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1.
考虑到新型H7N9禽流感病毒在禽类中低致病性而在人类中的高致病性,建立了一类总人口均变化的SE-SIR人一禽H7N9禽流感模型,其中禽间的疾病传播服从饱和接触率函数,病毒从禽到人的传播服从线性接触率函数.根据Poincare-Bendixson定理、LaSalle不变原理以及极限系统理论证明了系统平衡点的全局稳定性,理论结果很好地解释了现实的应对措施.最后通过计算机仿真进一步评估了防控措施的效果. 相似文献
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目的 在禽畜饲养、销售、宰杀场所和发生人禽流感疫情的疫点开展人感染禽流感的监测,探索禽流感病毒感染人的流行病学特征。方法 采集广州市禽流感相关高危人群的血清样本,用微量血凝抑制半加敏法进行检测。对监测到的H9N2阳性病例和H5N1的感染者进行流行病学调查。结果 近年来广州市禽接触职业人群H9感染率为4.56%(0.51%~10.00%),各年龄组差异无显著性;H5N1患者有多个售卖活禽肉菜市场活动史,1例H9N2患者及1例H5N1感染者无直接接触禽类活动史,另1例H5N1感染者为活禽交易市场禽类宰杀人员。结论 H5N1和H9N2可在相关高危人群造成隐性感染或轻症感染;除禽饲养场所外,农贸市场的活禽销售、宰杀场所也存在禽流感病毒感染的风险。 相似文献
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禽流感病毒主要在禽类之间流行传播,易造成禽类大量死亡,形成瘟疫。一般不在人类之间传染流行,但也得高度警惕。饲养直接接触病禽已有发生感染的情况。该病毒一旦发生变异传染给人,则会对人类构成生命威胁。这类非细胞形态致病因子有随着不同因素的变化而发生变异的可能性。在现实生活中多加注意是可以避免的,需防与治相结合。首先,此病毒要有适宜的受体才能生存繁衍(复制),并发挥作用。禽流感病毒通过某种载体物进入口中而感染肺部,其下端细胞表面的糖链正是它的侵染受体。有研究通过实验证明,可以利用酶把这种糖链切掉,阻止该病毒进一步传染。 相似文献
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腺病毒载体已经成为基因工程疫苗及癌症、遗传病基因治疗的重要工具。腺病毒可分为哺乳动物腺病毒和禽腺病毒,禽腺病毒包括20多个血清型,分别归属于三个群:Ⅰ群为传统的禽腺病毒(FAV),Ⅱ群包括火鸡出血性肠炎病毒(HEV)等,Ⅲ群禽腺病毒为减蛋综合征病毒(EDSV)。这些病毒广泛地存在于多种禽类的呼吸道、消化道,大多呈显性或不显性感染。以禽类腺病毒为载体表达禽类重要病原的保护性抗原基因,构建多价(联)活载体基因工程疫苗,有其重要特点:腺病毒的某些毒株可以在禽体 相似文献
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1.目前,禽流感仍是全球微生物学界普遍关心的问题。Webster认为单纯扑杀感染的禽不是一项有效措施。泰国曾以扑杀感染禽的方法控制了疫情近1年,但HSN1病毒已重返。因HSNl病毒在亚洲野鸟中存在,故控制禽流感不能仅靠扑杀。由于在亚洲的小养殖场是散养,没有将家禽与野鸟隔离的网等设施,疫苗免疫成为很重要的措施。印度尼西亚科技部的Amin Soebandrio认为有些疫苗质量有问题,禽类免疫后禽类感染H5N1病毒后不死,反而继续排毒。据认为,好的疫苗注射1次即可产生有效保护,因此应不断研发质量高的用于禽类的疫苗。 相似文献
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由衣原体引起的衣原体病是人畜共患疾病 ,危害牛、羊、马、猪、狗、猫及禽类 ,也危害人类。通常把引起鹦鹉类的衣原体病称为鹦鹉热 ,把引起其它鸟类的衣原体病称为鸟疫。人也能感染 2种衣原体 ,即沙眼 -生殖器衣原体和鹦鹉热衣原体。1 流行病学1.1 动物衣原体病的流行病学我国于 1980年在甘肃等主要养羊区发现了羊衣原体流产。英国 1980~ 1981年有 130 6个牧场发生了鹦鹉热引起的羊流产。美、德、法、日、以色列、西班牙等国都发现了衣原体流产。 10个目 130种以上的禽可感染衣原体。 2 4个国家 50个研究所 ,检测了 16539只鸽 ,4 4 58只 … 相似文献
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禽大肠杆菌、肠炎、鼠伤寒、鸡白痢及鸡伤寒沙门菌多重PCR方法的建立及应用 总被引:1,自引:0,他引:1
【背景】大肠杆菌病和沙门菌病是最常见的家禽细菌性疾病,给养禽业造成严重经济损失。另外,禽大肠杆菌和沙门菌也是重要的人畜共患病原菌,可通过禽类及其产品传播给人类,对人类健康造成严重威胁。加强禽大肠杆菌和沙门菌的快速鉴别检测,对养禽业和公共卫生都具有重要意义。【目的】建立禽大肠杆菌、肠炎沙门菌、鼠伤寒沙门菌、鸡白痢沙门菌和鸡伤寒沙门菌的多重PCR检测方法。【方法】通过比较分析确定禽致病性大肠杆菌、肠炎沙门菌、鼠伤寒沙门菌、鸡白痢沙门菌和鸡伤寒沙门菌的特异靶标基因,设计5对特异性引物,通过条件优化建立多重PCR方法,分析该多重PCR方法的特异性、敏感性及可靠性。【结果】该方法能特异性地鉴定禽致病性大肠杆菌、肠炎沙门菌、鼠伤寒沙门菌、鸡白痢沙门菌和鸡伤寒沙门菌,每个PCR反应的最低检出限分别为103 CFU细菌和100 pg基因组DNA。临床分离菌株检测显示,多重PCR与传统血清学方法结果一致。【结论】建立的多重PCR方法能够快速鉴别禽致病性大肠杆菌和不同血清型沙门菌,对禽大肠杆菌病和沙门菌病的流行病学调查及临床检测具有重要意义。 相似文献
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种蛋开窗技术及其对鸡胚发育影响的研究 总被引:2,自引:1,他引:1
种蛋开窗对禽胚实施操作的技术在转基因禽类、利用多能细胞保存禽类种质资源以及禽胚实验模型等领域的研究具有重要价值。以家鸡新产蛋(含有禽胚胎干细胞)为材料,研究出了种蛋开窗切块自动复位技术,并在此基础上以接近禽胚实施操作为目的,进行了不同封口方法、不同开窗位置和添加液体排除因开窗形成的空气泡等对种蛋孵化率影响的实验。结果表明:种蛋赤道面开窗不同封口方式对孵化率影响的差异不显著,最高孵化率可达到65%;赤道面开窗,通过添加液体排除空气泡的影响不会提高孵化率,空气泡的大小与孵化率没有明显相关性;种蛋气室端开窗(针刺透内壳膜操作胚胎)方式,比赤道面开窗方式的孵化率明显提高,两种方法能见胚率均在90%以上;采用以上技术对种蛋开窗、找胚和封口,制作效率在每人每小时30个以上。本文系统地研究和报道了种蛋开窗操作禽胚简单而实用的技术,有助于解决目前种蛋开窗技术复杂且孵化率低的困境。 相似文献
