Epidemiology and disease burden of tuberculosis in children: a global perspective

Our understanding of the tuberculosis (TB) epidemic in children is incomplete due to challenges in diagnosis and reporting. Children have also been largely excluded from research and advocacy. However, the tide appears to be turning and interest in pediatric TB is increasing. In this article, we explore the epidemiology of childhood TB by first reviewing the natural history of TB in children and the factors that impact on each of the stages from exposure to disease. We then discuss how these factors affect what we see at a country and regional level. Finally, we assess the burden of childhood TB globally. © 2014 Seddon and Shingadia

Linezolid-containing regimens for the treatment of drug-resistant tuberculosis in South African children.

BACKGROUND: Treatment options for drug-resistant tuberculosis (DR-TB) are limited. Linezolid has been successfully used to treat DR-TB in adults, but there are few case reports of its use in children for TB. The reported rate of adverse events in adults is high. METHODS: We conducted a retrospective review of children with DR-TB treated with linezolid-containing regimens from February 2007 to March 2012 at two South African hospitals. RESULTS: Seven children (three human immunodeficiency virus [HIV] infected) received a linezolid-containing regimen. All had culture-confirmed DR-TB; five had previously failed second-line anti-tuberculosis treatment. Four children were cured and three were still receiving anti-tuberculosis treatment, but had culture converted. None of the non-HIV-infected children experienced adverse events while receiving linezolid. Three HIV-infected children had adverse events, one of which was life-threatening; linezolid was permanently discontinued in this case. Adverse events included lactic acidosis (n = 1), pancreatitis (n = 2), peripheral neuropathy (n = 1) and asymptomatic bone marrow hypoplasia (n = 1). CONCLUSION: Linezolid-containing regimens can be effective in treating children with DR-TB even after failing second-line treatment. Adverse events should be monitored, especially in combination with medications that have similar adverse effects. Linezolid remains costly, and a reduced dosage and duration may result in fewer adverse events and lower cost

Captive Rearing Experiments Confirm Song Development without Learning in a Tracheophone Suboscine Bird

The origin of vocal learning in animals has long been the subject of debate, but progress has been limited by uncertainty regarding the distribution of learning mechanisms across the tree of life, even for model systems such as birdsong. In particular, the importance of learning is well known in oscine songbirds, but disputed in suboscines. Members of this diverse group (∼1150 species) are generally assumed not to learn their songs, but empirical evidence is scarce, with previous studies restricted to the bronchophone (non-tracheophone) clade. Here, we conduct the first experimental study of song development in a tracheophone suboscine bird by rearing spotted antbird (Hylophylax naevioides) chicks in soundproofed aviaries. Individuals were raised either in silence with no tutor or exposed to standardized playback of a heterospecific tutor. All individuals surviving to maturity took a minimum of 79 days to produce a crystallized version of adult song, which in all cases was indistinguishable from wild song types of their own species. These first insights into song development in tracheophone suboscines suggest that adult songs are innate rather than learnt. Given that empirical evidence for song learning in suboscines is restricted to polygamous and lek-mating species, whereas tracheophone suboscines are mainly monogamous with long-term social bonds, our results are consistent with the view that sexual selection promotes song learning in birds

Drug-resistant tuberculosis in children

The number of children globally who develop drug-resistant tuberculosis is unclear, in part due to diagnostic challenges and limited resistance testing, and in part because recording and reporting is not comprehensive. Large numbers of children, however, are exposed to drug resistant bacilli each year and it is clear that the very young and those immune-compromised are vulnerable to developing disease. Few studies have looked at the progression from exposure to infection or from infection to disease in the child contacts of adults with drug-resistant tuberculosis. It is uncertain which factors influence this progression and also whether any interventions can prevent it. Finally, few studies have analysed the presentation, treatment and outcome of children with disease. This thesis starts by reviewing what is published regarding drug-resistant tuberculosis in children. This includes systematic reviews of the management of children exposed to drug resistant tuberculosis as well as the management of those with multi drug-resistant tuberculosis disease. It reviews what is known regarding the second-line tuberculosis drugs in children and then clarifies the definitions that are used throughout the rest of the work. The thesis then systematically examines each of the stages from infection to disease with a series of inter-related studies. The first study attempts to quantify the burden of drug resistance in the context that the work is carried out. The following study investigates the risk factors for infection and prevalent disease in children exposed to a multi drug-resistant tuberculosis source case. This is followed by two studies which explore the transmission of drug-resistant bacilli from adults to children. The identification and referral patterns and obstacles to referral for exposed children are examined through operational studies that include qualitative and quantitative components. A descriptive cohort study assesses the toxicity and efficacy of a standardised preventive treatment regimen given to child contacts. The final part of the thesis includes a series of studies to investigate the treatment of drug resistant tuberculosis disease in children and the adverse effects of the second-line medications

Song evolution, speciation, and vocal learning in passerine birds

Phenotypic divergence can promote reproductive isolation and speciation, suggesting a possible link between rates of phenotypic evolution and the tempo of speciation at multiple evolutionary scales. To date, most macroevolutionary studies of diversification have focused on morphological traits, whereas behavioral traits─including vocal signals─are rarely considered. Thus, although behavioral traits often mediate mate choice and gene flow, we have a limited understanding of how behavioral evolution contributes to diversification. Furthermore, the developmental mode by which behavioral traits are acquired may affect rates of behavioral evolution, although this hypothesis is seldom tested in a phylogenetic framework. Here, we examine evidence for rate shifts in vocal evolution and speciation across two major radiations of codistributed passerines: one oscine clade with learned songs (Thraupidae) and one suboscine clade with innate songs (Furnariidae). We find that evolutionary bursts in rates of speciation and song evolution are coincident in both thraupids and furnariids. Further, overall rates of vocal evolution are higher among taxa with learned rather than innate songs. Taken together, these findings suggest an association between macroevolutionary bursts in speciation and vocal evolution, and that the tempo of behavioral evolution can be influenced by variation in developmental modes among lineages

Graz. Sanatorium am Rosenberg

Ehemaliges Sanatorium in Mariagrü

Species interactions regulate the collapse of biodiversity and ecosystem function in tropical forest fragments

Competitive interactions among species with similar ecological niches are known to regulate the assembly of biological communities. However, it is not clear whether such forms of competition can predict the collapse of communities and associated shifts in ecosystem function in the face of environmental change. Here, we use phylogenetic and functional trait data to test whether communities of two ecologically important guilds of tropical birds (frugivores and insectivores) are structured by species interactions in a fragmented Amazonian forest landscape. In both guilds, we found that forest patch size, quality, and degree of isolation influence the phylogenetic and functional trait structure of communities, with small, degraded, or isolated forest patches having an increased signature of competition (i.e., phylogenetic and functional trait overdispersion in relation to null models). These results suggest that local extinctions in the context of fragmentation are nonrandom, with a consistent bias toward more densely occupied regions of niche space. We conclude that the loss of biodiversity in fragmented landscapes is mediated by niche-based competitive interactions among species, with potentially far-reaching implications for key ecosystem processes, including seed dispersal and plant damage by phytophagous insects