Quantifying neighbourhood socioeconomic effects in clustering of behaviour-related risk factors: a multilevel analysis

Background

The extent to which neighbourhood characteristics explain accumulation of health behaviours is poorly understood. We examined whether neighbourhood disadvantage was associated with co-occurrence of behaviour-related risk factors, and how much of the neighbourhood differences in the co-occurrence can be explained by individual and neighbourhood level covariates.

Methods

The study population consisted of 60 694 Finnish Public Sector Study participants in 2004 and 2008. Neighbourhood disadvantage was determined using small-area level information on household income, education attainment, and unemployment rate, and linked with individual data using Global Positioning System-coordinates. Associations between neighbourhood disadvantage and co-occurrence of three behaviour-related risk factors (smoking, heavy alcohol use, and physical inactivity), and the extent to which individual and neighbourhood level covariates explain neighbourhood differences in co-occurrence of risk factors were determined with multilevel cumulative logistic regression.

Results

After adjusting for age, sex, marital status, and population density we found a dose-response relationship between neighbourhood disadvantage and co-occurrence of risk factors within each level of individual socioeconomic status. The cumulative odds ratios for the sum of health risks comparing the most to the least disadvantaged neighbourhoods ranged between 1.13 (95% confidence interval (CI): 1.03–1.24) and 1.75 (95% CI, 1.54–1.98). Individual socioeconomic characteristics explained 35%, and neighbourhood disadvantage and population density 17% of the neighbourhood differences in the co-occurrence of risk factors.

Conclusions

Co-occurrence of poor health behaviours associated with neighbourhood disadvantage over and above individual''s own socioeconomic status. Neighbourhood differences cannot be captured using individual socioeconomic factors alone, but neighbourhood level characteristics should also be considered.     

Thunderstorm associated asthma: a detailed analysis of environmental factors.

OBJECTIVES--To seek associations between meteorological factors, concentrations of air pollutants or pollen, and an asthma epidemic which occurred in London on 24 and 25 June 1994 after a thunderstorm. DESIGN--Retrospective study of patients'' accident and emergency department records, with bivariate and multivariate analysis of environmental factors and data collection for the two months surrounding the epidemic. SETTING--The accident and emergency department of St Mary''s Hospital in west central London. SUBJECTS--148 patients presenting with asthma between 1 June and 31 July 1994, of whom 40 presented in the 24 hours after the storm. RESULTS--The asthma epidemic was significantly associated with a drop in air temperature six hours previously and a high grass pollen concentration nine hours previously. Non-epidemic asthma was significantly associated with lightning strikes, increase in humidity or sulphur dioxide concentration, a drop in temperature or high rainfall the previous day, and a decrease in maximum air pressure or changes in grass pollen counts over the previous two days. CONCLUSIONS--New episodes of asthma during the epidemic on 24 and 25 June 1994 were associated with a fall in air temperature and a rise in grass pollen concentration. Non-epidemic asthma was significantly associated with a greater number of environmental changes. This may indicate that the patients with thunderstorm associated asthma were a separate population, sensitive to different environmental stimuli.     

Host selection by the Louse Fly Crataerina pallida, an avian nest ectoparasite of the Common Swift Apus apus

Preferences by parasites for particular hosts may have important implications for the functioning of host–parasite systems, however, this parasitic life-history trait remains little studied. No detrimental effect of Louse Fly Crataerina pallida parasitism has been found on Common Swift Apus apus nestling hosts. Host selection choices may be mediating the effect this parasite has and account for this apparent avirulence. Two aspects of parasite host selection were studied at a breeding colony of Common Swifts during 2008; (1) intra-brood differences in C. pallida parasitism were studied to determine the influence of nestling rank, (2) differences in male and female C. pallida parasitism were investigated, as they may result in varying costs of parasitism to hosts. C. pallida populations were found to preferentially parasitize higher rather than lower ranking nestlings within broods of both two and three chicks. Greater proportions of females were seen upon nestlings than at the nest, and upon higher ranking than lower ranking nestlings within broods. These results indicate that host selection occurs and this may thus account for the lack of parasitic virulence reported within this host–parasite system.     

