Characteristic Microscopic Lesions Research Articles

​Dermal Response to Experimental Orfvirus (ORFV) Infection in Goats, Mice and Rabbit

Background: During a study on the outbreak of orf in goats, it was intended to study the disease transmissibility in different hosts from field samples and ascertain the infective potential of the agent in laboratory animals compared to goats. Methods: Cutaneous clinical materials from orf virus (ORFV) infected goats was used to experimentally infect naive goats, rabbits and mice and ascertain its infective potential and transmissibility in different hosts. The processed inoculum was applied topically to mimic a natural transmission through injured skin. Regular skin biopsies were taken that revealed characteristic macroscopic and microscopic lesions typical of orf. Result: Virus inoculum applied on abraded skin in goats successfully established the lesions of orf. A parallel inoculation in rabbit and mice could not successfully reproduce the disease in these unnatural hosts beyond a subtle vesicular stage on 3 dpi with subsequent healing by 7 dpi. The lesions in goats regressed spontaneously by 28 days post-infection (dpi). Intracytoplasmic inclusions were associated only in the vesicular stage. Immunopathological progression was observed by immunoperoxidase staining of CD4+ and CD8+ T-cells which were found to appear by day 5 in the dermis and became more abundant and distributed by day 8, but subsequently reduced in number by 15 dpi. CD4+ cells were found to be more numerous and widespread. Viral antigen in tissues could be demonstrated by 4 dpi by immunohistological methods that increased in signal intensity progressively and disappear by 28 dpi. Similarly, viral nucleic acid in the skin could be detected on day 8 dpi but not on 28 dpi by PCR. The present experiment depicts the ease of disease transmissibility through traumatized skin in the primary hosts, but establishment in unnatural hosts may not be readily achieved. The infection was self-limiting with possibly no virus latency as indicated by immunofluorescence and PCR studies.

The pathology of natural and experimentally induced Campylobacter jejuni abortion in sheep.

We describe here the gross and microscopic lesions in 18 experimentally induced and 120 natural Campylobacter abortions. In natural Campylobacter abortions, gross lesions were reported infrequently; placentitis was recorded in 6% and hepatic lesions in 4% of our field cases. Placentitis was the microscopic lesion identified most consistently in natural abortions (93%) and was often observed in association with abundant bacterial colonies in chorionic villi (54%) and less often with placental vasculitis (13%). In natural abortions, suppurative fetal pneumonia (48%), necrosuppurative hepatitis (16%), and purulent meningitis (7%) were also observed. The better-preserved specimens from experimentally induced abortions were utilized to define placental changes more precisely. Placentitis was identified in all 18 experimentally induced abortions and was observed most consistently in the chorionic villus stroma (100%), often accompanied by suppurative surface exudate (89%). An inflammatory infiltrate was less commonly identified in the cotyledonary hilus (39%) and intercotyledonary placenta (22%). Bacteria were visualized in H&E-stained sections in 89% of placentas from experimentally infected ewes, primarily as well-demarcated bacterial colonies within subtrophoblastic, sinusoidal capillaries (89%), in the cotyledonary villus stroma (89%), and within the cytoplasm of trophoblasts (22%). Transmission electron microscopy and immunohistochemistry confirmed that the vast majority of the well-demarcated bacterial colonies characteristic of Campylobacter abortion were within subtrophoblastic sinusoidal capillaries. The most characteristic microscopic lesions identified in cases of Campylobacter abortion in sheep were placentitis with placental bacterial colonies, placental vasculitis, and fetal pneumonia.

Molecular Characterization and Pathogenicity of an Indian Isolate of Duck Enteritis Virus Recovered From a Natural Outbreak

Background: Duck plague is a highly contagious viral disease reported in our country very often with significant economic loss. There are some bottlenecks with the currently used ‘Holland strain’ vaccine that involves cumbersome process of vaccine production in embryonated chicken eggs. With the future goal of development of an indigenous cell culture vaccine for duck plague, the present study is aimed at isolation of an Indian strain of DEV from a natural outbreak and its characterization for the seed virus purpose. Methods: Liver samples were collected from the suspected ducks died during a natural outbreak in Kerala and subjected to polymerase chain reaction (PCR) to confirm presence of viral DNA. The duck enteritis virus (DEV) was isolated by inoculation of PCR positive samples in embryonated duck eggs/ducklings and its pathogenicity was studied. Further, the DEV recovered from the infected duck embryo and duckling liver was confirmed by PCR amplification of the viral DNA polymerase gene and its sequence analysis. Result: Out of 12 liver samples tested eight (8) were found to be positive for duck plague by PCR. The DEV infected duck embryos and ducklings died showing typical signs and characteristic gross and microscopic lesions. PCR amplification of viral DNA targeting the DNA polymerase gene yielded amplicon of expected size of 446bp. The amplicon sequence showed 99-100% homology with other DEV isolates, thus confirming the new isolate as DEV, named as DEV/India/IVRI-2016 and the gene sequence has NCBI acc. no. KX511893.

