SEARCH · Search PubMed

Results for “veterinary pathogens”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources

PubMed1993

Etiology and pathology of equine placentitis.

Placentas from aborted, stillborn, and premature foals were examined during the 1988 and 1989 foaling seasons, and 236 of 954 (24.7%) had placentitis. Microorganisms associated with placentitis were isolated or demonstrated from 162 of 236 (68.6%) placentitis cases. Leptospira spp. and a nocardioform actinomycete were 2 important, newly emerging bacteria associated with equine placentitis. Major pathogens identified in decreasing order were Streptococcus zooepidemicus, Leptospira spp., Escherichia coli, a nocardioform actinomycete, fungi, Pseudomonas aeruginosa, Streptococcus equisimilis, Enterobacter agglomerans, Klebsiella pneumoniae, and alpha-hemolytic Streptococcus. Pathogens were not recovered in 64 cases (27.1%) and overgrowth by saprophytic bacteria was recorded in 10 cases (4.2%). Twenty-seven cases (16.6%) had mixed bacterial growth and 93 cases (57.4%) had bacteria cultured from both placenta and fetal organs. The majority of the placentitis cases caused by bacteria, with the exception of Leptospira spp. and the nocardioform actinomycete, occurred in 2 forms. One was acute, focal or diffuse; had an infiltration of neutrophils in the intervillous spaces or necrosis of chorionic villi; was associated with bacteremia; and frequently occurred in the placenta from fetuses expelled before or at midgestation. The other was observed from foals expelled at late gestation, was mostly chronic and focal or focally extensive, and occurred mostly at the cervical star area. Chronic placentitis was characterized by the presence of 1 or a combination of the following lesions: necrosis of chorionic villi, presence of eosinophilic amorphous material on the chorion, and infiltration of mononuclear inflammatory cells in the intervillous spaces, villous stroma, chorionic stroma, vascular layer, and allantois.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗

PubMed1997

Comparison of five tests for the detection of antibodies against chlamydial (enzootic) abortion of ewes.

Five tests for antibodies against chlamydial (enzootic) abortion of ewes were compared using 255 sera from experimentally (group 1) or naturally (group 2) infected animals, flocks free of the disease (group 3) and individual animals testing positively by the complement fixation test but from flocks with no evidence of chlamydial abortion (group 4). Sera from five specific pathogen-free lambs vaccinated with two different subtypes of Chlamydia pecorum were also included (group 5). All tests used some form of processed culture of C psitiaci as antigen. Specificities, established with group 3 and 4 sera, ranged between 96 per cent (ELISA using lipopolysaccharide antigen) and 59 per cent (Immunocomb). Reactions with group 5 sera suggested that the cause of false positive results in the field might be cross-reactive antibodies against the arthritogenic subtype of C pecorum. Sensitivities, established with groups 1 and 2 sera, ranged between 81 per cent (Immunocomb) and 51 per cent (ELISA using solubilised protein antigen). The minimum sample sizes required to be 95 per cent certain of detecting at least five seropositives in two infected flocks (combined data) were 15 to 48, dependent on the test applied. The Western blot test, applied to a proportion of samples, yielded no false positives with group 3 sera but 31.7 per cent with group 4 sera. Thus, none of the tests in this comparison emerged as sufficiently satisfactory in all respects, suggesting that further improvements in chlamydial serology must come through the use of non-native antigens or in the form of a competitive ELISA.

Abortion, Septic↗

PubMed2002

Characterisation of the first Australian isolate of Neospora caninum from cattle.

OBJECTIVE: To isolate Neospora caninum from a congenitally infected calf. PROCEDURE: A calf was obtained from a N. caninum infected dam maintained in a dairy herd of Holstein-Friesian cattle located on the south coast of NSW near Nowra. The calf was euthanased and samples collected for serology and pathology. Samples of brain and spinal cord of the calf were homogenised and injected into immunocompromised mice in an attempt to recover protozoa by in vivo culture. Sequential passage of brain homogenate through IFNgammaPKO mice was performed and tissue culture flasks were inoculated with brain homogenate. Parasites were identified by electron microscopy and DNA sequencing. The antigen profile of the isolate was analysed using Western blotting. Pathogenicity was examined in BALB/c mice and transmission of the parasite during pregnancy was examined in Qs mice. RESULTS: The calf was seropositive for N. caninum and histopathological examination of sections of cerebrum identified lesions consistent with a very mild infection with N. caninum. The parasites isolated using tissue culture were identified as N. caninum, based on the sequence of the ribosomal DNA and electron microscopy. The antigen profile of the new isolate was similar to that of the NC-Liverpool isolate, but quite different from that of Toxoplasma gondii. In BALB/c mice inoculated with the new isolate, severe clinical signs developed in only three of ten infected mice, compared with six of ten mice infected with NC-Liverpool. Mild to moderate nonsuppurative encephalitis was observed in BALB/c mice infected with the new isolate, compared with mice infected with NC-Liverpool, that developed severe nonsuppurative encephalitis. Transplacental transmission of the isolate arising from an acute infection during pregnancy occurred in about 87% of pups. CONCLUSION: This is the first isolation of bovine Neospora caninum in Australia. This isolate, called NC-Nowra, appears to be a less virulent form and may prove to be a suitable candidate for vaccine development.