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Influenza A subtype H5N1 has represented a growing alarm since its recent identification in Asia. Previously thought to infect only wild birds and poultry, H5N1 has now infected humans, cats, pigs and other mammals in an ongoing outbreak, often with a fatal outcome. In order to evaluate the risk factors for human infection with influenza virus H5N1, here we summarize 53 case patients confirmed with H5N1 infection during 2006. The review also compares the mortality rate among human cases from late 2003 until 15 June 2006 in different countries. Neither how these viruses are transmitted to humans nor the most effective way to reduce the risk for infection is fully understood. The association between household contact with diseased poultry in human infection has been demonstrated. This association could possibly operate by 2 mechanisms. First, transmission may be by inhalation or conjunctival deposition of large infectious droplets which may travel only in short distances. Second, having infected poultry in the home and preparation of infected poultry for consumption may result in exposure to higher virus concentrations than other types of exposure. There is so far no significant evidence for repeated human to human transmission, yet some cases of human to human transmission among the family relatives in Indonesia, Azerbaijan, Iraq and Turkey have been described. Recent outbreaks of highly pathogenic avian influenza A virus (H5N1 subtype) infections in poultry and humans (through direct contact with infected birds) have raised concerns that a new influenza pandemic might occur in the near future. 相似文献
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Characterization of H5N1 Influenza Viruses That Continue To Circulate in Geese in Southeastern China 总被引:19,自引:0,他引:19 下载免费PDF全文
Robert G. Webster Yi Guan Malik Peiris David Walker Scott Krauss Nan Nan Zhou Elena A. Govorkova Trevor M. Ellis K. C. Dyrting Thomas Sit Daniel R. Perez Kennedy F. Shortridge 《Journal of virology》2002,76(1):118-126
The H5N1 influenza virus, which killed humans and poultry in 1997, was a reassortant that possibly arose in one type of domestic poultry present in the live-poultry markets of Hong Kong. Given that all the precursors of H5N1/97 are still circulating in poultry in southern China, the reassortment event that generated H5N1 could be repeated. Because A/goose/Guangdong/1/96-like (H5N1; Go/Gd) viruses are the proposed donors of the hemagglutinin gene of the H5N1 virus, we investigated the continued circulation, host range, and transmissibility of Go/Gd-like viruses in poultry. The Go/Gd-like viruses caused weight loss and death in some mice inoculated with high virus doses. Transmission of Go/Gd-like H5N1 viruses to geese by contact with infected geese resulted in infection of all birds but limited signs of overt disease. In contrast, oral inoculation with high doses of Go/Gd-like viruses resulted in the deaths of up to 50% of infected geese. Transmission from infected geese to chickens occurred only by fecal contact, whereas transmission to quail occurred by either aerosol or fecal spread. This difference is probably explained by the higher susceptibility of quail to Go/Gd-like virus. The high