Focal duodenal necrosis in chickens: attempts to reproduce the disease experimentally and diagnostic considerations.

Focal duodenal necrosis (FDN) is an intestinal disease of egg-layer chickens characterized by multifocal necrosis of the duodenal loop and proximal jejunum. Affected flocks usually have decreased egg weights and drops in egg production. Previous studies have associated this condition with Clostridium perfringens infection. We tried to reproduce FDN by experimental infection of egg-laying chickens using different netB-positive and netB-negative C. perfringens strains, and duodenal homogenate obtained from FDN lesions. Chickens challenged with C. perfringens and/or duodenal homogenate developed duodenitis after challenge. Gross lesions included mucosal erosions, hyperemia, mucosal hemorrhages, and watery intestinal content. Microscopic lesions included mild enterocyte degeneration and necrosis, and mild-to-moderate hemorrhage and lymphoplasmacytic and heterophilic infiltration of the lamina propria. Two netB-positive C. perfringens strains closely related to necrotic enteritis pathogenic strains, by genomic composition, were re-isolated from lesions. Necrosis of intestinal crypts was observed in chickens challenged with duodenal homogenate with or without C. perfringens coinfection. Characteristic microscopic FDN lesions with significant necrosis and loss of villus enterocytes were not reproduced.

Morphological Characteristics of Skin Lesions in Cattle Naturally Infected with Lumpy Skin Disease Virus in Serbia

Abstract Lumpy skin disease (LSD) is a disease of cattle and domestic buffaloes caused by Capripoxvirus which can lead to significant economic losses. Until several years ago it was limited to Africa and the Middle East, but recently it was reported in Turkey (2013), Greece (2015), and in 2016 it spread to Bulgaria, North Macedonia, Albania, Montenegro and Serbia. The aim of this study was to determine the microscopic lesions in the skin of naturally infected animals, highlight their features and compare them to the findings of other authors. Gross lesions in the skin of cattle infected with Lumpy skin disease virus (LSDV) were manifested in the form of skin nodules which were round, raised, clearly circumscribed, firm and randomly distributed in the whole skin including the vulva and udder. Histopathological lesions included degeneration of epithelial cells, hyperkeratosis, spongiosis, and acanthosis present in 85.88%, 81.18%, 84.71%, and 80.0% of samples, respectively. Intracytoplasmic inclusion bodies were noted in keratinocytes of the stratum spinosum in 56.47% of samples, and in hair follicle cells and sebaceous glands epithelial cells in 45.88% of samples. Cutaneous lesions were in the form of inflammatory infiltrate present in the dermis and subcutis in 97.65% of samples. Since there are only a few literature data in this field, this study expands the knowledge relating to morphological alterations in LSD. Based on the characteristic microscopic lesions described in the present study, histopathology should be considered as a very useful method for the diagnosis of LSD.

PREVALENCE AND PATHOLOGICAL FEATURES OF OVINE LUNGWORM IN NILE DELTA

A cross-sectional study was conducted from March 2017 to March 2018, to determine the prevalence of ovine lungworm infection, and to describe the related pathological lesions in naturally infected local breed sheep. A total of 200 whole lungs were collected from fifteen slaughter houses in Nile Delta, Egypt. The overall prevalence for ovine lungworm infection was 4.5%. The prevalence rates in Ossimi, Rahmani, and Barki breeds were 5.55, 4.28, and 2.5%, respectively. The only identified species of lungworms was Dictyocaulus filaria (D. filaria) (100%). Grossly, the fundamental lesions were multiple patchy consolidated pulmonary tissues with the presence of adult parasites mixed with foamy and sometimes mucous exudate in the lumens of trachea and bronchi. Histopathologically, alveolitis, obstructive bronchiolitis, bronchiolar hyperplasia, emphysema, granulomatous pneumonia, pleural thickening, peribronchiolar lymphoid hyperplasia and trapped different developmental stages and adult parasites besides degenerated and necrotic parasites in the pulmonary tissue were the hallmarks of the histopathological features. In conclusion, ovine lungworms were prevalent in sheep at Nile Delta, Egypt, causing significant damage to the lung and produce characteristic gross and microscopic lesions.

