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Development of new generation rinderpest vaccines.

Veterinary science has benefited much from the advances in biotechnology during the past 20 years. New and improved diagnostic techniques for infectious diseases have been developed and new and highly effective vaccines to prevent such diseases have been introduced and more have been, or are about to be, field-tested. The latest development in negative strand virology, reverse genetics, the ability to rescue live virus from a DNA copy of the RNA genome, is being used to address questions concerning virus pathogenicity at the molecular level and to produce "marker" vaccines, i.e. vaccines that allow serological identification of all vaccinated animals. Such a vaccine would greatly benefit the continuing campaign for the global eradication of rinderpest since it would then be possible, by serological means, to detect wild type virus circulating in local areas or regions where it is still necessary to vaccinate and where the vaccination levels are below those required to eliminate the virus. Here we describe different approaches we have taken to produce such a vaccine using reverse genetics to add a marker to the existing and widely used Plowright rinderpest vaccine.

Animals↗

The pathogenicity in mice of respiratory, abortion and paresis isolates of equine herpesvirus-1.

Eleven isolates of equine herpesvirus-1 (subtype 1) all infected the brain following intracerebral inoculation of 2 d.o. mice. Most isolates were from cases of paresis, abortion or respiratory disease in the U.K., but established strains were also included. They divided into two subgroups. The 5 less pathogenic isolates were characterized by being restricted predominantly to the olfactory lobes. The 6 pathogenic isolates included the three known to cause equine paresis and were detected in neurones throughout the brain as well as giving rise to viraemia and infecting bronchial and renal epithelium and lymphoid cells in the spleen. Five respiratory isolates of subtype-2 were not recovered from inoculated mice.

Abortion, Veterinary↗

Experimental infection and abortion of pregnant guinea pigs with a unique spirillum-like bacterium isolated from aborted ovine fetuses.

Study was made of the pathogenicity of a spirillum-like, anaerobic, gram-negative bacterium, originally isolated from aborted lambs, for pregnant guinea pigs. Reproducible conditions for propagation and preservation of the bacterium were determined as requisite for the preparation of cultures for animal inoculation. A preliminary experiment was done with 10 pregnant guinea pigs to test for an infective dose of organisms that would produce abortion. High-passage cultures (n = 50) were used to inoculate these guinea pigs intraperitoneally. Six of 10 guinea pigs aborted, and the organism was cultured from fetal tissues of 5 guinea pigs. Isolates from 3 of the 6 guinea pigs were propagated through 4 passages on blood agar and used to infect 3 groups, each of 5 guinea pigs. A 4th group of 5 guinea pigs was inoculated with the original culture. Three of 5 animals in the first 3 groups, which had been given the low-passage cultures from the preliminary trial, and 2 of 5 guinea pigs in the 4th group, which had been given the original culture, aborted. Antibody against the spirillum was detected in 19 of 30 inoculated guinea pigs. The major microscopic lesions were acute suppurative placentitis and splenitis. This bacterium retained pathogenic properties sufficient to cause infection, abortion, and microscopic lesions in two-thirds of the guinea pigs, in spite of high in vitro passage. The organism has unique ultrastructures, and its genus and species are yet to be determined.

Abortion, Veterinary↗

Development of a practical immunochromatographic test with recombinant P50 for the diagnosis of Babesia gibsoni infection in dogs.

An immunochromatographic test (ICT), using recombinant truncated P50 (P50t), for the detection of antibodies to Babesia gibsoni was developed and evaluated. Whereas all sera from specific pathogen-free dogs were clearly negative, all sera from dogs experimentally infected with B. gibsoni were clearly positive in the ICT. In addition, the ICT detected no cross-reactivity with sera from dogs experimentally infected with closely related parasites, B. canis canis, B. canis vogeli, and B. canis rossi, or with Neospora caninum, and Leishmania infantum. Sequential sera from a dog experimentally infected with B. gibsoni were tested with the ICT; it was shown that the specific antibodies are detectable as early as 6 days post-infection (p.i.) and that strong antibody responses remained until the end of the experiment (144 days p.i.). To evaluate the clinical application of the ICT, a total of 54 serum samples collected from domestic dogs that had been identified as having signs of anaemia at veterinary hospitals in Japan, were tested with the ICT, the previously established enzyme-linked immunosorbent assay (ELISA) and with the indirect fluorescent antibody test (IFAT). Twenty-four of the tested samples (44.4%) were positive in both ICT and ELISA, and (51.8%) in IFAT. The concordance between ELISA and ICT was found to be 100%, and 85.7% with IFAT. Taken together, the results above suggest that the ICT using P50t is rapid, simple, accurate, and suitable for use at clinical sites for the diagnosis of B. gibsoni infection in dogs.

