Urinary tract infections in culled sows from Greek herds: prevalence and associations between findings of histopathology, bacteriology and urinalysis

Background

Urinary tract infections (UTI) of sows characterized by cystitis, which may progress to ureteritis and pyelonephritis, can affect their productivity, longevity and welfare. In this study, we determined the prevalence of UTI by histopathology and bacteriology. Furthermore, we investigated possible associations between histologically confirmed cystitis and the results of urinalysis and urine cultures in culled sows from three farrow-to-finish herds in Greece.

Materials and methods

One hundred eighty-five routinely culled sows were included in the study. Their urinary bladder was collected from abattoirs and subjected to histopathology. Furthermore, urinalysis and urine cultures were performed on urine samples aseptically collected from the bladders.

Results

Histologically confirmed cystitis was evident in 85/185 (45.94%) culled sows. Among those, 44 (51.76%) suffered from acute and 41 (48.24%) from chronic inflammation. The majority of positive urine cultures were due to colonization of the urinary tract with E.coli, which accounted for 55.81% of the total cases, followed by Staphylococcus spp. which accounted for 18.60% of detected infections. Evidence of cystitis was associated with bacteriuria and sows with bacteriuria were 2.30 (P = 0.03, 95% CI: 1.10–4.83) times more likely to have histologically confirmed cystitis compared to sows with negative urine cultures. Bacteriuria was associated with proteinuria (P < 0.01, OR = 9.72, 2.63–35.88), increased urine pH (P < 0.01, 3.40, 1.10–10.56) and presence of sediment (P < 0.01, 6.00, 1.50–23.76) in urine. Sows with proteinuria had 9.72 (P < 0.01, 2.63–35.88) times higher odds of bacteriuria than those without. Histologically defined cystitis was associated with proteinuria (P < 0.01, 2.03–13.20) and decreased urine pH (P < 0.01, 0.13–0.72). Sows with proteinuria were 5.18 (P < 0.01, 2.03–13.2) times more likely to have histological lesions consistent with cystitis, than those without. For one unit increase in pH, it was 3.20 (P = 0.006, 1.39–7.69) times less likely for a sow to have chronic or acute cystitis compared to absence of cystitis.

Conclusion

In the studied population, UTI affected almost one out of two culled sows. Bacteriuria, which was more common among sows with UTI than those without, was mainly ascribed to members of the intestinal and environmental bacteria. Proteinuria and the existence of urine sediment which were associated with UTI, could be used as proxy traits for UTI in live sows.

Thymoma associated exfoliative dermatitis in a rabbit with hepatic cirrhosis

A 6.5-year-old, male, non-castrated pet rabbit was presented with generalized exfoliative dermatitis, depression and anorexia. Skin laboratory examinations were negative for ectoparasites, bacteria and fungi whereas thoracic radiography revealed a large mediastinal mass. Complete blood and biochemical examinations did not show anything abnormal. Thymoma was suspected and therapeutic options were discussed but the owner declined. Supportive and symptomatic therapy was of no avail and severe deterioration of systemic symptoms necessitated euthanasia. Necropsy revealed a whitish-gray mass on the anterior and lower part of the mediastinum and pale voluminous liver. Histopathology confirmed the presence of thymoma and the hypothesis of thymoma-associated exfoliative dermatitis along with hepatic cirrhosis.

Development of real-time PCR-based methods for the detection of enzootic nasal tumor virus 2 in goats

Enzootic nasal adenocarcinoma (ENA) is a contagious neoplasm of sheep and goats, associated with the oncogenic retroviruses enzootic nasal tumor virus (ENTV) 1 and 2, respectively. It appears to be common in countries with substantial small ruminant-production. ENA diagnosis in goats is based on autopsy and histopathology, and there is no real-time PCR method available for ENTV-2 detection. Here, a novel one-tube real-time RT-PCR (RT-qPCR) method for the detection and quantification of ENTV-2 in nasal swabs is presented. The method targets the env gene/U3 region. For the design of ENTV-2-specific oligonucleotides, molecular characterization of seven Greek ENTV-2 strains was performed. Phylogenetic analysis revealed three distinct phylogenetic clades of ENTV-2 that correlate with the country of sample collection. Evaluation of the analytical performance of the RT-qPCR revealed an amplification efficiency of 92.8% and a linear range of quantification between 2 × 10⁸ and 2 × 10² RNA transcripts. Analysis of nasal swabs from 23 histopathologically confirmed, naturally occurring ENA cases via RT-qPCR yielded positive results. Moreover, modification of the method for use in a real-time PCR (qPCR) assay enables detection of proviral DNA in tumor specimens. Both methods are highly specific and can be used for the confirmation of ENA-suspected cases. Future applications could include ante-mortem diagnosis, verification of the ENTV-2-free status in animal trade, disease surveillance, and control programs.

Epidemiological characteristics and clinicopathological features of bluetongue in sheep and cattle, during the 2014 BTV serotype 4 incursion in Greece

During 2014, an outbreak of Bluetongue virus (BTV) infections attributed to serotype 4 occurred in Greece and spread to south-eastern Europe. In the present article, the clinical and epidemiological data of 15 sheep flocks and 5 dairy cattle herds affected in Greece are described. In sheep, the most frequent clinical signs observed were fever, hyporexia, and edema of the face. A number of clinically affected sheep had chronic laminitis resulting in chronic lameness. Confirmation of suspect clinical cases was performed using BTV-specific real-time RT-PCR, and serotype 4-specific RT-PCR. The average morbidity of bluetongue in the sheep flocks was estimated to be 15.3 % (95 % C.I. 6.8-23.8 %) and the average mortality and case fatality were 4.5 % (95 % C.I. 1.5-7.6 %) and 32.0 % (95 % C.I. 18.1-42.9 %), respectively. The BTV seroprevalence and the ratio of clinical manifestations-to-infections determined in seven of these flocks, were on average 36.5 % (95 % C.I. 15.7-57.3 %) and 24.6 % (95 % C.I. 12.8-36.3 %). BTV ratio of clinical manifestations-to-infections was higher in the imported western European sheep breeds examined compared to the local ones. In dairy cattle, the average herd prevalence of viremia was 48.8 % (95 % C.I. 15.3-82.4 %) and none had signs associated with bluetongue. The results of this study indicate that the 2014 Greek BTV-4 has significant impact on the health status and the viability of sheep in affected flocks but does not cause clinical signs in cattle, despite the high prevalence of viremia.

Evidence for European brown hare syndrome virus introduction with translocated brown hares (Lepus europaeus): implications for management of restocking operations

Context Criticisms of wildlife restocking operations typically focus on concerns that translocations can lead to the introduction of pathogens, and risk the integrity of locally adapted genetic diversity. Restocking programs aiming to stabilise population declines of European brown hares using captive-bred individuals have been carried out in several European countries, including Greece. Aims To assess the potential for imported hares to introduce novel strains of European brown hare syndrome virus (EBHSV) during restocking operations, by (1) inferring the origin of wild Greek hares on the basis of their mitochondrial DNA (mtDNA) haplotype, (2) screening the hares to detect and characterise EBHSV, and (3) determining whether certain hare origin–EBHSV combinations occur in the wild. Methods RNA extraction, polymerase chain reaction (PCR) amplification, and sequence and phylogenetic analyses of EBHSV were performed on 53 hares. Diagnostic RFLP markers of the mtDNA were used to infer the origins of sampled hares. Key results Thirty-three hares had ‘typical’ native Greek haplotypes and 20 had mtDNA haplotypes matching those found in imported and released hares. Twelve of the latter and none of the former were positive for EBHSV. Phylogenetic analysis showed that nine virus isolates formed a single genetic lineage distinct from northern–central European ones. Three virus sequences from three imported reared-and-released hares, from Chalkidiki, were closely related to the northern–central European EBHS viruses. Conclusions Alien strains of EBHSV are co-introduced with released captive-bred animals, possibly resulting in negative impacts on populations of Greek hares that have not evolved resistance to these novel virus strains. Implications The identification of these allopatric EBHSV strains has led the authorities to ban captures and transportations of local brown hares for any restocking operation. We consider it imperative to reinforce microbiological and genetic controls before further releases of captive-bred game species in the wild in Greece.

Acute coenurosis of dairy sheep from 11 flocks in Greece

CASE HISTORY

A syndrome of acute neurological dysfunction with increased mortality was observed in lambs of 10 dairy sheep flocks and adult animals in one flock in Central and Northern Greece. Each farmer completed a questionnaire regarding the management and feeding of their flocks. In seven of the 11 flocks the affected animals were grazing pasture, while in the remaining four flocks (5, 8, 9, 10) the animals were fed alfalfa hay (Medicago sativa) and concentrates indoors. A follow-up study of the affected flocks was conducted during the next 12 months.

CLINICAL FINDINGS

Of 42 sheep with acute coenurosis that were examined, the most prominent neurological abnormalities were ataxia, depression, blindness, scoliosis, coma and dysmetria. Except for the four sheep that were comatose, all other animals had normal body temperatures and their appetites remained normal or were slightly decreased. Haematological findings of 15 examined sheep were within normal limits. The affected sheep were subject to euthanasia. A histopathological examination was performed in 13 cases. Faecal samples from dogs associated with these flocks were negative for taeniid infections. During the following 12 months cases of chronic coenurosis in these flocks were observed.

PATHOLOGICAL FINDINGS

In the 42 animals that were necropsied, the main gross findings were cystic formations between 0.5-1 cm in diameter with translucent walls that were seen lying free on the leptomeninges or partly penetrating the brain tissue, sterile microabscecess and brain necrosis. Histopathological evaluation of tissue sections of 13 brains showed multifocal purulent or pyogranulomatous meningoencephalitis, accompanied by eosinophilic infiltrations. No bacteria were isolated following bacterial culture of brain tissue Parasitological examination of the cysts from five cases revealed whitish specks on the transparent cyst wall and germination membrane representing the scolices.

DIAGNOSIS

Acute coenurosis was diagnosed in all cases studied.

CLINICAL RELEVANCE

Acute coenurosis can be one of the causes of acute encephalopathy mainly in lambs, but also in adult sheep. This condition is incurable, but can be controlled by changing the feeding regime. Cases of chronic coenurosis may be seen a few months later in the same flock.

Multilobular tumour of the caudal cranium causing severe cerebral and cerebellar compression in a dog

Multilobular tumour of bone (MTB) is an uncommon tumour and is usually located in the skull. A 13-year-old mixed breed dog was presented with a two-week history of progressively worsening vestibular dysfunction and cognitive abnormalities; it appeared demented and showed asymmetric ataxia and hypermetria of all limbs. The owner opted to have the animal euthanised. Necropsy revealed a large mass occupying the right occipital, parietal and temporal bones, severely compressing the cerebellum and the right occipital lobe. Histologically, it was characterised by the presence of multiple lobules containing osteoid or cartilage and separated by fibrous septae, features typical of MTB. Lung metastases were evident. To our knowledge, this is the first report of an MTB causing both severe cerebral and cerebellar compression and the second detailed report of an MTB of the occipital bone. MTB should be included in the differential diagnosis of bone tumours as well as in cases with central vestibular disease.

Lethal Ozolaimus megatyphlon infection in a green iguana (Iguana iguana rhinolopa)

An imported 2.5-yr-old female green iguana (Iguana iguana rhinolopa) kept in Greece was presented with a history of anorexia and allotriophagy of 1 mo duration. Upon clinical examination, it was cachectic and had severe abdominal distension and fibrous osteodystrophy. Despite treatment, it died a month later. On necropsy, massive accumulations of threadlike nematode parasites were observed in the large intestine, identified as Ozolaimus megatyphlon, a member of the Oxyuridae family of Pharyngodonidae, a usually nonpathogenic intestinal parasite of iguanas. To the authors' knowledge, its presence has not been reported previously in Europe, although one pathogenic infection has been reported previously in Japan. The animal was presumably infected before importation. Although death was attributed to the heavy parasitic overload, the poor diet and terrarium hygiene, and absence of an anthelminthic regime further contributed to the deterioration of the animal's condition. Recognition of this condition, which may be recently introduced or underdiagnosed, may help improve medical and trade standards concerning this species in practice.

Histopathological and immunohistochemical features of natural goat scrapie

Histopathological and immunohistochemical examinations were performed on the brain and spinal cord of 37 goats from two Greek herds in which scrapie had been reported. Of the 37 animals, 18 were from a herd consisting only of goats and 19 were from a herd of goats mixed with sheep. The goats studied were grouped on the basis of the presence or absence of clinical signs. Distinctive lesions and PrP(sc) (PrP, prion protein) deposition were found in the central nervous system (CNS) of eight clinically affected animals and six symptomless animals. The lesion profile and PrP(sc) distribution varied both between and within groups, variation being particularly pronounced in the symptomless goats. The results concerning the latter group suggested a poor correlation between the intensity of lesions, the amount of PrP(sc) in the CNS, and the manifestation of clinical signs. Immunohistochemical examination revealed 10 different PrP(sc) types, four of which are reported for the first time in goats. All scrapie-affected animals carried the VV(21)II(142)HH(143)RR(154) genotype, with the exception of two goats that carried the HR(143) dimorphism and had detectable PrP(sc) deposits. The results suggest that the histopathological and immunohistochemical profile of the natural disease in goats is influenced by the PrP genotype and age of the animals but may not be directly associated with the presence or otherwise of clinical signs.

Pathogenesis of experimental encephalomyocarditis: a histopathological, immunohistochemical and virological study in mice

Mice (n=20) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 18-59 days post-infection (dpi), except for two mice that died at 6 and 32 dpi, and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical examination. Apart from the two deaths, the experimental infection was inapparent, but virus was invariably recovered from faeces and several organs. The main histopathological lesions were focal interstitial pancreatitis, depletion of thymus and Peyer's patches, and interstitial pneumonia. Additionally, in the two mice that died, multifocal interstitial myocarditis was observed. EMCV antigen was detected in the cytoplasm of pancreatic acinar cells and in macrophages of the lung and the thymus. Antigen was also detected in the cytoplasm of cardiac muscle cells from three animals, including the two that died. The results support the role of mice, in addition to rats, as reservoir hosts in the epidemiology of EMCV infections on pig farms.

European brown hare syndrome in wild European brown hares from Greece

From 1999 to mid-2003, 97 European brown hares (Lepus europaeus) found dead throughout Greece were examined by necropsy, histopathology, and reverse-transcription polymerase chain reaction (RT-PCR) for the presence of European brown hare syndrome (EBHS) and EBHS virus (EBHSV), respectively. Hare losses were sporadic, starting in the cold season and lasting for many months (December to May). The most prominent gross lesions were observed in the liver and included swelling and discoloration; congestion and hemorrhages were present mainly in lungs and tracheal mucosa. Necropsy findings were suggestive of EBHS, which was confirmed by histopathology and RT-PCR. This study documents, for the first time, EBHS in Greece.

Pathogenesis of experimental encephalomyocarditis: a histopathological, immunohistochemical and virological study in rats

Rats (n=40) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 11-62 days post-infection (dpi) and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical evaluation. This experimental infection was inapparent, but virus was isolated from faeces and several organs of all animals. The main histopathological changes were focal interstitial pancreatitis, degeneration and necrosis of pancreatic acinar cells, depletion of thymus and Peyer's patches, and interstitial pneumonia. EMCV antigen was detected in the cytoplasm of cardiac muscle cells, pancreatic acinar cells and hepatic epithelial cells, and in macrophages of the spleen, lung and thymus. In the heart (the target organ of EMCV in pigs), the presence of EMCV in cardiac muscle cells without lesions lends support to the hypothesis that the rat is a natural reservoir host species of EMCV. The persistence of virus in the macrophages of the thymus may represent a mechanism of perpetuation and reactivation, under immunosuppressive conditions, of the infection.

Effect of challenge dose and age in experimental infection of pigs with encephalomyocarditis virus

Two experiments were performed to compare the severity of encephalomyocarditis virus (EMCV) infection in pigs. The pigs were challenged with the Greek myocardial strain, at different ages and with different doses. In the first experiment, nineteen susceptible pigs, 40 days old, were divided into three groups and were experimentally infected with 10(6) TCID(50), 10(4) TCID(50) or 10(2) TCID(50) of the Greek EMCV strain. In the second experiment, 10 susceptible pigs, of either 20 or 105 days, were divided into two groups according to age and were experimentally infected with 10(6) TCID(50) of the Greek EMCV strain. In addition, five piglets, each one the same age as its experimental group, were used as uninfected controls. No clinical signs were observed after infection, except a transient temperature rise in some pigs. Another important observation was the difference in mortality between groups. The survival rate of the 40-day-old pigs was inversely related to the viral dose. In these pigs, a positive association between the viral dose and the severity of macroscopical and histopathological lesions of the heart was also evident. Viral isolations from various organs of the challenged 40-day-old pigs increased with the increasing dose level. When challenged with 10(6) TCID(50) of EMCV, there was no difference in the fatality rate of the 20- and 40-day-old pigs, but none of the 105-day-old pigs died. The severity of the macroscopical and the histopathological heart lesions was inversely related to the age of the pigs. Furthermore, viral isolations from the various organs were higher in 20- and 40-day-old pigs than in the older ones. In 40-day-old pigs, neutralizing antibodies linearly increased as the dose increased. These antibodies were consistently lower in 20-day-old pigs. Viraemia, and nasal and faecal excretions were detected in all groups and lasted 1-3 days, except for the 105-day-old pigs whose symptoms lasted for an additional day.

Prion protein gene polymorphisms in healthy and scrapie-affected sheep in Greece

A total of 216 local crossbred sheep from 16 scrapie-affected Greek flocks and 210 purebred sheep of the milk breeds Chios and Karagouniko from healthy flocks were analysed for scrapie-linked polymorphisms in the prion protein (PrP) gene. Of the 216 sheep in this case–control study, 96 sheep were clinical cases, 25 subclinical cases (asymptomatic at the moment of euthanasia but positive by histopathology and/or ELISA detecting proteinase-resistant PrP) and 95 healthy controls (negative by all evaluations). Polymorphisms at codons 136, 154 and 171 were determined by denaturing gradient gel electrophoresis, followed by RFLP and sequencing. Scrapie, both clinical and subclinical, was associated with the genotypes ARQ/ARQ (88 of 110 sheep of that genotype), ARQ/TRQ (9 of 13), ARQ/AHQ (15 of 38) and VRQ/VRQ (9 of 17). Histopathological lesions were more severe in the clinical cases. Genotypes ARQ/ARR (26 sheep), ARQ/ARK (seven sheep), AHQ/ARR (one sheep), ARH/ARH (one sheep) and ARR/ARH (three sheep) were detected exclusively in healthy control sheep. In the purebred survey, four genotypes were present in the Chios sheep (ARQ/ARQ, ARQ/TRQ, ARQ/AHQ and ARQ/ARR) and four in the Karagouniko sheep (ARQ/ARQ, ARQ/AHQ, ARQ/ARR and ARQ/ARH).

Sclerosing encapsulating peritonitis in a dog with leishmaniasis

Canine sclerosing encapsulating peritonitis is a rarely reported condition. A 10-year-old male German shepherd dog cross was presented with a history of ascites, vomiting, soft faeces, anorexia and depression. Gathering of the intestinal loops in the middle portion of the abdomen was detected by radiography and ultrasonography. Cytological examination of Giemsa-stained smears from the popliteal lymph nodes revealed Leishmania species. The results of culture of serosanguineous fluid obtained by abdominocentesis were negative for bacteria and fungi. Laparotomy revealed a sac of fibrous tissue encasing most of the intestinal loops and numerous adhesions extending between them. Histologically, an uneven, diffusely thickened, visceral peritoneal membrane was found. A diagnosis of idiopathic sclerosing encapsulating peritonitis was made. The dog was euthanased because the intestinal wall was torn at many sites during dissection of the membrane.

Equine infectious anemia in mules: virus isolation and pathogenicity studies

There appears to be a lack of information concerning responses of mules to natural infection or experimental inoculation with equine infectious anemia virus (EIAV). In the present study EIAV was isolated from mules, for the first time, and its pathogenicity in naturally infected and experimentally inoculated animals was investigated. Two naturally infected (A and B) and three EIAV free mules (C, D and E) were used for this purpose. Mule A developed clinical signs, whereas mule B remained asymptomatic until the end of the study. Mules C and D were each inoculated with 10ml of blood from mule A and developed signs of the disease; they were euthanatized or died at day 22 and 25 post-inoculation, respectively. Mule E served as a negative control. The virus was isolated from the plasma samples of mules with clinical signs of the disease (A, C and D), but not from the asymptomatic mule B. Both proviral DNA and viral RNA were amplified from blood and tissues of the infected animals by nested polymerase chain reaction (nPCR). Antibodies were not detected in the two experimentally infected mules until their natural death or euthanasia. Clinicopathological and laboratory findings showed that, in mules, EIAV produced clinical signs similar to those observed in horses and ponies. Nested PCR proved to be a rapid, sensitive and specific diagnostic method for the detection of EIAV, regardless of the disease stage.

