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1.
Serum samples from children immunized with a meningococcal serogroup B vaccine demonstrated potent serum bactericidal antibody activity against the hypervirulent Neisseria meningitidis serogroup W strain circulating in England. The recent introduction of this vaccine into the United Kingdom national immunization program should also help protect infants against this endemic strain.  相似文献   
2.
Lake Baikal, lying in a rift zone in southeastern Siberia, is the world''s oldest, deepest, and most voluminous lake that began to form over 30 million years ago. Cited as the “most outstanding example of a freshwater ecosystem” and designated a World Heritage Site in 1996 due to its high level of endemicity, the lake and its ecosystem have become increasingly threatened by both climate change and anthropogenic disturbance. Here, we present a record of nutrient cycling in the lake, derived from the silicon isotope composition of diatoms, which dominate aquatic primary productivity. Using historical records from the region, we assess the extent to which natural and anthropogenic factors have altered biogeochemical cycling in the lake over the last 2,000 y. We show that rates of nutrient supply from deep waters to the photic zone have dramatically increased since the mid-19th century in response to changing wind dynamics, reduced ice cover, and their associated impact on limnological processes in the lake. With stressors linked to untreated sewage and catchment development also now impacting the near-shore region of Lake Baikal, the resilience of the lake’s highly endemic ecosystem to ongoing and future disturbance is increasingly uncertain.

Ancient lakes have long been associated with both high levels of biodiversity and endemicity. However, they are also being threatened by anthropogenic forcings that have led to impacts ranging from the warming of lake waters (1), hydrological modifications (2), increases in aquatic toxicity (3), and declining endemic populations due to introductions of nonnative species (4). With global populations increasingly reliant on large and ancient lakes for ecosystem services, the biodiversity (5) and value of aquatic systems to society (6), particularly in ancient lake systems (7), are at risk. Lake Baikal (Russia) is an exceptional example of an ancient lake (Fig. 1). In addition to containing ∼20% of global surface freshwater, the lake is characterized by its high degree of biodiversity with over 2,500 flora and fauna, the majority of which are endemic (8). This has been attributed to the lake’s age and fully oxygenated water column, driven by seasonal overturning and deep water renewal (9, 10) that sustains an almost completely endemic deep water fauna (8).Open in a separate windowFig. 1.Location of Lake Baikal and its catchment (gray) together with the location of World Meteorological Organization station in Irkutsk, major catchment rivers (brown), coring sites (BAIK13-1, BAIK13-4), and sites providing additional data used in this study (BAIK13-7).Concerns exist over the future health of this unique ecosystem, amid evidence of extensive shoreline eutrophication (11, 12) and climate-induced shifts in primary productivity (13, 14). Together, these changes have impacted organisms ranging from sponges and gastropods to ciliates, flagellates, and algal communities (15). Given the likelihood of future anthropogenic disturbance on Lake Baikal, further disrupting productivity exchanges through the lake’s food web, there is a need to place these contemporary observations into their historical setting. In Lake Baikal, we have evidence that algal communities have undergone rapid multidecadal to multicentennial timescale changes over the last 2,000 y (16). However, there is a need to also gain a clearer insight into how biogeochemical and nutrient cycling has altered over the same timescale, both to contextualize natural and anthropogenic drivers of change and to understand the susceptibility of the lake’s ecosystem to further alteration under different climate states (17). Annual primary productivity in Lake Baikal is ultimately regulated by photic zone nutrient availability, in addition to ice/snow cover, which regulates light availability for photosynthesis (10, 18). Here, by analyzing the silicon isotope composition of diatom silica (δ30Sidiatom), we show that nutrient supply to the surface waters of Lake Baikal has rapidly increased through the 20th and 21st centuries coincident with increased wind-driven Ekman transport and reduced ice cover. These changes in photic zone nutrient availability have the potential to alter resource competition and prey–predator interactions across the lake (15, 19).  相似文献   
3.
