Appraisal of Phlebotomus argentipes habitat suitability using a remotely sensed index in the kala-azar endemic focus of Bihar, India

Visceral leishmaniasis, or kala-azar, is recognised as a serious emerging public health problem in India. In this study, environmental parameters, such as land surface temperature (LST) and renormalised difference vegetation indices (RDVI), were used to delineate the association between environmental variables and Phlebotomus argentipes abundance in a representative endemic region of Bihar, India. The adult P. argentipes were collected between September 2009-February 2010 using the hand-held aspirator technique. The distribution of P. argentipes was analysed with the LST and RDVI of the peak and lean seasons. The association between environmental covariates and P. argentipes density was analysed a multivariate linear regression model. The sandfly density at its maximum in September, whereas the minimum density was recorded in January. The regression model indicated that the season, minimum LST, mean LST and mean RDVI were the best environmental covariates for the P. argentipes distribution. The final model indicated that nearly 74% of the variance of sandfly density could be explained by these environmental covariates. This approach might be useful for mapping and predicting the distribution of P. argentipes, which may help the health agencies that are involved in the kala-azar control programme focus on high-risk areas.

Virulence profiles of bacteremic extended-spectrum β-lactamase-producing Escherichia coli: association with epidemiological and clinical features.

There is scarce data about the importance of phylogroups and virulence factors (VF) in bloodstream infections (BSI) caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBLEC). A prospective multicenter Spanish cohort including 191 cases of BSI due to ESBLEC was studied. Phylogroups and 25 VF genes were investigated by PCR. ESBLEC were classified into clusters according to their virulence profiles. The association of phylogropus, VF, and clusters with epidemiological features were studied using multivariate analysis. Overall, 57.6%, 26.7%, and 15.7% of isolates belonged to A/B1, D and B2 phylogroups, respectively. By multivariate analysis (adjusted OR [95% CI]), virulence cluster C2 was independently associated with urinary tract source (5.05 [0.96-25.48]); cluster C4 with sources other than urinary of biliary tract (2.89 [1.05-7.93]), and cluster C5 with BSI in non-predisposed patients (2.80 [0.99-7.93]). Isolates producing CTX-M-9 group ESBLs and from phylogroup D predominated among cluster C2 and C5, while CTX-M-1 group of ESBL and phylogroup B2 predominantes among C4 isolates. These results suggest that host factors and previous antimicrobial use were more important than phylogroup or specific VF in the occurrence of BSI due to ESBLEC. However, some associations between virulence clusters and some specific epidemiological features were found.

Wandering, verbally and physically abusive behaviour and their relation with pain in nursing homes residents

Backgrounds:¦Behavioural and psychological symptoms of dementia (BPSD) include, among others, hallucinations, delusions, depression, euphoria, agitation, aggression, sexual desinhibition, sleep disturbances, and apathy (1). To our knowledge, surprisingly few studies looked into the possible association between pain and BPSD in nursing home residents. Given this dearth of studies, we wondered whether or not there is an association, in nursing home residents, between pain and BPSD, in particular wandering as well as verbally and physically abusive behaviour, and whether or not this possible association changes with the degree of cognitive impairment.¦Method:¦All nursing home residents in the three Swiss cantons Aargau, Basel-City, and Solothurn (corresponding to 13.5%¦of the total Swiss population) receive a Resident Assessment Instrument Minimum Data Set (RAI-MDS)¦assessment within the first two weeks upon entry. This yielded a total sample of 16'430 nursing home residents considering that the residents' assessment took place between 1997 and 2007 and that we only took into account the admission RAI-MDS assessment. Only residents for whom data on pain was recorded were included in the study (n = 16'183).¦Results:¦Wandering correlated significantly with pain although the effect size was small (Spearman correlation coefficient = 0.052; p = 0.000), a result very similar to that found for VAB (Spearman correlation coefficient = 0.034; p = 0.000) and PAB (Spearman correlation coefficient = 0.043; p = 0.000). Likewise, using linear regression analyses, pain was very significantly associated with any of the three BPSD considered, but it predicted astonishingly little of the¦variance observed (wandering: B = 0.036; p = 0.000; R2 = 0.002; VAB: B = 0.021; p = 0.000; R2 = 0.001 PAB: B = 0.012; p = 0.000; R2 = 0.001). The interaction of pain and cognition had a significant effect on the three BPSD, suggesting that cognition was a moderator of the relationship between pain and all three behaviours.¦Conclusion:¦Wandering behaviours, VAB and PAB seem to be predicted by many factors. Although pain predicts only a small part of variance of these behaviours, it still remains important to recognise and treat pain in order to reduce these behaviours at least a little both in intensity and frequency. Given the dearth of studies and their somewhat contradictory results, further studies ought to investigate the role, the type and localisation of pain might play on the expression of different BPSD or how residents suffering from dementia perceive pain.