degree of susceptibility of quail to Go/Gd (H5N1)-like viruses and the continued circulation of H6N1 and H9N2 viruses in quail support the hypothesis that quail were the host of origin of the H5N1/97 virus. The ease of transmission of Go/Gd (H5N1)-like viruses to land-based birds, especially quail, supports the wisdom of separating aquatic and land-based poultry in the markets in Hong Kong and the need for continued surveillance in the field and live-bird markets in which different types of poultry are in contact with one another. 相似文献
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Background
The threat posed by highly pathogenic avian influenza A H5N1 viruses to humans remains significant, given the continued occurrence of sporadic human cases (499 human cases in 15 countries) with a high case fatality rate (approximately 60%), the endemicity in poultry populations in several countries, and the potential for reassortment with the newly emerging 2009 H1N1 pandemic strain. Therefore, we review risk factors for H5N1 infection in humans.Methods and Findings
Several epidemiologic studies have evaluated the risk factors associated with increased risk of H5N1 infection among humans who were exposed to H5N1 viruses. Our review shows that most H5N1 cases are attributed to exposure to sick poultry. Most cases are sporadic, while occasional limited human-to-human transmission occurs. The most commonly identified factors associated with H5N1 virus infection included exposure through contact with infected blood or bodily fluids of infected poultry via food preparation practices; touching and caring for infected poultry; consuming uncooked poultry products; exposure to H5N1 via swimming or bathing in potentially virus laden ponds; and exposure to H5N1 at live bird markets.Conclusions
Research has demonstrated that despite frequent and widespread contact with poultry, transmission of the H5N1 virus from poultry to humans is rare. Available research has identified several risk factors that may be associated with infection including close direct contact with poultry and transmission via the environment. However, several important data gaps remain that limit our understanding of the epidemiology of H5N1 in humans. Although infection in humans with H5N1 remains rare, human cases continue to be reported and H5N1 is now considered endemic among poultry in parts of Asia and in Egypt, providing opportunities for additional human infections and for the acquisition of virus mutations that may lead to more efficient spread among humans and other mammalian species. Collaboration between human and animal health sectors for surveillance, case investigation, virus sharing, and risk assessment is essential to monitor for potential changes in circulating H5N1 viruses and in the epidemiology of H5N1 in order to provide the best possible chance for effective mitigation of the impact of H5N1 in both poultry and humans.Disclaimer
The opinions expressed in this article are those of the authors and do not necessarily reflect those of the institutions or organizations with which they are affiliated. 相似文献14.
