Management of latent Mycobacterium tuberculosis infection:WHO guidelines for low tuberculosis burden countries

ABSTRACT Latent tuberculosis infection (LTBI) is characterised by the presence of immune responses to previously acquired Mycobacterium tuberculosis infection without clinical evidence of active tuberculosis (TB). Here we report evidence-based guidelines from the World Health Organization for a public health approach to the management of LTBI in high risk individuals in countries with high or middle upper income and TB incidence of <100 per 100000 per year. The guidelines strongly recommend systematic testing and treatment of LTBI in people living with HIV, adult and child contacts of pulmonary TB cases, patients initiating anti-tumour necrosis factor treatment, patients receiving dialysis, patients preparing for organ or haematological transplantation, and patients with silicosis. In prisoners, healthcare workers, immigrants from high TB burden countries, homeless persons and illicit drug users, systematic testing an

A high-resolution belemnite geochemical analysis of Early Cretaceous (Valanginian-Hauterivian) environmental and climatic perturbations

International audienceThe Early Cretaceous Weissert event, characterized by a positive carbon isotope excursion and coincident with the Paraná-Etendeka volcanism, saw a biogeochemical chain of events that ultimately led to an increase in carbon burial. A conclusive link between the Paraná-Etendeka volcanism and its impact upon the environment remains, however, elusive. Here we reconstruct temperature through the Weissert event from Mg/Ca ratios of belemnites from the Vocontian Trough (France) and SE Spain and use carbon isotopes to link our temperature reconstruction to marine records of carbon cycling. We provide evidence that the Paraná-Etendeka volcanism, unlike some large igneous provinces, did not cause a climate warming. The case can be made for cooling in the last stages of the Weissert event, which possibly reflects substantial CO 2 drawdown. In the absence of warming and consequent accelerated hydrological cycling and the relatively long duration of the eruptive phase of the Paraná-Etendeka, an alternate trigger for increased fertilization of the oceans is implicated

Geochemical indicators of early paleogene climate change in central Utah

This research focuses on the climate and basin evolution of the southwestern United States from the late Paleocene to the early Eocene, from approximately 60 to 50 million years ago. I applied geochemical proxy techniques, including conventional light stable isotope measurements of multiple substrates, as well as the novel clumped isotope paleothermometry technique, to investigate this subject. The early Paleogene topography of western North America was very different from today, with a major mountain range known as the Sevier Thrust Belt existing in the area now occupied by the Basin and Range physiographic province. The foreland to the east of this orogenic belt was divided into a series of endorheic basins occupied by large lakes. The lake which existed in central Utah, referred to today as paleo-Lake Flagstaff from the formation of the same name which records it, has previously been regarded as an arm of paleo-Lake Uinta which existed to the northeast. Using carbon and oxygen isotope measurements of authigenic carbonate sediments, I have confirmed that the sediments of the Flagstaff Formation were the product of a single, large lake. However, the isotopic signatures of Lakes Flagstaff and Uinta are distinct, indicating that they were not connected during this interval. Instead, Lake Flagstaff may have undergone hydrologic connection with paleo-Lake Claron to the southwest. Utilizing the clumped isotope paleothermometer with soil carbonate nodules, I investigated the climate conditions of central Utah across the Paleocene-Eocene boundary, one of the warmest intervals of the past 65 million years. The temperature estimates I produced using this method are considerably warmer than those previously generated for the region using fossil botanical indices. This is partially a product of the differing biases inherent to each estimate, but also indicates that mid-latitude continental temperatures may have been much warmer during the early Eocene than previously thought, addressing one of the major existing questions regarding climate during this epoch. Finally, I analyzed hydrogen isotope ratios of authigenic clay minerals from the same soils spanning the Paleocene-Eocene boundary. At this site, the proxy records time-averaged hydrologic conditions, which can be useful in studies of paleotopographic evolution