Geographical Distribution Trends Research Articles

Gender difference of geographic distribution of physicians in Japan: three-point analysis of 1994, 2004 and 2014

BackgroundJapan's medical education system produces 9,000 graduates annually. Despite the government's implementation of several strategies, including increasing the number of doctors trained, the country still struggles with a shortage of physicians in rural areas. This study examined this issue, focusing on gender and considering years of physician experience, demographic and geographic factors.MethodsWe analyzed the Physician Census from 1994, 2004, and 2014, examining data on physicians’ gender and the number of years since licensure. To correct the impact of municipal mergers, the analysis was aligned with the number of municipalities in 2014 (1741). We examined data from each physician (gender and years of medical experience) and analyzed the demographic and geographic distribution trend using Spearman correlation coefficients. We then used the Gini coefficient to evaluate the distribution change of physicians based on gender and years of experience.ResultsThe number of physicians increased 1.29-fold over the 20-year observation period (1.23-fold for male physicians and 2.17-fold for female physicians), and the percentage of female physicians increased from 13.4% to 20.4%. We found that 87.7% of physicians were concentrated in the top 1/3 municipalities in terms of population. The number of female physicians was higher at 91.8% compared to 86.8% for male physicians. The Gini coefficients were lower for veteran physicians of both sexes than for younger physicians. The Gini coefficient for all physicians was 0.315–0.298–0.298 (male physicians: 0.311–0.289–0.283, female physicians: 0.394–0.385–0.395) The Gini coefficients for female compared to male physicians were higher in all age groups, showing that The distribution of female physicians is skewed toward urban areas.ConclusionFemale physicians are less distributed in rural areas than male physicians. In addition, despite the fact that the number of female physicians has increased more than male physicians over the past 20 years, the geographic ubiquity of female physicians has not improved. Since the trend of increasing the number of female physicians is expected to continue in the future, it is necessary to take some measures, such as providing a work-life balance suitable for female physicians.

Review of livestock biosecurity resources and trainings: Local, state, federal, and international organizations

PurposeThis study evaluates the accessibility and availability of publicly accessible biosecurity resources in the Fall of 2021, as part of the IN-PREPared and Gearing Up for Safety program. The research into the quantity of material underscores the importance of these resources for disease threat awareness and highlights the need for improved biosecurity resource development for small-scale farming communities and overall biosecurity resources which impact global agricultural operations and food security. Design/methodology/approachThis review consisted of resources on agricultural biosecurity literature, websites, and training materials, involving over 125 agencies and organizations. This analysis provides insights into the distribution of resources across different regions and their availability based on farm scale and production type. FindingsOur research reveals both a geographic distribution trend of material that favors Midwestern states and significant disparities in available materials. Additionally, there are more resources that have content that focus on “general biosecurity’ and are focused on larger operations than that of small-farm biosecurity operations. International resources generally focus on overall importance of biosecurity and aspects of One Health. Practical ImplicationsThis review underscores the crucial role of biosecurity resources in enhancing disease threat awareness and safeguarding the food supply and global impact of international trade within agriculture. This emphasizes the need to address resource deficiencies for small-scale farms, particularly regarding specific livestock concentrations. Theoretical ImplicationsThe study confirms with previous research on limited resources, emphasizing the need for a more equitable approach to disseminating biosecurity information, especially for small-scale farming. Implications highlight the importance of resources, training, and informed decision-making for all farming communities, highlighting the significance of risk-based agricultural materials. Originality/ValueThe research adds value by shedding light on the unequal distribution of biosecurity resources, especially concerning small-scale farming operations. While the study primarily focuses on livestock and animal health, it acknowledges the importance of crop biosecurity, thus contributing to a broader understanding of agricultural protection. The significance of collaboration and information sharing in the global context of biosecurity extends beyond national borders and requires a coordinated effort.

