Paratuberculosis in saiga antelope (Saiga tatarica) and experimental transmission to domestic sheep.

Mycobacterium paratuberculosis was isolated in low numbers from the small intestine and associated mesenteric lymph nodes of a saiga antelope (Saiga tatarica) using routine culture techniques in spite of histologic evidence of high numbers of acid-fast bacteria in these tissues. Two newborn domestic sheep were fed the ground intestinal tissue containing acid-fast bacteria and the progression of the experimental disease was followed by fecal culture, immunodiffusion (AGID) and lymphocyte stimulation (LST) tests. One experimentally infected sheep developed progressive clinical illness 1 yr postinoculation. Few M. paratuberculosis were isolated from feces or tissues although an extensive granulomatous mycobacterial enteritis, lymphadenitis and lymphangitis were observed containing large numbers of typical acid-fast organisms. No clinical illness was observed in the second inoculated sheep after 18 mo of observation, although infection was demonstrated at necropsy. Both sheep developed AGID and LST reactions indicative of paratuberculosis. This study demonstrated that a difficult to culture isolate of M. paratuberculosis was responsible for paratuberculosis in captive wild ruminants and was transmissible to domestic sheep. Diagnosis of paratuberculosis in four of eight of the imported saiga antelope and in eleven of their 18 offspring indicates the importance of this disease in management of captive wild ruminants and the ease with which this organism can be transmitted.     

Serological,culture and molecular survey of <Emphasis Type="Italic">Mycobacterium avium paratuberculosis</Emphasis> in a goat flock in Tuscany

Mycobacterium avium paratuberculosis (Map) is a pathogen which causes a chronic progressive granulomatous enteritis known as paratuberculosis or Johne’s disease and it primarily affects wild and domestic ruminants. The aim of this research was to examine a flock which consisted of 294 goats and was located in Garfagnana district (Tuscany, Italy) performing ELISA tests, culture and IS900 PCR assay; direct diagnostic methods were carried out not only on bulk tank milk and cheese samples but also on individual milk and tissue specimens collected from nine subjects positive to ELISA tests. Out of 294 animals, 20 goats (6.8%) were positive to ELISA surveys. Bulk tank milk samples were negative to culture and to PCR assay carried out on the DNA extracted directly from them, while, with respect to cheese, Map was detected by culture in 2/12 (16.66%) cheeses ripened for 3–7 days, and by PCR in 2/12 (16.66%) cheeses ripened for 3–7 days and in 3/12 (25%) cheeses ripened for 45 days. Regarding individual milk samples, Map was detected by culture in 2/9 (22.22%) specimens and by PCR in 5/9 (55.55%) samples. Furthermore, Map was isolated from the intestine in 9/9 (100%) animals, from the mesenteric lymph nodes in 8/9 (88.88%) subjects, from the liver in 4/9 (44.44%) goats, from the spleen in 5/9 (55.55%) animals, while Map DNA was found in all the tissue samples analyzed.The results demonstrated the presence of paratuberculosis in a goat flock located in Garfagnana district (Tuscany, Italy).     

Post-Mortem Examination in the Diagnosis of Johne’s Disease in Goats

Post-mortem examinations play an important role in Johne’s disease programmes in Norway. The results of such examinations of samples of viscera from 2997 goats carried out during the 5-year period 1972–1976 are given. The investigations show that the demonstration of macroscopical changes in mesenteric lymph nodes and small intestine has only limited value as a guideline in the post-mortem diagnosis of Johne’s disease in goats. Often macroscopical changes were not seen or they were non-specific. Caseous and/or calcified foci in mesenteric lymph nodes in infected animals were demonstrated quite often whilst observed intestinal changes were strikingly few. Corrugation of the mucosa was rare. However, in sections of macroscopically unchanged intestine marked epithelioid cell infiltrations and abundant acid-fast bacilli were not uncommon. In sporadic cases productive inflammation with tubercle formation was seen in lymph nodes in infected animals. Bacteriological culture was by far the most reliable post-mortem diagnostic method. By this method 92% of the infected goats were detected. The corresponding figures for histological examination and microscopy were 54% and 47%, respectively.     

Paratuberculosis (Johne's disease) in bighorn sheep and a Rocky Mountain goat in Colorado.

Between May, 1972 and February, 1978, six cases of paratuberculosis (Johne's Disease) caused by Mycobacterium paratuberculosis were diagnosed in free-ranging Rocky Mountain bighorn sheep (Ovis canadensis) and one Rocky Mountain goat (Oreamnos americanus) on or near Mt. Evans in Colorado. Diagnosis of paratuberculosis was based on gross and histopathologic examination of the animals and by isolation of M. paratuberculosis from three sheep and the goat. The clinical signs and pathologic changes seen in the bighorn sheep resembled those described in cattle, while the lesions in the goat were similar to those described for domestic sheep and goats.     