Host genetics and environmental factors regulate ecological succession of the mouse colon tissue-associated microbiota

Background

The integration of host genetics, environmental triggers and the microbiota is a recognised factor in the pathogenesis of barrier function diseases such as IBD. In order to determine how these factors interact to regulate the host immune response and ecological succession of the colon tissue-associated microbiota, we investigated the temporal interaction between the microbiota and the host following disruption of the colonic epithelial barrier.

Methodology/Principal Findings

Oral administration of DSS was applied as a mechanistic model of environmental damage of the colon and the resulting inflammation characterized for various parameters over time in WT and Nod2 KO mice.

Results

In WT mice, DSS damage exposed the host to the commensal flora and led to a migration of the tissue-associated bacteria from the epithelium to mucosal and submucosal layers correlating with changes in proinflammatory cytokine profiles and a progressive transition from acute to chronic inflammation of the colon. Tissue-associated bacteria levels peaked at day 21 post-DSS and declined thereafter, correlating with recruitment of innate immune cells and development of the adaptive immune response. Histological parameters, immune cell infiltration and cytokine biomarkers of inflammation were indistinguishable between Nod2 and WT littermates following DSS, however, Nod2 KO mice demonstrated significantly higher tissue-associated bacterial levels in the colon. DSS damage and Nod2 genotype independently regulated the community structure of the colon microbiota.

Conclusions/Significance

The results of these experiments demonstrate the integration of environmental and genetic factors in the ecological succession of the commensal flora in mammalian tissue. The association of Nod2 genotype (and other host polymorphisms) and environmental factors likely combine to influence the ecological succession of the tissue-associated microflora accounting in part for their association with the pathogenesis of inflammatory bowel diseases.     

Host range of an NPV and a GV isolated from the common cutworm, Agrotis segetum: pathogenicity within the cutworm complex

The term cutworm covers a range of species with a similar life history that can be very damaging pests on a wide range of crops. Attacks by cutworms are often made up of more than one species; thus, the most cost effective microbial control agent needs to be pathogenic for multiple species within this complex. In this study we investigate the host range of Agrotis segetum NPV and A. segetum GV for other cutworm species and closely related Noctuinae. Eight species, A. segetum, Agrotis ipsilon, Agrotis exclamationis, Agrotis puta, Noctua comes, Peridroma saucia, Xestia sexstrigata, and Xestia xanthographa, were clearly susceptible to AgseNPV, which was confirmed by DNA analysis. Aglais urticae, Diarsia rubi, Noctua pronuba, and Xestia c-nigrum were not susceptible to AgseNPV at the doses used. Noctua fimbriata, Noctua janthina, and Ochroplura plecta gave ambivalent results: larvae died of NPV infection when they were challenged with AgseNPV, but these individuals only produced weak positives in a squash blot analysis and there was insufficient DNA for confirmation by restriction endonuclease profiling. These ambivalent results could suggest either a weak infection by AgseNPV or partial homology between their own virus and AgseNPV. The untreated control insects of several species died of NPV infection, which indicates that these field-collected insects were probably carrying a vertically transmitted NPV. Fewer species were tested with AgseGV and only N. pronuba and N. comes were susceptible. N. fimbriata and Helicoverpa armigera were not susceptible to AgseGV.     

Leprosy among patient contacts: a multilevel study of risk factors

Background

This study aimed to evaluate the risk factors associated with developing leprosy among the contacts of newly-diagnosed leprosy patients.

