Aedes aegypti abundance in urban neighborhoods of Maricopa County, Arizona, is linked to increasing socioeconomic status and tree cover

BACKGROUND

Understanding coupled human-environment factors which promote Aedes aegypti abundance is critical to preventing the spread of Zika, chikungunya, yellow fever and dengue viruses. High temperatures and aridity theoretically make arid lands inhospitable for Ae. aegypti mosquitoes, yet their populations are well established in many desert cities.

METHODS

We investigated associations between socioeconomic and built environment factors and Ae. aegypti abundance in Maricopa County, Arizona, home to Phoenix metropolitan area. Maricopa County Environmental Services conducts weekly mosquito surveillance with CO2-baited Encephalitis Vector Survey or BG-Sentinel traps at > 850 locations throughout the county. Counts of adult female Ae. aegypti from 2014 to 2017 were joined with US Census data, precipitation and temperature data, and 2015 land cover from high-resolution (1 m) aerial images from the National Agricultural Imagery Program.

RESULTS

From 139,729 trap-nights, 107,116 Ae. aegypti females were captured. Counts were significantly positively associated with higher socioeconomic status. This association was partially explained by higher densities of non-native landscaping in wealthier neighborhoods; a 1% increase in the density of tree cover around the trap was associated with a ~ 7% higher count of Ae. aegypti (95% CI: 6-9%).

CONCLUSIONS

Many models predict that climate change will drive aridification in some heavily populated regions, including those where Ae. aegypti are widespread. City climate change adaptation plans often include green spaces and vegetation cover to increase resilience to extreme heat, but these may unintentionally create hospitable microclimates for Ae. aegypti. This possible outcome should be addressed to reduce the potential for outbreaks of Aedes-borne diseases in desert cities.

Differences in Longevity and Temperature-Driven Extrinsic Incubation Period Correlate with Varying Dengue Risk in the Arizona–Sonora Desert Region

Dengue transmission is determined by a complex set of interactions between the environment, Aedes aegypti mosquitoes, dengue viruses, and humans. Emergence in new geographic areas can be unpredictable, with some regions having established mosquito populations for decades without locally acquired transmission. Key factors such as mosquito longevity, temperature-driven extrinsic incubation period (EIP), and vector–human contact can strongly influence the potential for disease transmission. To assess how these factors interact at the edge of the geographical range of dengue virus transmission, we conducted mosquito sampling in multiple urban areas located throughout the Arizona–Sonora desert region during the summer rainy seasons from 2013 to 2015. Mosquito population age structure, reflecting mosquito survivorship, was measured using a combination of parity analysis and relative gene expression of an age-related gene, SCP-1. Bloodmeal analysis was conducted on field collected blood-fed mosquitoes. Site-specific temperature was used to estimate the EIP, and this predicted EIP combined with mosquito age were combined to estimate the abundance of “potential” vectors (i.e., mosquitoes old enough to survive the EIP). Comparisons were made across cities by month and year. The dengue endemic cities Hermosillo and Ciudad Obregon, both in the state of Sonora, Mexico, had higher abundance of potential vectors than non-endemic Nogales, Sonora, Mexico. Interestingly, Tucson, Arizona consistently had a higher estimated abundance of potential vectors than dengue endemic regions of Sonora, Mexico. There were no observed city-level differences in species composition of blood meals. Combined, these data offer insights into the critical factors required for dengue transmission at the ecological edge of the mosquito’s range. However, further research is needed to integrate an understanding of how social and additional environmental factors constrain and enhance dengue transmission in emerging regions.

Gym staff perspectives on disability inclusion: a qualitative study

PURPOSE

To explore gym staff perspectives on the inclusion of people with disability in the gym setting.

MATERIALS AND METHODS

Semi-structured interviews were conducted with 16 staff at four urban gym facilities, exploring perspectives on disability inclusion. An interpretive descriptive approach was adopted with reflexive thematic analysis of interview data and subsequent mapping of themes to the socioecological model.

