犬贾第虫包囊排出规律的研究

对自然感染贾第虫的比格犬进行粪检调查 ,结果表明犬贾第虫包囊排出呈间歇性 ,其间歇期为 7～ 8d ,排囊后 1 2～ 1 4d达到排囊高峰期 ,峰期持续 2～ 3d,排囊持续时间为 2 5～ 2 7d。用 2只幼犬进行免疫抑制接种犬贾第虫 ,接种后第 7天出现排包囊 ,排囊后 6～ 7d达到排囊高峰期 ,峰期持续 4～ 5d。受染动物出现腹泻 ,体重减轻     

用犬贾第虫包囊人工感染幼犬后排虫规律研究

用大量犬贾第虫包囊人工感染幼犬后进行粪便检测,结果表明其排虫呈周期性,接虫后第8天检测到贾第虫包囊。接虫后第18天出现第一个排虫高峰,高峰期持续1～2 d。高峰期过后2～3 d再次出现一个高峰期,但高峰期持续的时间都不超过2 d。     

犬贾第虫包囊排出规律的研究

对自然感染贾第虫的比格犬进行粪检调查,结果表明犬贾第虫包囊排出呈间歇性,其间歇期为７～８ｄ,排囊后１２～１４ｄ达到排囊高峰期,峰期持续２～３ｄ,排囊持续时间为２５～２７ｄ。用２只幼犬进行免疫抑制接种犬贾第虫,接种后第７ｄ出现排包囊,排囊后６～７ｄ达到排囊高峰期,高峰期持续４～５ｄ。受染动物出现腹泻,体重减轻。     

牦牛的住肉孢子虫两新种宿主范围的研究

对牦牛的两新种住肉孢子虫进行了宿主范围的研究,其结果是:耗牛住肉孢子虫(S.Poephagi sp nov.),用20只无卵囊的健康幼犬,10只无卵囊的健康幼猫,分别口服感染其包囊4000条/只,感染后每天连续进行粪便检查,幼犬未见有印囊或孢子囊排出,幼猫感染后第7～10天开始排出孢子囊,排出持续期为8～12天,平均每克粪便内有43.6(11～71)个,孢子囊呈圆形或卵圆形,无色透明,大小为13.68×9.39(9～15.8×7～13.2)μm,牦牛住肉孢子虫是猫源性虫体,犬不能作为终未宿主。牦牛犬住肉孢子虫(S.Poephagicanis sp.nov.),用20只无卵囊的健康幼犬和10只幼猫,分别人工感染其包囊4000条/只,感染后连续检查粪便,幼犬在感染后第7～20天开始排出孢子囊,大多数是在第7～9天排出,持续期为13～26天,每克粪便内平均排出孢子囊203(15～286)个,孢子囊呈椭圆形,两端较钝,大小为14.63×10.63(10.5～18.5×7～14.25)μm,有两层囊壁,外膜光滑,该种为犬源性虫体,猫不能作为终末宿主。大白鼠、小白鼠、豚鼠、家兔和小鸡分别口服感染两种住肉孢子虫包囊,感染后经粪便检查,均未发现有孢子囊,上述实验动物各口服从幼猫粪便获取的牦牛住肉孢子虫孢子囊,或从幼犬粪便获取的牦牛犬住肉孢子虫孢子囊,90天后剖检,肌肉内均无包囊存在,证明这些动物均不能作其宿主动物。     

硝唑尼特治疗犬贾第虫病的研究

选择试验犬8只,将其随机分为4个小组,每组2只.连续6 d对8只试验犬分剐进行粪检,确定无贾第虫感染后,用体外纯培养的犬贾第虫滋养体接种试验犬,然后每天采集试验犬新鲜粪便40 g,用硫酸锌漂浮法进行粪检,当检测犬贾第虫感染呈阳性时,分别用1、2、4 mg/kg体质量剂量的硝唑尼特时1、2、3组试验犬进行灌服治疗,第4组试验犬不用药作为对照.用药后,每天以同样的方法检测贾第虫包囊,并计数.结果表明,以2、4 mg/kg体质量给药的试验犬1 d后粪检结果转为阴性,以1 mg/kg体质量给药的试验犬4 d后粪检结果转为阴性.结果表明以2、4 mg/kg体质量剂量的硝唑尼特对犬贾第虫痛有很好的疗效.     

