Caprine herpesvirus infection in Switzerland: some aspects of its pathogenicity.
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Abortion, Veterinary↗
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Results for “veterinary pathogens”
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USDA expands plan for low-pathogenic avian influenza.
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Animal Welfare↗
Recombinant vaccine technology in veterinary medicine.
Recombinant technology is relatively new to veterinary medicine. It combines safety, purity, potency, and efficacy in the vaccine. Its positive features include not exposing the vaccinate to the pathogen, the lack of need for adjuvants, and stability that allows some vaccine to remain viable at ambient temperatures. These recombinants can receive multiple genetic inserts and present an opportunity to have multiple combination vaccines for use in animals. Licensed recombinant vaccines in veterinary medicine include those protecting against Lyme disease, pseudorabies, rabies, canine distemper, Newcastle disease, and a strain of avian influenza.
Animal Diseases↗
The hazards of retroviruses associated with monoclonal antibody production.
The majority of mammalian cells contain in their chromosomes genetic information related to retroviruses. Mice, and in particular, the inbred strains used in laboratory studies, have a number of different types of these viruses and murine cell lines frequently express virus. Retrovirus production has been noted in a number of myeloma cell lines and in hybridomas prepared from them. Therefore crude monoclonal antibody preparations may contain large numbers of these viruses. Retroviruses have been shown to be capable of activating or of acquiring oncogenes from cells. They may also recombine with endogenous leucosis virus to produce a recombinant virus with pathogenic properties. Comparison of endogenous cell DNA and retrovirus sequences has shown that retroviruses are capable of crossing genus and even class barriers. Retroviruses that are harmless in one species may be pathogenic in another. Hence care is required in the manufacturing and quality control procedures applied to monoclonal antibodies, particularly with products intended for medical and veterinary use. Widespread inoculation of retroviruses into a range of animal species may result only in trauma for the occasional individual but it is not possible to preclude the formation of a new type of pathogenic agent that can spread throughout the population.
Animals↗
The design of veterinary vaccination programmes.
The optimal design of a veterinary vaccination programme depends on both the characteristics of the vaccine and the epidemiology of the pathogen or parasite. Relevant vaccine characteristics are the proportion of those vaccinated that are initially protected, the duration of protection and the coverage achieved by the vaccination programme. The most important epidemiological parameter is the basic reproduction number, R0. Mathematical theory can integrate this information to address such questions as: whether it is possible to eliminate an infection; what proportion of hosts must be vaccinated to achieve this: what age should hosts first be vaccinated; and at what interval should hosts be revaccinated? Examples of rabies in foxes and foot-and-mouth disease in cattle suggest that theory can be used to guide the design of vaccination programmes.
Animals↗
Cryptosporidium species a "new" human pathogen.
Publications describing aspects of the coccidian protozoan parasite Cryptosporidium, increased greatly during 1983 and 1984 as a result of not only increasing veterinary interest but also in the role of the parasite in the newly recognised acquired immune deficiency syndrome (AIDS). The reports reflected widespread collaboration, not only between clinicians, microbiologists, and histopathologists, but also between veterinary and human health care workers. Cryptosporidium was first described in mice in 1907 and subsequently in various other species; it was not described in man until 1976. Several likely putative species have been described, but there is probably little host specificity. Experimental and clinical studies have greatly increased the knowledge about the organism's biology. The parasite undergoes its complete life cycle within the intestine, although it may occasionally occur in other sites. The main symptom produced is a non-inflammatory diarrhoea, which, in patients with AIDS and children in Third World countries, may be life threatening: even in immunocompetent subjects this symptom is usually protracted. Attempts to find effective chemotherapeutic agents have been unsuccessful. Epidemiologically the infection was thought to be zoonotic in origin, but there is increasing evidence of person to person transmission. Diagnosis has depended upon histological examination, but simple methods of detection have now been described: more invasive methods need no longer be used. The parasite, which is found more commonly in children, occurs in about 2% of faecal specimens examined and seems to be closely associated with production of symptoms. A serological response has been shown. Much remains to be learned about its epidemiology and pathogenic mechanisms, while the expected increase in incidence of AIDS makes an effective form of treatment essential.