RESULTS

Consistent with the socioecological model, the themes identified were "people with disability benefit from participation in gym settings" (personal); "positive interactions with people with disability" (interpersonal); "managing expectations of other gym users" (interpersonal); "inclusion is supported by a positive ethos, staff training and accessible facilities" (organisational); "people with disability lack awareness of inclusive exercise opportunities" (community); "desire to increase collaboration with healthcare professionals" (community); "access to transport can facilitate gym attendance" (community) and "local gym policy" (policy).

CONCLUSION

Although an overall ethos of inclusion was apparent, areas identified for enhancement were: awareness of gym services in the community; inter-sectoral collaboration with healthcare and disability organisations; comprehensive disability inclusion training; transport systems and accessibility; engaging people with disability in gym service planning. Implications for rehabilitationGym staff value collaboration with healthcare and rehab professionals to support inclusion of people with disability in exercise.Standardised disability inclusion training for gym staff is recommended.Individuals with disability should be empowered to contribute to the development of inclusive gym facilities and services.Rehab professionals have a role to play in raising awareness and advocating for inclusive exercise opportunities.

212 FATIGUE EXPERIENCED BY ADULTS WITH LONG-COVID WAS NOT ASSOCIATED WITH AN EMG-DERIVED MUSCLE FATIGUE INDEX

Background

One of the most prominent challenges of the COVID-19 pandemic is the emergence of the post-COVID-19 syndrome or ‘long-COVID’ following the acute phase of the viral infection. With a plethora of debilitating symptoms across many physiological systems, the pathophysiology of long-COVID remains elusive and subject of intense research efforts. Adults with long COVID are often affected by prolonged fatigue, which could be linked to neuromuscular function impairment. We hypothesised that there might be a correlation between subjective fatigue and an Electromyograph(EMG)-derived muscle fatigue index in adults with long-COVID.

Methods

As part of a neuro-cardiovascular instability assessment protocol, participants were asked to squeeze the thigh muscles as hard as possible for ten seconds during both supine resting and after active and passive standing (head-up tilt) tests. Surface EMG was used to capture on each leg the physiological activity of the vastus lateralis and rectus femoris during the squeezes, from which the muscle fatigue index was computed based on both the mean and median frequencies of each 10-second maximum prompted muscle contraction. Using two-sided Spearman correlation coefficients, we examined the associations between the muscle fatigue indices and self-reported fatigue measured by the Chalder Fatigue Scale (CFQ).

Results

108 participants were included, 77 female and 31 male, with a mean age of 46 (range 25-78) years, 22% of whom were hospitalised in the acute phase of SARS-CoV-2 infection. Strong intercorrelations were found between the muscle fatigue indices derived from the mean and median frequencies of thigh muscle contractions. However, no significant correlations were detected between the muscle fatigue indices and CFQ scores.

Conclusion

Self-reported fatigue as measured by the CFQ was not associated with an EMG-derived muscle fatigue index in this long-COVID cohort.

Transcription factors evolve faster than their structural gene targets in the flavonoid pigment pathway

Dissecting the relationship between gene function and substitution rates is key to understanding genome-wide patterns of molecular evolution. Biochemical pathways provide powerful systems for investigating this relationship because the functional role of each gene is often well characterized. Here, we investigate the evolution of the flavonoid pigment pathway in the colorful Petunieae clade of the tomato family (Solanaceae). This pathway is broadly conserved in plants, both in terms of its structural elements and its MYB, basic helix–loop–helix, and WD40 transcriptional regulators, and its function has been extensively studied, particularly in model species of petunia. We built a phylotranscriptomic data set for 69 species of Petunieae to infer patterns of molecular evolution across pathway genes and across lineages. We found that transcription factors exhibit faster rates of molecular evolution (dN/dS) than their targets, with the highly specialized MYB genes evolving fastest. Using the largest comparative data set to date, we recovered little support for the hypothesis that upstream enzymes evolve slower than those occupying more downstream positions, although expression levels do predict molecular evolutionary rates. Although shifts in floral pigmentation were only weakly related to changes affecting coding regions, we found a strong relationship with the presence/absence patterns of MYB transcripts. Intensely pigmented species express all three main MYB anthocyanin activators in petals, whereas pale or white species express few or none. Our findings reinforce the notion that pathway regulators have a dynamic history, involving higher rates of molecular evolution than structural components, along with frequent changes in expression during color transitions.