Abortion, Veterinary↗

PubMed2000

Cytochromes and cytokines: changes in drug disposition in animals during an acute phase response: a mini-review.

Diseases are a major cause of variation in drug response. Although many different diseases are known that have an effect on the pharmacokinetics or sometimes the pharmacodynamics of a drug, disorders associated with a so-called acute phase response (APR) are the most important in this respect. During APR, for example caused by tissue damage or invasion of a pathogen, a group of symptoms can be observed that often include fever, lassitude, inhibition of gastric function and synthesis of acute phase proteins. All phases that together determine the pharmacokinetic profile of a drug, absorption, distribution, metabolism and excretion, can be affected during APR. From a clinical point of view however, the effects on absorption and metabolism are the most relevant. For drugs that are given orally, a slower absorption rate is often observed during APR due to a delayed gastric emptying. Even more important from a clinical point of view is the depression of biotransformation capacity in the liver during APR, especially affecting the enzymes of the cytochrome P450 (CYP450) complex. Although much has become known about the mechanism of this effect, a number of questions remain. Cytokines, nitric oxide and possibly the enzyme heme oxygenase are playing a role in a complex process that depends on a mutual interaction between Kupffer cells (macrophages) and hepatocytes in the liver. The clinician should be aware of unexpected changes in drug effects or residue levels due to cumulation of the compound during disease or after vaccination. In these situations, drugs that are excreted unchanged may be better alternatives.

Acute-Phase Reaction↗

PubMed1975

Perinatal lamb mortality in Western Australia. 6. Listeric infection.

Listeric abortion was diagnosed in sheep on 14 occasions between 1963-65, and 4 of these were associated with other major abortion pathogens. Except for infection in one district, the outbreaks were scattered sporadically over the southern agricultural area. The diagnosis in 1963 was the first time listeriosis had been found in animals or man in Western Australia. L. monocytogenes was readily recovered in pure culture from all organs and sites cultured. All the strains were serotype 5 Ivanov, with a distinctive double zone of haemolysis. The time-of-death of the 40 infected lambs was: ante-parturient death 50%, parturient death 10% and post-parturient death 40%. Three-quarters of the lambs had gross lesions, the most consistent being small necrotic foci in the liver. Typically, lambs with congenital listeriosis had subcutaneous oedema, hydrothorax, hydroperitoneum, distended abdomen, enlarged pale bronze-red friable livers with small necrotic foci, small abomasal erosions, increased yellow-orange mucoid meconium and enlarged mesenteric lymph nodes. The finding of small yellowish, necrotic foci in the liver, small abomasal erosions and yellow-orange meconium in an aborted lamb was considered to be almost pathognomonic for listeriosis. The origin of these outbreaks was unknown. No evidence of Listeria was found in 61 specimens from 7 species of native fauna caught in the infected areas. Epizootiological observations are reported. No cases of neuro-listeriosis were observed.

Abortion, Veterinary↗

PubMed2026

High within-herd prevalence and assessment of production impacts of Coxiella burnetii in postpartum cattle from a Scottish dairy herd.

Coxiella burnetii is endemic in Great Britain dairy herds but detailed investigations of C. burnetii epidemiology and impacts on livestock production in this region are scarce. The objectives of this cross-sectional study were to first determine the within-herd prevalence of C. burnetii on a commercial Scottish dairy farm with prior detection of C. burnetii and second assess the relationship between pathogen load and individual health and performance traits. Vaginal swabs were collected from cows up to seven days postpartum. DNA extracts were tested for C. burnetii by IS1111 qPCR assay. Generalized linear models were used to estimate the relationships between bacterial load and health and performance traits. A total of 313 swabs were collected between 15 December 2022 and 06 July 2023, of which 301 (96.1%) had detectable C. burnetii DNA with Ct ≤ 40. The Ct values observed (12.9-38.7) corresponded to estimated genome equivalents per reaction of < 1 to ∼2.5 million genomes. Higher bacterial loads were seen in primiparous compared to multiparous cows. Higher bacterial loads were also more likely in cows that had experienced one or more negative reproductive outcomes, including abortion, premature delivery, prolonged gestation, stillbirth and dystocia. The direction of causation underlying the observed associations and representativeness of findings from this single herd require further investigation. This study provides insights into the within-herd dynamics of C. burnetii and evidence generated through sampling and diagnostic testing approaches that can inform future work to characterize the epidemiology and impacts of this infection in Great Britain dairy cattle and globally.