Pathogenic Characterization of European Genotype Porcine Reproductive and Respiratory Syndrome Virus Recently Isolated in Mainland China.

Background:Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen in pig that causes tremendous economic loss in the global swine industry. PRRSV is divided into the European and North American genotypes, with virulence ranging from apathogenic-moderately virulent to highly pathogenic. The emergence of new highly virulent type 1 strains and coexistence of the two genotypes complicate the differential diagnosis, disease prevention, and control of PRRSV. Although the emergence of a novel type 1 PRRSV strain in mainland China was first confirmed in 2011, there is no information available concerning the pathogenesis of this strain.Objectives:We sought to determine the pathogenesis of a newly emerged Chinese type 1 PRRSV strain HLJB1.Methods:Pigs were infected with HLJB1 and characterized using serological and histopathological tests.Results:HLJB1 infection induced transient chemosis, reddened conjunctiva, skin cyanosis, mild transient pyrexia, dyspnea, and tachypnea between 7 and 13 days post-infection. Gross pneumonic lesions were characterized by multifocal, tan-mottled areas. Lymph nodes and spleen were enlarged. Characteristic microscopic lesions consisted of pulmonary consolidation and alveolar septal thickening with red blood cell infiltration, depletion of splenic lymphocytes, and hyperplasia and activation of macrophage. No pigs infected with HLJB1 died during the experiment.Conclusion:Our findings indicate that Chinese type I PRRSV strain HLJB1 caused classic PRRSV-specific lesions. As it caused lower viremia in pigs compared with other classic type 1 isolates, HLJB1 is less virulent than other type I strains.

Histopathological and immunohistochemical approaches for the diagnosis of Pasteurellosis in swine population of Punjab.

Aim:Infectious porcine bronchopneumonia, caused by Pasteurella multocida, is a widespread disease of major economic significance. Thus, the aim of the present study was to diagnose swine Pasteurellosis using gross, histopathological, and immunopathological approaches in the swine population of Punjab and to compare the efficacy of immunohistochemical (IHC) techniques with conventional diagnostic techniques.Materials and Methods:A total of 71 adult swine lung samples showing gross pneumonic changes were collected along with the associated lymph nodes to carry out the study. The collected samples were then processed for histopathological and IHC studies.Results:Out of the total 71 lung samples, 26 samples were found to be suspected for Pasteurellosis as per the microscopic changes observed, and out of these 26 samples, 16 cases were confirmed to be positive for Pasteurellosis by IHC. Varied macroscopic changes noted in lungs were pneumonic patches with consolidation of many lobes, congestion, and focal hemorrhages. Main lesions associated with lymph nodes were its enlargement and hemorrhages. Histologically, the lung showed fibrinous and suppurative bronchopneumonia, multifocal suppuration, thickening of septa with fibrin combined with cellular infiltration and edema. The higher IHC expression of P. multocida was seen in the bronchial epithelium besides in alveolar and bronchial exudate. Moreover, on comparing the histopathological and IHC scores which were calculated on the basis of characteristic microscopic lesions and number of antigen positive cells, respectively, a significant positive correlation (r=0.4234) was found.Conclusion:It was concluded that swine population of Punjab is having P. multocida infection. The gross and histopathological lesions can be helpful in the preliminary diagnosis of Pasteurellosis but needs to be supplemented by other immunodiagnostic tests. Moreover, IHC technique proved to be a specific, reliable, precise, and rapid technique to supplement these conventional methods of diagnosis for Pasteurellosis.

Veterinary Forensic Pathology: Drowning and Bodies Recovered From Water.