Methodology/Principal Findings

A total of 6,158 contacts and 1,201 leprosy patients of the cohort who were diagnosed and treated at the Leprosy Laboratory of Fiocruz from 1987 to 2007 were included. The contact variables analyzed were sex; age; educational and income levels; blood relationship, if any, to the index case; household or non-household relationship; length of time of close association with the index case; receipt of bacillus Calmette-Guérin (BGG) vaccine and presence of BCG scar. Index cases variables included sex, age, educational level, family size, bacillary load, and disability grade. Multilevel logistic regression with random intercept was applied. Among the co-prevalent cases, the leprosy-related variables that remained associated with leprosy included type of household contact, [odds ratio (OR) = 1.33, 95% confidence interval (CI): 1.02, 1.73] and consanguinity with the index case, (OR = 1.89, 95% CI: 1.42–2.51). With respect to the index case variables, the factors associated with leprosy among contacts included up to 4 years of schooling and 4 to 10 years of schooling (OR = 2.72, 95% CI: 1.54–4.79 and 2.40, 95% CI: 1.30–4.42, respectively) and bacillary load, which increased the chance of leprosy among multibacillary contacts for those with a bacillary index of one to three and greater than three (OR = 1.79, 95% CI: 1.19–2.17 and OR: 4.07–95% CI: 2.73, 6.09), respectively. Among incident cases, household exposure was associated with leprosy (OR = 1.96, 95% CI: 1.29–2.98), compared with non-household exposure. Among the index case risk factors, an elevated bacillary load was the only variable associated with leprosy in the contacts.

Conclusions/Significance

Biological and social factors appear to be associated with leprosy among co-prevalent cases, whereas the factors related to the infectious load and proximity with the index case were associated with leprosy that appeared in the incident cases during follow-up.     

环境因子对球孢白僵菌侵染桔小实蝇致病力的影响

本文测定了温湿度、紫外线及常见杀虫剂等环境因子对球孢白僵菌B6菌株侵染桔小实蝇致病力的影响。结果表明,在19℃-31℃的温度范围内,B6菌株对桔小实蝇成虫、蛹与老熟幼虫均有致病力。在19℃-25℃条件下,桔小实蝇上述三种虫态的死亡率均随着温度的升高而增加,但在28℃和31℃温度条件下,桔小实蝇的死亡率则随着温度升高而降低。在1.8×10^8孢子/ml浓度条件下,成虫在25℃温度条件下的致死中时LT50为6.6d,在31℃的LT50为30.2d。在不同温度条件下,B6菌株对桔小实蝇成虫的致死中时差异较大。湿度越大,球孢白僵菌致病力越强,桔小实蝇的死亡速率越快。球孢白僵菌孢子萌发率随着紫外线照射时间增加而逐步降低。测定了7种常见的杀虫剂对球孢白僵菌菌落的生长影响,其中25%高效氯氟氰菊酯、2.0%阿维菌素、40%辛硫磷和10%除尽对菌落生长有促进作用。     

Host and pathogen ecology drive the seasonal dynamics of a fungal disease,white-nose syndrome

Seasonal patterns in pathogen transmission can influence the impact of disease on populations and the speed of spatial spread. Increases in host contact rates or births drive seasonal epidemics in some systems, but other factors may occasionally override these influences. White-nose syndrome, caused by the emerging fungal pathogen Pseudogymnoascus destructans, is spreading across North America and threatens several bat species with extinction. We examined patterns and drivers of seasonal transmission of P. destructans by measuring infection prevalence and pathogen loads in six bat species at 30 sites across the eastern United States. Bats became transiently infected in autumn, and transmission spiked in early winter when bats began hibernating. Nearly all bats in six species became infected by late winter when infection intensity peaked. In summer, despite high contact rates and a birth pulse, most bats cleared infections and prevalence dropped to zero. These data suggest the dominant driver of seasonal transmission dynamics was a change in host physiology, specifically hibernation. Our study is the first, to the best of our knowledge, to describe the seasonality of transmission in this emerging wildlife disease. The timing of infection and fungal growth resulted in maximal population impacts, but only moderate rates of spatial spread.     

