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1.
目的为了解猪源大肠杆菌中Ⅰ型整合子的流行情况,探讨Ⅰ型整合子与大肠杆菌耐药表型的相关性。方法采用微量肉汤稀释法测定119株猪源大肠杆菌对8类14种抗菌药物的耐药性,并采用PCR法检测猪源大肠杆菌Ⅰ型整合酶基因(int I1)并扩增其可变区,对PCR产物进行酶切分析,测序分析整合子可变区携带的耐药基因盒。结果 119株大肠杆菌耐药现象十分严重,对四环素、磺胺异恶唑、新诺明全部耐药,所有菌株均呈多重耐药。119株猪源大肠杆菌中有92株含Ⅰ型整合子,检出率77.31%。扩增出7类大小不同的基因盒插入区片段,范围为1008bp～3149bp。7类Ⅰ型整合子在119株猪源大肠杆菌中存在13种流行组合。78.15%大肠杆菌菌株的Ⅰ型整合子携带2种或2种以上的基因盒,其中以携带编码氨基糖苷类药物耐药基因(aadA1、aadA2、aadA5、aadA22、aadB)最多,其次为编码磺胺类药物耐药基因(dfrA1、dfrA12、dfrA17、dfrA27),此外还携带编码利福平、林可霉素和氯霉素的基因lnuF、cmlA6、aar-3、orf。结论Ⅰ型整合子普遍存在于大肠杆菌中,且呈流行上升趋势;Ⅰ型整合子参与耐药及多重耐药,但单株细菌携带的耐药基因盒与其耐药表型无对应关系。  相似文献   

2.
为研究分离自四川省食品动物源大肠杆菌多重耐药菌株整合子-基因盒分布及分子特征,采用多重PCR方法检测327株多重耐药菌株中I、Ⅱ、Ⅲ型整合酶基因,用PCR-测序法对整合子阳性菌进行基因盒序列分析.结果表明327株Escherichia coli中294株(89.91%)检出有I型整合子,未检出Ⅱ、Ⅲ型整合子.在随机选取的81株l型整合子阳性菌中,67株(82.72%)能扩增出800～3000 bp的耐药基因盒插入区.基因盒以编码对甲氧磺胺嘧啶类和氨基糖苷类药物耐药的dfrA、dhfrI和aadA基因家族为主,尤其以dfrA17+aadA5为优势基因盒.分别在2株菌中检出aacA4+catB3+dfrA1和aadA22基因盒.aadA22是四川分离菌株中首次报道,介导氨基糖苷类耐药.结果表明I型整合子普遍存在于大肠杆菌临床菌株中.尽管菌株携带的整合子-基因盒与其多重耐药谱间不存在对应关系,但不同来源菌株中检测出相同的耐药基因盒片段,说明了通过整合机制耐药基因可在不同菌株问水平传递.  相似文献   

3.
试验旨在了解山东地区乳房炎牛奶中大肠杆菌的污染状况及耐药情况。选择山东省3个地区的规模化奶牛场共采集227份牛奶样品,采用细菌学方法对大肠杆菌进行分离鉴定,用微量肉汤稀释法检测分离菌对11种常规抗菌药物的敏感性,采用PCR方法对常见的13种耐药基因、8种毒力基因和Ⅰ类整合子基因盒结构进行分析。结果显示,从227份牛奶样品中共分离出71株大肠杆菌;大肠杆菌对1种及1种以上抗菌药耐药的菌株达到77.5%,多重耐药率为15.5%,其中对多黏菌素耐药率为52.2%,对阿莫西林-克拉维酸耐药率为39.4%,而所有菌株均对新霉素表现为敏感。PCR检测耐药基因、毒力基因和Ⅰ类整合子结果显示,β-内酰胺类耐药基因中blaTEM基因携带率为100%,其中全部为blaTEM-1基因,blaCTX-M基因携带率为32.4%,其中主要为blaCTX-M-15基因,没有检测到blaSHV、blaOXA基因;多黏菌素的耐药基因mcr-1携带率为29.6%;喹诺酮类耐药基因中aac(6’)-Ⅰb-cr基因携带率为29.6%,qnrB基因携带率为20.8%,没有检测到qnrA和qnrC耐药基因;对8种毒力基因检测分析结果显示,仅Hly毒力基因没有被检出,Ecs3703、Irp2基因的检出率较高,分别为90.1%和63.4%,71株大肠杆菌中共有11株携带Ⅰ类整合子,检出率为15.5%,11株大肠杆菌携带6种耐药基因盒结构,最主要的耐药基因盒排列为dfr17-aadA5。本研究结果表明,山东地区乳房炎牛奶中大肠杆菌的耐药现象严重,携带毒力基因Ecs3703、Irp2的大肠杆菌可能是引起奶牛乳房炎的致病菌,Ⅰ类整合子的检测在细菌耐药性与基因携带率方面发挥着关键作用,可为临床预防和治疗奶牛乳房炎大肠杆菌病提供理论依据。  相似文献   