Determining the cause of death in animals recovered from bodies of water, swimming pools, or other water-containing vessels is challenging. Animals recovered from water may or may not have drowned. The diagnosis of drowning is usually one of exclusion, requiring information from the crime scene, recovery scene, the medical history or reliable witness accounts. While there are characteristic macroscopic and microscopic lesions of drowning, none are specific and are dependent on the volume and tonicity of the drowning medium. Beyond interpreting the postmortem findings, the court may ask pathologists to comment on the behavioral and welfare implications of drowning. This requires an understanding of the drowning process, which is a complex series of sequential, concurrent, and overlapping cardiorespiratory reflexes, electrolyte and blood gas abnormalities, aspiration, physical exhaustion, and breathlessness eventually culminating in death. This review addresses the mechanisms, lesions, and diagnostic issues associated with drowning in nonaquatic companion animals.

Association of Beta2-Positive Clostridium perfringens Type A With Focal Duodenal Necrosis in Egg-Laying Chickens in the United States.

Focal duodenal necrosis (FDN) is a poorly understood intestinal disease of egg layers, and has been associated with drops in egg production and decreased egg weights. The etiology of this disease is still unknown, but the condition has been associated with Clostridium colinum and Clostridium perfringens. In order to investigate the etiology, duodenal samples were taken from hens with FDN. The hens originated from table egg layer farms in three states. The samples were examined by histopathology, bacteriology, and immunohistochemistry. Macroscopically, all samples contained focal to multifocal, variably sized, reddened or brownish gray areas of mucosal erosion. Histopathology revealed mild to severe heterophilic and lymphoplasmacytic enteritis with loss of enterocytes at the villous tips, luminal fibrinonecrotic exudate, and variable numbers of Gram-positive and Gram-negative rod-shaped bacteria within the lesions in 16/30 samples. Clostridium perfringens was isolated by anaerobic bacteriology from 4/13 samples that had characteristic microscopic lesions of FDN. Polymerase chain reaction (PCR) revealed that all four isolates were Type A C. perfringens, positive for beta2 gene and negative for necrotic enteritis toxin B and enterotoxin genes. PCR for Clostridium colinum applied to DNA extracted from frozen intestinal samples yielded negative results in 14/14 duodenal samples. Immunohistochemistry (IHC) for 7C. perfringens, alpha and beta2 toxins stained a few to numerous long rod-shaped bacteria present in the lesions. IHC for alpha and beta2 toxins also stained enterocytes at the villous tips, inflammatory cells in the lamina propria, as well as degenerated and sloughed enterocytes present within the luminal exudate. These findings suggest that C. perfringens may play a role in the development of FDN. Experimental challenge studies with these isolates still need to be performed in order to reproduce the disease and fulfill Koch's postulates.

Transmissible Viral Proventriculitis Identified in Broiler Breeder and Layer Hens

Transmissible viral proventriculitis (TVP) is a recognized cause of production losses in broiler chickens, but previously it has not been reported in broiler breeder and commercial layer hens. In this study, TVP was identified in broiler breeder and commercial layer hens, 9-20 wk of age, based on histopathologic detection of characteristic microscopic lesions. Microscopic lesions in proventriculi of affected hens consisted of glandular epithelial necrosis, ductal epithelial hyperplasia, replacement of glandular epithelium with ductal epithelium, and diffuse interstitial lymphoid infiltration. Additionally, chicken proventricular necrosis virus (CPNV), a virus previously identified as the etiology of TVP in broiler chickens, was detected in proventriculi of TVP-affected hens using a reverse transcriptase-polymerase chain reaction procedure. The findings identify TVP as a potential cause of production losses in broiler breeder and commercial layer hens and provide additional evidence for etiologic involvement in TVP by CPNV.

Novel relapsing fever Borrelia detected in African penguins (Spheniscus demersus) admitted to two rehabilitation centers in South Africa

The African penguin, Spheniscus demersus, the only penguin species that breeds in Africa, is endangered, and several diseases including avian malaria, babesiosis, and aspergillosis are common in some populations. From 2002 to 2010, spirochetes morphologically consistent with Borrelia were observed on thin blood smears from 115 of 8,343 (1.4%) African penguins admitted to rehabilitation centers in the Western Cape and Eastern Cape provinces of South Africa. Prevalence rates were significantly higher among chicks and juveniles compared with adults and for birds sampled during the summer months of October to February compared with winter months. The majority of infected birds were ultimately released, despite lack of antibiotic treatment; however, at least one bird is believed to have died of borreliosis based on characteristic gross and microscopic lesions. Analysis of partial flaB gene sequences indicated this was a relapsing fever Borrelia most similar to a Borrelia sp. detected in soft ticks from a seabird colony in Japan. This represents the fourth report of a relapsing fever Borrelia sp. in an avian species and highlights the need for additional studies of potentially pathogenic organisms infecting the African penguin in South Africa.