123 ACUTE-PHASE BED-REST DURATION WAS ASSOCIATED WITH LOWER GRIP STRENGTH IN A POST-COVID-19 COHORT

Background

Though age-related muscle loss is traditionally associated with older cohorts, strong evidence suggests a life-spanning precipitation of decreasing muscle mass and strength beginning as early as the fourth decade of life, with established deleterious consequences for later-life morbidity and mortality. Periods of low activity and bed rest (LA/BR) can further compound this depletion of muscle strength. Our aim was to examine such associations in a post-COVID-19 cohort.

Methods

Participants reporting ongoing symptomatology and fatigue post COVID-19 underwent assessments of grip strength via hand-held dynamometry (2 measures on each hand). Demographics of COVID-19 illness, including time since diagnosis, duration of LA/BR during acute illness, and levels of fatigue were captured via self-reported questionnaires. Independent predictors of mean grip strength were investigated using a linear regression model.

Results

Forty-nine participants underwent assessments (69% female, mean age 44(12) years). At the time of assessment, days post COVID-19 diagnosis ranged from 39–522 (mean 262(140)). The mean self-reported period of LA/BR during the acute illness was 15(18) days. In general, participants reported significant levels of fatigue (median Chalder Fatigue Scale score 22(8)). Mean grip strength was 41.3(6.3) Kg for men and 22.8(6.7) Kg for women. When predictors of grip strength were investigated, an increased duration of LA/BR was found to be associated with lower grip strength, independently of age, gender, time since COVID-19 diagnosis, and self-reported fatigue (Beta = −0.158, 95% Confidence Interval − 0.242 to −0.074, p = 0.001).

Conclusion

In this cohort, every day of LA/BR during acute COVID-19 illness was independently associated with subsequent lower grip strength of approximately 150 g. These results underscore the importance of early mobilization and discouraging bed rest in the acute phase of COVID-19. Patients who are isolating should be encouraged to maintain physical activity and muscle strength as part of a modified isolation-friendly rehabilitation programme.

A Case-Crossover Analysis of Indoor Heat Exposure on Mortality and Hospitalizations among the Elderly in Houston, Texas

BACKGROUND

Despite the substantial role indoor exposure has played in heat wave-related mortality, few epidemiological studies have examined the health effects of exposure to indoor heat. As a result, knowledge gaps regarding indoor heat-health thresholds, vulnerability, and adaptive capacity persist.

OBJECTIVE

We evaluated the role of indoor heat exposure on mortality and morbidity among the elderly (≥65 years of age) in Houston, Texas.

METHODS

Mortality and emergency hospital admission data were obtained through the Texas Department of State Health Services. Summer indoor heat exposure was modeled at the U.S. Census block group (CBG) level using building energy models, outdoor weather data, and building characteristic data. Indoor heat-health associations were examined using time-stratified case-crossover models, controlling for temporal trends and meteorology, and matching on CBG of residence, year, month, and weekday of the adverse health event. Separate models were fitted for three indoor exposure metrics, for individual lag days 0-6, and for 3-d moving averages (lag 0-2). Effect measure modification was explored via stratification on individual- and area-level vulnerability factors.

RESULTS

We estimated positive associations between short-term changes in indoor heat exposure and cause-specific mortality and morbidity [e.g., circulatory deaths, odds ratio per 5°C increase=1.16 (95% CI: 1.03, 1.30)]. Associations were generally positive for earlier lag periods and weaker across later lag periods. Stratified analyses suggest stronger associations between indoor heat and emergency hospital admissions among African Americans compared with Whites.

DISCUSSION

Findings suggest excess mortality among certain elderly populations in Houston who are likely exposed to high indoor heat. We developed a novel methodology to estimate indoor heat exposure that can be adapted to other U.S.

LOCATIONS

In locations with high air conditioning prevalence, simplified modeling approaches may adequately account for indoor heat exposure in vulnerable neighborhoods. Accounting for indoor heat exposure may improve the estimation of the total impact of heat on health. https://doi.org/10.1289/EHP6340.