Animals↗

Isolation and characterization of an H10N7 avian influenza virus from poultry carcasses smuggled from China into Italy.

Intensified official veterinary controls on warehouses supplying Chinese retailers resulted in the seizure of smuggled poultry products. Frozen and vacuum-packed frozen raw duck and chicken carcasses, and anatomic parts (legs) of these species, were collected and processed for laboratory investigations aiming at the detection of avian influenza virus. Real-time reverse transcription-polymerase chain reaction (RRT-PCR) targeting the M gene, performed on the lung and trachea from duck and chicken carcasses, yielded positive results. Virus isolation attempts in specific pathogen free embryonated eggs yielded an H10N7 virus from the duck carcass. The isolate had an intravenous pathogenicity index of 0.0, and phylogenetic analysis revealed a nucleotide homology of 97 and 96% with virus A/duck/Zhejiang/52/2000 (H5N1) for the PB2 and NS genes, respectively. The results of this study indicate that low-pathogenicity avian influenza viruses may be introduced into a country through trade of carcasses regardless of the non-systemic nature of this disease. The export ban applied to countries affected by the H5N1 epidemic may result in increased smuggling of poultry products, which remains one of the means by which influenza viruses can cross-national boundaries. Increased surveillance at borders and at a national level is recommended.

Animals↗

Antibiotic resistance: who is winning the war? Introductory remarks.

The evolutionary response of bacteria, fungi, viruses, and parasites to the selective pressure exerted by antimicrobial agents is the emergence of populations that resist the action of the antimicrobial. The emergence and dissemination of such resistance in a variety of these pathogens is a growing public health concern. In response, the scientific community developed an action plan to address this public health issue. Antimicrobial, antifungal, and antiviral drug development for the treatment of diseases caused by resistant pathogens is one component of this strategy. In addition, due to the targeting of specific drugs against resistant pathogens, we may more readily accept a given drugs toxicity profile for the added therapeutic benefit. This symposium provides a discussion of the modes of action and mechanisms of resistance to antimicrobial agents, and the use of surveillance systems to help understand the nature and magnitude of resistance. The goal is to help guide antimicrobial drug product development and use. Specific toxicity issues are presented that should be considered in phase 1 development of antimicrobial drug products for use in clinical medicine and veterinary medicine. Finally, the national and global strategies developed by federal agencies in the Public Health Action Plan to Combat Antimicrobial Resistance are outlined.

Animals↗

Clonality and recombination in genetically differentiated subgroups of Cryptococcus gattii.

Cryptococcus gattii is a pathogenic yeast that together with Cryptococcus neoformans causes cryptococcosis in humans and animals. High numbers of viable C. gattii propagules can be obtained from certain species of Australian Eucalyptus camaldulensis trees, and an epidemiological link between Eucalyptus colonization and human exposure has been proposed. However, the highest prevalence of C. gattii cryptococcosis occurs in Papua New Guinea and in regions of Australia where the eucalypt species implicated to date are not endemic. This study investigated the population structure of three geographically distinct clinical and veterinary populations of C. gattii from Australia and Papua New Guinea. All populations that consisted of a genotype found frequently in Australia (VGI) were strongly clonal and were highly differentiated from one another. Two populations of the less common VGII genotype from Sydney and the Northern Territory had population structures inferring recombination. In addition, there was some evidence of reduced genetic differentiation between these geographically remote regions. In a companion study presented in this issue, VGII isolates were overwhelmingly more fertile than those of the VGI genotype, giving biological support to the indirect assessment of sexual exchange. It appears that the VGI genotype propagates clonally on eucalypts in Australia and on an unknown substrate in Papua New Guinea, with infection initiated by an unidentified infectious propagule. VGII isolates are completing their life cycles and may be dispersed via sexually produced basidiospores, which are also likely to initiate respiratory infection.

Animals↗

[Some viral zoonoses transmitted by pets (author's transl)].

Besides dogs and cats, various other animals are more or less popular as pets in the Netherlands. It is importance to the veterinary practitioner to know which diseases may be transmitted to man by these animals. Of the viral zoonoses. rabies constitutes a menace to man, in which dogs and, to a less extent, cats supply a link between man and free-living wild animals. Another viral zoonosis in which interest was centered in recent years, is lymphocytic choriomeningitis (LCM) caused by a virus which often is latent in mice but which may also be detected in young hamsters. A human disease caused by a pathogenic agent which should not be classified with the viruses, is chlamydiosis (psittacosis, ornithosis), which disease is usually transmitted to man by psittacine birds or pigeons. Of the above disease, the pathogenic agents, the clinical pictures in man and animals, the mode of transmission and possible preventive and therapeutic measures are discussed. Finally, the risk of transmission of viral zoonoses by less current "pets" is stressed.