Cattle↗

PubMed2000

Occurrence, selection and spread of resistance to antimicrobial agents used for growth promotion for food animals in Denmark.

UNLABELLED: 14.1 INTRODUCTION: This thesis is based on a number of monitoring and research programmes initiated at the Danish Veterinary Laboratory with the aim to determine the occurrence, selection and spread of resistance to antimicrobial agents used for growth promotion. The thesis gives a brief overview of the use, consumption, function and benefit of antimicrobial growth promoters and a more thorough description of the potential resistance problems arising by the use of these agents. 14.2 THE USE OF ANTIMICROBIAL AGENTS IN A HISTORICAL PERSPECTIVE: Soon after the introduction of antimicrobial agents for therapy of bacterial infections in humans and animals, the growth promoting effect of antimicrobial agents was observed, and since the beginning of the 1950'ties antimicrobial agents have been included in feed for food animals as a way to improve growth and reduce production costs. 14.3 CONSUMPTION OF ANTIMICROBIAL GROWTH PROMOTERS: Exact figures on the consumption of antimicrobial agents for clinical and growth promoting purposes are very difficult to get, and estimates are only available for a few countries. In Denmark, the total annual consumption of antimicrobial agents for growth promotion increased from 67 tonnes to 116 tonnes from 1989 to 1995. After the ban on avoparcin in 1995 the total consumption of growth promoters decreased to 94 tonnes. An increase up to 107 tonnes took place during 1996 and 1997, but during 1998, the consumption decreased to approximately 49 tonnes. The data that are available for different countries show that the use of antimicrobial agents for growth promotion normally equals or exceeds the usage of antimicrobial agents for therapy for food animals. Based on the information available, it can be estimated that the financial sale of antimicrobial agents for animals amounts to approximately 25% to 35% of the world-wide sale, of which the use of antimicrobial agents as feed additives is at least 50%. 14.4 MODE OF ACTION OF ANTIMICROBIAL GROWTH PROMOTERS: The mode of action of antimicrobial growth promoters is not fully understood. However, the main effects are believed to be a reduction of the growth of bacteria in the intestinal tract and thereby less microbial degradation of useful nutritients, and the prevention of infections with pathogenic bacteria. 14.5 BENEFIT FROM THE USE OF ANTIMICROBIAL GROWTH PROMOTERS: Numerous studies on the economic benefit of the use of antimicrobial growth promoters have been performed. The growth response is normally larger in young animals than in older animals. Large variations in the estimates have been observed, but in general a improvement in growth rate and feed utilisation has been observed. 14.6 SUSCEPTIBILITY AND RESISTANCE TO ANTIMICROBIAL GROWTH PROMOTERS: The definition of a bacterium as susceptible or resistant to an antimicrobial agent ultimately depends on clinical outcome. Since the exact mode of action of antimicrobial growth promoters are not known, the only way to define break points is based on the population distributions of susceptibilities to different agents. For antimicrobial agents used both for therapy and growth promotion the break points for therapy have been used. For avilamycin, avoparcin, flavomycin, monensin and salinomycin, that are used for growth promotion only, tentative break points based on population distributions have to be defined. The tentative break points for avoparcin and avilamycin have been confirmed by cross-resistance to other antimicrobial agents belonging to the same class and the presence of resistance mechanisms. 14.7 OCCURRENCE OF AND SELECTION FOR RESISTANCE TO ANTIMICROBIAL AGENTS USED FOR GROWTH PROMOTION: Information on the occurrence of resistance is needed to guide policy and detect changes that require intervention strategies. In 1995, a continuous monitoring of antimicrobial resistance in bacteria isolated from food animals was established in Denmark. Among food animals three categories of bacteria (indicator bacteria, zoonotic bacteria and animal pathogens) are continuously isolated from broilers, cattle and pigs and tested for susceptibility to antimicrobial agents used for therapy and growth promotion by disc diffusion or MIC-determinations. In all known cases antimicrobial resistance has emerged following the introduction of new antimicrobial compounds for therapy. The occurrence of resistance to antimicrobial agents used for growth promotion indicates that resistance will also emerge following the introduction of antimicrobials for growth promotion. Comparison of the occurrence of resistance among reservoirs with different usage of antimicrobial agents for growth promotion also shows that the occurrence of resistance will follow the usage. (ABSTRACT TRUNCATED)

Animal Husbandry↗

PubMed1996

Identification of bovine Neospora parasites by PCR amplification and specific small-subunit rRNA sequence probe hybridization.