Intersecting vulnerabilities: climatic and demographic contributions to future population exposure to Aedes-borne viruses in the United States

Understanding how climate change and demographic factors may shape future population exposure to viruses such as Zika, dengue, or chikungunya, transmitted by Aedes mosquitoes is essential to improving public health preparedness. In this study, we combine projections of cumulative monthly Aedes-borne virus transmission risk with spatially explicit population projections for vulnerable demographic groups to explore future county-level population exposure across the conterminous United States. We employ a scenario matrix-combinations of climate scenarios (Representative Concentration Pathways) and socioeconomic scenarios (Shared Socioeconomic Pathways)-to assess the full range of uncertainty in emissions, socioeconomic development, and demographic change. Human exposure is projected to increase under most scenarios, up to + 177% at the national scale in 2080 under SSP5*RCP8.5 relative to a historical baseline. Projected exposure changes are predominantly driven by population changes in vulnerable demographic groups, although climate change is also important, particularly in the western region where future exposure would be about 30% lower under RCP2.6 compared to RCP8.5. The results emphasize the crucial role that socioeconomic and demographic change play in shaping future population vulnerability and exposure to Aedes-borne virus transmission risk in the United States, and underline the importance of including socioeconomic scenarios in projections of climate-related vector-borne disease impacts.

Characterizing the role of socioeconomic pathways in shaping future urban heat-related challenges

Urban dwellers worldwide are increasingly affected by more frequent and intense extreme temperature events, ongoing urbanization, and changes in socioeconomic conditions. Decades of research have shown that vulnerability is a crucial determinant of heat-related risk and mortality in cities, yet assessments of future urban heat-related challenges have largely overlooked the contribution of changes in socioeconomic conditions to future heat-related risk and mortality. The scenario framework for climate change research, made up of socioeconomic scenarios (Shared Socioeconomic Pathways - SSPs) combined with climate scenarios (Representative Concentration Pathways - RCPs), facilitates the integration of socioeconomic scenarios into climate risks assessments. In this study, we used Greater Houston (Texas) as a case study to implement the scenario framework at the intra-urban scale. Integrating locally extended SSPs along with a range of sectoral modelling approaches, we combined projections of urban extreme heat - which account for SSP-specific urban heat islands - with projections of future population and vulnerability. We then produced estimates of future heat-related risk and mortality for 2041-2060 (2050s) summers at Census tract level, for multiple combinations of climate and socioeconomic scenarios. Using a scenario matrix, we showed that the projected ~15,738-24,521 future summer excess mortalities compared to 1991-2010 are essentially driven by population growth and changes in vulnerability, with changes in climatic conditions alone being of little influence. We outline methods to apply the new scenario framework at intra-urban scale and to better characterize the contribution of socioeconomic pathways to future urban climate risks. This socio-climatic approach provides comprehensive estimates of future climate risks in urban areas, which are essential for adaptation planning under climatic and socioeconomic uncertainty.

Application of geostatistical approaches to predict the spatio-temporal distribution of summer ozone in Houston, Texas

Mitigation of adverse effects of air pollution requires understanding underlying exposures, such as ambient ozone concentrations. Geostatistical approaches were employed to analyze temporal trends and estimate spatial patterns of summertime ozone concentrations for Houston, Texas, based on hourly ozone observations obtained from the Texas Commission on Environmental Quality. We systematically assess the accuracy of several spatial interpolation methods, comparing inverse distance weighting, simple kriging, ordinary kriging, and universal kriging methods utilizing the hourly ozone observations and meteorological measurements from monitoring sites. Model uncertainty was assessed by leave-one-out cross-validation. Kriging methods performed better, showing greater consistency in the generated surfaces, fewer interpolation errors, and lower biases. Universal kriging did not significantly improve the interpolation results compared to ordinary kriging, and thus ordinary kriging was determined to be the optimal method, striking a balance between accuracy and simplicity. The resulting spatial patterns indicate that the more industrialized areas east and northeast of Houston exhibit the highest summertime ozone concentrations. Estimated daily maximum 8 h ozone concentration fields generated will be used to inform research on population health risks from exposure to surface ozone in Houston.