猪弓形虫病的鉴别诊断及防治

弓形虫是由龚地弓形虫寄生于猪、羊、牛、犬、猫、兔等多种动物和人的细胞内而引起的一种人畜共患的原虫病。该病以患病动物的高热、呼吸困难及神经系统症状、动物死亡和妊娠动物流产、死胎、胎儿畸形为特征。弓形虫根据其发育阶段的不同可分为5型,即滋养体、包囊、裂殖体、配子体和卵囊。其中滋养体和包囊出现在中间宿主(人、猪、犬、猫等)体内,裂殖体、配子体和卵囊只出现在终末宿主(猫)体内。以滋养体、包囊和感染性卵囊这3种类型具有感染能力。1临床症状常为急性感染,潜伏期3～7d,病初体温升高至40℃～42℃,呈稽留热3～10d,最高可达42.9…     

犬弓形虫病的病原与诊治

犬弓形虫病由龚地弓形虫引起的人畜及野生动物共患原虫病,主要侵害犬呼吸系统和神经系统。本病发生的原因主要是犬吞食了发育成熟的弓形虫卵囊或含有滋养体的包囊而感染。1病原弓形虫病是由肉孢子虫科弓形虫属的龚地弓形虫引起的人、畜及野生动物共患原虫病。根据其发育阶段的不同可分为滋养体、包囊、裂殖体、配子体和卵囊五型。滋养体和包囊出现在犬及其他中间宿主的体内,裂殖体、配子体和卵囊只出现在猫的体内。     

猪弓形虫病的常规检疫

弓形虫病是由龚地弓形虫寄生于猪、羊、牛、犬等多种动物和人的细胞内而引起的一种人畜共患的原虫病。该病以患病动物的高热、呼吸困难及神经系统症状、动物死亡和妊娠动物的流产、死胎、胎儿畸形为特征。弓形虫根据其发育阶段的不同可分为5型,即滋养体、包囊、裂殖体、配子体和卵囊。其中以滋养体、包囊和感染性卵囊这3种类型最具感染能力。1临床表现常为急性感染,潜伏期3～7d,病初体温可达40℃～42℃,呈稽留热3～10d,最高可达42.9℃,食欲减退,仅吃几口稀的或废绝,喜卧,精神萎顿。多便秘,有时下痢,呼吸困难。有的病猪有咳嗽和呕吐症状,流少…     

犬病防治技术问答(四)

<正>二十八 世界性分布的大弓形虫病怎样防治?答:弓形虫病是一种世界性的人兽共患寄生虫病,在我国各地都发生.据报道(大岛慧等,1979),日本犬感染率为10%～30%,幼犬达80%发病,死亡率为50%左右.病原是龚地弓形虫,为细胞内寄生原虫.其发育阶段不同分为5种形态,滋养体和包襄出现在犬等200余种中间宿主动物体内;裂殖体、配子体和卵囊出现在终宿主猫体内.犬吃了被猫粪中的感染卵囊或含有弓形虫滋养体和包囊的中间宿主的肉、内脏、渗出物、排泄物和乳汁而感染,并在体内组织细胞中反复增殖.     