Distinct population structure for co-occurring Anopheles goeldii and Anopheles triannulatus in Amazonian Brazil

To evaluate whether environmental heterogeneity contributes to the genetic heterogeneity in Anopheles triannulatus, larval habitat characteristics across the Brazilian states of Roraima and Pará and genetic sequences were examined. A comparison with Anopheles goeldii was utilised to determine whether high genetic diversity was unique to An. triannulatus. Student t test and analysis of variance found no differences in habitat characteristics between the species. Analysis of population structure of An. triannulatus and An. goeldii revealed distinct demographic histories in a largely overlapping geographic range. Cytochrome oxidase I sequence parsimony networks found geographic clustering for both species; however nuclear marker networks depicted An. triannulatus with a more complex history of fragmentation, secondary contact and recent divergence. Evidence of Pleistocene expansions suggests both species are more likely to be genetically structured by geographic and ecological barriers than demography. We hypothesise that niche partitioning is a driving force for diversity, particularly in An. triannulatus.

Profitability, uncertainty and multi-product firm product proliferation: The Spanish car industry

This article studies how product introduction decisions relate to profitability and uncertainty in the context of multi-product firms and product differentiation. These two features, common to many modern industries, have not received much attention in the literature as compared to the classical problem of firm entry, even if the determinants of firm and product entry are quite different. The theoretical predictions about the sign of the impact of uncertainty on product entry are not conclusive. Therefore, an econometric model relating firms’ product introduction decisions with profitability and profit uncertainty is proposed. Firm’s estimated profits are obtained from a structural model of product demand and supply, and uncertainty is proxied by profits’ variance. The empirical analysis is carried out using data on the Spanish car industry for the period 1990-2000. The results show a positive relationship between product introduction and profitability, and a negative one with respect to profit variability. Interestingly, the degree of uncertainty appears to be a driving force of entry stronger than profitability, suggesting that the product proliferation process in the Spanish car market may have been mainly a consequence of lower uncertainty rather than the result of having a more profitable market

Maternal and paternal contributions to pathogen resistance dependent on development stage in a whitefish (Salmonidae)

It is often assumed that maternal and paternal contributions to offspring phenotype change over the lifetime of an individual. However, studies on parental effects typically suffer from the problems that heritabilities and maternal environmental effects are difficult to separate, and that both may depend on environmental factors and developmental stage. In order to experimentally disentangle maternal from paternal contributions and the likely effects of developmental stage from ecological effects, we sampled a natural population of the whitefish Coregonus palaea, used gametes for full-factorial in vitro fertilizations, raised over 10000 of the resulting offspring singly at controlled conditions, and exposed them at different points during embryonic development to one of two strains of Pseudomonas fluorescens that differed in their virulence characteristics (only one caused mortality, while both delayed hatching and reduced growth). Vulnerability to infection increased markedly over embryo development. This change coincided with a distinct shift in the importance of maternal to additive genetic effects on survival. Timing of exposure also affected the variance components for hatching time and larval length, but in a less consistent direction than the variance components for mortality. No significant genetic variation was found for any reaction norms across time points of exposure, indicating a uniformity among genotypes in how susceptibility changed over development. Phenotypes were also typically correlated across time points, which could constrain the evolution of the reaction norms. Our experiment demonstrates that the relative maternal and paternal contributions to susceptibility to an infection, and hence the evolutionary potential to respond to pathogen-induced selection, depends not only on the kind of pathogenic stress but also on the timing of the challenge.