Anders Engvall 《Acta veterinaria Scandinavica》2002,43(Z1):S85
Organic farming of meat producing poultry like broilers, means that the animals should be kept outdoors as much as possible. This pose a risk that they get infected with Campylobacter. At slaughter, carcasses may be contaminated with campylobacter. If cross contamination occurs in the kitchen or if the meat is undercooked people may ingest the bacteria and suffer from enteritis. It seems possible that close to 100 percent of organically farmed flocks may be infected with campylobacter while under Swedish conditions only 10 percent of conventionally reared flocks are infected. 相似文献
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Bacteriological analyses were made on 45 swab samples secured from hands of poultry workers on processing line, on 31 bruised and 15 normal poultry tissue samples, and on 15 swabs obtained from infected lacerations and exudates of abcesses on hands, arms, chest, and abdomen of poultry workers. A total of 170 Staphylococcus cultures were isolated from samples examined. These cultures were characterized morphologically and biochemically and then grouped into six distinct patterns. S. aureus was found in 86.6% of swab samples obtained from infected workers, in 40% of swabs from hands of workers who handle bruised birds, and in 38.7% of bruised tissues, and was absent from all samples obtained from hands of workers who do not handle bruised birds. All the coagulase-positive staphylococcal isolates were bacteriophage-typed, and the results showed that the same phage-type S. aureus was found in many poultry bruises and in infected lesions of poultry workers as well as on hands of workers who handle bruised birds. These results indicate that poultry bruises are a source of staphylococcal infection encountered among poultry workers. 相似文献
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Jeremy W. Ellis J. Jeffrey Root Loredana M. McCurdy Kevin T. Bentler Nicole L. Barrett Kaci K. VanDalen Katherine L. Dirsmith Susan A. Shriner 《PLoS pathogens》2021,17(8)
Avian influenza A viruses (IAVs) pose risks to public, agricultural, and wildlife health. Bridge hosts are spillover hosts that share habitat with both maintenance hosts (e.g., mallards) and target hosts (e.g., poultry). We conducted a comprehensive assessment of European starlings (Sturnus vulgaris), a common visitor to both urban and agricultural environments, to assess whether this species might act as a potential maintenance or bridge host for IAVs. First, we experimentally inoculated starlings with a wild bird IAV to investigate susceptibility and replication kinetics. Next, we evaluated whether IAV might spill over to starlings from sharing resources with a widespread IAV reservoir host. We accomplished this using a specially designed transmission cage to simulate natural environmental transmission by exposing starlings to water shared with IAV-infected mallards (Anas platyrhynchos). We then conducted a contact study to assess intraspecies transmission between starlings. In the initial experimental infection study, all inoculated starlings shed viral RNA and seroconverted. All starlings in the transmission study became infected and shed RNA at similar levels. All but one of these birds seroconverted, but detectable antibodies were relatively transient, falling to negative levels in a majority of birds by 59 days post contact. None of the contact starlings in the intraspecies transmission experiment became infected. In summary, we demonstrated that starlings may have the potential to act as IAV bridge hosts if they share water with IAV-infected waterfowl. However, starlings are unlikely to act as maintenance hosts due to limited, if any, intraspecies transmission. In addition, starlings have a relatively brief antibody response which should be considered when interpreting serology from field samples. Further study is needed to evaluate the potential for transmission from starlings to poultry, a possibility enhanced by starling’s behavioral trait of forming very large flocks which can descend on poultry facilities when natural resources are scarce. 相似文献
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Emergence and transmission of infectious diseases have an enormous impact on the poultry industry and present a serious threat to the health of humans and wild birds. Noncommercial poultry operations, such as backyard poultry facilities in China, are potential sources of virus exchange between commercial poultry and wild birds. It is particularly critical in wetland areas where backyard poultry have close contact with commercial poultry and migratory birds, therefore increasing the risk of contracting infectious diseases. To evaluate the transmission risks, a cross-sectional study was undertaken in the Poyang Lake area, China, involving 309 residents in the backyard poultry farms in three counties (Region A, B, and C) of Jiangxi Province. We examined the backyard poultry population, poultry species, presence of poultry deaths from infectious diseases, food sources, and biosecurity practices. Region B ranked highest for biosecurity while region C ranked lowest. The risks of infectious diseases were assessed by adjusted odds ratio based on multivariate logistic regression analysis. Potential risk factors in the three regions of the study site were compared. In Region A, significant