Trends in Geographic Distribution of Visual Disability – United States, 2010-2019

ABSTRACT Purpose We aimed to describe changes in the geographic distribution of self-reported visual impairment (VI) over the last decade (2010–2019) in the U.S. Methods Our study was an analysis of publicly available data collected between 2010 and 2019 from the Census Bureau American Community Survey. Results The mean overall prevalence of self-reported VI from 2010 to 2019 was 2.31% in the United States, and there was a significant increase in VI over the past decade from 2.25% in 2010–2014 to 2.37% in 2015–2019 (p < .001). VI was significantly higher in rural counties (3.58%), compared to urban (3.10%) or metropolitan counties (2.18%) (p < .001). In terms of geographic region, the South of the United States had the highest rate of VI (2.63%) (p < .001). For age groups > 17-years-old in the 2010–2019 data, women had higher rates of VI compared to men. Conclusions Prevalence of self-reported visual impairment has risen and disproportionately affects certain communities. This includes individuals living in the South, in rural counties, and women.

Rural cancer care access in the United States: A worsening problem?

e18521 Background: Rural counties have a decreased incidence of cancer relatively to non-rural counties; however, they have higher death rates from cancer. This disparity in death rates is worsening. Patients in rural areas face significant barriers to accessing oncologic care – limited access to oncologic providers and significant travel distances to treatment chief among them. We aimed to assess trends in geographic distribution of medical and radiation oncologists to ascertain trends in access to oncologic specialists in rural areas. Methods: We used the Medicare Physician &amp; Other Practitioners database published by the Centers for Medicare &amp; Medicaid Services from 2013 and 2019 (the earliest and latest available) to identify radiation oncologists and medical oncologists (including hematology/oncology) based on the Provider Type field. We used the Rural Urban Commuting Area Codes as defined by the US Department of Agriculture; rural was defined as non-metropolitan areas with a &lt; 30% commuting flow to a large urban center consistent with the definition from the WWAMI Rural Health Research Center. The US Health Resources &amp; Services Administration, using a similar definition, defines 19.7% of the US population as rural. Results: In 2013, we identified 10,440 medical oncologists and 4,292 radiation oncologists in the United States. 7.6% of medical oncologists and 8.9% of radiation oncologists practiced in rural areas. In 2019, 7.4% of medical oncologists and 8.5% of radiation oncologists practiced in rural areas (Table). There were 1,430 more medical oncologists practicing in 2019 as compared to 2013; only 83 (5.8%) practice in a rural area. There were 436 additional radiation oncologists with only 21 (4.8%) practicing in a rural area. Growth in both medical oncologists (χ2 = 8.47, p = 0.02) and radiation oncologists (χ2 = 8.47, p = 0.004) was more likely to be in urban than rural areas. Conclusions: While disparities in oncologist distribution along the rural-urban continuum are well known, we establish that these disparities are becoming more pronounced despite increasing awareness. This raises concern that disparities in cancer outcomes in rural patients will continue to worsen. Alternative strategies to increases access to cancer care in rural areas are critical.[Table: see text]

Trends in Competition among Digital Platforms for Shared Mobility: Insights from a Worldwide Census and Prospects for Research

Mobility systems in metropolitan areas in both the Global North and the Global South have entered an era of rapid change since the early 2010s under the influence of mobile information and communication technologies (ICTs). Mobile ICT-based shared mobility platforms have been filling some of the gaps in transport supply left by historical modes of transport (i.e., private cars, public transit, and for-hire services). Shared mobility digital platforms are a subcategory of mobility applications that give individual customers direct and full access to one or several shared mobility services. Based on a worldwide systematic census, this paper documents the diversity of services provided by such platforms, then analyzes the trends in geographic distribution and competition among platforms across the world’s metropolises. It proposes a new classification of shared mobility services. Since innovations in shared mobility are also taking a leading place in the Global South, future research avenues in this field are discussed in an effort to break away from the prior focus of the scientific literature on the Global North. The census brings out four original findings. First, the rise of shared mobility digital platforms is a worldwide metropolitan phenomenon transcending the traditional distinction between the Global North and the Global South. Second, emerging countries have become clusters for innovation and competition among platforms. Third, three types of shared mobility digital platforms are identified based on geographic reach (local, regional, or global). Fourth, shared mobility digital platforms providing for-hire services are the most widespread in the world.