Animals↗

Historical perspectives and current global challenges of Trichinella and trichinellosis.

Trichinella spiralis and related species of Trichinella have had a long history of causing human disease, and as a foodborne pathogen have had a major impact on international commerce of pork and other meat animal species which are known to transmit the parasite. Our knowledge of Trichinella has increased substantially over the past few years particularly in the areas of phylogeny, host diversity, epidemiology and control. In this paper, we provide a brief overview of our understanding of Trichinella from its discovery to present time. Past and current challenges of the control of Trichinella and trichinellosis are summarized. As editors of this special issue of Veterinary Parasitology, we introduce a series of invited review articles prepared by experts from around the world, summarizing recent knowledge in Trichinella and trichinellosis.

Animals↗

Naturally acquired leptospirosis in 36 dogs: serological and clinicopathological features.

Case records of 36 dogs with confirmed leptospirosis diagnosed at the New York State College of Veterinary Medicine from 1980 to 1995 were reviewed retrospectively, and clinical, serological and pathological findings were recorded to characterise the epidemiology of this disease in upstate New York. Titres were directed predominantly against serovars grippotyphosa and/or pomona in 31 of 34 dogs. Convalescent titres were measured for 53 per cent of dogs. The most common clinical presentation was acute renal failure. Increased liver enzyme activity was documented in 22 of 36 dogs. It is clear from this study that Leptospira pomona and grippotyphosa are important pathogens capable of causing severe renal and hepatic injury in dogs.

Animals↗

Macrophage cell cultures for rapid isolation of intracellular bacteria: the Mycobacterium bovis model.

Isolation of Mycobacterium bovis from suspected cases of bovine tuberculosis demands laborious and time-consuming procedures. Also, direct PCR procedures on tissue samples show poor sensitivity, whereas radiometric and fluorescence-based identification procedures demand high running costs and do not reduce the time needed for isolation to less than 10 to 15 d. Owing to the aforementioned obstacles, the human macrophage cell line THP-1 and other macrophage cell lines were investigated in experiments of M. bovis propagation and isolation from organ samples. Macrophage cells can support a high-titered propagation within 48 h of minute amounts of both BCG and fully pathogenic M. bovis strains from organ samples. A proper antibiotic mixture prevents contamination of cell cultures. A seminested PCR for tuberculosis complex-specific insertion sequence IS6110 revealed M. bovis infection in infected cells. The same result can be obtained by a flow cytometry assay for expression of M. bovis chaperonin 10. The reduced time for isolation and identification of M. bovis (48-72 h) and the consistency of the test results make the use of macrophage cell lines attractive and cost-effective for veterinary laboratories involved in surveillance of bovine tuberculosis.

Animals↗

[Udder disinfection and mastitis in cattle: a literature review].

Postmilking teat disinfection is accepted as an important part of standard preventive measures against mastitis in dairy cattle. The efficacy of postmilking teat disinfection against infections with contagious pathogens such as Staphylococcus aureus and Streptococcus agalactiae is beyond doubt. However, the efficacy of teat disinfection against infections with environmental pathogens such as Escherichia coli is disputed, and a negative effect has even been described in some situations. This article reviews the practice of teat disinfection in dairy cattle. Premilking and postmilking teat disinfection are discussed, as is the efficacy, different ways of teat disinfection, and different disinfectants. It is concluded that post-milking teat disinfection is an effective management measure in most herds. Selection of teat disinfectants should be based on proven efficacy, which is required for registration of the preparation as a veterinary medical product in the Netherlands.

Animals↗

Emerging zoonoses and pathogens of public health significance--an overview.

Emerging zoonotic diseases have assumed increasing importance in public and animal health, as the last few years have seen a steady stream of new diseases, each emerging from an unsuspected quarter and causing severe problems for animals and humans. The reasons for disease emergence are multiple, but there are two main factors--expansion of the human population and globalisation of trade. Current issues such as the increasing movement of a variety of animal species, ecological disruption, uncultivatable organisms, and terrorism, all imply that emerging zoonotic diseases will in all probability, not only continue to occur, but will increase in the rate of their emergence. The recurring nature of the crises dictates that closer integration of veterinary and medical communities is warranted, along with improved education of the general public and policy makers.

Animals↗

[Bacterial infection in cows associated with abortion, endometritis and sterility].

