Build up of patches caused by Rhizoctonia solani

Rhizoctonia solani is a complex species that is composed of different anastomosis groups (AG). Although these different AGs show differences in their host ranges, generally R. solani is a phytopathogenic species with a wide spectrum of hosts. It has the ability to grow as a saprotroph, which further complicates its behaviour as a parasite. The losses caused by R. solani are very important and need a sustainable management strategy. The patchy appearance of the disease caused by this pathogen is well-known. The patches show within and between season dynamics. The factors which affect the spread of the disease can be grouped into three main categories: host plant, pathogen and environment. However, each of the categories in its detail may depend on or react with the other categories. There are a number of factors that may be involved in dynamics of patches. These potential mechanisms are discussed. It is essential to know about the mechanisms involved to develop an effective control strategy. Although more work is needed to investigate different mechanisms of parasitism deployed by different AGs in different hosts, it seems that many mechanisms external to the host are operating at the same time which necessitates an integrative research approach to study and control the diseases caused by R. solani.     

雏番鸭鸭疫里默氏杆菌与大肠杆菌混合感染诊疗

吉林市船营区某鸭场雏番鸭发病死亡,经流行病学调查、临床症状、病理剖检、实验室诊断,最终确认为大肠杆菌与鸭疫里默氏杆菌混合感染。经过综合治疗,疫情得到控制。     

碧流河水库鱼类寄生虫调查

本文报导了1984—1986年碧流河水库鱼类寄生虫调查.共检查、解剖鱼类49种,计846尾。查见寄生虫13个类群.计51种.对寄生虫在鱼体上的寄生部位、感染率、感染强度作了记录.根据调查和鱼种放养情况.提出了鱼病预防建议.     

牛病毒性腹泻病毒持续感染的免疫学研究进展

牛病毒性腹泻病毒(BVDV)是危害养牛业的重要病原之一。BVDV感染能够引起广泛的临床症状,包括牛病毒性腹泻-黏膜病、持续感染、免疫耐受、繁殖障碍、血小板减少与出血综合征等。由于其病原的复杂性,给该病的控制及疫苗研制带来了一定的困难。近年来,对其免疫学的研究取得了一定进展,特别是在病原的基本免疫学特征、体液免疫、细胞免疫、免疫耐受和免疫调节方面做了深入研究,同时也在参与免疫应答的细胞因子方面做了研究,这些都为牛病毒性腹泻-黏膜病的预防和控制研究提供了新的思路。     

Experimental Final Hosts of Metagonimus Hakubaensis (Trematoda: Heterophyidae) and Their Suitability to the Fluke

Seven laboratory mammal and bird species were orally inoculated with 200–1,000 encysted Metagonimus hakubaensis metacercariae that had been isolated from naturally infected lampreys (Lethenteron reissneri) captured in Aomori Prefecture. At 8 and 15 days post-infection, adult flukes were recovered from all of the laboratory animals tested, and therefore, hamster, rat, mouse, dog, cat, chicken and quail were considered as final hosts of M. hakubaensis. Recovery rates of the fluke were higher in dogs and hamsters than in cats, rats, mice, chickens and quails. The flukes recovered from dogs and hamsters showed increased body length and higher fecundity than those recovered from the other hosts. These results indicate that the suitability of dogs and hamsters for M. hakubaensis infection is higher than that of the other laboratory animals.     

方斑东风螺急性死亡症的病原病理研究

对海南发生的方斑东风螺（Babylonia areolata）急性死亡症进行了病原分离纯化、人工感染试验,以及病原16S rDNA分析和生理生化鉴定。结果显示病原菌为哈维弧菌（Vibrio harveyi）;药敏试验结果显示,该病原菌对常见的抗菌药物如恩诺沙星、复合磺胺等敏感,而对青霉素表现为耐药;组织病理结果显示鳃叶、腹足、肝胰腺、消化道、肾等器官的细胞出现变性、坏死、血细胞浸润等现象。     

东洞庭湖鱼类寄生虫区系调查报告

系统调查了东洞庭湖鱼类寄生虫区系,42种鱼类的寄生虫共有117种,分别隶属于38科50属9纲23目,较详细地研究了该区系寄生虫对寄主的感染情况及其在鱼体的分布频率,可为湖区的鱼病防治和有关寄生虫方面的研究提供参考.     

具有路途感染和出境健康检查的SIQS传染病模型

提出了SIQS模型,研究了路途感染和出境健康检查对疾病传播的影响,获得了如下结果:如果基本再生数R0γθ≤1,无病平衡点全局渐近稳定;如果基本再生数R0γθ>1,综合利用Routh-Hurwitz准则和Gersgorin圆盘定理,得到了地方性平衡点局部渐近稳定性;此外,还证明了如果地方性平衡点存在,疾病是持久的.数学结论表明,出境健康检查能减少感染者出境数量和路途感染的发生率,有利于疾病的消失.     

Multi metric evaluation of leaf wetness models for large-area application of plant disease models

Leaf wetness (LW) is one of the most important input variables of disease simulation models because of its fundamental role in the development of the infection process of many fungal pathogens. The low reliability of LW sensors and/or their rare use in standard weather stations has led to an increasing demand for reliable models that are able to estimate LW from other meteorological variables. When working on large databases in which data are interpolated in grids starting from weather stations, LW estimation is often penalized by the lack of hourly inputs (e.g., air relative humidity and air temperature), leading researchers to generate such variables from the daily values of the available weather data.Although it is possible to find several papers about models for the estimation of LW, the behavior and reliability of these models were never assessed by running them with inputs at different time resolutions aiming at large-area applications. Furthermore, only a limited number of papers have assessed the suitability of different LW models when used to provide inputs to simulate the development of the infection process of fungal pathogens. In this paper, six LW models were compared using data collected at 12 sites across the U.S. and Italy between 2002 and 2008 using an integrated, multi metric and fuzzy-based expert system developed ad hoc. The models were evaluated for their capability to estimate LW and for their impact on the simulation of the infection process for three pathogens through the use of a potential infection model. This study indicated that some empirical LW models performed better than physically based LW models. The classification and regression tree (CART) model performed better than the other models in most of the conditions tested. Finally, the estimate of LW using hourly inputs from daily data led to a decline of the LW models performances, which should still be considered acceptable. However, this estimate may require further work in data collection and model evaluation for applications at finer spatial resolutions aimed at decision support systems.     

河南省郏县红牛肠道寄生虫感染情况调查

为了解河南省郏县红牛肠道寄生虫感染情况,采用卢戈氏碘液染色法、饱和蔗糖溶液漂浮法和改良抗酸染色法对河南省郏县地区某红牛养殖场及散养红牛的218份新鲜粪便样本进行了检查,结果发现寄生虫总感染率为66.5%,共检出4种肠道寄生虫,其中球虫、圆线虫、鞭虫和绦虫感染率分别为61.5%、2.3%、6.9%和7.8%,混合感染率为11.5%,阳性粪便中虫卵或卵囊感染强度以轻度感染为主。结果表明,河南省郏县红牛肠道寄生虫感染较为普遍,应加强其肠道寄生虫病的防治。