Prevalence and age-related variation of Cryptosporidium species and genotypes in dairy calves   总被引：8，自引：0，他引：8  

Santín M  Trout JM  Xiao L  Zhou L  Greiner E  Fayer R 《Veterinary parasitology》2004,122(2):103-117

Fifteen dairy farms in seven states on the east coast of the US were each visited on two consecutive years to determinate the prevalence of Cryptosporidium species in pre-weaned (5 days to 2 months) and post-weaned calves (3-11 months), respectively. After each of 971 fecal specimens collected directly from each calf was sieved and subjected to density gradient centrifugation to remove debris and concentrate oocysts, specimens were examined by immunofluorescence microscopy, and polymerase chain reaction (PCR). For all PCR-positive specimens the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified from all farms. Types of housing appeared to have no influence with regard to prevalence of infection. Of 971 calves, 345 were infected with Cryptosporidium (35.5%), but more pre-weaned calves (253 of 503; 50.3%) than post-weaned calves (92 of 468; 19.7%) were found to be infected. A total of 278 PCR-positive specimens characterized by gene sequencing revealed Cryptosporidium parvum, Cryptosporidium andersoni, and two unnamed Cryptosporidium genotypes Bovine B (AY120911) and deer-like genotype (AY120910). The prevalence of these Cryptosporidium species and genotypes appeared to be age related between pre- and post-weaned calves. C. parvum, the only zoonotic species/genotype, constituted 85% of the Cryptosporidium infections in pre-weaned calves but only 1% of the Cryptosporidium infections in post-weaned calves. These findings clearly demonstrate that earlier reports on the presence and prevalence of C. parvum in post-weaned cattle that were based solely on oocyst morphology must be reassessed using molecular methods to validate species and genotype. This finding also indicates that persons handling or otherwise exposed to calves under 2 months of age are at greater risk of zoonotic infection from Cryptosporidium than the risk of infection from exposure to older calves.  相似文献   

Concentrating, purifying and detecting waterborne parasites   总被引：1，自引：0，他引：1  

Zarlenga DS  Trout JM 《Veterinary parasitology》2004,126(1-2):195-217

There has been recent emphasis on developing better methods for detecting diseases of zoonotic and veterinary importance. This has been prompted by an increase in human disease agents detectable in environmental samples, the potential for bioterrorism, and the lowering of international trade barriers and expansion of personal travel, which are bringing previously considered exotic diseases to new geographical localities. To appreciate the complexities of developing detection methods and working with environmental samples, it is appropriate to review technologies currently in use, as well as those in development and presently limited to research laboratories. Discussion of parasite detection would not be possible without including methods for parasite sampling, concentration, and purification because it is often necessary to process large sample volumes prior to analysis, and no reliable methods are available for significantly amplifying parasites in vitro. Reviewing proven methods currently in use will provide a baseline for generating, accepting and implementing the more sensitive and specific methods under development today.  相似文献   

Prevalence of Giardia duodenalis genotypes in pre-weaned dairy calves   总被引：1，自引：0，他引：1  

Trout JM  Santín M  Greiner E  Fayer R 《Veterinary parasitology》2004,124(3-4):179-186

To determine the prevalence of Giardia genotypes in pre-weaned dairy calves, fecal samples were collected from a minimum of 18, 1-7-week-old dairy calves per farm on two farms each in the states of Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida. Samples cleaned of fecal debris and concentrated using CsCl density gradient centrifugation were stained and examined by immunofluorescence microscopy and also subjected to PCR and gene sequence analysis. Prevalence by PCR ranged from 9% on a farm in Pennsylvania to 93% on a farm in Vermont, with an average prevalence for 407 calves on 14 farms of 40%. Gene sequence analysis of the TPI, beta-giardin and 16S rRNA genes revealed 85% of the positive samples to be Assemblage E, while 15% were Assemblage A, although the percentages of these genotypes varied greatly from farm to farm. Some farms had no Assemblage A Giardia. Thus, while a majority of the calves were infected with a genotype that is not known to be infectious for humans, calves on 7 of 14 farms did harbor Assemblage A Giardia. Calves should be considered as a potential source of human infectious cysts in the environment.  相似文献   

Cryptosporidium, Giardia and Enterocytozoon bieneusi in cats from Bogota (Colombia) and genotyping of isolates     

Santín M  Trout JM  Vecino JA  Dubey JP  Fayer R 《Veterinary parasitology》2006,141(3-4):334-339

