Global Patterns in Seasonal Activity of Influenza A/H3N2, A/H1N1, and B from 1997 to 2005: Viral Coexistence and Latitudinal Gradients

Despite a mass of research on the epidemiology of seasonal influenza, overall patterns of infection have not been fully described on broad geographic scales and for specific types and subtypes of the influenza virus. Here we provide a descriptive analysis of laboratory-confirmed influenza surveillance data by type and subtype (A/H3N2, A/H1N1, and B) for 19 temperate countries in the Northern and Southern hemispheres from 1997 to 2005, compiled from a public database maintained by WHO (FluNet). Key findings include patterns of large scale co-occurrence of influenza type A and B, interhemispheric synchrony for subtype A/H3N2, and latitudinal gradients in epidemic timing for type A. These findings highlight the need for more countries to conduct year-round viral surveillance and report reliable incidence data at the type and subtype level, especially in the Tropics

25-hydroxyvitamin D deficiency, exacerbation frequency and human rhinovirus exacerbations in chronic obstructive pulmonary disease.

BACKGROUND: 25-hydroxyvitamin D deficiency is associated with COPD and increased susceptibility to infection in the general population. METHODS: We investigated whether COPD patients deficient in 25-hydroxyvitamin D were more likely to be frequent exacerbators, had reduced outdoor activity and were more susceptible to human rhinovirus (HRV) exacerbations than those with insufficient and normal levels. We also investigated whether the frequency of FokI, BsmI and TaqIα 25-hydroxyvitamin D receptor (VDR) polymorphisms differed between frequent and infrequent exacerbators. RESULTS: There was no difference in 25-hydroxyvitamin D levels between frequent and infrequent exacerbators in the summer; medians 44.1 nmol/L (29.1 - 68.0) and 39.4 nmol/L (22.3 - 59.2) or winter; medians 24.9 nmol/L (14.3 - 43.1) and 27.1 nmol/L (19.9 - 37.6). Patients who spent less time outdoors in the 14 days prior to sampling had lower 25-hydroxyvitamin D levels (p = 0.02). Day length was independently associated with 25-hydroxyvitamin D levels (p = 0.02). There was no difference in 25-hydroxyvitamin D levels between baseline and exacerbation; medians 36.2 nmol/L (IQR 22.4-59.4) and 33.3 nmol/L (23.0-49.7); p = 0.43. HRV positive exacerbations were not associated with lower 25-hydroxyvitamin D levels at exacerbation than exacerbations that did not test positive for HRV; medians 30.0 nmol/L (20.4 - 57.8) and 30.6 nmol/L (19.4 - 48.7). There was no relationship between exacerbation frequency and any VDR polymorphisms (all p > 0.05). CONCLUSIONS: Low 25-hydroxyvitamin D levels in COPD are not associated with frequent exacerbations and do not increase susceptibility to HRV exacerbations. Independent of day length, patients who spend less time outdoors have lower 25-hydroxyvitamin D concentration

A molecular and cellular model to explain the differences in reactivation from latency by herpes simplex and varicella–zoster viruses

There are marked similarities in the biological properties of the human neurotropic herpesviruses herpes simplex virus type 1 (HSV–1) and varicella–zoster virus (VZV), including their ability to establish lifelong latent infections in human peripheral sensory ganglia (PSG). Despite this, their patterns of reactivation are quite different: HSV–1 reactivations occur many times during a lifetime, they are localized to the cutaneous distribution of a single sensory nerve, they are not associated with sensory symptomatology and their frequency decreases with age. VZV recurrence on the other hand is usually a single event which tends to appear with advancing age, its cutaneous eruption involves an entire dermatome and is usually extremely painful. To help explain these differences, we have formulated a model based on current knowledge of the molecular and cellular basis of latent infection in the nervous system. We suggest that the amount of latent viral DNA and RNA in the latently infected tissue (higher with HSV–1), the cellular location of latent virus (neuronal in HSV–1, probably non–neuronal in VZV), the presence or absence of viral replication in the PSG during reactivation together with the host immune response, are all key determinants of the clinical expression of viral reactivation

New ages for human occupation and climatic change at Lake Mungo, Australia

© 2003 Nature Publishing Group, a division of Macmillan Publishers Limited.Australia's oldest human remains, found at Lake Mungo, include the world's oldest ritual ochre burial (Mungo III) and the first recorded cremation (Mungo I). Until now, the importance of these finds has been constrained by limited chronologies and palaeoenvironmental information. Mungo III, the source of the world's oldest human mitochondrial DNA, has been variously estimated at 30 thousand years (kyr) old, 42-45 kyr old and 62 +/- 6 kyr old, while radiocarbon estimates placed the Mungo I cremation near 20-26 kyr ago. Here we report a new series of 25 optical ages showing that both burials occurred at 40 +/- 2 kyr ago and that humans were present at Lake Mungo by 50-46 kyr ago, synchronously with, or soon after, initial occupation of northern and western Australia. Stratigraphic evidence indicates fluctuations between lake-full and drier conditions from 50 to 40 kyr ago, simultaneously with increased dust deposition, human arrival and continent-wide extinction of the megafauna. This was followed by sustained aridity between 40 and 30 kyr ago. This new chronology corrects previous estimates for human burials at this important site and provides a new picture of Homo sapiens adapting to deteriorating climate in the world's driest inhabited continent.James M. Bowler, Harvey Johnston, Jon M. Olley, John R. Prescott, Richard G. Roberts, Wilfred Shawcross and Nigel A. Spoone

Herpes Zoster and Exposure to the Varicella Zoster Virus in an Era of Varicella Vaccination

Objectives. We performed a case–control study to determine if participants with herpes zoster had fewer contacts with persons with varicella or zoster, and with young children, to explore the hypothesis that exposure to persons with varicella zoster virus (VZV) results in “immune boosting.