Targeting Trachoma Control through Risk Mapping: The Example of Southern Sudan

Background

Trachoma is a major cause of blindness in Southern Sudan. Its distribution has only been partially established and many communities in need of intervention have therefore not been identified or targeted. The present study aimed to develop a tool to improve targeting of survey and control activities.

Methods/Principal Findings

A national trachoma risk map was developed using Bayesian geostatistics models, incorporating trachoma prevalence data from 112 geo-referenced communities surveyed between 2001 and 2009. Logistic regression models were developed using active trachoma (trachomatous inflammation follicular and/or trachomatous inflammation intense) in 6345 children aged 1–9 years as the outcome, and incorporating fixed effects for age, long-term average rainfall (interpolated from weather station data) and land cover (i.e. vegetation type, derived from satellite remote sensing), as well as geostatistical random effects describing spatial clustering of trachoma. The model predicted the west of the country to be at no or low trachoma risk. Trachoma clusters in the central, northern and eastern areas had a radius of 8 km after accounting for the fixed effects.

Conclusion

In Southern Sudan, large-scale spatial variation in the risk of active trachoma infection is associated with aridity. Spatial prediction has identified likely high-risk areas to be prioritized for more data collection, potentially to be followed by intervention.     

Prevalence and Risk Factors for Trachoma in Central and Southern Malawi

Background

Trachoma, one of the neglected tropical diseases is suspected to be endemic in Malawi. Objectives: To determine the prevalence of trachoma and associated risk factors in central and southern Malawi.

Methodology/Principal Findings

A population based survey conducted in randomly selected clusters in Chikwawa district (population 438,895), southern Malawi and Mchinji district (population 456,558), central Malawi. Children aged 1–9 years and adults aged 15 and above were assessed for clinical signs of trachoma. In total, 1010 households in Chikwawa and 1016 households in Mchinji districts were enumerated within 108 clusters (54 clusters in each district). A total of 6,792 persons were examined for ocular signs of trachoma. The prevalence of trachomatous inflammation, follicular (TF) among children aged 1–9 years was 13.6% (CI 11.6–15.6) in Chikwawa and 21.7% (CI 19.5–23.9) in Mchinji districts respectively. The prevalence of trachoma trichiasis (TT) in women and men aged 15 years and above was 0.6% (CI 0.2–0.9) in Chikwawa and 0.3% (CI 0.04–0.6) in Mchinji respectively. The presence of a dirty face was significantly associated with trachoma follicular (TF) in both Chikwawa and Mchinji districts (P<0.001).

Conclusion/Significance

Prevalence rates of trachoma follicles (TF) in Central and Southern Malawi exceeds the WHO guidelines for the intervention with mass antibiotic distribution (TF>10%), and warrants the trachoma SAFE control strategy to be undertaken in Chikwawa and Mchinji districts.     

Rapid Assessment of Trachoma in Underserved Population of Car-Nicobar Island,India

Purpose

To determine the burden of trachoma and its related risk factors amongst the native population of Car-Nicobar Island in India.

Methods

Rapid assessment for trachoma was conducted in ten villages of Car- Nicobar Island according to standard WHO guidelines. An average of 50 children aged 1–9 years were assessed clinically for signs of active trachoma and facial cleanliness in each village. Additionally, all adults above 15 years of age in these households were examined for evidence of trachomatous trichiasis and corneal opacity. Environmental risk factors contributing to trachoma like limited access to potable water & functional latrine, presence of animal pen and garbage within the Nicobari hut were also noted in all villages.

Results

Out of a total of fifteen villages in Car-Nicobar Island, ten villages were selected for trachoma survey depending on evidence of socio-developmental indicators like poverty and decreased access to water, sanitation and healthcare facilities. The total population of the selected clusters was 7277 in the ten villages. Overall, 251 of 516 children (48.6%;CI: 46.5–55.1) had evidence of follicular stage of trachoma and 11 children (2.1%;CI:1.0–3.4) had evidence of inflammatory stage of trachoma. Nearly 15%(CI:12.1–18.3) children were noted to have unclean faces in the ten villages. Trachomatous trichiasis was noted in 73 adults (1.0%;CI:0.8–1.2). The environmental sanitation was not found to be satisfactory in the surveyed villages mainly due to the co-habitance of Nicobari people with domestic animals like pigs, hens, goats, dogs, cats etc in most (96.4%) of the households.