Varying Trends in Geographical Distribution and Patterns of Dermatophytosis and its Antifungal Susceptibility

Background: Dermatophytosis is seen worldwide, causing severe physical, mental, and psychosocial morbidity to the patient. Owing to indiscriminate, inadequate and irregular use of various drugs, cases of anti-fungal resistance have emerged in recent times, leading to ineffective treatment needing multiple drugs over longer treatment durations. Hence, this study was taken up to evaluate the changing geographical trends in the clinico-mycological profile of dermatophytosis and its antifungal susceptibility patterns. Materials and Methods: Two hundred and eleven patients with clinically diagnosed dermatophytosis were evaluated with history, examination followed by a Potassium Hydroxide wet mount. Skin scrapings were also taken for fungal culture and antifungal susceptibility tests against ten commonly used antifungal agents using the Broth Microdilution method as per CLSI M38-A2 guidelines. Results: Tinea incognito was the most common presentation, and Trichophyton rubrum was the predominant dermatophyte isolated. Recurrent dermatophytosis was seen in 11.84% subjects. Terbinafine was the most effective systemic agent, while Luliconazole was the most effective topical agent. Itraconazole and Luliconazole were the most effective systemic and topical agents, respectively, at their lowest minimum inhibitory concentrations inhibiting T. rubrum isolates in vivo. Fluconazole, followed by Griseofulvin, showed the least efficacy. In vitro microbiological resistance to Griseofulvin was found in 15.3% of cases (P &lt; 0.00001). Conclusion: The rapidly evolving geographical trends in clinico-epidemiological profiles of dermatophytosis and its varying antifungal susceptibility patterns highlight the need for updating the knowledge of this disease in the global scenario as well as counseling the rural populations with behavioral and lifestyle modifications.

PRODUCTION AND CONSUMPTION TRENDS OF NATURAL GAS OF TURKMENISTAN THE YEARS FROM 2009 TO 2019

In this study, natural gas production and consumption of Turkmenistan has been mentioned for years. Leaving the Soviet system in 1991, Turkmenistan started to take the first steps to move its economy from a closed system to a free market system. To raise its economy to the level of developed states, Turkmenistan has come by implementing new regulations in social and industrial areas within 10 years. Turkmenistan has chosen an international, open, and pluralist economic model since its independence. This model has projected the "10-Year National Development Program" to ensure the economic development of the country and to be carried out according to the targets and plans. The main goal of the development program can be shown as placing the country among the first world countries, a social market economy, managing the country within its means, and encouraging international investors to structural and economic investments. Today, World trade represents the liberalization trend. Liberalization of trade and markets provides the necessary foreign savings and foreign exchange needs to finance economic development with the help of foreign investments in developing countries such as Turkmenistan. Being a country with very rich natural resources, Turkmenistan aims to improve the country's economy by processing these resources and presenting them to the world markets. According to data in 2009, Russia is the largest importer of natural gas, the country's most important export product, while Iran is the second. During this period, exports to China are at a low level. However, while gas exports to Russia and Iran decreased to very low levels over time, China became the biggest consumer of Turkmenistan natural gas. In this, the relations of countries, energy needs, and investments made by demanding countries and the geographical distribution trends of the natural gas consumption-supply demand balance in the world. 2009-2019 is the economic advancement decade in the energy sector of Turkmenistan as a result of exploring and producing new gas reserves in the country, after which consumers gained conscious consumption as well as concluding new agreements with investors.

Google Earth Engine for geo-big data applications: A meta-analysis and systematic review