犬两种常见寄生虫病的防治

<正>一、犬蛔虫病犬蛔虫病是由犬弓首蛔虫(主要寄生于幼犬)和狮弓首蛔虫(主要寄生于成犬)寄生于犬的小肠、胃内而引起的一种主要危害幼犬的常见线虫病。在我国各地普遍分布,1～3月龄的幼犬最易感,危害也最大,不但影响生长和发育,严重感染时甚至可导致犬死亡。(一)病原及生活史犬弓首蛔虫通过消化道感染,成年母犬误食了具有感染性的犬弓首蛔虫卵,幼虫即可通过血液循环到达机体各个组织器官,形成包囊,并随血液循环进入胎儿体     

Giardiasis in a cattery

Giardia sp infection was believed responsible for chronic, intermittent diarrhea in a group of 14 Persian cats. Seven of the cats were shedding Giardia sp cysts, and 6 of these cats had diarrhea at the time of fecal examination. Conversely, only 1 of 6 clinically normal cats in the group was shedding Giardia sp cysts. Cysts were not detected in feces of 2 cats with diarrhea. Cats less than or equal to 3 years old were more likely to be found shedding cysts. The parasite apparently was eradicated from the cattery by a combination of cage disinfection (1% sodium hypochlorite solution) and oral furazolidone treatment (4 mg/kg of body weight, BID for 5 consecutive days). During treatment, clinical signs resolved, and all cats remained clinically normal 2 months after treatment.     

Prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in range beef calves and their dams

The prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in 20 ranch raised beef calves and their dams from birth to weaning was determined. Rectal fecal samples were collected from calves at 3 days of age and weekly thereafter; cows' fecal samples were collected at the time of calving, 1 week later and four times during the summer grazing period. Blood samples were collected from the calves at 3 days of age to determine IgG(1) concentrations. Giardia lamblia cysts were shed by all 20 calves (100%) at some date during the duration of the study. However, only one calf (5%) shed Cryptosporidium parvum on two sample dates during the trial. Giardia cysts were first detected at 3.9+/-1.37 weeks of age with a range of 2-7 weeks of age. The geometric mean number of Giardia cysts in the calf feces increased from none at 1 week of age to a maximum of 2230 cysts/g of feces at 5 weeks of age and then decreased to 2 cysts/g at 25-27 weeks of age. Infection rate of calves shedding Giardia cysts peaked at 85% at 5 weeks of age and then decreased to 21% at 25-27 weeks of age. Giardia cysts, shed by calves peaked 1 week after initial shedding and decreased (P<0.05) for the remainder of the trial with the exception of week 3. There was a lower (P<0.05) percentage of calves shedding Giardia cysts weeks 3-10 and 15-25 compared to when shedding was first detected. All calves had complete or partial transfer of passive immunity as measured by IgG(1) levels. The rate of infection (15%) and the geometric mean number of Giardia cysts in the cows' feces (38.49 cysts/g) numerically increased at 1 week post-calving compared to levels at calving. The rate of infection (40%) numerically increased and the geometric mean number of Cryptosporidium andersoni oocysts in the cow feces (37.48 oocysts/g) increased (P<0.05) at 1 week post-calving and decreased to 0 at 13-16 weeks post-calving. This study is the first to document the cumulative prevalence and infection patterns of Giardia and Cryptosporidium in beef cattle under ranch conditions.     

Efficacy of a combination febantel-praziquantel-pyrantel product, with or without vaccination with a commercial Giardia vaccine, for treatment of dogs with naturally occurring giardiasis

OBJECTIVE: To determine efficacy of treatment with a combination febantel-praziquantel-pyrantel product, with or without vaccination with a commercial Giardia vaccine, in dogs with naturally occurring giardiasis. DESIGN: Prospective trial. ANIMALS: 16 Beagles naturally infected with Giardia duodenalis. PROCEDURES: During phase 1, 6 dogs were treated with the parasiticide for 3 days (4 were also vaccinated). Four weeks later, all 6 dogs were treated with the parasiticide again for 5 days and were bathed and moved to clean cages after the last treatment (phase 2). Nine dogs were treated with the parasiticide for 3 (n = 4) or 5 (5) days and bathed and moved to clean cages after the last treatment (phase 3). Fecal samples were collected twice weekly for 24 days after treatment and tested for cysts with a quantitative zinc sulfate flotation technique and for Giardia antigen with an immunoassay. RESULTS: Dogs in phase 1 were all shedding cysts again by day 24. In phase 2, only 1 dog shed cysts after treatment, and shedding was transient (day 17). In phase 3, neither cysts nor antigen was detected in fecal samples from 2 of 4 dogs treated for 3 days and 4 of 5 dogs treated for 5 days. In 18 of 57 (31.6%) fecal samples, cysts were seen, but results of the immunoassay were negative. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that when a combination febantel-praziquantel-pyrantel product is used to treat dogs with giardiasis, bathing and changing the environment after treatment may be more important in preventing recurrence than duration of treatment.     

