关于禽流感发生与传播的历史回顾与研究进展威胁人类生存的元凶:流感病毒(5)

导读:人类面临可能发生的流感大流行威胁主要来自H5N1病毒引起的高致病性禽流感.但H5N1,病毒要引起人间的大流行,必须经过禽间大流行、禽类传染给人类、人间大流行几个阶段.正如WHO提出的关于判断一种传染病大流行是否能够来临的四项标准:一是人类对该病毒没有免疫力;二是该病毒很容易从动物的身上传到人的身上;三是该病毒对人有致命性;四是该病毒可以形成有效的人与人之间的传播.     

猪输血传播病毒的研究进展

输血传播病毒(Torgue teno virus,TTV)是继甲、乙、丙、丁、庚型肝炎病毒之后发现的又一种新型肝炎相关病毒.1997年,Nishizawa T等首次报道了该病毒.由于输血传播病毒是从肝炎患者体内分离获得的,当时的学者怀疑该病毒与肝炎有关.流行病学调查发现,输血传播病毒在不同的人群中高度流行,它可导致人...     

呼吸道合胞病毒黏附蛋白G在昆虫杆状病毒表达系统中的表达

呼吸道合胞病毒(Respiratory syncytial virus,RSV)是在世界范围内引起婴幼儿下呼吸道感染的重要病毒之一,首次感染多发生于1岁以内的婴儿,2月龄婴儿的发病率最高.感染该病毒后不能产生持久的免疫力,可以反复感染,是造成婴幼儿住院的主要原因,也是青少年、老年人以及免疫缺陷人群呼吸道感染的重要病原,因此世界卫生组织要求对其严加监控.呼吸道合胞病毒在我国不但有散发流行,而且还曾引起数次大规模的流行.在南方,呼吸道合胞病毒流行高峰主要在炎热的夏秋季,而北方则发生在寒冷的冬春季.用单克隆抗体对我国部分地区呼吸道合胞病毒分离株亚型监测的结果表明,目前我国流行的呼吸道合胞病毒主要为A亚型.     

以接触暴露的方法使生长猪适应猪繁殖与呼吸综合征

通过将6.5周龄的未曾接触过PRRSv的小母猪与年龄一致但接种了该病毒地方流行株的小母猪混合饲养、或将10.5周龄小母猪通过与接种或接触暴露过PRRS病毒地方流行株的小母猪混合饲养,以验证能否使PKKsv敏感型小母猪适应该病毒地方流行株.     

一例羊病毒性口炎的诊治

羊病毒性口炎又叫羊口疮.该病毒对外界环境的抵抗力很强,散落于地面的病毒可以越冬,至来年春季仍有感染性,由于病毒的这一特点,它可以在羊群里面危害多年.本病以3至6月龄的羔羊发病居多,常呈群发性流行.成年羊也可感染发病,但呈散发性流行.该病毒主要通过损伤的皮肤、粘膜感染.引入的病羊或带毒羊是传染的来源.     

奶牛流行热的诊断及中西医防治

牛流行热以前简称牛流行性感胃,是由流行热病毒引起急性、热性、高度接触性传染病.流行具有一定的周期性,一般每隔几年或3～4年发生1次较大规模的流行.发病以夏秋季较多发生,尤其是天气闷热多雨季或昼夜温差较大易引起流行. 1 病原学 牛流行热病毒为弹状病毒科暂时热病属成员,只有1个血清型.该病毒对外界的抵抗力不强,对热敏感,56℃10分钟,37℃18小时可灭活;pH值在2.5以下或pH值在9以上于10分钟内可以使之灭活,对一般消毒药物较敏感.     

牛呼吸道合胞体病毒的流行与诊断

牛呼吸道合胞体病毒是引起牛呼吸道疾病综合征的主要病原之一.该病毒在世界各地广泛分布,牛群中的流行与感染率较高.本文主要介绍了牛呼吸道合胞体病毒的流行病学与诊断.     

H7亚型禽流感病毒对家禽和人感染回顾及H7N9亚型流感防控建议

截止于2013年4月2日,国家卫生和计划生育委员会通报我国上海市、安徽省和江苏省共发现7例人感染H7N9禽流感病例,其中2例死亡.由于H7N9禽流感病毒感染人是世界范围首次出现的事件,该消息一经报出,立即引发了很大的反响,人们担忧此次出现的新型流感病毒是否会形成大流行.鉴于当前对该病毒的基因特性、生物学特性及传播能力尚不清晰,为了使读者更好的认识H7N9亚型禽流感病毒,本文回顾H7亚型流感病毒的特性、H7亚型禽流感病毒在家禽中的流行情况和对人类的感染情况,以及如何采取有效措施控制该病毒的流行.     

猪口蹄疫的特点与防治

1 口蹄疫病毒特征 口蹄疫是由口蹄疫病毒(FMDV)感染引起的偶蹄动物共患的急性、热性、高度接触性传染病,最易感染的动物是牛、猪、骆驼、羊、鹿等,野猪、野牛等野生动物也易感染此病.本病以牛最易感,羊的感染率较低.口蹄疫在亚洲、非洲和中东以及南美均有流行,在非流行区也有散发病例.该病毒具有多型性、易变的特点.口蹄疫病毒有O、A、C、Asial、SAT1、SAT2、SAT3等7个血清型和60多个亚型.     

尼帕病毒的研究进展

尼帕病毒(Nipah virus,NiV)是近年来在东南亚地区多发的一种较新且具有极高传染性的病毒,该病毒不但感染生猪,严重危害养猪业的发展,还威胁人类健康,是一种目前已知的较为烈性的人畜共患传染病.该病毒1999年在马来西亚被发现正式命名后,至今已经出现了数次大流行,造成了较为严重的后果.该病毒在猪群体中传播速度较快...     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein