Comparative studies on the pathogenicity and tissue distribution of three virulence variants of classical swine fever virus, two field isolates and one vaccine strain, with special regard to immunohistochemical investigations

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to compare the tissue distribution and pathogenicity of three virulence variants of classical swine fever virus (CSFV) and to investigate the applicability of various conventional diagnostic procedures.</p> <p>Methods</p> <p>64 pigs were divided into three groups and infected with the highly virulent isolate ISS/60, the moderately virulent isolate Wingene'93 and the live attenuated vaccine strain Riems, respectively. Clinical signs, gross and histopathological changes were compared in relation to time elapsed post infection. Virus spread in various organs was followed by virus isolation, by immunohistochemistry, applying monoclonal antibodies in a two-step method and by <it>in situ </it>hybridisation using a digoxigenin-labelled riboprobe.</p> <p>Results</p> <p>The tissue distribution data are discussed in details, analyzing the results of the various diagnostic approaches. The comparative studies revealed remarkable differences in the onset of clinical signs as well as in the development of the macro- and microscopical changes, and in the tissue distribution of CSFV in the three experimental groups.</p> <p>Conclusion</p> <p>The present study demonstrates that in the case of highly and moderately virulent virus variants the virulence does not affect the pattern of the viral spread, however, it influences the outcome, the duration and the intensity of the disease. Immunohistochemistry has the advantage to allow the rapid detection and localisation of the virus, especially in cases of early infection, when clinical signs are still absent. Compared to virus isolation, the advantage of this method is that no cell culture facilities are required. Thus, immunohistochemistry provides simple and sensitive tools for the prompt detection of newly emerging variants of CSFV, including the viruses of very mild virulence.</p

Diseases and causes of death among alpacas in Sweden: a retrospective study

Background: Due to increasing popularity in Sweden during the last decade, alpacas are frequently encountered by practising veterinarians and pathologists. Knowledge regarding their health and diseases under Swedish conditions is, however, limited. Objectives: To improve knowledge about the health of alpacas in Sweden by collecting information on diseases and health status. Design: A retrospective study was made of 93 necropsies conducted on alpacas in Sweden during the period 2001–2013. Setting Data were obtained from the two major veterinary pathology centres in Sweden. The alpacas were hobby or farm animals and they were submitted by veterinarians in local practices or at a national animal healthcare organisation. Results: The digestive system was most frequently affected (29 per cent), with parasitic gastroenteritis (17 per cent) and hepatic disease being especially prevalent (15 per cent fascioliasis and 7 per cent hepatitis). Cardiovascular conditions (9 per cent), systemic diseases (7 per cent) and perinatal deaths were also common, including abortions (10 per cent) and fatal septicaemia (4 per cent). Wasting/emaciation was a frequent finding (26 per cent). Other diagnoses included dermatitis (8 per cent), diseases of the central nervous system (8 per cent), traumatic injuries (7 per cent), neoplasia (5 per cent), pneumonia (5 per cent) and nephritis (3 per cent). Conclusions: This study identified areas of concern regarding diagnostic and pathological procedures, for which specific measures have been recommended. One particular cause for concern was the number of deaths from emaciation in weanling alpacas during late winter or early spring. For adult alpacas, infectious and noninfectious causes of death were approximately equally frequent. Many of the diseases were considered clinically acute but pathology often showed them to be chronic conditions that had eventually deteriorated and presented as acute cases in the late stages. This study revealed similarities in the health/disease status reported in other European countries and in North America. The results can be used by alpaca keepers and veterinary practitioners to improve management, diagnosis and treatment of alpacas

Pre-registration efficacy studies of a novel marker vaccine against classical swine fever on target animals

SUMMARY Background: Classical swine fever (CSF) or hog cholera is a highly contagious and devastating disease of Suidae caused by an enveloped single-stranded RNA virus (CSFV) of the family Flaviviridae, genus Pestivirus. CSF has vast economic and trade significance all over the world, and it has the massive potential to spread rapidly from country to country. This is the reason why the World Organisation for Animal Health has listed CSF as a Notifiable Disease and it is also considered a transboundary animal disease.Objective: The objective of the present studies was to determine the efficacy of a single dose of a newly developed marker vaccine candidate against CSF, administered intramuscularly or orally in 6-week-old domestic piglets with and without maternally derived antibodies (MDAs) against Pestiviruses, to provide protection against a challenge with the highly virulent CSFV strain “Koslov” 14 days post vaccination. Materials and Methods: In both experiments two test groups were formed with 15 animals each, one group for intramuscular (im.), while another one for oral (p.o.) immunisation. The control groups contained 10 animals as unvac-cinated controls, respectively. All piglets were oronasally challenged with the highly virulent CSF virus (CSFV) strain “Koslov” 14 days post-vaccination. Results and Discussion: The vaccine candidate when administered im. provided complete protection in MDA- animals, while p.o. administration triggered only partial protection. Furthermore, we found that the presence of the MDAs had negative effect on the efficacy of the vaccine candidate. However, this was greatly influenced by the route of administration. Based on our observations, im. administration is recommended to achieve better immune response during the CSF control programs. The vaccine candidate met the criteria of Ph. Eur Mono-graph 0065, “Swine-fever vaccine (live, prepared in cell cultures), classical” 7th Edition. Fulfilling these validity criteria is a key step in the registration procedure for a vaccine candidate

Post mortem findings in sows and gilts euthanised or found dead in a large Swedish herd

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to get information on post mortem diagnoses of sows found dead or euthanised and to understand the diagnoses aetiology (causative background). Moreover, the study was to evaluate the association between the clinical symptoms observed on farm and post mortem findings.</p> <p>Methods</p> <p>A large Swedish herd was studied from January to September 2006. During the 32-week period 3.9% of the removed sows and gilts (old enough to be mated) were found dead, 12.0% were euthanised and the rest were sent to slaughter. Of 32 sows/gilts found dead 17 (53%) were post mortem examined, and of 98 sows euthanised 79 (81%) were examined. The 96 examined carcasses were after 70 sows and 26 gilts. The findings at examination were together with data from the herd monitoring program PigWin Sugg the base for the descriptive statistics presented.</p> <p>Results</p> <p>The average parity number at removal was 2.8 for those found dead and 2.1 for those euthanised. The highest number euthanised and found dead was in parity 0 (gilts). The main proportion of post mortem examinations was made on sows being in the period = 28 d of gestation at death (37.5%), followed by weaning to next service period (24.0%). Arthritis, with an incidence of 36.4% was the most common main finding of pathological-anatomical diagnosis (PAD). Of sows/gilts found dead were circulatory/cardiac failure (23.5%) and trauma related injuries (23.5%) most common PAD. The most commonly observed clinical symptom and reason for euthanasia of the sows/gilts was lameness. Notably, in 43% of the cases with PAD arthritis, the clinical symptoms suggested it being a fracture. Further one or more abscesses (38.5%) and teeth injuries (31.0%) were common findings when also incidental findings were included.</p> <p>Conclusion</p> <p>This post mortem study based on carcasses from sows/gilts found dead or euthanised showed that arthritis was a significant problem in the studied herd and that post mortem examination was important to get proper diagnosis.</p