Google Earth Engine (GEE) is a cloud-based geospatial processing platform for large-scale environmental monitoring and analysis. The free-to-use GEE platform provides access to (1) petabytes of publicly available remote sensing imagery and other ready-to-use products with an explorer web app; (2) high-speed parallel processing and machine learning algorithms using Google’s computational infrastructure; and (3) a library of Application Programming Interfaces (APIs) with development environments that support popular coding languages, such as JavaScript and Python. Together these core features enable users to discover, analyze and visualize geospatial big data in powerful ways without needing access to supercomputers or specialized coding expertise. The development of GEE has created much enthusiasm and engagement in the remote sensing and geospatial data science fields. Yet after a decade since GEE was launched, its impact on remote sensing and geospatial science has not been carefully explored. Thus, a systematic review of GEE that can provide readers with the “big picture” of the current status and general trends in GEE is needed. To this end, the decision was taken to perform a meta-analysis investigation of recent peer-reviewed GEE articles focusing on several features, including data, sensor type, study area, spatial resolution, application, strategy, and analytical methods. A total of 349 peer-reviewed articles published in 146 different journals between 2010 and October 2019 were reviewed. Publications and geographical distribution trends showed a broad spectrum of applications in environmental analyses at both regional and global scales. Remote sensing datasets were used in 90% of studies while 10% of the articles utilized ready-to-use products for analyses. Optical satellite imagery with medium spatial resolution, particularly Landsat data with an archive exceeding 40 years, has been used extensively. Linear regression and random forest were the most frequently used algorithms for satellite imagery processing. Among ready-to-use products, the normalized difference vegetation index (NDVI) was used in 27% of studies for vegetation, crop, land cover mapping and drought monitoring. The results of this study confirm that GEE has and continues to make substantive progress on global challenges involving process of geo-big data.

Spatio-Temporal Distribution of Water Quality Parameters in Ramsar Site-Kolleru Lake

Kolleru lake is one of Asia’s largest freshwater lakes, which has undergone tremendous changes in the water quality due to the sewage, pollution and development of aquaculture in its surrounding area. This study is undertaken to evaluate the present water quality scenario existing in Kolleru lake, which has been affected seriously due to the anthropogenic disturbances since long. Water samples were collected from ten sampling locations within the lake during pre and post-monsoon seasons of 2017-18. A total of 11 water quality parameters were analysed such as pH, temperature, EC, TDS, TSS, total alkalinity, total hardness, dissolved oxygen, salinity, COD, and nitrates. Parameters were estimated by using a standard protocol of APHA 2012. The spatial distribution maps of water quality were generated from pre and post monsoon data using Arc GIS software. Spatio-temporal variation of all parameters indicated that the water quality found was unsatisfactory within the Kolleru lake. The present study shows the better water quality in the post-monsoon season. The Inverse Distance Weighting (IDW) interpolation spatial mapping was also used for water quality mapping to observe the environmental variation for protecting the important freshwater ecosystem-Kolleru lake. The outcome of GIS analysis demonstrated the spatial visualization of the lodging evolution and geographical distribution trends of water quality parameters within the study area.

Cover Image

The cover image is based on the Review Article A systematic review of Toxoplasma gondii genotypes and feline: Geographical distribution trends, by Afsaneh Amouei et al., https://doi.org/10.1111/tbed.13340.

Analysis on the exposure level and geographic distribution trend of toxicological indicators in rural drinking water, Shandong Province, in 2015

Objective: To analyze the exposure level and the geographical distribution trend of toxicological indicators of rural drinking water in Shandong Province. Methods: The drawing method was used to randomly select no less than 60% villages and towns from 137 counties (cities, districts) of 17 cities in Shandong Province in 2015, and then 1-3 rural centralized water supply units were selected according to the circumstance of rural centralized water supply units in each village and town. In total, 735 villages and towns, 1 473 rural centralized water supply units were selected, and 1 473 water samples were collected. The water treatment process, water supply population and other circumstances of the rural centralized water supply units were investigated, the water quality was monitored, the content of toxicological indicators of drinking water in different areas was compared, and the trend surface isogram of excessive toxicological indicators was drawn. Results: The qualified rate of toxicological indicators in 1 473 water samples was 83.64% (n=1 232). The main toxicological indicators that affected the qualified rate of toxicological indicators of drinking water in rural areas in Shandong Province were nitrate and fluoride. The excessive rate of fluoride was 5.70% (n=84) and the exposed population was 1 736 709 (4.22%). The excessive rate of nitrate (as nitrogen) was 12.29% (n=181) and the exposed population was 1 393 612 (3.39%). The P(5)0 content of fluoride in the eastern, middle and western regions was 0.24, 0.29 and 0.59 mg/L, respective;which was higher in the western region than in the east and the middle regions (P<0.05). There was no significant difference between the eastern and the middle regions (P>0.05). The P(50) content of nitrate (as nitrogen) in the eastern, middle and western regions was 8.00, 7.48, and 2.00 mg/L, which was higher in the eastern and middle regions than in the west region (P<0.05), there was no significant difference between the eastern and the middle regions (P>0.05). The trend surface isogram of nitrate and fluoride content showed that the content of nitrate (as nitrogen) in rural drinking water in the eastern region was significantly higher than that in the western region, especially there was a high peak area in the northeastern region, and this high content distribution extended diagonally to the central region, while the other regions were in a relatively low range. The content of fluoride in rural drinking water in the western region was significantly higher than that in the eastern region, and there were high peaks in the southwest and northwest regions, and the other regions were in a relatively low range. Conclusion: The high exposed toxicological indicators in rural drinking water in Shandong Province were nitrate (as nitrogen) and fluoride, and their distribution showed obvious geographical distribution trend.