Experimental Reproduction of Porcine Circovirus Type 2 (PCV2)-Associated Enteritis in Pigs Infected with PCV2 Alone or Concurrently with Lawsonia intracellularis or Salmonella typhimurium

Porcine circovirus (PCV)-associated disease (PCVAD) has emerged to become one of the most economically important pig diseases globally. One of the less commonly recognized clinical manifestations of PCVAD is PCV2 type 2 (PCV2)-associated enteritis in growing pigs; however, experimental confirmation of the ability of PCV2 alone or PCV2 coinfection with other agent(s) to induce enteritis is lacking. In this study, 120 specific-pathogen-free (SPF) pigs were divided randomly into six groups: controls (negative control pigs), PCV2 (inoculated with PCV2), LAW (inoculated with Lawsonia intracellularis), SALM (inoculated with Salmonella typhimurium), PCV2-LAW (concurrently inoculated with PCV2 and Lawsonia intracellularis) and PCV2-SALM (concurrently inoculated with PCV2 and Salmonella typhimurium). One half of the pigs in each group were subject to necropsy examination 14 days postinoculation (dpi) and the remaining pigs were examined at 28 dpi. The average daily weight gain was not different (P>0.05) between groups. Individual pigs inoculated orally with PCV2 regardless of coinfection status (2/10 PCV2, 1/10 PCV2-LAW, 3/10 PCV2-SALM) developed PCVAD with diarrhoea and reduced weight gain or weight loss between 14 and 28 dpi. Those pigs had characteristic microscopic lesions in lymphoid and enteric tissues associated with abundant PCV2 antigen. Enteric lesions were characterized by necrosuppurative and proliferative enteritis with crypt elongation and epithelial hyperplasia in LAW and PCV2-LAW pigs by 14 dpi, ulcerative and necrosuppurative colitis in SALM and PCV2-SALM pigs by 14 dpi, and lymphohistiocytic enteritis with depletion of Peyer's patches in PCV2, PCV2-SALM and PCV2-LAW pigs by 28 dpi. To the authors' knowledge, this is the first report documenting that under experimental conditions, PCV2 can induce enteritis independently from other enteric pathogens and that oral challenge is a potentially important route and perhaps the natural route of PCV2 transmission in growing pigs.

Hepatic Encephalopathy in Two Goat Kids with Common Paternity

Two juvenile, intact, female mixed-breed goats from a common sire were presented for periodic neurologic deficits, seizures, and a generalized loss of body condition that occurred over a 4-6-week period. On physical examination, both goats were thin, obtunded, blind, and ataxic. Laboratory diagnostics revealed increased serum bile acids (95 micromol/l; reference interval: 0-50 micromol/l) in one of the goats. Both goats exhibited progressive physical and mental deterioration, and were eventually euthanized. Upon necropsy, no significant macroscopic lesions were noted. Microscopic examination, however, demonstrated hepatocellular atrophy and anomalies in the hepatic microvasculature, including duplication of hepatic arteries, small-to-indistinct portal veins, and oval cell hyperplasia. In addition, spongiform change was microscopically identified throughout the parenchyma of the brain, most notably within the white matter and along the junction of gray and white matter. The diagnosis of congenital portal vein hypoperfusion (suggestive of a portosystemic shunt) with resultant hepatic encephalopathy was proposed in each case based on the characteristic microscopic lesions in conjunction with the signalment and history of the goats. The observation that the affected kids were sired by the same buck suggests a hereditary basis for the condition in these animals as well.

A new method to identify cell types that support porcine circovirus type 2 replication in formalin-fixed, paraffin-embedded swine tissues

Porcine circovirus type 2 (PCV2) is detected in high amounts within the characteristic microscopic lesions of postweaning multisystemic wasting syndrome (PMWS) affected pigs. In spite of recent advances on disease pathogenesis, the precise cell types that support viral replication are still a major issue of scientific discussion. In this study, a new methodology to detect cell types that support PCV2 replication was designed. For this purpose, two in situ hybridisation (ISH) methods were developed and applied on tissues of PMWS naturally affected pigs using two probes designed from the ORF1 sequence of the virus. While the complementary probe (CP) detected ssDNA, ORF1 mRNA and replicative form (RF) of PCV2, the RF probe (RFP) exclusively hybridised with the RF of the virus, thus, only labelling cells where PCV2 replication is taking place. Both probes demonstrated to be specific and equally sensitive by an in vitro Southern blot hybridisation assay. ISH labelling with the CP was extensive in lymphoid tissues and of variable amount in other non-lymphoid tissues. With this probe, mainly macrophage-like cells were labelled but also other cell types such as hepatocytes and other epithelial cells. Tissues in which RFP labelling was found more frequently were lung, inguinal and mesenteric lymph nodes, tonsil and liver. Labelling with the RFP was always nuclear, and found in the same cell types as with the CP, although in a relatively low proportion of them; labelling of macrophage-like cells was infrequent. Therefore, the results indicate that at least a certain proportion of macrophages may support PCV2 replication, but main cells where PCV2 replicates are of epithelial/endothelial origin. In summary, the present study permitted the study of cell types that support PCV2 replication by the use of ISH on formalin-fixed, paraffin-embedded tissues of PMWS affected pigs.

Isolation and molecular characterization of a new Muscovy duck parvovirus from Muscovy ducks in the USA

Between 1997 and 1999 several cases of a new disease in Muscovy ducks were reported in Pennsylvania, USA. The cases were characterized by locomotor dysfunction, weakness, recumbency, 40 to 60% morbidity and 10 to 40% mortality. The most characteristic microscopic lesions were moderate to severe degenerative rhabodomyopathy. In order to characterize the aetiological agent, virus isolation was attempted from the spleen, liver, heart, skeletal muscle and intestine by inoculation of 14-day-old Muscovy duck embryos with tissue homogenates. Deaths occurred on the second egg passage and parvoviruses were isolated by serial passage of allantoic fluid from dead embryos and then in Muscovy duck embryo fibroblast (MDEF) cultures. Parvovirus particles were observed in allantoic fluids and supernatants of MDEF cultures by transmission electron microscopy. Two genomic fragments, comprising 1108 nucleotides of the right open reading frame that codes for the structural viral proteins 1, 2 and 3, were amplified by polymerase chain reaction from one of the isolates, Muscovy duck parvovirus (MDPV)/PSU-31010. Comparison of this fragment with available sequences of other MDPV and related goose parvovirus (GPV) isolates showed that it had only 84.5% sequence identity with other MDPV isolates and 84.6% identity with the GPV isolates. This region shares over 99% identity among previously sequenced MDPV isolates and 95% identity among the related GPV isolates. This suggests that MDPV/PSU-31010 is divergent from all other sequenced MDPV and GPV isolates, and may represent a new group of avian parvoviruses.

Histologic Features Associated withTritrichomonas foetus-induced Colitis in Domestic Cats

Tritrichomonas foetus is a venereal pathogen of naturally bred cattle. In domestic cats, T. foetus colonizes the colon, resulting in chronic, large-bowel diarrhea. The infection is prevalent among young, densely housed cats, and there is no effective treatment. To the authors' knowledge, the characteristic microscopic lesions of T. foetus infection in naturally infected cats have not been described. The aim of the study reported here was to characterize the histologic changes in the colon of seven cats with T. foetus infection and chronic diarrhea. All cats were 1 year old or younger (mean, 6.7 +/- 1.7 months), and a diagnosis of T. foetus infection was made on the basis of direct fecal smear examination (five cats), fecal culture in InPouch TF medium (four cats), single-tube nested polymerase chain reaction (PCR) analysis of DNA extracted from feces (two cats), or observation of trichomonads in sections of colon followed by PCR confirmation on DNA extracted from paraffin-embedded tissue (two cats). The presence of colonic trichomonads was the most diagnostic histologic feature. Organisms were identified in all cats, but in only 24 of 43 (56%) sections of colon. Trichomonads were generally present in close proximity to the mucosal surface and less frequently in the lumen of colonic crypts. The presence of colonic trichomonads was consistently associated with mild-to-moderate lymphoplasmacytic and neutrophilic colitis, crypt epithelial cell hypertrophy, hyperplasia and increased mitotic activity, loss of goblet cells, crypt microabscesses, and attenuation of the superficial colonic mucosa. In two of the cats, histologic lesions were more severe and were associated with invasion of trichomonads into the lamina propria and/or deeper layers of the colon.