Acquired Immunodeficiency Syndrome↗
The immune system of the respiratory tract in pigs.
Although the lung is not a lymphoid organ it contains large numbers of lymphocytes. These can be found in different compartments: (1) the pulmonary intravascular pool, which is organ-specific and shows a unique migration pattern; (2) the interstitial lymphocyte pool, which is equivalent in size to the whole blood pool; (3) the bronchus-associated lymphoid tissue (BALT) which develops as a result of microbial stimulation; (4) the intraepithelial and lamina propria lymphocytes of the bronchi, with their typical subset composition; (5) the lymphocytes in the bronchoalveolar space, which can be sampled by bronchoalveolar lavage. The size and kinetics of the lymphocyte pools have been studied in the pig in more detail than in most other species. Despite this organotypic compartmentalisation of the pulmonary lymphoid cells in the pig, the lung is part of the integrated mucosal immune system, as shown by protective oral immunisation against the lung-pathogenic bacteria Actinobacillus pleuropneumoniae. The lung immune system in the pig is not only of veterinary interest, but also a relevant model for the human respiratory tract.
Actinobacillus Infections↗
The dsRNA viruses.
The dsRNA viruses represent a large, diverse group of pathogens (affecting a very wide range of host species), several of which are of medical, veterinary or agricultural importance. Many of the icosahedral dsRNA viruses show striking structural and functional similarities that reflect the similar problems that they face replicating their dsRNA genomes while avoiding the dsRNA activated defence mechanisms of their host species. These similarities appear to indicate a common if distant ancestry that is not always evident simply by comparison of nucleotide or amino acid sequences. To facilitate the identification and comparisons of cognate proteins from different species, genera and families of dsRNA viruses, a series of tables were originally constructed for the 7th International Symposium of dsRNA viruses held in Aruba in 2000. These have now been updated and extended (for the 8th Symposium, held in Tuscany 2003) and are available from the dsRNA virus website at.
Animals↗
Occurrence and characterization of "avium-like" Mycobacteria isolated from animals in Sweden.
431 cultures of "avium-like" mycobacteria (ALM) were isolated from wild and domestic animals during 1974--76 at the National Veterinary Institute, Stockholm. Of these, 50 isolates from pigs were studied by growth-chromogenicity, pathogenicity, and biochemical tests. Furthermore, thin-layer chromathography was performed, and on some isolates serotyping. All 50 isolates belonged to Runyon's group III and were pathogenic for chicken; none was capable of splitting oleic acid from Tween 80. 47 gave tellurite reduction within a period of three days; one was arylsulphatase-positive after three days and a further four after 14 days. The biological and biochemical tests permit assignation of the 50 isolates to the M. avium-intracellulare complex. The lipid patterns of the isolates examined were analysed by thin-layer chromatography. Thirty-five of the isolates showed a lipid pattern similar to that of A 2 of the fowl reference strain; three belonged to lipid type A 1 and four to A 3. Eight could not be typed. Of 22 isolates, 14 could be assigned to M. avium serotypes.
Animal Population Groups↗
Immune regulation during pregnancy and host-pathogen interactions in infectious abortion.
The immunological mechanisms that govern the success of pregnancy in outbred mammals are complex. During placental formation the invasion of fetal cells into maternal tissue must be controlled to prevent damage to the mother. Equally, maternal recognition of pregnancy must be such that allorejection of the fetus does not occur. Despite the complexity of this phenomenon, it is clear that cytokines play a crucial role at the maternofetal interface and in the periphery to ensure that pregnancy proceeds successfully. Inflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) can exert detrimental effects in the placenta and tend to be present at low concentrations, whereas the regulatory cytokines interleukin (IL)-10 and tranforming growth factor-beta (TGF-beta) are beneficial and tend to predominate. This means that infection with pathogens that target the placenta and that elicit inflammatory responses may cause abortion by giving rise to a detrimental combination of cytokines that causes damage but does not control the disease. Infectious abortion is discussed in the context of the modulation of host immune responses during pregnancy, taking into account the different placental structures present in human beings, rodents and ruminants.