Characterization of common bean wild populations for their in situ conservation in Northwestern Argentina

In situ conservation of wild species is a method of conservation that allows keeping populations in their natural environments, and set the strategies for maintaining the natural populations. The Active Bank of Northwestern Argentina (BANOA) is in charge of the in situ conservation of wild populations of common bean (Phaseolus vulgaris L.) in Northwestern Argentina (NOA), and has an ex situ collection of 401 landraces and 221 wild accessions from the NOA. We evaluated the phenotypic diversity of 68 common bean wild populations from the NOA both in protected and unprotected areas, finding a moderate variation among them. Ten phenotypic reproductive characteristics related to pod and seed displayed significant differences in the analysis of variance; these traits together with the seed weight were the basis for the multivariate analysis. The cluster analysis ordered the populations in 12 groups but trends in geographical distribution or phenotypical variation were not recognized. For the conservation in situ of the wild bean populations, their diversity should be considered. Two types of populations can be highlighted: (i) candidates for in situ conservation in order to preserve the novel variation generated by convergence with cultivated sympatric germplasm (populations 433, 437, 471, 509, 513 and 517) and (ii) those whose phenotype represents clearly the wild status and should be preserved in situ as such in their current status (populations 480, 495, 496, 525 and 533).

Geographical distribution of medical graduates from a public university.

To evaluate the geographic distribution and career trajectory of medical graduates and the factors associated with their choice of practice location. A cross-sectional study involving graduates from December 2001 to December 2010 was conducted. A self-administered questionnaire collected demographics and geographic information (place of birth, place of residence at the time of medical school admission, place of residency training and practice location), and reason for choosing the current location. Statistical analyses assessed trends in geographic distribution of graduates, and identified factors associated with location choice (through the population density of the location chosen for professional practice). A total of 563 graduates completed the questionnaire. Of those, 4.3% (n=24) reported family medicine as their medical specialty, 19.9% (n=112) reported other primary care specialties (internal medicine, pediatrics, surgery and obstetrics-gynecology) and the others chose subspecialties. Larger cities were more likely to be chosen for practice, particularly for newly-graduated doctors. Job invitations received during medical residency training increased the likelihood of choosing high-populated cities. In contrast, job invitations received during medical school increased the likelihood of choosing cities less populated. Amongst those in cities with lower population density, proximity to family members was an additional influencing factor; those who chose more densely populated cities did so because of better infrastructure and recreational options. Most of the physicians included in this study pursue subspecialties training and were practicing medicine in large cities. Knowing the multiple factors that influenced the choice of practice location can assist in planning future strategies to reduce physician workforce misdistribution.

Analysis of Trends in Geographic Distribution of US Dermatology Workforce Density

This study examines the geographic distribution of the US dermatology workforce density using data from the American Academy of Dermatology and the Society for Dermatology Physician Assistants.

Analysis of Trends in Geographic Distribution and Density of US Dermatologists

Analysis of Trends in Geographic Distribution and Density of US Dermatologists

Trends in geographic distribution of nursing staff in Japan from 2000 to 2010: a multilevel analysis.