Postweaning multisystemic wasting syndrome (pmws) in pigs in Croatia: Detection and characterisation of porcine circovirus type 2 (pcv2)

The objective of this study was to characterise porcine circovirus type 2 (PCV2) from pigs with naturally occurring postweaning multisystemic wasting syndrome (PMWS) in Croatia, and to determine the epizootiological, clinical and pathomorphological features of the disease. During a systematic health monitoring programme conducted in the period from January 2002 to June 2003, PMWS was suspected on eight different pig-producing farms in Croatia. The diagnosis of PMWS met all three key criteria: the presence of compatible clinical signs, the presence of the characteristic microscopic lymphoid lesions, and the detection of PCV2 within the lesions by polymerase chain reaction (PCR) and by in situ hybridisation (ISH). Moreover, PCV2 DNA from swine tissues was extracted and sequenced. The phylogenetic analysis of 4 Croatian PCV2 strains showed close relationship to PCV2 strains isolated in Slovenia, France, the Netherlands, the United Kingdom, China and Hungary. PCV2 was also demonstrated by electron microscopy in the lymph node of an affected animal. This is the first demonstration of PMWS in Croatia based on all scientifically accepted diagnostic criteria.

Postweaning multisystemic wasting syndrome: a review of aetiology, diagnosis and pathology

This review paper concentrates on the aetiology, diagnosis, and pathological aspects of postweaning multisystemic wasting syndrome (PMWS). PMWS was first recognized in Canada in 1996 as a new emerging disease which caused wasting in postweaned pigs. Since then, PMWS has been recognized in pigs in many countries. The syndrome is caused by a DNA virus referred to as porcine circovirus 2 (PCV2), which is classified in the family Circoviridae. PMWS primarily occurs in pigs between 25 and 120 days of age with the highest number of cases occurring between 60 and 80 days of age. The diagnosis of PMWS must meet three criteria: (i) the presence of compatible clinical signs, (ii) the presence of characteristic microscopic lesions, and (iii) the presence of PCV2 within these lesions. In order to establish the diagnosis, techniques are required that link virus and tissue lesions, such as immunohistochemistry and in situ hybridization, but not polymerase chain reaction or virus isolation. The three criteria considered separately are not diagnostic of PMWS. For example, the detection of PCV2 alone does not indicate PMWS but merely PCV2 infection. A hallmark of microscopic lesions of PMWS is granulomatous inflammation in the lymph nodes, liver, spleen, tonsil, thymus, and Peyer’s patches. Large, multiple, basophilic or amphophilic grape-like intracytoplasmic inclusion bodies are often seen in the cytoplasm of macrophages and multinucleated giant cells.

Lack of an effect of a commercial vaccine adjuvant on the development of postweaning multisystemic wasting syndrome (PMWS) in porcine circovirus type 2 (PCV2) experimentally infected conventional pigs.

The objective of this study was to evaluate the effect of a commercial vaccine adjuvant on the clinical and pathological outcome of PCV2 experimentally infected 8 to 9-week-old conventional pigs. Forty-four pigs were divided into four groups: non-infected control pigs, pigs that received a vaccine adjuvant, pigs inoculated with PCV2, and pigs inoculated with PCV2 together with the vaccine adjuvant. Infection was monitored until 69 days post-inoculation (PI). Some PCV2 inoculated pigs had hyperthermia, but no other clinical signs were recorded. No characteristic PMWS gross or microscopic lesions were observed in any of the pigs. PCV2 DNA was detected in lymphoid tissues by in situ hybridisation in 6 PCV2 inoculated pigs on day 69 PI. All PCV2 inoculated pigs seroconverted between days 21 and 49 PI, shortly after viremia detection. Moreover, viremia was detected between days 7 and 69 PI using PCR. A peak of the virus load was detected by real-time quantitative PCR between days 14 and 21 PI. There were no significant differences in the proportion of PCV2 positive serum and in the viral load between PCV2 and PCV2 + adjuvant inoculated pigs. Although PMWS was not reproduced in neither PCV2 nor PCV2 + adjuvant inoculated pigs, viremia detection and seroconversion indicated that all PCV2 inoculated pigs developed a chronic long-term asymptomatic infection. An increase of PCV2 replication was not observed in pigs inoculated with the adjuvant. These results indicate that the principle of immunostimulation may not be applicable under the experimental conditions used, suggesting that not all adjuvants used in commercial vaccines are capable of triggering mechanisms for PMWS development.