Pathogenesis of encephalomyocarditis virus (EMCV) infection in piglets during the viraemia phase: a histopathological, immunohistochemical and virological study

Six piglets aged 20 days were inoculated oranasally with 5 ml of a suspension (10(6) TCID(50)/ml) of a Greek myocardial strain of encephalomyocarditis virus (EMCV). The animals either died (n=2) or were killed for examination on days 1,2 or 3 post-inoculation (pi). EMCV was isolated from virtually all organs examined (heart, tonsils, palatine glands, pancreas, spleen, small intestine and mesenteric lymph nodes). Histopathologically, interstitial myocarditis, necrosis of cardiac muscle cells and Purkinje fibres, and necrotizing tonsillitis were detected in all inoculated piglets. Focal interstitial pancreatitis, necrosis of pancreatic acinar cells and Langerhans islet cells, and necrosis of germinal centre lymphocytes of the lymph nodes and Peyer's patches were detected in two piglets that died or were killed on day 3 pi. Immunohistochemically, viral antigen was detected in epithelial cells of all organs examined, including the tonsils, palatine glands, pancreatic interlobular ducts and small intestine. This suggests that EMCV is epitheliotropic, in addition to its known myocardial tropism. The frequent presence of intracytoplasmic EMCV in macrophages of the tonsils and spleen supports the hypothesis that macrophages play a role in viral replication and dissemination in the body.

Prion protein gene polymorphisms in natural goat scrapie

A total of 51 goats, including seven clinical cases, from the first herd in Greece reported to have scrapie was examined to discern an association between scrapie susceptibility and polymorphisms of the gene encoding the prion protein (PrP). Each animal was evaluated for clinical signs of the disease, histopathological lesions associated with scrapie, the presence of detectable protease-resistant PrP in the brain and PrP genotype. Eleven different PrP genotypes encoding at least five unique predicted mature PrP amino acid sequences were found. These genotypes included the amino acid polymorphisms at codons 143 (H-->R) and 240 (S-->P) and 'silent' nucleotide alterations at codons 42 (a-->g) and 138 (c-->t). Additionally, novel caprine amino acid polymorphisms were detected at codons 21 (V-->A), 23 (L-->P), 49 (G-->S), 154 (R-->H), 168 (P-->Q) and 220 (Q-->H) and new silent mutations were found at codons 107 (g-->a) and 207 (g-->a). The following variants were found in scrapie-affected goats: VV(21), LL(23), GG(49,) SS(49), HH(143), HR(143), RR(154), PP(168), PP(240), SP(240) and SS(240). All scrapie-affected animals carried the HH(143)RR(154) genotype, with the exception of two goats (HR(143)), both of which had detectable protease-resistant PrP but showed no clinical signs or histopathological lesions characteristic of scrapie.

Evaluation of ultrastructural changes associated with encephalomyocarditis virus in the myocardium of experimentally infected piglets

OBJECTIVE

To evaluate the ultrastructural changes and localization of encephalomyocarditis virus (EMCV) and viral pathogenesis in the myocardium of experimentally infected piglets.

ANIMALS

Eight 20-day-old piglets.

PROCEDURE

Six piglets were inoculated oronasally with 5 ml (10(6) median tissue culture infective dose/ml) of EMCV suspension, and 2 were used as uninfected controls. Piglets were euthanatized or died between postinoculation days 1 and 3. Samples of heart tissue from all piglets were evaluated histologically, by virus isolation, and by use of immunohistochemistry and electron microscopy.

RESULTS

All infected piglets had gross or microscopic lesions of interstitial myocarditis. immunohistochemically, EMCV antigen was detected in the cytoplasm of cardiac muscle cells, Purkinje fibers, and endothelial cells and in the nucleus of cardiac muscle cells and Purkinje fibers. Ultrastructural lesions were characterized by degeneration and necrosis of cardiac muscle cells and Purkinje fibers. Virus was present intracytoplasmically in cardiac muscle cells, Purkinje fibers, and endothelial cells of capillaries and intranuclearly in cardiac muscle cells. The cell membranes of the Purkinje fibers and endothelial cells had distinct protrusions that contained virus particles. In control piglets, no lesions were found, and no EMCV antigen was detected.

CONCLUSIONS

Localization of EMCV intracytoplasmically or intranuclearly in various myocardial cells may well reflect the sites of viral proliferation. The presence of virus particles in cell membrane protrusions and in vacuoles within the lumen of capillaries indicates that virus is released not only by disintegration of the host cell but also via exocytosis.