factor was contact of poultry with wild birds (OR: 6.573, 95% CI: 2.148–20.115, P=0.001). In Region B, the most significant factor was contact of poultry with neighboring backyard waterfowls (OR: 3.967, 95% CI: 1.555–10.122, P=0.004). In Region C, significant factors were poultry purchase from local live bird markets (OR: 3.740, 95% CI: 1.243–11.255, P=0.019), and contact of poultry with wild birds (OR: 3.379, 95% CI: 1.058–10.791, P=0.040). In summary, backyard poultry was significantly affected by neighboring commercial poultry and close contact with wild birds. The results are expected to improve our understanding of the transmission risks of infectious diseases in a typical backyard poultry environment in rural China, and address the need to improve local farming practices and take preventive measures. 相似文献
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Chronic viral diseases such as human immunodeficiency virus (HIV) and hepatitis B virus (HBV) afflict millions of people worldwide. A key public health challenge in managing such diseases is identifying infected, asymptomatic individuals so that they can receive antiviral treatment. Such treatment can benefit both the treated individual (by improving quality and length of life) and the population as a whole (through reduced transmission). We develop a compartmental model of a chronic, treatable infectious disease and use it to evaluate the cost and effectiveness of different levels of screening and contact tracing. We show that: (1) the optimal strategy is to get infected individuals into treatment at the maximal rate until the incremental health benefits balance the incremental cost of controlling the disease; (2) as one reduces the disease prevalence by moving people into treatment (which decreases the chance that they will infect others), one should increase the level of contact tracing to compensate for the decreased effectiveness of screening; (3) as the disease becomes less prevalent, it is optimal to spend more per case identified; and (4) the relative mix of screening and contact tracing at any level of disease prevalence is such that the marginal efficiency of contact tracing (cost per infected person found) equals that of screening if possible (e.g., when capacity limitations are not binding). We also show how to determine the cost-effective equilibrium level of disease prevalence (among untreated individuals), and we develop an approximation of the path of the optimal prevalence over time. Using this, one can obtain a close approximation of the optimal solution without having to solve an optimal control problem. We apply our methods to an example of hepatitis B virus. 相似文献
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Problem of influenza and acute respiratory virus infections (ARVI) remains one of the most urgent medical and socio-economic issues in despite of certain achievements in vaccine and chemoprophylaxis. In Russia influenza and ARVI account for up to 90% of the total annual incidence of infectious disease (up to 30 million of sick people; 45-60% of them are children). Economic damage, caused by influenza and ARVI, makes around 86% of total economic damage, caused by infectious diseases. WHO predicts that in the years coming a new antigenic influenza virus will appear, which can lead to development of large pandemia with 4-5 times increase in disease incidence and 5-10 times increase in death rate. During 2005 some changes in animal influenza epidemiology were registered. New cases of people infections are detected, the virus has spread to some new countries. Avian influenza is a high contagious virus infection that can affect all bird species. For birds influenza is enteral infection, it severely affects parenchymatous organs, especially spleen, and lungs. By now it is known that carriers of avian influenza virus H5N1 can be all known species of wild waterfowl and near-water birds. Poultry is highly susceptible to many stocks of influenza virus H5N1, death rate reaches 100%. At that hens, especially chickens, are most susceptible. From January 2004 to 24th November 2005 in the world there were detected 131 cases of influenza, caused by virus A/H5N1/, 68 of them (51%) ended in lethal outcome (Vietnam--92 cases, Thailand--21 cases, Cambodia--4, Indonesia--11, China--3). Most of the described cases of avian influenza resulted from direct contact with infected birds (handling bird internal organs is especially dangerous). In frozen meat of infected birds the virus can remain for about one year. Heating kills virus (no cases of infection caused by use for food of poultry products were detected). In order to prevent wide ranging spread of infection over Russia it is necessary to organize medical monitoring of sea ships, aircraft and train crews, arriving from the countries where influenza H5N1 cases were detected, in case of need to arrange raids to outlets and markets to detect poultry and poultry products brought from these countries. In Russia it is necessary to prepare a reserve of vaccine strains of viruses--potential causative agent of pandemic, including H5N1 and H7N7, that can start to vaccine reproduction immediately in case of pandemic. 相似文献
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Manabe T Pham TP Vu VC Takasaki J Dinh TT Nguyen TM Shimbo T Bui TT Izumi S Tran TH Ngo QC Kudo K 《PloS one》2011,6(8):e23711