4.
《中国兽医学报》2017,(3):438-442
为了了解宁夏地区牛源大肠杆菌中Ⅰ型整合子-基因盒携带情况及其对细菌耐药性的影响。在获得245株大肠杆菌对16种抗菌药耐药情况的基础上,采用PCR技术对菌株的Ⅰ型整合子-基因盒进行扩增,PCR产物进行测序分析。结果显示Ⅰ型整合子检出率为14.29%;35株Ⅰ型整合子阳性菌株中32株菌扩增出7种类型的基因盒插入区片段,以介导甲氧苄啶和氨基糖苷类耐药的dfrA和aadA为主,基因盒排列dfrA17-aadA5和dfrA7较为流行,并且dfrA7为国内首次从牛源性大肠杆菌中发现。分析表明宁夏地区牛源大肠杆菌中Ⅰ型整合子目前还不是很流行,菌株的多重耐药表型与Ⅰ型整合子高度正相关。  相似文献   

5.
为了解广东省水禽源大肠杆菌中Ⅰ型整合子基因盒流行情况,本试验对251株广东地区水禽源大肠杆菌的Ⅰ型整合子进行了检测分析。采用PCR方法扩增Ⅰ型整合酶基因和Ⅰ型整合子基因盒,经限制性内切酶酶切和测序鉴定基因盒插入区。结果显示:98%水禽大肠杆菌检测到Ⅰ型整合酶基因,但只有67.7%大肠杆菌扩增出Ⅰ型整合子基因盒。携带Ⅰ型整合子的大肠杆菌共扩增出8类(A、B、C、D、E、F、G和H)不同的基因盒插入区,其中C类(插入基因为dfrA1-aadA1)检出率最高,高达57.1%(97/170),而A类和H类检出率最低,仅1.15%(2/170)。52株大肠杆菌扩增出2个基因盒,2株大肠杆菌扩增出3个基因盒,分别占携带Ⅰ型整合子大肠杆菌的30.6%和1.15%。结果表明:大肠杆菌Ⅰ型整合子插入的耐药基因盒较多,结构较复杂,促进细菌多重耐药菌株的进化。  相似文献   