The prevalence of Cryptosporidium, Giardia, and Enterocytozoon bieneusi in cats from Bogota (Colombia) was determined from fecal specimens and scrapings of duodenal and ileal mucosa screened by PCR. All PCR-positive specimens were sequenced to determine the genotype(s) present. Of 46 cats, 6 (13%) were positive for Cryptosporidium, 5 (11%) were infected with C. felis and one (2%) with C. muris. Three (6.5%) cats were infected with Giardia duodenalis Assemblage F. Eight (17%) cats were infected with four genotypes of E. bieneusi: genotype D-like (9%), K (4%), Peru 10 (2%), and Peru 5 (2%). This is the first report on the presence of zoonotic species/genotypes of Cryptosporidium and E. bieneusi in cats in Colombia.  相似文献   

Detection of Assemblage A, Giardia duodenalis and Eimeria spp. in alpacas on two Maryland farms     

Trout JM  Santín M  Fayer R 《Veterinary parasitology》2008,153(3-4):203-208

Sixty-one fecal samples were collected from adult alpacas and crias (ages 10 weeks to 10 years) on two farms in central Maryland. The farms raised both suri (silky-haired) and huacaya (crimpy-haired) breeds. Females and crias were housed together on pasture, whereas older/breeding males were maintained on separate pastures. Samples were subjected to a density gradient centrifugation protocol to concentrate parasites and remove fecal debris and were examined by immuno-fluorescent and differential interference contrast microscopy. Oocysts of Eimeria spp. were noted in 14 fecal samples, 6 on MD-1 and 8 on MD-2. Based on oocyst morphometrics two species of Eimeria were present: E. punoensis (19.2 microm x 16.5 microm) and E. alpacae (23.7 microm x 19.5 microm). Five animals shed exclusively E. punoensis, seven shed exclusively E. alpacae, and two had mixed infections. The Eimeria infections were not associated with obvious clinical signs. To determine the presence of Cryptosporidium and Giardia species and genotypes, DNA was extracted from feces and subjected to PCR utilizing specific primers for the ssu-rRNA gene for both parasites. All PCR positive samples were further analyzed by DNA sequencing to identify the species or genotypes that were present. Assemblage A, G. duodenalis was detected in fecal samples from two alpacas on MD-1 and in one alpaca on MD-2. Assemblage E, G. duodenalis and Cryptosporidium spp. were not detected on either farm. Although the prevalence on these two farms was low, alpacas can harbor zoonotic G. duodenalis, and this should be borne in mind by persons interacting with the animals.  相似文献   

Prevalence of species and genotypes of Cryptosporidium found in 1-2-year-old dairy cattle in the eastern United States   总被引：6，自引：0，他引：6  

Fayer R  Santín M  Trout JM  Greiner E 《Veterinary parasitology》2006,135(2):105-112

The prevalence of Cryptosporidium species in 1-2-year-old heifers was determined for 571 animals on 14 dairy farms in seven states on the East Coast of the United States. A fecal specimen collected directly from each heifer was processed to concentrate oocysts that were then examined by polymerase chain reaction (PCR). For every PCR-positive specimen the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified by PCR from heifers on 13 of 14 farms. On all except four farms groups of heifers were housed in a barn or in large covered pens. Others were pastured. From many of the same farms an earlier study reported that 41% of 393 pre-weaned calves and 26.2% of 447 post-weaned calves were infected. In the present study, 11.9% of 571 heifers were infected with Cryptosporidium, 0.7% with Cryptosporidium parvum, the zoonotic species. Of 68 PCR-positive specimens characterized by gene sequencing 1, 4, 10, 24, and 29 calves were infected with Cryptosporidium suis, Cryptosporidium parvum, Cryptosporidium deer-like genotype, Cryptosporidium bovis, and Cryptosporidium andersoni, respectively. These findings demonstrate a lower prevalence of infection in 1-2-year-old dairy cattle than in younger cattle as well as a change in the diversity of species present. Consequently, the risk of humans acquiring infection with C. parvum from exposure to feces from yearling and older cattle appears much lower than from exposure to pre-weaned calves.  相似文献   

Effectiveness of a paraverterbral nerve block versus local portal blocks for laparoscopic closure of the nephrosplenic space: A pilot study     

Massimo M. Delli-Rocili DVM  Nicola C. Cribb MA VetMB  DVSc  DACVS  Donald R. Trout DVM  PhD  DACVS  Jeffrey J. Thomason BA  MSc  PhD  Alexander Valverde DVM  DVSc  DACVAA 《Veterinary surgery : VS》2020,49(5):1007-1014

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Quantification of naloxone binding sites in brains from suckled beef cows during postpartum anestrus and resumption of estrous cycles     