Conclusion

Active trachoma and trachomatous trichiasis was observed in all the ten villages surveyed, wherein trachoma control measures are needed.     

Southern and Northern analysis

This review on Southern and Northern analysis, rather than providing step-by-step protocols, focuses on a critical evaluation of the existing experimental methods and modifications thereof. Principal parameters influencing electrophoresis of DNA/RNA in agarose gels are outlined and at the same time alterations in these parameters for optimal resolution of DNA of varying length are discussed. Further, methods for evaluating the quality of DNA/RNA size separation in agarose gels are described. Since efficient transfer of DNA/RNA from the gel onto a membrane support is critical in both methods, several experimental approaches for transfer are compared. Also discussed in this review are alternative methods for radioactive and non-radioactive labelling of DNA probes. Finally, detailed protocols are provided for an effective hybridization of Southern and Northern blots.     

Fish communities in the eastern,seasonal-floodplain of the Sudd,Southern Sudan

Annual flooding of the permanent Sudd swamps innundates large areas of Oryza longistaminata grasslands. Fish migration into a southeast section of the seasonal floodplain was led by Clarias gariepinus, Polypterus senegalus and several small species which were intent on spawning. Channa obscura and juveniles of Oreochromis niloticus were prominent among later entrants. From a total of 23 species caught in seasonal habitats, 7 contributed over 97% of total estimated numerical and biomass densities. The latter ranged from 435–580 kg ha^–1. In the 1982–83 flood-season entry to the floodplain was essentially restricted to species tolerant of oxygen-deficient waters and thereby able to penetrate the papyrus and Typha swamps of the permanent wetland. Migrants became stranded in temporary pools and subject to heavy cropping by birds.     

The burden of trachoma in Ayod County of Southern Sudan

Background

Blindness due to trachoma is avoidable through Surgery, Antibiotics, Facial hygiene and Environmental improvements (SAFE). Recent surveys have shown trachoma to be a serious cause of blindness in Southern Sudan. We conducted this survey in Ayod County of Jonglei State to estimate the need for intervention activities to eliminate blinding trachoma.

Methodology and Findings

A cross-sectional two-stage cluster random survey was conducted in November 2006. All residents of selected households were clinically assessed for trachoma using the World Health Organization (WHO) simplified grading scheme. A total of 2,335 people from 392 households were examined, of whom 1,107 were over 14 years of age. Prevalence of signs of active trachoma in children 1–9 years of age was: trachomatous inflammation follicular (TF) = 80.1% (95% confidence interval [CI], 73.9–86.3); trachomatous inflammation intense (TI) = 60.7% (95% CI, 54.6–66.8); and TF and/or TI (active trachoma) = 88.3% (95% CI, 83.7–92.9). Prevalence of trachomatous trichiasis (TT) was 14.6% (95% CI, 10.9–18.3) in adults over 14 years of age; 2.9% (95% CI, 0.4–5.3) in children 1–14 years of age; and 8.4% (95% CI, 5.5–11.3) overall. The prevalence of corneal opacity in persons over 14 years of age with TT was 6.4% (95% CI, 4.5–8.3). No statistically significant difference was observed in the prevalence of trachoma signs between genders. Trachoma affected almost all households surveyed: 384/392 (98.0%) had at least one person with active trachoma and 130 (33.2%) had at least one person with trichiasis.

Conclusions

Trachoma is an unnecessary public health problem in Ayod. The high prevalence of active trachoma and trichiasis confirms the severe burden of blinding trachoma found in other post-conflict areas of Southern Sudan. Based on WHO recommended thresholds, all aspects of the SAFE strategy are indicated to eliminate blinding trachoma in Ayod.     