Isolated were two types of bacteria (having common morphologic and cultural behaviour and related antigenic composition) from aborted fetuses and placentae of cows with a positive reaction after both Huddleson and placentae of cows with a positive reaction afterboth Huddleson and Wright. They were shown to be new species of the group Mimeae and the genus Yersinia. It was demonstrated through immunodiffusion and immunoelectrophoresis that these new bacteria present antigenic relationship with Brucella organisms. A common O-antigen determinant was found to exist in the isolated bacteria and the S-and R-Brucellae and Br. ovis. The pathogenic effect was tested of the newly isolated bacteria on experimental animals, establishing a certain degree of uterotropism. An abortion was reproduced in a pregnant heifer by means of the intravenous injection of a bacterial culture. The serologic reaction presented by the animal proved comparable with that of cows exhibiting a natural infection process.

Abortion, Veterinary↗

A survey of mycoplasma detection in veterinary vaccines.

Nine live virus veterinary vaccines from six sources were found to be contaminated with mycoplasma. The vaccines were for use in canine, feline and avian species, and 53 batches of the products were at fault. The isolates were identified as Mycoplasma hominis, M. arginini, M. orale, M. hyorhinis and M. gallinarum. Investigation of the contamination rate of other batches or other products from the same source in some cases helped to determine the source of infection. Mycoplasma contaminants can be considered important not only because of their role as pathogens but also because they may indicate that insufficient care has been taken during vaccine manufacture or quality control.

Animals↗

Emerging parasite zoonoses associated with water and food.

The environmental route of transmission is important for many protozoan and helminth parasites, with water, soil and food being particularly significant. Both the potential for producing large numbers of transmissive stages and their environmental robustness, being able to survive in moist microclimates for prolonged periods of time, pose a persistent threat to public and veterinary health. The increased demands on natural resources increase the likelihood of encountering environments and produce contaminated with parasites. For waterborne diseases, the protozoa, Cryptosporidium, Giardia and Toxoplasma, are the most significant causes, yet, with the exception of Toxoplasma, the contribution of zoonotic transmission remains unclear due to the absence of 'standardised' methods. The microsporidia have been documented in one waterborne outbreak, but the role of animals as the cause of contamination was not elucidated. In foods, surface contamination is associated with the faecal-oral pathogens, and some data are available to indicate that animal wastes remain an important source of contamination (e.g. cattle faeces and apple cider outbreaks), however, further work should focus on examining the source of contamination on fruit and vegetables. Increasing recognition of the burden of human fascioliasis has occurred; it is now recognised as an emerging zoonosis by the WHO. Toxoplasma, Trichinella and Taenia spp. remain important meatborne parasites, however, others, including Pleistophora-like microsporidians may be acquired from raw or lightly cooked fish or crustaceans. With increased international travel, the public health importance of the foodborne trematodiases must also be realised. Global sourcing of food, coupled with changing consumer vogues, including the consumption of raw vegetables and undercooking to retain the natural taste and preserve heat-labile nutrients, can increase the risk of foodborne transmission. A greater awareness of parasite contamination of our environment and its impact on health has precipitated the development of better detection methods. Robust, efficient detection, viability and typing methods are required to assess risks and to further epidemiological understanding.

Animals↗

Conclusions and activities of previous expert groups: the Scientific Steering Committee of the EU.

In 1998, the EU Commission consulted its Scientific Steering Committee (SSC) to give advice on actions against anti-microbial resistance based on scientific evidence. The SSC set up a working group and adopted in 1999 an Opinion on Antimicrobial Resistance. Statements given in the well-structured document are clear, and precise recommendations were proposed. Summarizing, the Committee stated: There is evidence to suppose a continuous flow of resistance genes between pathogenic and commensal bacteria and of transfer of these bacteria between different compartments of the biosphere, thus changing the genetic resources continuously. There exist numerous factors which influence the emergence and spread of anti-bacterial resistance. However, it is likely that restriction in the use of anti-microbials will lead to a containment or a reduction of the drug resistance problem. Actions should be taken promptly to reduce the overall use of anti-microbials in a balanced way in all areas: human medicine, veterinary medicine, animal production and plant protection.

Animals↗

[Salmonella gastroenteritis: causes, sequelae, therapeutic perspectives].

Enteric salmonella are the most frequently isolated pathogens of bacterial diarrhea in Switzerland. Since 1987, increasing numbers have been reported to the Federal Health Office. The causes of this rise in salmonellosis prevalence, which has been observed in a number of countries, are the high rates of contamination in different foods, mainly in poultry and eggs. It has been shown that the usual kinds of egg preparation are not suitable for the elimination of salmonella, which may also be found inside the egg-shells. The solution to this problem involves measures of veterinary epidemiology and food hygiene. The epidemiologic significance of the asymptomatic carrier is considered to be rather slight. However, prolonged excretion of salmonella repeatedly results in social and economic problems, because the carrier food handlers are excluded from work when and for as long as they are excreting salmonella. Current possibilities in antibiotic treatment for these and other salmonellosis patients are discussed.

Carrier State↗