Neospora is a newly recognized genus of pathogenic coccidia, closely related to Toxoplasma gondii, that can cause abortion or congenital disease in a variety of domestic animal hosts. On the basis of the small-subunit rRNA gene sequences of Neospora spp. and other apicomplexa coccidia, oligonucleotide primers COC-1 and COC-2 were used for PCR amplification of conserved sequences of approximately 300 bp in size. A Neospora-specific chemiluminescent probe hybridized to Southern blots of amplification products from Neospora DNA but not to Southern blots with amplified DNA from the other coccidian parasites tested. A Toxoplasma-specific probe whose sequence differed from that of the probe for Neospora spp. by a single base pair was used to distinguish these parasites by specific Southern blot hybridization. The PCR system detected as few as one Neospora tachyzoite in the culture medium or five tachyzoites in samples of whole blood or amniotic fluid spiked with Neospora parasites. In addition, Neospora PCR products were successfully amplified from whole blood and amniotic fluid samples of experimentally infected bovine and rhesus macaque fetuses. These results indicate that this PCR and probe hybridization system could be a valuable adjunct to serology and immunohistochemistry for the diagnosis of Neospora infections in bovine or primate fetuses.

Abortion, Veterinary↗

PubMed2004

[New methods for the diagnosis of Cryptosporidium and Giardia].

The accurate identification of a parasite at the species and/or genotype level has major implications for various aspects of human and veterinary parasitology, including the diagnosis, the taxonomy, the treatment and the control. The advent of molecular techniques, in particular those based on the in vitro amplification of nucleic acids, has dramatically improved our ability to detect infections caused by parasites. To illustrate the progress in molecular diagnostics, Cryptosporidium and Giardia are used here as examples of parasites for which both the diagnosis and the taxonomy have traditionally been problematic. These protozoan parasites, while very different for many aspects of their biology, shares a complex series of transmission routes, including anthroponotic and zoonotic transmission, as well as waterborne and foodborne transmission. The resistant stages produced by Cryptosporidium and Giardia (oocysts and cysts, respectively) are remarkably stable, and can survive for weeks to months in the environment. Further, the infective dose is low, and infectious dose studies and models suggest that even a single oocyst or cyst carries some probability of causing an infection. Finally, most faeces that contain (oo)cysts end up in the environment and can be spread to foods by irrigation or by direct contact, and can persist in the water, as routine treatments eliminate only a fraction of these stages. This situation explains the growing interest towards the development of methods that allows such stages to be detected with the highest sensitivity and specificity. A variety of Polymerase Chain Reaction (PCR) assays have been described for both Cryptosporidium and Giardia. The choice of a particular assay mainly depends on the amount of information carried by the genetic locus under analysis. Indeed, some assays can be used to identify the different species within a genus, while others allowed to distinguish between isolates of the same species (genotypes), and some can even be used for both purposes. Post-PCR analyses are usually based on the direct sequencing of the amplification products, or on the digestion with endonucleases followed by gel electrophoresis of the restriction fragments. In the last few years, the molecular characterization of a large number of isolates, collected from infected hosts and from the environment, has considerably changed our view of the epidemiology of cryptosporidiosis and giardiasis. Indeed, several species/genotypes have been established as human pathogens, and the nature of the parasites present in the water and in food have been investigated, allowing a better understanding of the complex circulation of the parasites in the environment, that may eventually led to implemented control measures. Finally, phylogenetic analysis of several nuclear genes is having a major impact in the revision of the taxonomy of Cryptosporidium and Giardia. The main limitation of PCR is that it doesn't provide information on the viability and infectivity of the pathogen. To obtain additional information on these important aspects, indirect methods, such as inclusion/exclusion assays using vital dyes or the Reverse-Transcriptase PCR (RT-PCR), can be used. Since RT-PCR relies on the integrity of mRNA, which usually has very short half-life (seconds), its use is thought to provide a more closely correlated indication of viability status compared to DNA-based methods. RT-PCR assays usually target the heat shock protein (hsp) 70 gene. The rationale behind this choice is that hsps are known to be synthesized with a high level of efficiency in stressed organisms; therefore, when (oo)cysts are exposed to a thermal shock, the induction of heat shock response provides both a level of amplification to increase detection sensitivity and an index of viability. Moreover, with the recent introduction of real-time PCR, that allows the continuous monitoring of amplicon formation throughout the reaction, quantitative aspect of the infection could be studied with exquisite sensitivity. This will, for example, allow (1) to detect carrier states, (2) to determine the number of oocysts/cysts present in a sample, (3) to study quantitative aspects of gene expression during the various phases of the infection.