Abortion, Septic↗
Why is anti-microbial resistance a veterinary problem as well?
Resistance to anti-microbial agents has become one of the main issues in public health strategies world-wide. Much attention has been paid to the emergence of pathogenic micro-organisms such as enterococci or Salmonella that have developed resistance mechanisms that render them almost untreatable with current antibiotics. One of the alleged reasons for such an emergence is the non-medical use of antibiotics, especially in animals. However, only recently have veterinary forums and journals begun to discuss this topic. On the other hand, anti-microbial resistance has also become a problem in veterinary medicine and the number of reports indicating high rates of resistance among animal-originated micro-organisms is considerable. The present review deals with the mechanisms of resistance known for antibiotics in common veterinary use, the problem of anti-microbial resistance in veterinary medicine and the links between the use of antibiotics in animals and the emergence of anti-microbial resistance in humans.
Animals↗
Host-parasite interaction in bovine infection with Tritrichomonas foetus.
Tritrichomonas foetus is a parasite of particular veterinary importance causing bovine tritrichomonosis, a sexually transmitted disease leading to infertility and abortion. The present review summarizes the current knowledge on potential mechanisms of pathogenicity of T. foetus, the immunology of host-parasite interaction in bovine tritrichomonosis, and the experimental model systems of this parasitic disease.
Abortion, Veterinary↗
Cyclospora cayetanensis, a food- and waterborne coccidian parasite.
Food- and waterborne coccidia including Cryptosporidium parvum, Cyclospora cayetanensis, Sarcocystis hominis and Sarcocystis suihominis, and Isospora belli are cyst-forming apicomplexan protozoa that cause intracellular infections, predominantly in the epithelial cells of the intestine. They are transmitted by oocysts from person-to-person by the fecal-oral route or via contaminated water or food. The most common symptom of infection is diarrhea, however, asymptomatic infections occur. Infections are associated with intestinal inflammation, with pathological lesions such as villus blunting, and abnormal function such as malabsorption. Mild-to-moderate, self-limiting diarrhea is common in healthy individuals ingesting infective stages of these organisms. However, patients with immune dysfunction can have severe intestinal injury and prolonged diarrhea. Diagnosis in many cases is made by a microscopic examination of the stool, and the use of appropriate staining techniques, but more recently molecular methods for detection are used increasingly. Effective antimicrobial treatment for prolonged infection in immunocompromised patients is available for most of these infections. These gastrointestinal coccidial pathogens have important similarities in epidemiology, disease pathogenesis, clinical manifestations, diagnosis, and treatment. Although there are many other cyst-forming coccidia of public health, veterinary and/or economic importance, discussion in this chapter will be limited to C. cayetanensis, as an important example of the group. Aspects of the biology, epidemiology, diagnosis, disease, treatment and control are considered. This parasite is considered to be an emerging pathogen. From 1990 to 2000, there were 11 foodborne outbreaks of cyclosporosis in North America that affected at least 3600 people. There are many outstanding questions regarding this parasite and under-reporting is common because general diagnostic methods for intestinal parasites are inadequate for detection of Cyclospora.
Animals↗
[Pathogenic effect of neuramindase in Trichomonas foetus].
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Abortion, Veterinary↗
Fluoroquinolones in animal health.
The fluoroquinolones are a series of synthetic antibacterial agents that are undergoing extensive investigation for both human and veterinary use in the treatment of a variety of bacterial infections. These agents work through the inhibition of DNA gyrase, interfering with the supercoiling of bacterial chromosomal material. As a result, these agents are rapidly bactericidal primarily against gram-negative bacteria, mycoplasma, and some gram-positive bacteria, with most having little to no activity against group D streptococci and obligate anaerobic bacteria. Resistance develops slowly and is almost always chromosomal and not plasmid-mediated. However, development of resistance to the fluoroquinolones and transfer of that resistance among animal and human pathogens have become a hotly debated issue among microbiologists. The fluoroquinolones are a current antimicrobial class whose use in veterinary medicine is being scrutinized. From a pharmacokinetic perspective, these agents are variably but well absorbed from the gastrointestinal tract and almost completely absorbed from parenteral injection sites, and they are well distributed to various tissues in the body. The fluoroquinolones are metabolized and renally excreted, with many of them having approximately equal excretion by the hepatic and the renal excretory systems. The primary toxicity observed at therapeutic doses involves the gastrointestinal system and phototoxicity, although at higher doses central nervous system toxicity and ocular cataracts are observed. Administration to immature animals may result in erosive arthropathies at weight-bearing joints, and administration of high doses to pregnant animals results in maternotoxicity and occasionally embryonic death. The fluoroquinolones are approved for indications such as urinary tract infections and soft tissue infections in dogs and cats and colibacillosis in poultry. Approval for bovine respiratory disease in the United States is being sought. Other indications for which the fluoroquinolones have been used in animal health include deep-seated infections, prostatitis, and other bacterial infections resistant to standard antimicrobial therapy.