The aim of this study was to examine trends in the geographic distribution of nursing staff in Japan from 2000 to 2010. We examined time trends in the rates of nursing staff per 100,000 population across 349 secondary health service areas. Using the Gini coefficient as a measure of inequality, we separately analyzed the data of 4 nursing staff types:public health nurses (PHN), midwives (MW), nurses (NS), and associate nurses (AN). Then, using multilevel Poisson regression models, we calculated the rate ratios (RRs) and their 95% confidence intervals (CIs) for each type of nursing staff per 1-year change. Overall, the distribution of PHN, MW, and NS improved slightly in terms of the Gini coefficient. After adjusting for prefectural capital and population density, PHN, MW, and NS significantly increased;the RRs per 1-year increment were 1.022 (95% CI:1.020-1.023), 1.021 (95% CI:1.019-1.022), and 1.037 (95% CI:1.037-1.038), respectively. In contrast, AN significantly decreased;the RR per 1-year increment was 0.993 (95% CI:0.993-0.994). Despite the considerable increase in the absolute number of nursing staff in Japan (excluding AN), this increase did not lead to a sufficient improvement in distribution over the last decade.

Genetic variation in mitochondrial DNA amongEnterobius vermicularisin Denmark

Despite being the most prevalent nematode infections of man in Western Europe and North America, our knowledge of the genetic variability in Enterobius vermicularis is fragmented. We here report on a genetic study of pinworms in Denmark, performed using the cytochrome oxidase I (cox1) gene, with DNA extracted from individual eggs collected from clinical (human) samples. We collected cellophane-tape-test samples positive for pinworm eggs from 14 Departments of Clinical Microbiology in Denmark and surface-sterilized the eggs using a 1% hypochlorite solution before performing conventional PCR. Twenty-two haplotypes were identified from a total of 58 Danish patients. Cluster analysis showed that all Danish worms grouped together with human samples from Germany and Greece and with samples from Japanese chimpanzees designated as 'type B'. Analysis of molecular variance showed no significant difference or trends in geographical distribution of the pinworms in Denmark, and several haplotypes were identical or closely related to samples collected in Germany, Greece and Japan. However, worms from the 4 countries were found to belong to different populations, with Fst values in the range of 0·16 to 0·47. This study shows pinworms in Denmark to be a homogenous population, when analysed using the cox1 mitochondrial gene.

Ten Good Years

I take this opportunity to look back at the 10 years of my editorship. Circulation Research has been a force to be reckoned with in my life and career for the last 10 eventful years. Much has been accomplished, much has changed: in the journal, as in cardiovascular science. We, my Associate Editors, and I have done our best to usher in the new millennium, while remaining true stewards of this venerable publication. Circulation Research had another banner year in 2008. In total, we received 1983 manuscript submissions in 2008, a 53% increase in manuscript submissions over those received in 1999, when the Marban editorship began. Figure 1 tracks the steadily increasing manuscript submissions received since 1990. Submissions are tracking on course in 2009 to date. As in past years, the Editors of Circulation Research have maintained a competitively low acceptance rate, now 15% (Figure 2). When we took over the reins in July 1999, the acceptance rate was 22%. We sought to continue to improve the journal by tightening the acceptance rate; corollary efforts included determinations to reduce the reject de novo rate, to triage inappropriate papers at an early editorial stage, and to give authors meaningful feedback in our decision letters. Figure 3 highlights the trends in acceptance rates for the last 10 years, noting the steady decrease from 22% in 1999% to 16% in 2008. Figure 1. Annual manuscript submissions to Circulation Research for 1990 to 2008. Figure 2. Percentage of final decisions rendered by Circulation Research 2009 to date. Figure 3. Trends in annual acceptance rates for 1998 to 2009 to date. Circulation Research has an unmistakable global presence, evidenced by the diverse geographic distribution of manuscripts submitted to the journal in 2008 (Figure 4 …

Chronic wasting disease of cervids.