Animals↗

PubMed1980

Bovine virus diarrhoea-mucosal disease virus: pathogenicity for the fetal calf following maternal infection.

Fifteen pregnant, bovine virus diarrhoea-mucosal disease (BVD-MD) antibody-free Jersey heifers were infected experimentally with a mixture of 10 cytopathic strains of BVD-MD virus isolated from cattle in Britain. Each cow was inoculated intramuscularly on gestation day 100 with a high or a low dose of virus grown in primary calf testis tissue cultures. None of the cows showed clinical signs of illness following exposure, but all had seroconverted within six weeks. Six fetuses, including one set of twins, died in utero following infection. Of these five were aborted between days 136 and 154; the sixth one was mummified and still retained at day 300. The remaining 10 fetuses survived to term, but all showed evidence of intrauterine growth retardation with or without gross malformation and/or dysmyelination of the central nervous system. Three were clinically affected with congenital nervous disease. Of the 10 liveborn fetuses, two had specific serum antibodies to BVD-MD. Non-cytopathic BVD-MD virus was recovered from all of the remaining eight. When non-immune cows become infected with BVD-MD virus in mid gestation: transplacental infection of the fetus will probably result; apart from the risk of fetal death, with or without abortion, there is a high probability of fetal mal-development which may not always be clinically obvious; the immunological competence of the fetus may be impaired; congenital infection is likely in a substantial proportion of liveborn calves. About one in 16 bovine fetuses in British herds are estimated to be at risk from BVD-MD virus infection.

Abortion, Veterinary↗

PubMed2004

Effect of timing of first clinical mastitis occurrence on lactational and reproductive performance of Holstein dairy cows.

Objectives of this study were to determine the influence of timing of first clinical mastitis case occurrence on lactational and reproductive performance in high producing lactating dairy cows during the first 320 days in milk (DIM). Holstein cows, 1001, from two commercial dairy farms in California were retrospectively divided into four treatment groups according to timing of first clinical mastitis case caused by environmental pathogens: control with no recorded clinical cases of mastitis (C; n=501); first clinical mastitis prior to first postpartum AI (MG1; n=250); first clinical mastitis between first postpartum AI and pregnancy diagnosis (MG2; n=147); and first clinical mastitis after diagnosed pregnant (MG3; n=103). Clinical cases of mastitis were identified at every milking by the herd personnel based on abnormal milk or swelling of the mammary gland. A fore sample of milk was aseptically collected from every clinical case for microbiological culture. Mastitis decreased yields of milk, 3.5% fat-corrected milk, and milk components, but the effect was only observed for MG1 and MG2. Cows in the control group had lower linear somatic cell count (SCC) score throughout the lactation. Culling was increased by mastitis, and cows in the mastitis groups left the study earlier than controls. Conception rate at first postpartum AI and pregnancy rate at the end of the study were both decreased by mastitis prior to or after first AI, and MG1 and MG2 cows had extended days open. Furthermore, cows experiencing mastitis during lactation had a higher incidence of abortions. The negative effects of mastitis on reproduction were observed regardless of clinical case being caused by either Gram positive or negative bacteria. Mastitis either prior to or after first postpartum AI impairs lactation performance, increases culling, and decreases reproductive efficiency in high producing Holstein dairy cows.

Abortion, Veterinary↗

PubMed2026

A One Health approach to Antimicrobial Resistance: Concepts, challenges, and advances in omics.