Administration, Oral↗
Review of the pharmacodynamics of antibiotic use in animal food production.
Much attention has been focused on food-producing animals as a potential source of antimicrobial-resistant bacteria in humans. These efforts, however, have been met with continued debate and disagreement within the medical, veterinary, and regulatory communities as to whether the veterinary use of antimicrobials is a significant risk factor for the development of antimicrobial-resistant pathogens. As such, it is the purpose of our paper to assess factors involved in the pharmacokinetics and pharmacodynamics of antibiotic use in animal food production. We conclude that, based on the number of variables involved and the lack of definitive studies, it is difficult to determine the AUC:MIC for antimicrobials. Unfortunately, we are left only with general principles that indicate that low doses of antibiotic tend to select for bacterial resistance, and high doses tend to kill the microorganism. In the case where animal-associated pathogens cause human disease, those practices that target adequate exposures (AUC:MIC) of antimicrobials should continue, whereas those practices producing low exposures should be modified or halted to prevent the emergence and spread of resistant organisms.
Animal Feed↗
Staphylococcus pseudintermedius sp. nov., a coagulase-positive species from animals.
Four staphylococcal isolates from clinical and necropsy specimens from a cat, a dog, a horse and a parrot (Psittacus erithacus timneh) were found to constitute a distinct taxon. 16S rRNA gene sequence analysis revealed that its closest phylogenetic relatives are Staphylococcus intermedius and Staphylococcus delphini. Growth characteristics, biochemical features and DNA-DNA hybridizations demonstrated that the strains differ from these and other known species and that they represent a single, novel Staphylococcus species for which the name Staphylococcus pseudintermedius sp. nov. is proposed. The novel species is commonly confused with S. intermedius in routine diagnostic veterinary bacteriology. Although the strains described were isolated from lesions and show several characteristics typical of pathogenic staphylococci, such as coagulase, DNase and beta-haemolysin production, the pathogenic significance of the novel species remains unclear. The type strain, LMG 22219(T) (=ON 86(T)=CCUG 49543(T)), was isolated from lung tissue of a cat.
Animals↗
Application of fluorescent amplified fragment length polymorphism for comparison of human and animal isolates of Yersinia enterocolitica.
An amplified fragment length polymorphism (AFLP) method, developed to genotype Yersinia enterocolitica, has been used to investigate 70 representative strains isolated from humans, pigs, sheep, and cattle in the United Kingdom. AFLP primarily distinguished Y. enterocolitica strains according to their biotype, with strains dividing into two distinct clusters: cluster A, comprising largely the putatively pathogenic biotypes (BT2 to -4), and cluster B, comprising the putatively nonpathogenic biotype 1A strains and a single BT1B isolate. Within these two clusters, subclusters formed largely on the basis of serotype. However, AFLP profiles also allowed differentiation of strains within these serotype-related subclusters, indicating the high discriminatory power of the technique for Y. enterocolitica. Investigation of the relationship between strain AFLP profile and host confirmed that pigs are, and provides further proof that sheep may be, potential sources of human infection with putatively pathogenic strains. However, the results suggest that some strains causing human disease do not come from veterinary sources identifiable at this time. The distribution of some BT1A isolates within cluster A raises questions about the relationship between virulence potential and biotype.
Abattoirs↗