Number of Cryptosporidium parvum oocysts or Giardia spp cysts shed by dairy calves after natural infection

OBJECTIVE: To determine the total number of Cryptosporidium parvum oocysts and Giardia spp cysts shed by dairy calves during the period when they are most at risk after natural infection. ANIMALS: 478 calves naturally infected with C. parvum and 1,016 calves naturally infected with Giardia spp. PROCEDURE: Oocysts or cysts were enumerated from fecal specimens. Distribution of number of oocysts or cysts versus age was used to determine the best fitting mathematic function. Number of oocysts or cysts per gram of feces for a given duration of shedding was computed by determining the area under the curve. Total number of oocysts or cysts was calculated by taking the product of the resultant and the expected mass of feces. Results: Intensity of Cparvum oocyst shedding was best described by a second-order polynomial function. Shedding increased from 4 days of age, peaked at day 12, and then decreased. An infected 6-day-old calf would produce 3.89 x 10(10) oocysts until 12 days old. Pattern of shedding of Giardia spp cysts was best described by exponential functions. Intensity of shedding increased from 4 days of age, peaked at day 14, and then decreased. An infected calf would produce 3.8 x 10(7) cysts from day 50 until day 56. CONCLUSIONS AND CLINICAL RELEVANCE: The large number of oocysts and cysts shed indicates that shedding by dairy cattle poses a risk for susceptible calves and people. Estimates reported here may be useful to aid in designing cost-effective strategies to manage this risk.     

Evaluation of fenbendazole for treatment of Giardia infection in cats concurrently infected with Cryptosporidium parvum

OBJECTIVE: To determine whether fenbendazole effectively eliminates Giardia organisms from chronically infected cats that have a concurrent Cryptosporidium parvum infection. ANIMALS: 16 clinically normal cats. PROCEDURE: Eight cats with chronic concurrent Giardia and C parvum infections received fenbendazole (50 mg/kg, PO, q 24 h) for 5 days (treatment-group cats). Feces from each cat were collected and processed 3 days weekly for 23 days after treatment. By use of an immunofluorescent assay for detection of Giardia lamblia cysts and C parvum oocysts, organism numbers were counted and scored. Fecal results from treatment-group cats were compared with those of 8 untreated cats with Giardia infection but no C parvum infection (control-group cats). RESULTS: Four of 8 treatment-group cats had consistently negative results for Giardia infection after treatment. These 4 cats had consistently positive results for C parvum oocysts prior to treatment and consistently negative results after treatment. One treatment-group cat had positive results for cysts on all fecal samples, and 3 treatment-group cats had 1 to 3 negative results and then resumed shedding large numbers of cysts; each of these cats had consistently positive results for C parvum oocysts. When compared with control-group cats, treatment-group cats shed less Giardia cysts during week 1 after treatment but not during week 2. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of fenbendazole decreases Giardia cyst shedding to less than detectable numbers in some cats. In our study, persistent C parvum infection may have been associated with failure of fenbendazole to eliminate Giardia infection.     

Incidence of and risks associated with Giardia infections in herds on dairy farms in the New York City Watershed

Background

The primary aims of this study were to determine the incidence of Giardia infections in dairy herds on farms in the New York City Watershed region and to evaluate risk factors associated with infections. Because co-infections of Giardia and Cryptosporidium spp. are common in this population, we also evaluated the effect of herd infection status on Giardia infections.