Antimicrobial resistance (AMR) is a global threat driven by the interplay between microbial evolution and human activity. Antimicrobial use in human and veterinary medicine, as well as in agriculture, accelerates the selection and dissemination of resistant bacteria and genes across interconnected human, animal, and environmental reservoirs. These dynamic exchanges render single-sector interventions ineffective. A One Health approach integrating human, animal, and environmental health is therefore essential to understand and mitigate the emergence and spread of AMR. This chapter focuses on bacterial antimicrobial resistance, addressing key concepts, major challenges, and emerging technologies within a One Health framework. Advances in next-generation sequencing and omics technologies have transformed our capacity to resolve AMR at unprecedented scale and resolution. These tools enable the tracking of resistance genes and high-risk clones across ecosystems, uncover transmission pathways, and identify key drivers of dissemination. Such insights support real-time epidemiological surveillance, outbreak detection, and targeted interventions. However, translating these advances into routine practice remains a major challenge, requiring harmonized methodologies, data integration, and cross-sector coordination. Addressing AMR demands sustained collaboration across disciplines and stakeholders, including clinicians, veterinarians, farmers, researchers, policymakers, industry, and the public. And framing AMR as a shared ecological and societal responsibility underscores the urgency of coordinated global action. We call for the urgent integration of One Health principles into surveillance, policy, and innovation to preserve antimicrobial effectiveness and safeguard future health.

Humans↗

PubMed2003

Detection of Tritrichomonas foetus by polymerase chain reaction in cultured isolates, cervicovaginal mucus, and formalin-fixed tissues from infected heifers and fetuses.

A rapid, reliable polymerase chain reaction (PCR) assay, originally developed for definitive laboratory identification of the bovine venereal pathogen Tritrichomonas foetus from cultures of male reproductive tract fluids, was used for testing the following: 1) cultured, geographically disparate trichomonad isolates, 2) formalin-fixed tissues from infected heifers and naturally infected fetuses, and 3) cervicovaginal mucus (CVM) from experimentally infected females. In 12 of 12 Western Hemisphere isolates of pathogenic T. foetus (isolated from outbreaks of clinical trichomoniasis or from screening surveys) and in 1 of 1 American Type Culture Collection strain of Tritrichomonas suis, PCR yielded a positive result, i.e., a 347-base pair amplicon in the 5.8S ribosomal RNA and internal transcribed spacer (5.8S-ITS) region of the genome, whereas cultures of Trichomonas vaginalis and Trichomonas gallinae did not produce a PCR product. The PCR assay was also positive in formalin-fixed, paraffin-embedded endometrial samples from 4 of 4 experimentally infected heifers, as well as in archived tissues from 2 of 2 T. foetus-infected aborted bovine fetuses that were submitted to the diagnostic laboratory from a natural outbreak. It was negative in fixed, embedded uterine tissues of 2 of 2 uninfected virgin heifers used as negative controls and in archived fixed gut tissue of a T. gallinae-infected pigeon. In another experiment, CVM aspirated from 4 of 4 experimentally infected heifers in the fifth or sixth postinfection week yielded a positive PCR product of the expected size, whereas CVM from 2 of 2 controls were PCR negative. Pending validation in larger clinical studies, the PCR assay for the 5.8S-ITS coding region of the T. foetus genome offers the prospect of definitive identification of this agent directly from CVM or from formalin-fixed tissues or when false-positive culture results are suspected.

Abortion, Veterinary↗

PubMed1994

Experimental reproduction of bovine fetal Neospora infection and death with a bovine Neospora isolate.

Studies were conducted to determine the pathogenic potential of the recently isolated bovine Neospora protozoa (BPA-1) for the bovine fetus. Cows chosen for study had Neospora titers < 160 using an indirect immunofluorescent antibody (IFA) test. Four experimental groups were studied. In group 1, 2 fetuses were inoculated in utero at 118 days gestation with culture-derived Neospora tachyzoites. A pregnant control cow was housed in the same pen, observed daily and screened serologically for evidence of exposure to Neospora. In group 2, 2 cows were infected with Neospora tachyzoites at 138 or 161 days gestation, and 1 control cow was given uninfected cell culture suspension simultaneously at 154 days gestation. Groups 3 (85 days gestation) and 4 (120 days gestation) each consisted of 2 cows infected with Neospora tachyzoites and 1 control cow given uninfected material at the same stage of gestation. Dead fetuses were surgically removed from the infected cows in group 1 on postinfection day (PID) 17. The histopathology was compatible with protozoal fetal infection, and protozoa were identified by immunohistochemistry. Viable fetuses were removed surgically from cows in group 2 on PID 28-30. The histopathology was compatible with protozoal fetal infection, protozoa were identified by immunoperoxidase techniques, and Neospora tachyzoites were reisolated in vitro from tissues of the 2 infected fetuses. In groups 3 and 4, the control fetus and 1 infected fetus were removed surgically between PID 26 and PID 33. The remaining infected cows were observed until fetal death or abortion occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Veterinary↗

PubMed1995

[Cryptosporidia and other endoparasites in heifers imported into the Czech Republic].