A comparison between Northern and Southern Hemisphere tundras and related ecosystems

Summary Climatic, edaphic, and vegetation parameters are compared among three Subantarctic islands and one Maritime Antarctic island, and Northern Hemisphere tundras and tundra-like ecosystems (ranging from higharctic to cool-temperate oceanic and temperate alpine), mainly by Principal Component Analyses (PCA). All analyses of abiotic variables emphasized the extreme oceanicity of the Southern Hemisphere sites and showed the strong influence of seaspray on soil nutrient ratios in the southern sites. Analyses of climate classified all the southern sites as Cold Oceanic within a series of very oceanic climates that were distinct from the continental/subalpine climates more typical of the northern sites. Four factorial groups were derived from the vectors in PCA of soils and climate combined. Each was a grouping of several variables that was essentially independent of the other groups. They were: general climatic severity, soil base status, supply of labile nutrients, and a combined index of oceanicity with organic/mineral balance and drainage. The ecological significance of these is discussed. The range of soil nutrient levels in the southern sites is approximately equal to that of the northern sites; however, in the southern sites soil nutrient levels are inversely related to climatic severity while in the north the reverse is true. The two most important causes of these opposed trends are the relative ages of the sites and the much greater effects of sea-based vertebrates (e.g. seals and seabirds) in the southern islands. Cluster analyses of component scores derived from climatic and soil data linked the southern sites with northern sites at higher latitudes, indicating the effect of the Antarctic continent on the Southern Ocean (hence on the overall climate of the southern islands) and of wind-chill on the aerial and soil climates of the southern sites. Vegetation patterns (derived from PCA of life form data) were more complex because of the serial replacement of one lifeform by onother along continuous environmental gradients. Wind exposure was an important element in the first two vectors derived from the PCA of the botanical data. The Southern Hemisphere sites exhibited almost the full range of vegetation types found in the Northern Hemisphere, despite their floristic poverty. Variation within individual islands was comparable with that found at considerably higher (up to 30° more) northern latitudes and reflects the overriding importance of wind exposure in the southern islands. Subarctic ecosystems are generally less severe forms of Arctic ones, and decreasing latitude leads to increasingly milder environments with no great changes overall in continentality. In contrast, the Subantarctic combines elements from the extremes of the range of northen tundras (i.e. high-Arctic and cool-temperate oceanic) with its own peculiar features (e.g. animal influences) to produce ecosystems that are qualitatively different both from Subarctic systems and from the continental Antarctic regions to which they are geographically closest.     

Genetic assessment,illegal trafficking and management of the Mediterranean spur-thighed tortoise in Southern Spain and Northern Africa

Wild populations of many species are declining as a result of habitat destruction and climate change but also through the over-collection for wild meat and the pet trade. With a long history of trade around the Mediterranean, populations of the spur-thighed tortoise (Testudo graeca graeca) have become highly disturbed. In this study we utilise a molecular approach to investigate the diversity, population admixture and structure of T. g. graeca populations in northern Africa and southern Spain, as well as to obtain an insight into the origin of newly established populations in the south of Europe. We infer this from the sequencing of two partial regions of the mitochondria (12s rRNA + cyt b) and genotyping at 16 microsatellite markers in 448 tortoises. Our results are consistent with the hypothesis that Spanish populations were founded from North Africa, the consequence of multiple introductions or exchanges in genetic material as a result of trans-oceanic dispersal. Despite the trade of individuals between both sides of the Gibraltar Strait, our analysis of population structure showed clear differences between both the African and European populations, suggesting an incipient evolutionary lineage in southeast of Spain. As such, these populations possess unique genetic identities and should be treated as different management units. Surprisingly, the genetic data identified a great deal of diversity contained within pet (captive) stock and also allowed us to infer hybrids among individuals with another species of terrestrial tortoise from northern Spain (T. hermanni hermanni). Additionally, our results provide insight into the local movement and trade of individuals that has occurred around the Mediterranean basin (between northern Africa and southern Spain) and as such provides guidance for the effective management of T. g. graeca captive stock and the illegal trafficking.     

Genetic Heterogeneity of Oesophageal Cancer in High-Incidence Areas of Southern and Northern China

Background and Objective

Oesophageal cancer is one of the most common and deadliest cancers worldwide. Our previous population-based study reported a high prevalence of oesophageal cancer in Chaoshan, Guangdong Province, China. Ancestors of the Chaoshan population migrated from the Taihang Mountain region of north-central China, which is another high-incidence area for oesophageal cancer. The purpose of the present study was to obtain evidence of inherited susceptibility to oesophageal cancer in the Chaoshan population, with reference to the Taihang Mountain population, with the eventual goal of molecular identification of the disease genes.

