High Burden of Impetigo and Scabies in a Tropical Country

Background

Impetigo and scabies are endemic diseases in many tropical countries; however the epidemiology of these diseases is poorly understood in many areas, particularly in the Pacific.

Methodology/Principal Findings

We conducted three epidemiological studies in 2006 and 2007 to determine the burden of disease due to impetigo and scabies in children in Fiji using simple and easily reproducible methodology. Two studies were performed in primary school children (one study was a cross-sectional study and the other a prospective cohort study over ten months) and one study was performed in infants (cross-sectional). The prevalence of active impetigo was 25.6% (95% CI 24.1–27.1) in primary school children and 12.2% (95% CI 9.3–15.6) in infants. The prevalence of scabies was 18.5% (95% CI 17.2–19.8) in primary school children and 14.0% (95% CI 10.8–17.2) in infants. The incidence density of active impetigo, group A streptococcal (GAS) impetigo, Staphylococcus aureus impetigo and scabies was 122, 80, 64 and 51 cases per 100 child-years respectively. Impetigo was strongly associated with scabies infestation (odds ratio, OR, 2.4, 95% CI 1.6–3.7) and was more common in Indigenous Fijian children when compared with children of other ethnicities (OR 3.6, 95% CI 2.7–4.7). The majority of cases of active impetigo in the children in our study were caused by GAS. S. aureus was also a common cause (57.4% in school aged children and 69% in infants).

Conclusions/Significance

These data suggest that the impetigo and scabies disease burden in children in Fiji has been underestimated, and possibly other tropical developing countries in the Pacific. These diseases are more than benign nuisance diseases and consideration needs to be given to expanded public health initiatives to improve their control.     

funrar: An R package to characterize functional rarity

Emphasis has been put in recent ecological research on investigating phylogenetic, functional and taxonomic facets of biological diversity. While a flourishing number of indices have been proposed for assessing functional diversity, surprisingly few options are available to characterize functional rarity. Functional rarity can play a key role in community and ecosystem dynamics. We introduce here the funrar R package to quantify functional rarity based on species trait differences and species frequencies at local and regional scales. Because of the increasing availability of big datasets in macroecology and biogeography, we optimized funrar to work with large datasets of thousands of species and sites. We illustrate the use of the package to investigate the functional rarity of North and Central American mammals.     

Differential gene expression in ovaries of pregnant pigs with high and low prolificacy levels and identification of candidate genes for litter size

Previous results from a genome scan in an F(2) Iberian × Meishan pig intercross showed several chromosome regions associated with litter size traits in this species. In order to identify candidate genes underlying these quantitative trait loci (QTL), we performed an ovary gene expression analysis during the sow's pregnancy. F(2) sows were ranked by their estimated breeding values for prolificacy: six sows with the highest estimated breeding value (EBV) (i.e., high prolificacy) and six sows with the lowest EBV (low prolificacy) were selected. Samples were hybridized using an Affymetrix GeneChip porcine genome array. Statistical analysis with a mixed model approach identified 221 differentially expressed probes, representing 189 genes. These genes were functionally annotated in order to identify genetic pathways overrepresented in this list. Among the functional groups most represented was, in first position, immune system response activation against external stimulus. The second group consisted of integrated genes that regulate maternal homeostasis by complement and coagulation cascades. A third group was involved in lipid and fatty acid enzymes of metabolic processes, which participate in the steroidogenesis pathway. In order to identify powerful candidate genes for prolificacy, the second approach of this study was to merge microarray data with the QTL positional information affecting litter size, previously detected in the same experimental cross. As a result, we have identified 27 differentially expressed genes colocalizing with QTL for litter size traits, which fulfill the biological, positional, and functional criteria.     

Regulation of the Na+/K+ ATPase by Klotho

Klotho-hypomorphic (Klotho(hm)) mice suffer from renal salt wasting and hypovolemia despite hyperaldosteronism. The present study explored the effect of Klotho on renal Na(+)/K(+) ATPase activity. According to immunohistochemistry and confocal microscopy Na(+)/K(+) ATPase protein abundance in isolated collecting ducts was lower in Klotho(hm) mice than in their wild type littermates (Klotho(+/+)). Analysis with dual electrode voltage clamp recording showed that expression of Klotho in Xenopus oocytes increased the Na(+)/K(+) ATPase pump current. Treatment of Xenopus oocytes with Klotho protein similarly increased the pump current. In conclusion, Klotho increases the membrane abundance and activity of the Na(+)/K(+) ATPase. Decreased Na(+)/K(+) ATPase activity could thus contribute to the volume-depletion of klotho(hm) mice.     

Overactive and underactive bladder dysfunction is reflected by alterations in urothelial ATP and NO release

ATP and NO are released from the urothelium in the bladder. Detrusor overactivity (DO) following spinal cord injury results in higher ATP and lower NO release from the bladder urothelium. Our aim was to study the relationship between ATP and NO release in (1) early diabetic bladders, an overactive bladder model; and (2) "diuretic" bladders, an underactive bladder model. To induce diabetes mellitus female rats received 65mg/kg streptozocin (i.v.). To induce chronic diuresis rats were fed with 5% sucrose. At 28 days, in vivo open cystometry was performed. Bladder wash was collected to analyze the amount of ATP and NO released into the bladder lumen. For in vitro analysis of ATP and NO release, a Ussing chamber was utilized and hypoosmotic Krebs was perfused on the urothelial side of the chamber. ATP was analyzed with luminometry or HPLC-fluorometry while NO was measured with a Sievers NO-analyzer. In vivo ATP release was increased in diabetic bladders and unchanged in diuretic bladders. In vitro release from the urothelium followed the same pattern. NO release was unchanged both in vitro and in vivo in overactive bladders whereas it was enhanced in underactive bladders. We found that the ratio of ATP/NO, representing sensory transmission in the bladder, was high in overactive and low in underactive bladder dysfunction. In summary, ATP release has a positive correlation while NO release has a negative correlation with the bladder contraction frequency. The urinary ATP/NO ratio may be a clinically relevant biomarker to characterize the extent of bladder dysfunction.     

Evaluation of matrix-assisted laser desorption ionization-time of flight whole cell profiles for assessing the cultivable diversity of aerobic and moderately halophilic prokaryotes thriving in solar saltern sediments

The moderately halophilic, cultivable fraction of prokaryotes thriving in hypersaline sediments of a solar saltern in Mallorca, Spain, has been studied by means of different cultivation media. A set of 374 isolates retrieved with six different culture conditions was screened, using whole-cell MALDI-TOF MS analysis to classify them into 25 phenotypic clusters at 52% similarity. The phylogenetic inference, made from comparative sequence analyses of the 16S rRNA genes of selected strains, indicated that each phenotypic cluster was comprised of a genealogically homogeneous set of strains. DNA-DNA hybridization (DDH) results among selected strains confirmed that each MALDI-TOF cluster encompassed members of the same species. On the other hand, the intra-cluster diversity, measured by several RAPD (Random Amplified Polymorphic DNA) amplifications, indicated that the clusters corresponded to several populations of the same phylogenetic unit coexisting in the same environment. The results encourage the use of MALDI-TOF MS for further exhaustive studies of the cultivable diversity of hypersaline environments.