Totally 887 heifers of Holstein-Friesian breed mostly in late pregnancy imported to the Czech Republic from France (597), Germany (89), Denmark (181) and Holland (20) were examined coprologically from September 1993 to March 1995 in the parasitological laboratory of the National Veterinary Institute (NVI). Prague. Feces were sampled individually, rectally, always on days 1-3 following importation from heifers housed in particular quarantine sheds. In compliance with presently valid veterinary regulations, all animals were examined for liver fluke disease (fascioliasis) and lungworm. Moreover, 634 heifers were submitted to qualitative coprological examination aimed at revealing the presence of cysts and oocysts of protozoa, eggs of taenias and nematodes of gastrointestinal tract. The method according to Pavlásek (1991), especially designed for proving oocysts of the genus Cryptosporidium, was applied in all fecal specimens delivered to the SVI from animals in quarantine (N = 887). From trematodes, 12 heifers imported from France were positive for eggs of Fasciola hepatica and in other two animals eggs of the genus Paramphistomum were found. None of the imported heifers showed lungworm disease. Summary of data on occurrence of endoparasites gained during qualitative examination of samples of feces taken from heifers imported from France, Germany and Denmark is presented in Tab. I. Parasitologically, 91.2 to 100% of imported animals were positive. Taeniasis (the genus Moniezia) was detected in 2.8% of heifers imported from France and in 9.8% animals from Denmark. Protozoal parasites were found in 58.8% (Denmark) and 92.8% (Germany) heifers. Coccidial oocysts most frequently observed represented the genus Eimeria (E. bovis, E. auburnensis and E. zuernii). Gastrointestinal nematodes of nine genera were found in 72.5 to 80.8% of heifers. The most frequent findings were genera Ostertagia, Haemonchus and Trichostrongylus. Oocysts, morphologically identical with Cryptosporidium muris Tyzzer (1907), 1910, were detected in 4.5% of heifers imported into the Czech Republic from France and in 7.9% of those from Germany. In view of the fact the imported heifers were sampled always on days 1-3 of their quarantine following their importation it is quite impossible, considering the development of the protozoon, they could become infected just in the territory of the Czech Republic. Therefore, with the highest probability, our findings of C. muris-like oocysts in heifers are of priority importance for France and Germany because in the literature these countries do not report cattle as a host of this protozoon. We have found out 57.9% out of 19 animals positive for C. muris on one farm of a private cattle keeper. On the basis of a long-term monitoring of three dairy cows and one bull, the duration of the patent period is longer than 18 months, while we do not know precise onset of shedding oocysts of the protozoon in these naturally infected animals. Furthermore, the paper discusses the need of future studies of C. muris from the point of view of spread, pathogenicity, specificity and host spectrum. The author proposes and recommends obligatory examinations of imported animals with special attention paid to presence of coccidia of the genus Cryptosporidium in order to maintain, with respect to their zoonotic character, these protozoal infections under proper control. At present the parasitological laboratory of the NVI in Prague has a bank of oocyst isolates of the C. muris type from cattle (Bos taurus), from desert hamsters (Phodopus roborovskii Satunin, 1903) and camels (Camelus bactrianus). Experimental infections is permanently kept in laboratory mice following successful transmission from desert hamsters.

Animals↗

PubMed2002

Serological diagnosis of ovine enzootic abortion by enzyme-linked immunosorbent assay with a recombinant protein fragment of the polymorphic outer membrane protein POMP90 of Chlamydophila abortus.

Ovine enzootic abortion (OEA) resulting from infection of sheep and goats with Chlamydophila abortus is of major economic importance worldwide. Over the last 50 years the serological diagnosis of infection has been based mainly on the complement fixation test (CFT), which lacks both sensitivity and specificity because of cross-reactive antibodies to other gram-negative bacteria, including another common chlamydial pathogen of sheep, Chlamydophila pecorum. In the present study, a series of overlapping recombinant antigens representing the polymorphic outer membrane protein POMP90 of C. abortus was assessed by enzyme-linked immunosorbent assay (ELISA) with a panel of 143 serum samples from sheep experimentally infected with C. abortus, from sheep clinically free of OEA, and from specific-pathogen-free lambs experimentally infected with different subtypes of C. pecorum. The results were compared to those obtained by CFT and another recently described test, an indirect ELISA (iELISA) with the recombinant OMP91B (rOMP91B) fragment (rOMP91B iELISA) (D. Longbottom, E. Psarrou, M. Livingstone, and E. Vretou, FEMS Microbiol. Lett. 195:157-161, 2001). The rOMP90-3 and rOMP90-4 ELISAs were identified as being more sensitive and specific than CFT. Assays with both fragments were evaluated further with a panel of 294 field serum samples from flocks with documented histories of abortion, from flocks with no clinical histories of abortion but which had a high proportion of samples seropositive by CFT, and from animals with no histories of abortion but from which various C. pecorum subtypes had been isolated. ELISAs with both POMP90 fragments outperformed CFT with serum samples from C. pecorum-infected animals, producing no false-positive results. However, the ELISA with the rOMP90-4 fragment appeared to be more sensitive than the one with rOMP90-3, as it identified more of the OEA-positive samples. The ELISA with the rOMP90-4 fragment was also able to identify apparently healthy animals that were infected with an enteric strain of C. abortus in flocks that were probably infected with both enteric C. abortus and C. pecorum strains. The identification of animals infected with enteric C. abortus is extremely important in controlling the spread of OEA. Overall, the new rOMP90-4 ELISA was found to be a more sensitive and specific test than CFT for differentiating animals infected with C. abortus from those infected with C. pecorum.