6.
试验旨在了解山东地区乳房炎牛奶中大肠杆菌的污染状况及耐药情况。选择山东省3个地区的规模化奶牛场共采集227份牛奶样品，采用细菌学方法对大肠杆菌进行分离鉴定，用微量肉汤稀释法检测分离菌对11种常规抗菌药物的敏感性，采用PCR方法对常见的13种耐药基因、8种毒力基因和Ⅰ类整合子基因盒结构进行分析。结果显示，从227份牛奶样品中共分离出71株大肠杆菌；大肠杆菌对1种及1种以上抗菌药耐药的菌株达到77.5%，多重耐药率为15.5%，其中对多黏菌素耐药率为52.2%，对阿莫西林-克拉维酸耐药率为39.4%，而所有菌株均对新霉素表现为敏感。PCR检测耐药基因、毒力基因和Ⅰ类整合子结果显示，β-内酰胺类耐药基因中blaTEM基因携带率为100%，其中全部为blaTEM-1基因，blaCTX-M基因携带率为32.4%，其中主要为blaCTX-M-15基因，没有检测到blaSHV、blaOXA基因；多黏菌素的耐药基因mcr-1携带率为29.6%；喹诺酮类耐药基因中aac（6'）-Ⅰb-cr基因携带率为29.6%，qnrB基因携带率为20.8%，没有检测到qnrA和qnrC耐药基因；对8种毒力基因检测分析结果显示，仅Hly毒力基因没有被检出，Ecs3703、Irp2基因的检出率较高，分别为90.1%和63.4%，71株大肠杆菌中共有11株携带Ⅰ类整合子，检出率为15.5%，11株大肠杆菌携带6种耐药基因盒结构，最主要的耐药基因盒排列为dfr17-aadA5。本研究结果表明，山东地区乳房炎牛奶中大肠杆菌的耐药现象严重，携带毒力基因Ecs3703、Irp2的大肠杆菌可能是引起奶牛乳房炎的致病菌，Ⅰ类整合子的检测在细菌耐药性与基因携带率方面发挥着关键作用，可为临床预防和治疗奶牛乳房炎大肠杆菌病提供理论依据。  相似文献   

7.
猪源大肠杆菌耐药性与I型整合子关系研究   总被引：1，自引：0，他引：1  
目的为了解猪源大肠杆菌中I型整合子的流行情况,探讨I型整合子与大肠杆菌耐药表型的相关性。方法采用微量肉汤稀释法测定119株猪源大肠杆菌对8类14种抗菌药物的耐药性,并采用PCR法检测猪源大肠杆菌I型整合酶基因（int11）并扩增其可变区,对PCR产物进行酶切分析,测序分析整合子可变区携带的耐药基因盒。结果119株大肠杆菌耐药现象十分严重,对四环素、磺胺异恶唑、新诺明全部耐药,所有菌株均呈多重耐药。119株猪源大肠杆菌中有92株含I型整合子,检出率77．31％。扩增出7类大小不同的基因盒插入区片段,范围为1008bp-3149bp。7类I型整合子在119株猪源大肠杆菌中存在13种流行组合。78．15％大肠杆菌菌株的I型整合子携带2种或2种以上的基因盒,其中以携带编码氨基糖苷类药物耐药基因（aadA1、aadA2、aadA5、aadA22、aadB）最多,其次为编码磺胺类药物耐药基因（dfrA1、dfrA12、dfrA17、dfrA27）,此外还携带编码利福平、林可霉素和氯霉素的基因1nuF、cm1A6、aar-3、off.结论I型整合子普遍存在于大肠杆菌中,且呈流行上升趋势;I型整合子参与耐药及多重耐药,但单株细菌携带的耐药基因盒与其耐药表型无对应关系。  相似文献   

8.
猪场大肠杆菌Ⅰ型整合子及其基因盒的分子流行病学研究   总被引：3，自引：0，他引：3  
对某猪场大肠杆菌Ⅰ型整合子及其基因盒的分子流行病学进行了研究。结果表明:猪场大肠杆菌Ⅰ型整合子流行普遍,192株分离菌中105株携带Ⅰ型整合子,检出率达54.7%。共检出6种Ⅰ型整合子,它们以8种组合形式在猪场大肠杆菌中流行。猪群、饲养员及饲养环境分离菌株Ⅰ型整合子检出种类、检出率相近,但同耐药谱菌株Ⅰ型整合子携带无一致性。各种Ⅰ型整合子整合不同种类、不同数目的耐药基因盒,其中100%整合有氨基糖腺苷转移酶基因(aadA),77%整合有二氢叶酸还原酶基因(dhfr),仅少数整合有链丝菌素乙酰转移酶基因(sat)、β-内酰胺酶基因(bla)及红霉素酯酶基因(ereA)。Ⅰ型整合子携带菌株均表现多重耐药,其中100%耐受复方新诺明,90%耐受链霉素,75%耐受大观霉素。该猪场长期使用磺胺类、氨基糖苷类抗菌药物,尤其是将它们用作抗菌促长剂,造成了携带dhfr及aadA两种基因盒的Ⅰ型整合子在猪场大肠杆菌中广泛流行。  相似文献   