Meta-analysis of the influence of lifestyle changes for preoperative weight loss on surgical outcomes

Background

The aim was to investigate whether preoperative weight loss results in improved clinical outcomes in surgical patients with clinically significant obesity.

Methods

This was a systematic review and aggregate data meta-analysis of RCTs and cohort studies. PubMed, MEDLINE, Embase and CINAHL Plus databases were searched from inception to February 2018. Eligibility criteria were: studies assessing the effect of weight loss interventions (low-energy diets with or without an exercise component) on clinical outcomes in patients undergoing any surgical procedure. Data on 30-day or all-cause in-hospital mortality were extracted and synthesized in meta-analyses. Postoperative thromboembolic complications, duration of surgery, infection and duration of hospital stay were also assessed.

Results

A total of 6060 patients in four RCTs and 12 cohort studies, all from European and North American centres, were identified. Most were in the field of bariatric surgery and all had some methodological limitations. The pooled effect estimate suggested that preoperative weight loss programmes were effective, leading to significant weight reduction compared with controls: mean difference –7·42 (95 per cent c.i. –10·09 to –4·74) kg (P < 0·001). Preoperative weight loss interventions were not associated with a reduction in perioperative mortality (odds ratio 1·41, 95 per cent c.i. 0·24 to 8·40; I2 = 0 per cent, P = 0·66) but the event rate was low. The weight loss groups had shorter hospital stay (by 27 per cent). No differences were found for morbidity.

Conclusion

This limited preoperative weight loss has advantages but may not alter the postoperative morbidity or mortality risk.

The impact of heat and impaired kidney function on productivity of Guatemalan sugarcane workers

BACKGROUND

Climate change has implications for human health and productivity. Models suggest that heat extremes affect worker health, reduce labor capacity, and commodity supply. Chronic health conditions are on the rise internationally. However there is a paucity of direct empirical evidence relating increasing temperatures to both agricultural worker health and productivity.

METHODS AND FINDINGS

We evaluated the relationship between temperature exposure, kidney function, and two measures of productivity-tons of commodity produced and job attrition, of 4,095 Guatemalan sugarcane cutters over a 6-month harvest. We used distributed lag non-linear models to evaluate associations between wet bulb globe temperature (WBGT) and productivity of workers with normal or impaired kidney function. The cumulative effect of exposure to a max WBGT of 34°C was 1.16 tons (95% CI: -2.87, 0.54) less sugarcane cut over the next five days by workers with impaired kidney function, compared to exposure to 29°C. Impaired kidney function was associated with premature workforce attrition. Workers starting the harvest season with impaired kidney function were more than twice as likely to leave employment (HR: 2.92, 95% CI: 1.88, 4.32).

CONCLUSIONS

Heat extremes may be associated with loss of agricultural worker productivity and employment, especially among those with impaired kidney function. Agricultural workers who develop health conditions, such as kidney disease, are particularly vulnerable in the face of climate change and increasing heat extremes. The resultant loss of employment and productivity has significant implications for global commodity supplies.

Vascular Lesions of the Head and Oral Cavity – Diagnosis and Management

Vascular anomalies constitute a diffuse group of conditions which can range in their significance from being completely harmless and of little clinical relevance to being potentially life threatening. It is important that dentists have a good understanding of these conditions so that the risk of potential complications of dental treatment in affected patients is reduced as much as possible. This article focuses on the pathogenesis, diagnosis and treatment of these conditions, with explanation on their relevance to the practising dentist. Clinical relevance: The paper describes several vascular anomalies that may be encountered in clinical practice with information that is relevant to their diagnosis and management.

Aedes aegypti (Diptera: Culicidae) Longevity and Differential Emergence of Dengue Fever in Two Cities in Sonora, Mexico

Dengue virus, primarily transmitted by the Aedes aegypti (L.) mosquito, has rapidly expanded in geographic extent over the past several decades. In some areas, however, dengue fever has not emerged despite established Ae. aegypti populations. The reasons for this are unclear and have sometimes been attributed to socio-economic differences. In 2013 we compared Ae. aegypti adult density and population age structure between two cities in Sonora, Mexico: Hermosillo, which has regular seasonal dengue virus transmission, and Nogales, which has minimal transmission. Larval and pupal abundance was greater in Nogales, and adult density was only higher in Hermosillo during September. Population age structure, however, was consistently older in Hermosillo. This difference in longevity may have been one factor that limited dengue virus transmission in Nogales in 2013, as a smaller proportion of Ae. aegypti females survived past the extrinsic incubation period.