Methods

We conducted familial correlation, commingling, and complex segregation analyses of 224 families from the Chaoshan population and 403 families from the Taihang population using the FPMM program of S.A.G.E. version 5.3.0. A second analysis focused on specific families having large numbers of affected individuals or early onset of the disease.

Results

For the general population, moderate sib-sib correlation was noticed for esophageal cancer. Additionally, brother-brother correlation was even higher. Commingling analyses indicated that a three-component distribution model best accounts for the variation in age of onset of oesophageal cancer, and that a multifactorial model provides the best fit to the general population data. An autosomal dominant mode and a dominant or recessive major gene with polygenic inheritance were found to be the best models of inherited susceptibility to oesophageal cancer in some large families.

Conclusions

The current results provide evidence for inherited susceptibility to oesophageal cancer in certain high-risk groups in China, and support efforts to identify the susceptibility genes.     

Spatial and Temporal Examination of Bivalve Communities in Several Estuaries of Southern California and Northern Baja California,MX

A combination of historical bivalve surveys spanning 30–50 years and contemporary sampling were used to document the changes in bivalve community structure over time at four southern California and one northern Baja California estuaries. While there are limitations to the interpretation of historic data, we observed generally similar trends of reduced total bivalve species richness, losses of relatively large and/or deeper-dwelling natives, and gains of relatively small, surface dwelling introduced species across the southern California estuaries, despite fairly distinct bivalve communities. A nearly 50-year absence of bivalves from two wetlands surveyed in a Baja California estuary continued. A combination of site history and current characteristics (e.g., location, depth) likely contributes to maintenance of distinct communities, and both episodic and gradual environmental changes likely contribute to within-estuary temporal shifts (or absences). We highlight future research needed to determine mechanisms underlying patterns so that we can better predict responses of bivalve communities to future scenarios, including climate change and restoration.     

Vegetation analogs and differences in the Northern and Southern Hemispheres: A global comparison

Biogeographic comparisons help to identify similarities, differences, larger contexts, and useful hypotheses. Between the (extra-tropical) Northern and Southern Hemispheres taxonomy differs almost completely, but other useful bases for vegetation comparison include phenophysiognomy, form composition and vegetation architecture, subphysiognomic morphology, environmental limits of plant types, taxonomic richness, and some aspects of function. All major biome types occur in both hemispheres except the boreal forests and analogous montane coniferous forests of the Northern Hemisphere. Some vegetation and plant types appear clearly unique, including Eucalyptus, campo cerrado, and flat-cushions such as Azorella, all of these in the Southern Hemisphere. Different but parallel adaptations to different but analogous conditions include the tall submediterranean forests, temperate rainforests, and continental versus maritime temperate deserts. Climatic limits appear similar in the two hemispheres, but mechanisms for some differences remain unresolved. Per unit land area, the Southern Hemisphere has higher annual net primary productivity than the Northern. Dissimilar analogs continue to suggest hypotheses and research questions.     

Phylogeny of Veronica in the Southern and Northern Hemispheres based on plastid,nuclear ribosomal and nuclear low-copy DNA

The cosmopolitan and ecologically diverse genus Veronica with approximately 450 species is the largest genus of the newly circumscribed Plantaginaceae. Previous analyses of Veronica DNA sequences were in stark contrast to traditional systematics. However, analyses did not allow many inferences regarding the relationship between major groups identified, hindering further analysis of diversification and evolutionary trends in the genus. To resolve the backbone relationships of Veronica, we added sequences from additional plastid DNA regions to existing data and analyzed matching data sets for 78 taxa and more than 5000 aligned characters from nuclear ribosomal DNA and plastid DNA regions. The results provide the best resolved and supported estimate of relationships among major groups in the Northern (Veronica s. str.) and Southern Hemisphere (hebes). We present new informal names for the five main species groups within the Southern Hemisphere sect. Hebe. Furthermore, in two instances we provide morphological and karyological characters supporting these relationships. Finally, we present the first evidence from nuclear low-copy CYCLOIDEA2-region to compare results from the plastid genome with the nuclear genome.