Porcine respiratory and reproductive syndrome virus (PRRSV) causes an economically important disease affecting commercial pork production worldwide. NADC34‐like PRRSV has had a strong impact on the U.S. and Peruvian pig industries in recent years and also emerged in northeastern China in 2017. However, the endemic status of NADC34‐like PRRSV in China is unclear. In this study, we examined 650 tissue samples collected from 16 Provinces in China from 2018 to 2019. Six NADC34‐like PRRSV strains were detected in samples from three Provinces, and the complete genomes of four of these strains were sequenced. Phylogenetic analysis showed that these novel PRRSV strains belong to sublineage 1.5 (or NADC34‐like PRRSV), forming two groups in China. Sequence alignment suggested that these novel strains share the same 100‐aa deletion in the Nsp2 protein that was identified in IA/2014/NADC34 isolated from the United States in 2014. Recombination analysis revealed that five of eight complete genome sequences are derived from recombination between IA/2014/NADC34 and ISU30 or NADC30. The number and distribution of NADC34‐like PRRSVs is increasing in China. Importantly, compared with the currently endemic strain NADC30‐like PRRSV, NADC34‐like PRRSV has the potential to be an endemic strain in China. This study will help us understand the epidemic status of NADC34‐like PRRSV in China and provide data for further monitoring this type of PRRSV in China.  相似文献   
4.
目的调查新疆奎屯高砷地区水砷含量及当地居民健康状况,分析砷对人体肝脏的损害作用,为进一步探讨砷的肝毒性作用机制提供基础资料。方法采用现场流行病学的调查方法在新疆奎屯水砷监测点进行调查,调查对象377例,其中砷暴露组137例,内对照组126例,外对照组114例;分别进行问卷调查、临床检查及样品采集,比较3组肝B超检查结果、尿砷含量及肝损伤血清标志物的差异。结果砷暴露组居民尿砷含量为(121.25±18.70)μg/L,高于内对照组的(22.47±19.21)μg/L和外对照组的(18.52±15.98)μg/L,3组差异有统计学意义(F=65.491,P<0.001)。B超检查结果显示肝功能正常者325例,异常者52例。砷暴露组和内对照组、外对照组发生肝脏异常分布比较差异有统计学意义(χ2=6.440,P=0.040)。血清肝纤维化指标检测显示砷暴露组的血清透明质酸、层粘连蛋白及Ⅳ型胶原含量与内对照组、外对照组比较差异有统计学意义;暴露组Ⅲ型前胶原肽与内对照组比较差异无统计学意义,而与外对照组比较差异有统计学意义;内对照组与外对照组的层粘连蛋白和Ⅳ型胶原差异有统计学意义。结论新疆奎屯高砷地区居民饮用高砷水与当地居民肝病高发有一定的联系,砷暴露可能是导致肝功能损害尤其是肝纤维化的主要原因之一,应进一步采取针对性措施降低肝损伤发生率,以促进高砷地区各族居民的身体健康。  相似文献   
5.
This study investigated the potential of pooled milk as an alternative sample type for foot‐and‐mouth disease (FMD) surveillance. Real‐time RT‐PCR (rRT‐PCR) results of pooled milk samples collected weekly from five pooling facilities in Nakuru County, Kenya, were compared with half‐month reports of household‐level incidence of FMD. These periodic cross‐sectional surveys of smallholder farmers were powered to detect a threshold household‐level FMD incidence of 2.5% and collected information on trends in milk production and sales. FMD virus (FMDV) RNA was detected in 9/219 milk samples, and using a type‐specific rRT‐PCR, serotype SAT 1 was identified in 3/9 of these positive samples, concurrent with confirmed outbreaks in the study area. Four milk samples were FMDV RNA‐positive during the half‐months when at least one farmer reported FMD; that is, the household‐level clinical incidence was above a threshold of 2.5%. Additionally, some milk samples were FMDV RNA‐positive when there were no reports of FMD by farmers. These results indicate that the pooled milk surveillance system can detect FMD household‐level incidence at a 2.5% threshold when up to 26% of farmers contributed milk to pooling facilities, but perhaps even at lower levels of infection (i.e., below 2.5%), or when conventional disease reporting systems fail. Further studies are required to establish a more precise correlation with estimates of household‐level clinical incidence, to fully evaluate the reliability of this approach. However, this pilot study highlights the potential use of this non‐invasive, routinely collected, cost‐effective surveillance tool, to address some of the existing limitations of traditional surveillance methods.  相似文献   
6.