Venous malformations of the head and neck: current concepts in management

Low-flow venous malformations are congenital lesions and they are the third most common vascular anomaly in the head and neck. In this paper, the third in a series of three educational reviews, we discuss current trends in their management, and include a summary of common sclerosant agents used in their control.

Estimating the Risk of Domestic Water Source Contamination Following Precipitation Events

Climate change is expected to increase precipitation extremes, threatening water quality. In low resource settings, it is unclear which water sources are most vulnerable to contamination following rainfall events. We evaluated the relationship between rainfall and drinking water quality in southwest Guatemala where heavy rainfall is frequent and access to safe water is limited. We surveyed 59 shallow household wells, measured precipitation, and calculated simple hydrological variables. We compared Escherichia coli concentration at wells where recent rainfall had occurred versus had not occurred, and evaluated variability in the association between rainfall and E. coli concentration under different conditions using interaction models. Rainfall in the past 24 hours was associated with greater E. coli concentrations, with the strongest association between rainfall and fecal contamination at wells where pigs were nearby. Because of the small sample size, these findings should be considered preliminary, but provide a model to evaluate vulnerability to climate change.

A 'compelling case' for bioliquids'

Bioliquid is often overlooked by organisations when they look to reduce carbon emissions by moving heating or power generation away from fossil fuels to 'renewables'. According to Andrew Monaghan, commercial director at a specialist bioliquid producer, UK Renewable Fuels (UKRF), "although it doesn't have the glamour of some of the 'new' technologies, and bioliquids suffer something of a bad press from the environmental lobby, by any rational and informed reasoning, it really should be first on the list". Here he outlines why, as he puts it, 'second generation bioliquids should be the renewable of choice for many applications, as either the primary or a supplementary source of energy'.

Research on Emissions, Air quality, Climate, and Cooking Technologies in Northern Ghana (REACCTING): study rationale and protocol

BACKGROUND

Cooking over open fires using solid fuels is both common practice throughout much of the world and widely recognized to contribute to human health, environmental, and social problems. The public health burden of household air pollution includes an estimated four million premature deaths each year. To be effective and generate useful insight into potential solutions, cookstove intervention studies must select cooking technologies that are appropriate for local socioeconomic conditions and cooking culture, and include interdisciplinary measurement strategies along a continuum of outcomes.

METHODS/DESIGN

REACCTING (Research on Emissions, Air quality, Climate, and Cooking Technologies in Northern Ghana) is an ongoing interdisciplinary randomized cookstove intervention study in the Kassena-Nankana District of Northern Ghana. The study tests two types of biomass burning stoves that have the potential to meet local cooking needs and represent different "rungs" in the cookstove technology ladder: a locally-made low-tech rocket stove and the imported, highly efficient Philips gasifier stove. Intervention households were randomized into four different groups, three of which received different combinations of two improved stoves, while the fourth group serves as a control for the duration of the study. Diverse measurements assess different points along the causal chain linking the intervention to final outcomes of interest. We assess stove use and cooking behavior, cooking emissions, household air pollution and personal exposure, health burden, and local to regional air quality. Integrated analysis and modeling will tackle a range of interdisciplinary science questions, including examining ambient exposures among the regional population, assessing how those exposures might change with different technologies and behaviors, and estimating the comparative impact of local behavior and technological changes versus regional climate variability and change on local air quality and health outcomes.

DISCUSSION

REACCTING is well-poised to generate useful data on the impact of a cookstove intervention on a wide range of outcomes. By comparing different technologies side by side and employing an interdisciplinary approach to study this issue from multiple perspectives, this study may help to inform future efforts to improve health and quality of life for populations currently relying on open fires for their cooking needs.