Social capital and mental health in Japan: a multilevel analysis

Background

A national cross-sectional survey was conducted in Japan. This is because the growing recognition of the social determinants of health has stimulated research on social capital and mental health. In recent years, systematic reviews have found that social capital may be a useful factor in the prevention of mental illness. Despite these studies, evidence on the association between social capital and mental health is limited as there have been few empirical discussions that adopt a multilevel framework to assess whether social capital at the ecological level is associated with individual mental health. The aim of this study was to use the multilevel approach to investigate the association between neighborhood social capital and mental health after taking into account potential individual confounders.

Methodology/Principal Findings

We conducted a multilevel analysis on 5,956 individuals nested within 199 neighborhoods. The outcome variable of self-reported mental health was measured by the one dimension of SF-36 and was summed to calculate a score ranging from 0 to 100. This study showed that high levels of cognitive social capital, measured by trust (regression coefficient = 9.56), and high levels of structural social capital, measured by membership in sports, recreation, hobby, or cultural groups (regression coefficient = 8.72), were associated with better mental health after adjusting for age, sex, household income, and educational attainment. Furthermore, after adjusting for social capital perceptions at the individual level, we found that the association between social capital and mental health also remained.

Conclusions/Significance

Our findings suggest that both cognitive and structural social capital at the ecological level may influence mental health, even after adjusting for individual potential confounders including social capital perceptions. Promoting social capital may contribute to enhancing the mental health of the Japanese.     

Multiple benefits drive helping behavior in a cooperatively breeding bird: an integrated analysis

Several hypotheses exist to explain the seemingly altruistic helping behavior of cooperative breeders, although the general utility of these hypotheses remains unclear. While the potential importance of inclusive fitness benefits (kin selection) is traditionally widely appreciated, it is increasingly recognized that direct benefits may be more important than assumed. We use an integrative two-step framework to assess support for current hypotheses in purple-crowned fairy wrens, a species where subordinates vary in relatedness to breeders and helping increases productivity. After establishing that assumptions of pay-to-stay and social prestige hypotheses (predicting that helping functions as "paying rent" to stay on the territory or as a signal of individual quality, respectively) were not met and that parentage by subordinates is extremely rare, we tested whether subordinates adjusted nestling feeding rates following the predictions of the kin selection and group augmentation hypotheses. Benefits of kin selection result from investment in relatives, and group augmentation benefits accrue when subordinates invest more in their own future helpers, for example, when they have a better chance of inheriting the breeding position. We found that subordinates fed siblings more than unrelated nestlings, indicating that kin selection could facilitate cooperation. Moreover, the effect of relatedness on feeding effort varied depending on the probability of inheriting a breeding position, suggesting that active group augmentation can explain investment by unrelated subordinates. This statistical interaction would have gone undetected had we not considered both factors simultaneously, illustrating that a focus on single hypotheses could lead to underestimation of their importance in explaining cooperative breeding.     

Identification of genetic and environmental factors stimulating excision from Streptomyces scabiei chromosome of the toxicogenic region responsible for pathogenicity

The genes conferring pathogenicity in Streptomyces turgidiscabies, a pathogen causing common scab of potato, are grouped together on a pathogenicity island (PAI), which has been found to be mobile and appears to transfer and disseminate like an integrative and conjugative element (ICE). However, in Streptomyces scabiei, another common scab‐inducing species, the pathogenicity genes are clustered in two regions: the toxicogenic region (TR) and the colonization region. The S. scabiei 87.22 genome was analysed to investigate the potential mobility of the TR. Attachment sites (att), short homologous sequences that delineate ICEs, were identified at both extremities of the TR. An internal att site was also found, suggesting that the TR has a composite structure (TR1 and TR2). Thaxtomin biosynthetic genes, essential for pathogenicity, were found in TR1, whereas candidate genes with known functions in recombination, replication and conjugal transfer were found in TR2. Excision of the TR1 or TR2 subregions alone, or of the entire TR region, was observed, although the excision frequency of TR was low. However, the excision frequency was considerably increased in the presence of either mitomycin C or Streptomyces coelicolor cells. A composite TR structure was not observed in all S. scabiei and Streptomyces acidiscabies strains tested. Of the ten strains analysed, seven lacked TR2 and no TR excision event could be detected in these strains, thus suggesting the implication of TR2 in the mobilization of S. scabiei TR.     