Immunohistochemical detection of encephalomyocarditis virus (EMCV) antigen in the heart of experimentally infected piglets

Seven 40-day-old piglets were inoculated with encephalomyocarditis virus (EMCV) strain 424/90, isolated from an outbreak of the myocardial form of the disease in Greece. Two non-infected animals were used as controls. Of the seven inoculated piglets, five died suddenly on day 1.5, 2 (two piglets), 2.5 or 4 post-inoculation (p.i. ). The remaining two and the control piglets were killed on day 8 p. i. EMCV antigen was detected immunohistochemically in endothelial cells of capillaries from 1.5 to 2.5 days p.i. only, but was found in cardiac muscle cells, Purkinje fibres and macrophages on all occasions up to day 8 p.i. In endothelial cells and macrophages, EMCV antigen was detected intracytoplasmically, but in cardiac muscle cells and Purkinje fibres it was observed intracytoplasmically or intranuclearly, or both. The frequent presence of EMCV antigen in Purkinje fibres suggests an explanation for the sudden death of the piglets.

A survey of more than 11 years of neurologic diseases of ruminants with special reference to transmissible spongiform encephalopathies (TSEs) in Greece

The first cases of scrapie were detected in Greece in a flock of sheep in October 1986. All the animals of the affected flock and all sheep in two flocks that were in contact were killed and buried. A systematic investigation of all available cases with signs indicating a neurological disease started in sheep and goats in late 1986, as well as in cattle in 1989. The investigation was based on clinical examination, necropsy or macroscopical examination of the brain and viscera, and histological examination of the brain in all animals except those with coenurosis. Histological examinations of specimens from the spinal cord and other tissues, and if considered necessary bacteriological, toxicological and serological examinations were also carried out. In October 1997, scrapie was diagnosed in sheep of a second flock (a mixed flock of sheep and goats), grazing in a pasture close to the place where scrapie was initially detected. All animals of the second flock were also killed and buried. Diagnosis in the first flock was based on clinical signs and histological lesions, and in the second immunoblotting was also used. Distinctive lesions of scrapie were found in the brain and/or the spinal cord of eight sheep with clinical signs from the two flocks. The lesions were revealed in the brain stem and/or in the cervical spinal cord, and tended to be symmetrical. In one sheep, severe lesions in the cortex of cerebral hemispheres and of the cerebellum were also found. In the brain of two sheep from the second flock the pathological isoform of PrP protein was detected. Despite the eradication scheme applied, scrapie in sheep reappeared after 11 years in a place close to where it occurred initially. This may indicate that the effectiveness of the eradication scheme implemented was not adequate and additional approaches may be needed.

Persistence of encephalomyocarditis virus (EMCV) infection in piglets

Six piglets that had survived experimental infection with encephalomyocarditis virus (EMCV) were treated with dexamethasone for a period of 5 days. The virus had not been detected in excretions of putative carriers for a period of 13-20 days before the treatment. All piglets showed a rise in cardiac isoenzyme (CK-MB) activity, from the first day of treatment, suggesting myocardial damage. Antibody titres against EMCV remained stable or slightly decreased during treatment. EMCV was isolated from blood, nasal and faecal samples from all piglets on days 2 and 3 after initiation of treatment and from various tissues of three piglets. Four contact piglets, that were housed together with the dexamethasone-treated piglets, became infected, indicating that EMCV was shed by treated piglets. It is suggested that recovered pigs may play an important role in the dissemination of EMCV.

A comparative study of the pathogenic properties and transmissibility of a Greek and a Belgian encephalomyocarditis virus (EMCV) for piglets

Thirteen susceptible piglets, aged 40 days, were divided into two groups and were experimentally infected either with a Greek (myocardial) or a Belgian (reproductive) encephalomyocarditis virus (EMCV) strain (total dose 5 x 10(6) TCID50, intramuscularly and intranasally). Six piglets were placed in the same rooms, 24 h later, as contact controls. The following criteria were studied: ante mortem: clinical signs, serum cardiac isoenzyme activities (CK-MB and LD-1), viraemia, nasal and faecal virus excretion and serological response. Post mortem (after death or euthanasia): gross lesions, virus isolation from tissues, RT-PCR, as well as histopathological and immunohistochemical findings. The Greek strain was more pathogenic, producing mortality, with high cardiac isoenzyme activities and pronounced macroscopic myocardium lesions. The Belgian strain was able to induce mild heart lesions, as detected only by cardiac isoenzyme activity and histopathologically. All contact pigs were infected, within the first 1-2 days of their introduction, that coincided with the period of viral excretion by the experimentally infected pigs (up to the 3rd day post infection). Disease was mild, with no mortality.