Seasonal fluctuations of small mammal and flea communities in a Ugandan plague focus: evidence to implicate Arvicanthis niloticus and Crocidura spp. as key hosts in Yersinia pestis transmission

Background

The distribution of human plague risk is strongly associated with rainfall in the tropical plague foci of East Africa, but little is known about how the plague bacterium is maintained during periods between outbreaks or whether environmental drivers trigger these outbreaks. We collected small mammals and fleas over a two year period in the West Nile region of Uganda to examine how the ecological community varies seasonally in a region with areas of both high and low risk of human plague cases.

Methods

Seasonal changes in the small mammal and flea communities were examined along an elevation gradient to determine whether small mammal and flea populations exhibit differences in their response to seasonal fluctuations in precipitation, temperature, and crop harvests in areas within (above 1300 m) and outside (below 1300 m) of a model-defined plague focus.

Results

The abundance of two potential enzootic host species (Arvicanthis niloticus and Crocidura spp.) increased during the plague season within the plague focus, but did not show the same increase at lower elevations outside this focus. In contrast, the abundance of the domestic rat population (Rattus rattus) did not show significant seasonal fluctuations regardless of locality. Arvicanthis niloticus abundance was negatively associated with monthly precipitation at a six month lag and positively associated with current monthly temperatures, and Crocidura spp. abundance was positively associated with precipitation at a three month lag and negatively associated with current monthly temperatures. The abundance of A. niloticus and Crocidura spp. were both positively correlated with the harvest of millet and maize.

Conclusions

The association between the abundance of several small mammal species and rainfall is consistent with previous models of the timing of human plague cases in relation to precipitation in the West Nile region. The seasonal increase in the abundance of key potential host species within the plague focus, but not outside of this area, suggests that changes in small mammal abundance may create favorable conditions for epizootic transmission of Y. pestis which ultimately may increase risk of human cases in this region.

The use of foam sclerotherapy to treat low-flow vascular malformations of the head and neck

Liquid sclerotherapy, laser and surgery have been used in the treatment of head and neck vascular anomalies with variable success for many years. A multidisciplinary team consisting of plastic surgery, maxillofacial surgery and interventional radiology currently treats such lesions by converting liquid sclerosant into foam. Foam sclerotherapy is currently used successfully to treat varicosities of the lower limbs and in this study, we present four cases in which 3% sodium tetradecyl sulfate has been used to treat low-flow vascular malformations in the head and neck.

Meteorological influences on the seasonality of Lyme disease in the United States

Lyme disease (Borrelia burgdorferi infection) is the most common vector-transmitted disease in the United States. The majority of human Lyme disease (LD) cases occur in the summer months, but the timing of the peak occurrence varies geographically and from year to year. We calculated the beginning, peak, end, and duration of the main LD season in 12 highly endemic states from 1992 to 2007 and then examined the association between the timing of these seasonal variables and several meteorological variables. An earlier beginning to the LD season was positively associated with higher cumulative growing degree days through Week 20, lower cumulative precipitation, a lower saturation deficit, and proximity to the Atlantic coast. The timing of the peak and duration of the LD season were also associated with cumulative growing degree days, saturation deficit, and cumulative precipitation, but no meteorological predictors adequately explained the timing of the end of the LD season.

Improvement of disease prediction and modeling through the use of meteorological ensembles: human plague in Uganda

Climate and weather influence the occurrence, distribution, and incidence of infectious diseases, particularly those caused by vector-borne or zoonotic pathogens. Thus, models based on meteorological data have helped predict when and where human cases are most likely to occur. Such knowledge aids in targeting limited prevention and control resources and may ultimately reduce the burden of diseases. Paradoxically, localities where such models could yield the greatest benefits, such as tropical regions where morbidity and mortality caused by vector-borne diseases is greatest, often lack high-quality in situ local meteorological data. Satellite- and model-based gridded climate datasets can be used to approximate local meteorological conditions in data-sparse regions, however their accuracy varies. Here we investigate how the selection of a particular dataset can influence the outcomes of disease forecasting models. Our model system focuses on plague (Yersinia pestis infection) in the West Nile region of Uganda. The majority of recent human cases have been reported from East Africa and Madagascar, where meteorological observations are sparse and topography yields complex weather patterns. Using an ensemble of meteorological datasets and model-averaging techniques we find that the number of suspected cases in the West Nile region was negatively associated with dry season rainfall (December-February) and positively with rainfall prior to the plague season. We demonstrate that ensembles of available meteorological datasets can be used to quantify climatic uncertainty and minimize its impacts on infectious disease models. These methods are particularly valuable in regions with sparse observational networks and high morbidity and mortality from vector-borne diseases.