Comparative genomic analysis of clinical and environmental strains provides insight into the pathogenicity and evolution of Vibrio parahaemolyticus

Background

Vibrio parahaemolyticus is a Gram-negative halophilic bacterium. Infections with the bacterium could become systemic and can be life-threatening to immunocompromised individuals. Genome sequences of a few clinical isolates of V. parahaemolyticus are currently available, but the genome dynamics across the species and virulence potential of environmental strains on a genome-scale have not been described before.

Results

Here we present genome sequences of four V. parahaemolyticus clinical strains from stool samples of patients and five environmental strains in Hong Kong. Phylogenomics analysis based on single nucleotide polymorphisms revealed a clear distinction between the clinical and environmental isolates. A new gene cluster belonging to the biofilm associated proteins of V. parahaemolyticus was found in clincial strains. In addition, a novel small genomic island frequently found among clinical isolates was reported. A few environmental strains were found harboring virulence genes and prophage elements, indicating their virulence potential. A unique biphenyl degradation pathway was also reported. A database for V. parahaemolyticus (http://kwanlab.bio.cuhk.edu.hk/vp) was constructed here as a platform to access and analyze genome sequences and annotations of the bacterium.

Conclusions

We have performed a comparative genomics analysis of clinical and environmental strains of V. parahaemolyticus. Our analyses could facilitate understanding of the phylogenetic diversity and niche adaptation of this bacterium.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-1135) contains supplementary material, which is available to authorized users.     

Fine-scale patterns of vegetation and environmental factors on an ombrotrophic mire expanse: a numerical approach

The vegetation within an ombrotrophic mire expanse in SE Norway is studied in detail. Percentage cover of 45 species in 436 sample plots (16 ×16 cm), dispersed on 26 transects, are recorded. In addition, species abundance in 6976 subplots (4×4 cm) are recorded. 14 variables are recorded for each of the sample plots, while only distance to the water-table is estimated for the subplots. Spatial co-ordinates are supplied for all sample- and subplots. DCA ordination of a data-set consisting of 412 sample plots reveals two ecologically interpretable vegetational gradients: the hummock-hollow gradient (DCA 1), and a gradient associated with the peat-production of the bottom layer (DCA 2). Passive DCA of subplots is used to get an impression of within sample plot heterogeneity, and shows that the fine-scale compositional turnover may be considerable. Partitioning of the variation in species abundance data is done by use of (partial) CCA. The fraction of unexplained variation is rather large for all the tested data-sets, but within the total variation explained, both distance to the water-table and spatial structure explain large parts.     

Of fleas and geese: the impact of an increasing nest ectoparasite on reproductive success

Past studies on the relationship between nest ectoparasites and avian fitness have been primarily limited to altricial hosts. Life history strategies of precocial and altricial birds vary considerably, limiting our ability to infer the effect of nest parasites on fitness of precocial species. Ross's Chen rossii and lesser snow goose Chen caerulescens caerulescens populations have been growing at unprecedented high rates. New limiting factors on vital rates of these precocial birds may arise after populations have been released from previously regulating factors. The flea Ceratophyllus vagabundus vagabundus is an apparently newly emerging nest parasite in the arctic goose colony at Karrak Lake, Nunavut, Canada. We examined the relationship between flea abundance (measured by the proportion of goose eggs covered by blood in each nest) and goose reproductive success from 2001–2004. In three of four years of study, nest success was inversely related to flea abundance in nests. Despite the potential for high costs to individuals, the overall effects of fleas on goose nesting success have thus far been small. We demonstrated that nest parasites negatively influence reproductive success of precocial bird hosts despite host life history strategy of leaving the nest quickly after hatch, which results in minimal exposure to nest parasites compared to altricial birds that raise their young in the nest.     

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.