Chronic wasting disease (CWD) has recently emerged in North America as an important prion disease of captive and free-ranging cervids (species in the deer family). CWD is the only recognized transmissible spongiform encephalopathy (TSE) affecting free-ranging species. Three cervid species, mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni), are the only known natural hosts of CWD. Endemic CWD is well established in southern Wyoming and northern Colorado, and has been present in this 'core area' for two decades or more. Apparently CWD has also infected farmed cervids in numerous jurisdictions, and has probably been endemic in North America's farmed deer and elk for well over a decade. Several free-ranging foci distant to the Colorado-Wyoming core area have been discovered since 2000, and new or intensified surveillance may well identify even more foci of infection. Whether all of the identified captive and free-ranging foci are connected via a common original exposure source remains undetermined. Some of this recently observed 'spread' may be attributable to improved detection or natural movements of infected deer and elk, but more distant range extensions are more likely caused by movements of infected captive deer and elk in commerce, or by some yet unidentified exposure risk factor. Research on CWD over the last 5 years has resulted in a more complete understanding of its pathogenesis and epidemiology. CWD is infectious, transmitting horizontally from infected to susceptible cervids. Early accumulation of PrP(CWD) in alimentary tract-associated lymphoid tissues during incubation suggests agent shedding in feces or saliva as plausible transmission routes. Residual infectivity in contaminated environments also appears to be important in sustaining epidemics. Improved tests allow CWD to be reliably diagnosed long before clinical signs appear. Implications of CWD are not entirely clear at this time. Natural transmission to humans or traditional domestic livestock seems relatively unlikely, but the possibility still evokes public concerns; impacts on wildlife resources have not been determined. Consequently, where CWD is not known to occur surveillance programs and regulations that prevent or reduce the likelihood that CWD will be introduced into these jurisdictions should be encouraged. Where CWD is known to occur, affected jurisdictions are conducting surveillance to estimate and monitor trends in geographic distribution and prevalence, managing deer and elk populations in attempts to limit spread, and developing and evaluating techniques for further controlling and perhaps eradicating CWD. Programs for addressing the challenges of CWD management will require interagency cooperation, commitment of funds and personnel, and applied research. Chronic wasting disease (CWD) is perhaps the most enigmatic of the naturally occurring prion diseases. Although recognized as a transmissible spongiform encephalopathy (TSE) since the late 1970s (Williams and Young 1980, 1982), interest in and concern about CWD has only recently emerged. CWD most closely resembles scrapie in sheep in most respects, but recent media and public reaction to CWD has been more reminiscent of that afforded to bovine spongiform encephalopathy (BSE) less than a decade ago. Yet, with the exception of transmissible mink encephalopathy (TME), CWD is the rarest of the known animal TSEs: fewer than 1,000 cases have been diagnosed worldwide, and all but two of these occurred in North America. CWD is unique among the TSEs in that it affects free-living species (Spraker et al. 1997; Miller et al. 2000). The three natural host species for CWD, mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni), are all in the family Cervidae and native to North America. Like scrapie, CWD is contagious: epidemics are self-sustaining in both captive and free-ranging cervid populations (Miller et al. 1998, 2000). The geographic extent of endemic CWD in free-ranging wildlife was initially thought to be quite limited and its natural rate of expansion slow; however, recent investigations have revealed that CWD has been inadvertently spread much more widely via market-driven movements of infected, farmed elk and deer. Both the ecological and economic consequences of CWD and its spread remain to be determined; moreover, public health implications remain a question of intense interest. Here, we review current understanding of CWD, its implications, and its management.

The relationship between the geographical distribution trends of flea species diversity and the important environmental factor in the Hengduan Mountains, Yunna

This paper is based on investigations of the vertical distribution of fleas and their hosts in nine sample areas in seven mountain ranges and refers to related data analyzed with statistical methods. According to the standardized mean of the diversity index for fleas in the vertical zones of each mountain range, the paper analyses and discusses the problems of the relationship of hosts and of important environmental factors with the geographical distribution trends and rules of flea species diversity in Yunnan Province’s Hengduan Mountains. The results show geographical distribution trends such that flea species diversity gradually decreases from the northwest to the south and the northeast. This trend is related primarily with humidity and rainfall, then secondarily with latitude, flea richness, geographical environmental condition, vertical zonation, human activities, etc. It is concluded that the different geographical distribution trends between fleas and hosts was the main cause of their different adaptability to the environment, of which humidity is one of the important factors. In addition, the flea species richness in the Hengduan Mountains is the highest in the Chinese flea fauna. It was demonstrated that habitat heterogeneity in the Hengduan Mountains affects species diversity, which acts on the relationship between species and area.