The Role of Weather in Meningitis Outbreaks in Navrongo, Ghana: A Generalized Additive Modeling Approach

Bacterial (meningococcal) meningitis is a devastating infectious disease with outbreaks occurring annually during the dry season in locations within the 'Meningitis Belt', a region in sub-Saharan Africa stretching from Ethiopia to Senegal. Meningococcal meningitis occurs from December to May in the Sahel with large epidemics every 5-10 years and attack rates of up to 1000 infections per 100,000 people. High temperatures coupled with low humidity may favor the conversion of carriage to disease as the meningococcal bacteria in the nose and throat are better able to cross the mucosal membranes into the blood stream. Similarly, respiratory diseases such as influenza and pneumonia might weaken the immune defenses and add to the mucosa damage. Although the transmission dynamics are poorly understood, outbreaks regularly end with the onset of the rainy season and may begin anew with the following dry season. In this paper, we employ a generalized additive modeling approach to assess the association between number of reported meningitis cases and a set of weather variables (relative humidity, rain, wind, sunshine, maximum and minimum temperature). The association is adjusted for air quality (dust, carbon monoxide), as well as varying degrees of unobserved time-varying confounding processes that co-vary with both the disease incidence and weather. We present the analysis of monthly reported meningitis counts in Navrongo, Ghana, from 1998-2008.

Percutaneous sclerotherapy of vascular malformations in children using sodium tetradecyl sulphate: the Birmingham experience

INTRODUCTION AND AIMS

Sclerotherapy has become first line treatment for most venous malformations and some lymphatic malformations. We aimed to measure our sclerotherapy treatment success using 3% sodium tetradecyl sulphate (STD) and describe our experience.

MATERIALS AND METHODS

Retrospective five year review (Jan 04-09) of children with vascular malformations treated at our centre with 3% STD. Patients were classified using the Birmingham classification and treatment success was measured through case note review and pre- and post-treatment photographs. FINDINGS AND RESULTS: Forty-three (84.3%) of the 51 patients with vascular malformations (VM) who underwent sclerotherapy derived a benefit. Twelve patients (23.5%) had an excellent result, 31 (60.8%) were improved whilst eight (15.7%) were unchanged. Using Fisher's exact test, there was a statistically significant difference in achieving complete resolution of superficial VMs compared to lesions involving the deeper layers of the head and neck. 17.6% of patients developed a complication with an overall complication rate of 12.2% per injection. There was one major complication with the remainder consisting of superficial skin necrosis that resolved conservatively.

CONCLUSIONS

Treatment with 3% STD sclerotherapy is effective in venous and some lymphatic vascular malformations. It should be considered an important treatment modality within a multi-disciplinary setting in these difficult problems.

Flea diversity as an element for persistence of plague bacteria in an East African plague focus

Plague is a flea-borne rodent-associated zoonotic disease that is caused by Yersinia pestis and characterized by long quiescent periods punctuated by rapidly spreading epidemics and epizootics. How plague bacteria persist during inter-epizootic periods is poorly understood, yet is important for predicting when and where epizootics are likely to occur and for designing interventions aimed at local elimination of the pathogen. Existing hypotheses of how Y. pestis is maintained within plague foci typically center on host abundance or diversity, but little attention has been paid to the importance of flea diversity in enzootic maintenance. Our study compares host and flea abundance and diversity along an elevation gradient that spans from low elevation sites outside of a plague focus in the West Nile region of Uganda (~725-1160 m) to higher elevation sites within the focus (~1380-1630 m). Based on a year of sampling, we showed that host abundance and diversity, as well as total flea abundance on hosts was similar between sites inside compared with outside the plague focus. By contrast, flea diversity was significantly higher inside the focus than outside. Our study highlights the importance of considering flea diversity in models of Y. pestis persistence.