9.
宠物源大肠杆菌耐药性与整合子关系的研究   总被引：1，自引：0，他引：1  
为阐明宠物源(犬、猫)大肠杆菌的耐药性及其与细菌携带的整合子的关系,采用CLSI (2010)推荐的纸片扩散法测定分离菌对15种抗生素的体外敏感性,以确定菌株的耐药性特点;采用PCR方法检测分离菌中Ⅰ、Ⅱ、Ⅲ型整合酶基因,用HinfⅠ核酸内切酶酶切和DNA序列分析技术确定整合子阳性菌株所携带的耐药基因盒类型;采用SPSS软件分析整合子基因盒系统与菌株多重耐药的相关性.结果显示82株临床分离宠物源大肠杆菌耐药现象严重,对氨苄西林、链霉素、四环素、复方新诺明的耐药率均超过了65％.82株菌中有60株含Ⅰ类整合子,阳性率73.17％,其中有57株(95％)整合酶阳性菌株扩增出可变区,共检测出5种耐药基因盒组合形式:dfrA15、aadA22、dfrA16+aadA2、dfrA17+aadA5、dfrA12+orfF+aadA2,未检出Ⅱ、Ⅲ型整合子.通过SPSS软件分析,Ⅰ型整合子阳性菌株的多重耐药率比阴性菌株的多重耐药率高,二者差异具有统计学意义(P＜0.05),说明整合子与细菌多重耐药的发生有相关性.本试验证明Ⅰ型整合子普遍存在于宠物源大肠杆菌临床菌株中,1型整合子与宠物源大肠杆菌耐药性密切相关,在多重耐药大肠杆菌耐药机制中起重要作用.  相似文献   

10.
采用微量肉汤稀释法检测455株大肠杆菌对24种抗菌药物的敏感性;多重PCR检测菌株Ⅰ、Ⅱ、Ⅲ型整合酶基因;采用PCR-RFLP和PCR-测序法对整合子-基因盒进行序列分析。结果显示,455株菌除对头孢唑啉、头孢曲松、头孢噻呋和阿米卡星耐药率低于40%外,对其余药物表现出高耐药率,99.23%菌株呈多重耐药性;455株菌Ⅰ型整合子阳性率87.69%,Ⅱ型整合子1.98%,未检出Ⅲ型整合子;随机选取的204株整合子阳性菌中174株(85.29%)扩增出了基因盒可变区。基因盒主要以编码氨基糖苷腺苷基转移酶和二氢叶酸还原酶的aadA、dfrA基因为主,耐药基因排列成Ⅰ型整合子8种基因盒,Ⅱ型整合子3种基因盒。Ⅰ型整合子以dfrA1-aadA1(32.76%)基因盒为主,其次是aadA22(24.14%)和dfrA17-aadA5(24.14%)。Ⅱ型整合子以dfrA1-sat2-aadA1(66.67%)为主,Ⅱ型整合子阳性菌含有Ⅰ型整合子-基因盒;菌株含整合子-基因盒越复杂,其多重耐药性越严重。结果表明,本次分离的健康动物肠道大肠杆菌耐药非常严重,整合子-基因盒分布广泛,已成为耐药基因储库,对耐药基因扩散起重要作用。  相似文献   

11.
试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。  相似文献   

12.
Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.  相似文献   

17.
The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
Comparison of different tests to diagnose feline infectious peritonitis   总被引：1，自引：0，他引：1  
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