated hepatitis A in Europe, 2009 to 2015.
BackgroundTravel to countries with high or intermediate hepatitis A virus (HAV) endemicity is a risk factor for infection in residents of countries with low HAV endemicity. Aim: The objective of this study was to estimate the risk for hepatitis A among European travellers using surveillance and travel denominator data. Methods: We retrieved hepatitis A surveillance data from 13 European Union (EU)/ European Economic Area (EEA) countries with comprehensive surveillance systems and travel denominator data from the Statistical Office of the European Union. A travel-associated case of hepatitis A was defined as any case reported as imported. Results: From 2009 to 2015, the 13 countries reported 18,839 confirmed cases of hepatitis A, of which 5,233 (27.8%) were travel-associated. Of these, 39.8% were among children younger than 15 years. The overall risk associated with travel abroad decreased over the period at an annual rate of 3.7% (95% confidence interval (CI): 0.7-2.7) from 0.70 cases per million nights in 2009 to 0.51 in 2015. The highest risk was observed in travellers to Africa (2.11 cases per million nights). Cases more likely to be reported as travel-associated were male and of younger age (< 25 years). Conclusion: Travel is still a major risk factor for HAV infection in the EU/EEA, although the risk of infection may have slightly decreased in recent years. Children younger than 15 years accounted for a large proportion of cases and should be prioritised for vaccination
Close companions to Brightest Cluster Galaxies: Support for minor mergers and downsizing
We identify close companions of Brightest Cluster Galaxies (BCGs) for the
purpose of quantifying the rate at which these galaxies grow via mergers. By
exploiting deep photometric data from the CFHTLS, we probe the number of
companions per BCG (Nc) with luminosity ratios down to those corresponding to
potential minor mergers of 20:1. We also measure the average luminosity in
companions per galaxy (Lc). We find that Nc and Lc rise steeply with luminosity
ratio for both the BCGs, and a control sample of other bright, red, cluster
galaxies. The trend for BCGs rises more steeply, resulting in a larger number
of close companions. For companions within 50kpc of a BCG, Nc= 1.38+/-0.14 and
Lc=(2.14+/-0.31)x10^(10)L_sun and for companions within 50kpc of a luminosity
matched control sample of non-BCGs, Nc=0.87+/-0.08 and
Lc=(1.48+/-0.20)x10^(10)L_sun. This suggests that the BCGs are likely to
undergo more mergers compared to otherwise comparable luminous galaxies.
Additionally, compared to a local sample of luminous red galaxies, the more
distant sample presented in this study (with redshifts between 0.15-0.39,)
shows a higher Nc, suggesting the younger and smaller BCGs are still undergoing
hierarchical formation. Using the Millennium Simulations we model and estimate
the level of contamination due to unrelated cluster galaxies. The contamination
by interloping galaxies is 50% within projected separations of 50kpc, but
within 30kpc, 60% of identified companions are real physical companions. We
conclude that the luminosity of bound merger candidates down to luminosity
ratios of 20:1 could be adding as much as 10% to the mass of a typical BCG over
0.5Gyr at redshifts of z~0.3.Comment: 10 pages, 7 figures. Accepted and to be published in MNRA
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