W E Trout  P V Malven 《Journal of animal science》1988,66(4):954-960

Thirty beef cows, approximately 3 yr of age, were randomly assigned to be slaughtered on d 7, 14, 28, 42 or 56 postpartum. Each cow suckled one calf until slaughter. Data from cows slaughtered on d 42 and 56 were pooled and further classified as anestrous or cyclic based on the presence of a corpus luteum and elevated serum concentrations of progesterone at slaughter. Specific binding of [3H]naloxone (3H-NAL) to homogenates of tissue from hypothalamus (HYP), preoptic area (POA) and basal forebrain (BF) was assessed using multiple-point Scatchard analyses. Nonspecific binding was estimated in the presence of 10(-6) M naloxone. Separation of bound from free 3H-NAL was achieved by centrifugation at 20,000 X g. Concentration (fmol/mg original tissue wet wt) of 3H-NAL binding sites in POA tissue was higher (P less than .05) on d 28 postpartum in anestrous cows than in cyclic cows on d 42 + 56 postpartum (2.58 +/- .32 vs 1.58 +/- .10). When all anestrous cows were compared with cyclic cows, concentrations of 3H-NAL binding sites in POA tissues and in BF tissue were higher (P less than .05) in anestrous cows (anestrous POA, 2.12 +/- .17, cyclic POA, 1.58 +/- .10; anestrous BF, 2.94 +/- .41, cyclic BF, 2.19 +/- .16). Compared across brain regions for all cows, the concentration of specific binding sites for 3H-NAL was greater (P less than .01) in BF (2.5 +/- .2) than in POA (1.9 +/- .1) and greater (P less than .01) in POA than in HYP (1.5 +/- .1).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Effects of in vitro corticosterone on chicken T‐ and B‐lymphocyte proliferation     

J. M. Trout  M. M. Mashaly 《British poultry science》1995,36(5):813-820

1. The effects of corticosterone and the time of its addition to cultures, on concanavalin A (Con‐A) and pokeweed mitogen (PWM)‐induced lymphocyte proliferation were studied.

2. Peripheral blood lymphocytes (PBL) were isolated from Cornell K‐strain Single Comb White Leghorn immature male chickens and cultured with various concentrations of Con‐A or PWM. Corticosterone, in different concentrations, was added to the cultures either 2 h before or 2 h after the addition of the respective mitogen.

3. Addition of corticosterone 2 h before the mitogens caused a significant suppression of lymphocyte proliferation in response to both Con‐A and PWM stimulation. Also addition of corticosterone 2 h after the mitogens caused significant suppression of proliferation in response to both mitogens; however, the degree of suppression was not as great.

4. The results indicate that after early activation events are initiated by the mitogens, lymphocytes are less sensitive to the effects of corticosterone. Because less suppression was seen in the cultures preincubated with PWM than those with Con‐A, it is likely that there are different sensitivities to corticosterone in the cell populations that respond to these mitogens.  相似文献   

Specific binding of naloxone to ovine brain tissue: comparison of brain regions and endocrine states     

G D Weesner  W E Trout  P V Malven 《Journal of animal science》1989,67(6):1532-1537

Binding of [3H]naloxone ([3H]NAL) to brain membranes was quantified by Scatchard analysis using two methods of separating bound from free [3H]NAL. In the centrifugation method, membranes that were soluble at 1,000 x g, but sedimented at 20,000 x g, were incubated with [3H]NAL. For filtration, all membranes that sedimented at 20,000 x g were incubated and filtered through glass filter fibers. Nonspecific binding was estimated using greater than 500-fold excess of unlabeled naloxone (10(-6) M). Specific binding of [3H]NAL was used to generate linear multiple-point Scatchard plots, which indicated a single class of high-affinity sites. In Exp. 1, 10 ovariectomized (OVX) ewes were injected with estradiol-17 beta alone or in combination with progesterone. Compared with OVX controls, these hormonal treatments did not affect binding of [3H]NAL (centrifugation method) to combined hypothalamus (HYP) + preoptic (POA) tissues. In cyclic ewes (Exp. 2, filtration method), affinity constants (2.4 +/- .2 x 10(8) M-1) did not differ among HYP, POA and basal forebrain (BF) tissues, but BF had more sites (39 +/- 3 fmol/mg) than either HYP (14 +/- 1) or POA (17 +/- 1). Binding affinity and concentration of sites within each brain area (HYP, POA, BF) did not differ between d 8 and d 16 (preovulatory but after luteolysis) in normally cycling ewes. Overall, neural tissue dissected from BF had a greater concentration of binding sites than HYP or POA. Exogenous and endogenous fluctuations in ovarian steroids did not affect binding of [3H]NAL to these tissues.  相似文献