Implementing effective health interventions in recent epidemics has been difficult due to the potentially global nature of their spread and sociocultural dynamics, raising questions concerning how to develop culturally-appropriate preventive measures, and how these health threats are understood locally. In Belize, health policy makers have only been marginally effective in managing infections and mosquito vectors, and Zika has been declared endemic in certain regions, particularly on the island of Caye Caulker. Based on ethnographic research conducted primarily in 2017, we examine how perspectives of Zika-related health consequences are shaped, and how state interventions to manage Zika are understood. We argue that despite its declared endemic status, Zika is not perceived as a true health concern for community members due to numerous neoliberal structural challenges. Moreover, the state’s restrictive form of reproductive governance which limits family planning services is forcing individuals to weigh conflicting conceptions of health consequences. This also contributes to an ambiguous healthcare environment for health practitioners, giving them an unclear picture of the scope of Zika as a public health concern. We also consider how critical medical anthropology and feminist analytical approaches are useful in exploring these questions and contributing to understandings of the health impacts of Zika.  相似文献   
7.
8.
Progression of kidney damage was studied in 18 patients with Balkan endemic nephropathy (BEN), with a mean 15-year follow-up after renal biopsy. According to kidney function, estimated by 99mTc-DTPA clearance, patients were divided into three groups: with apparently normal kidney function (clearance 103.5 ± 21.3 mL/min/1.73 m2), with incipient renal failure (clearance 65.5 ± 11.3), and with advanced renal failure (clearance 28.0 ± 6.2). The mean yearly decrease of glomerular filtration rate was 2.74 mL/min. In two patients, an increase of kidney function was recorded. Six patients become dialysis dependent, two from the group with incipient renal failure, but all four from the group with advanced renal failure. Three patients died after 8 to 12 years of follow-up, one from causes unrelated to kidney disease and two from end-stage renal failure. This study has shown that BEN is characterized by a slow course and prolonged evolution, modified by medical supervision and treatment.  相似文献   
9.
《Annals of medicine》2013,45(4):367-372
Endemic goitre occurs when the prevalence of thyroid enlargement in the population of an area exceeds 10%. With few exceptions its cause is iodine deficiency superimposed on other goitrogenic factors normally present and responsible for sporadic goitre. Iodine deficiency causes significant health problems and so, the term iodine deficiency disorders (IDD) has been introduced. The earliest sign of IDD is goitre, but these disorders also include cretinism, neonatal hypothyroidism and congenital defects, as well as retardation of mental and physical development etc. IDD are a worldwide problem: WHO estimates that substantially more than 800 million people are at risk and more than 190 millions suffer from IDD; over 3 million people have cretinism and in the largest and worst affected areas many millions suffer from mental and physical developmental defects. IDD can be totally eliminated by prophylaxis using iodine administered in salt, oil or some other vehicle. Problems over preventing iodine deficiency relate to difficulties in the handling and distribution of the iodized vehicle in some parts of the world and on the political will to introduce preventive schemes. In only a very few areas does the presence of goitrogenic agents in the environment cause endemic goitre despite adequate iodine supply. In a limited number of places excessive iodine from seaweed used as staple food results in endemic goitre.  相似文献   
10.
目的研究泗洪县高砷区居民体内砷的蓄积与排泄情况。方法在泗洪县选择一个高砷村和一个对照村,在每个村分别采集不少于20名30岁以上成年人的尿和头发样品,测定其砷含量。结果高砷村的尿砷、发砷含量明显高于对照村(P<0.05)。高砷村的男性尿砷、发砷含量和女性比较,差异均无统计学意义(P>0.05)。高砷村尿砷含量、发砷含量和年龄之间存在正相关(P<0.05)。结论泗洪县长期暴露于高砷环境但没有出现任何症状的人群,尿砷含量和发砷含量都要明显高于当地非病区正常值,且尿砷含量、发砷含量随着年龄增长而增加。  相似文献   
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