Abortion, Veterinary↗

PubMed1996

Serological diagnosis of ovine enzootic abortion by comparative inclusion immunofluorescence assay, recombinant lipopolysaccharide enzyme-linked immunosorbent assay, and complement fixation test.

Since the 1950s, serological diagnosis of ovine enzootic abortion (OEA), caused by strains of Chlamydia psittaci, has been based mainly on the complement fixation test (CFT), which is neither particularly sensitive nor specific since antibodies to other chlamydial and enterobacterial pathogens may be detected. In this study. a recombinant enzyme-linked immunosorbent assay (rELISA) (medac, Hamburg, Germany), based on a unique chlamydial genus-specific epitope of Chlamydia trachomatis L2 lipopolysaccharide, was evaluated for sensitivity and specificity as a primary screening assay for OEA by comparison with the CFT. A comparative inclusion immunofluorescence assay (IFA), in which antibody titers to C. psittaci and Chlamydia pecorum were examined, was used as the reference test for 573 serum samples from four flocks. Reactivity to C. pecorum was measured since inapparent intestinal infections by C. pecorum are believed to be common in British flocks. In detecting positive sera from an abortion-affected flock, in which a C. pecorum infection was also suggested by IFA, the rELISA outperformed the CFT with significant evidence for increased sensitivity (P = 0.003). In two flocks in which C. pecorum infections alone were suggested by IFA, the rELISA and CFT were prone to detect low levels of false-positive results, but the values were not significant. The rELISA provided results in one flock in which sera that were anticomplementary could not be resolved by the CFT. In another flock in which abortion had not occurred but infection by both chlamydial species was suspected, no significant difference was found between the sensitivities of the rELISA and CFT. The rELISA could not differentiate ovine C. psittaci and C. pecorum infections but was shown to be a more sensitive primary screening test for OEA than was the CFT, particularly where abortion had occurred and even when antibodies due to additional inapparent infection(s) by C. pecorum were present.

Abortion, Veterinary↗

PubMed1999

Susceptibility of B-cell deficient C57BL/6 (microMT) mice to Neospora caninum infection.

Neospora caninum is a coccidian parasite of veterinary importance by causing abortion or stillbirth in cattle among other problems in diverse animal species. We assessed an experimental murine model for its suitability to study the immune response to N. caninum infection. Thus, wild-type (wt) C57BL/6 mice and B-cell (and consequently antibody)-deficient microMT mice were infected with N. caninum tachyzoites and sacrificed at days 10, 24 and 29-44 post infection (dpi). Various organs were collected for parasitological and pathological analysis, spleen and serum for immunological investigations. Splenocytes were in vitro-stimulated with N. caninum (NC)- and T. gondii-antigens for assessing T cell proliferation and cytokine production. While wt mice were resistant to disease, microMT mice died starting from 29 dpi onwards. Histological examination of brain tissue from microMT mice exhibited a high infection intensity with multifocal necrotic cerebral lesions, which were absent in the brains of wt mice. NC antigen-stimulated spleen cells of both wt and microMT mice infected with N. caninum showed a marked proliferative depression at 10 dpi. At 24 dpi, this immunosuppression was still maintained in microMT mice whereas it was restored in wt mice. Stimulated splenocytes of infected microMT mice secreted significantly less IFN-gamma and less IL-10 than corresponding wt splenocytes. For IL-10, this difference increased with time. The susceptibility of microMT mice appeared associated to B-cell deficiency, allowing the persistent spread of the parasite causing immunosuppression and finally resulting in a lethal outcome of infection.

Animals↗