Methods

Farms were grouped into three cohorts based on their prior infection status with Giardia and/or Cryptosporidium spp. The sampling plan included collecting fecal samples from all calves below 30 days of age and proportional sampling of calves, young stock, and adults. A total of 10,672 fecal samples were collected and analyzed for the presence of Giardia cysts using zinc sulfate flotation. Herds enrolled in the study were sampled seasonally for a study period of two years. The probability of shedding cysts past a certain age and the factors that influenced the likelihood of shedding were evaluated using survival analysis. Linear regression was used to evaluate factors that were associated with the intensity of shedding.

Results

The majority of Giardia infections occurred in calves within their first 180 days of age, with the most number of calves shedding Giardia cysts between 11 and 20 days of age. The incidence of shedding of Giardia cysts ranged from 0.0004 per animal day for cattle in the low risk cohort to 0.0011 per animal day for cattle in the high risk cohort. The likelihood of shedding was influenced by the prior infection status of the herd and the season of collection. Infected animals shed on average 9,658 cysts/gram and the intensity of shedding Giardia cysts varied significantly with the age (p < 0.0001) and the season of collection (p = 0.0151 for Spring).

Conclusion

Giardia infections are common in dairy herds in the New York City watershed, particularly in calves less than 6 months of age. Seasonality may be an important factor in the perpetuation of infections based on changes in management practices corresponding to weather patterns of a particular season. A dairy herd''s prior infection status with Cryptosporidium influences the likelihood of infection with Giardia.     

Efficacy of vaccination in preventing giardiasis in calves

The objective of this study was to evaluate the efficacy of a vaccine in the prevention of Giardia duodenalis infection in calves. Six 2-week old calves were vaccinated subcutaneously with a sonicated G. duodenalis trophozoite vaccine. Six 2-week old control calves received a subcutaneous injection of sterile phosphate-buffered-saline mixed with adjuvant. Injections were repeated after 28 days. Eleven days after the second injection, calves were challenged orally with 1x10(5) purified G. duodenalis cysts from a naturally infected calf. Throughout the study, fecal samples were collected at regular intervals and examined for the presence of G. duodenalis cysts. Blood samples were collected weekly until G. duodenalis challenge and bi-weekly following challenge. Calves were euthanized 14 days after challenge and G. duodenalis trophozoites within the small intestines were enumerated. Serum antibody titers were significantly higher in vaccinated compared to non-vaccinated calves. Vaccinated calves tended to excrete more G. duodenalis cysts in their feces than non-vaccinated calves. The number of trophozoites in the small intestine was not different between vaccinated and non-vaccinated calves. Changes consistent of moderate enteritis were found in the intestines of one vaccinated and one non-vaccinated calf. Despite a serological immune response following vaccination, this vaccine was not efficacious in preventing giardiasis or reducing cyst shedding in calves.     

Temporal changes in the prevalence and shedding patterns of Giardia duodenalis cysts and Cryptosporidium spp. oocysts in a herd of dairy calves in Ontario

Giardia duodenalis and Cryptosporidium spp. infections, and the patterns of cyst and oocyst shedding, were observed in a herd of dairy calves in Ontario over a period of 3 mo. Cysts and oocysts were detected and enumerated in fecal samples using immunofluorescence microscopy; Giardia and Cryptosporidium DNA was detected using the polymerase chain reaction. The prevalence of G. duodenalis increased during the course of the study, reaching a peak of 93.1% when calves were 43 to 54 d old, and then decreased. Conversely, Cryptosporidium spp. prevalence was highest (75.9%) when calves were 11 to 22 d old, and subsequently decreased. The numbers of cysts and oocysts shed per gram of feces were positively correlated over time with the respective prevalence rates. Along with genotyping data, temporal changes in prevalence and shedding patterns should be considered when testing dairy calves for the presence and concentrations of cysts and oocysts, and when considering the potential for zoonotic transmission.