Culture and serologic survey for Mycobacterium avium subsp. paratuberculosis infection among southeastern white-tailed deer (Odocoileus virginianus)

From July 1998 through October 2002, radiometric culture (ileocecal lymph node, mesenteric lymph node, and feces) and serologic testing by enzyme-linked immunosorbent assay (ELISA) were used to survey white-tailed deer (Odocoilens virgianus) from the soutlheastern United States for infection by Mycobacterium avium subsp. paratuberculosis (Mptb), the causative agent of paratuberculosis (Johne's disease). Mycobacterium avium subsp. paratuberculosis was isolated from the ileocecal lymph node of one of 313 deer (0.3%) originating from 63 populations in Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennessee, and West Virginia (USA). Six deer (2%), all from different populations, had ELISA results above a 0.25 sample-to-positive cutoff value, but none of the ELISA reactors originated from the population from which the single Mptb isolation was made. These six deer were seronegative when tested by agar gel immunodiffusion (AGID). Collectively, these data indicate that white-tailed deer currently do not constitute a broad regional reservoir for Mptb; however, further study is warranted to clarify the significance, if any, of infected deer to the epizootiology of paratuberculosis on a local scale. Adaptation and validation of an ELISA or another serologic assay for use with deer and other wildlife would markedly enhance Mptb surveillanece among wild populations and would be a powerful tool for gaining information on the role of wild species in epidemiology of paratuberculosis.     

Paratuberculosis in PIGS

Oral administration of Mycobacterium paratuberculosis to 61 pigs resulted in the development of caseous lesions of the mesenteric lymph nodes in 27.9 % of the animals. Positive results were found by bacterioscopy in 31.1 %, by culture in 60.7 % and by histological examination in 42.6 % of the animals. Histological changes typical of infection with M. paratuberculosis were found in the ileum in eight pigs. These changes, which consisted of infiltrations with epithelioid cells, were usually limited to the Peyer patches, but in one case such infiltrations were also present in the propria mucosae, similarly as in paratuberculosis in cattle.     

IS<Emphasis Type="Italic">900</Emphasis> Restriction Fragment Length Polymorphism (RFLP) Analysis of <Emphasis Type="Italic">Mycobacterium avium</Emphasis> subsp. <Emphasis Type="Italic">paratuberculosis</Emphasis>Isolates from Goats and Cattle in Norway

In Norway, paratuberculosis has been frequently diagnosed in goats, while cattle have been almost free of the infection. This difference in prevalence between goats and cattle has led to speculations about the existence of a Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis) isolate that is non-pathogenic for cattle. There is little information available on genotypic variation of M. a. paratuberculosis isolated from animals in Norway. In the present study, genotypic information on 51 isolates from goats and four isolates from cattle in Norway was obtained by use of IS 900 restriction fragment length polymorphism (RFLP) analysis. All isolates from cattle and 84% of the isolates from goats had the same RFLP pattern (B-C1). Five RFLP patterns not previously detected were found. No genotypic variation that could explain a difference in host origin was found between the isolates from cattle and the majority of the Norwegian goat isolates. This lack of difference indicates that the most common M. a. paratuberculosis isolates in Norway may infect both cattle and goats.     

Antibody levels in goats fed Toxoplasma gondii oocysts

Outbred goats were fed 10(5) Toxoplasma gondii oocysts and were monitored twice weekly for 8 wk for rectal temperature, clinical signs, parasitemia, and antibody levels by indirect fluorescence antibody test (IFAT), latex agglutination test (LAT), and indirect enzyme-linked immunosorbent assay (ELISA). After 8 wk, all goats were killed, and samples of heart, skeletal muscle, brain, lymph nodes, kidneys, and liver were bioassayed in mice. Anorexia, fever, and lethargy were observed from day 3 to day 7 postinfection (PI). Parasitemia was detected by bioassay in 50% of infected goats from day 7 to day 14 PI. Viable T. gondii organisms were isolated from all infected goats. Antibodies to T. gondii were detected in some animals on day 10 PI by IFAT and LAT and on day 14 PI by ELISA. The infected goats were seropositive on day 17 PI.     

Evaluation of bioelectronics sensor compared to other diagnostic test in diagnosis of Johne's disease in goats

A bioelectronics sensor has been developed and it is evaluated for the diagnosis of paratuberculosis in goats. Initially hematite nanoparticles were prepared and using this nanoparticles as core, electrically active polyaniline coated magnetic (EAPM) nanoparticles are synthesized from aniline monomer (made electrically active by acid doping). These EAPM nanoparticles were fabricated with rabbit anti-goat IgG for the detection of goat antibodies on the capture pad. The protoplasmic antigen of Mycobacterium avium subspecies paratuberculosis (MAP) immobilized onto the capture pad will detect the antibody against MAP in the goat sera samples. This bound goat antibody will be detected by the anti-goat IgG previously bound to EAPM. Upon detection the EAPM nanoparticles bridges an electric circuit between the silver electrodes, flanking the capture membrane. The electrical conductance, caused by EAPM, was measured as direct charge transfer between the electrodes. Testing of the biosensor with known Johne's disease (JD) positive and negative serum samples gave significant difference in the electrical conductance value. Further the efficacy of this biosensor was compared with other serological tests like agar gel immunodiffusion (AGID) and absorbed ELISA using field sera. Out of 265 goat sera tested, positive results recorded were; AGID 36 (13.59%), bioelectronics sensor 49 (19.14%), and absorbed ELISA 51 (19.25%). This biosensor was also compared in live animals using intradermal Johnin test and nested PCR (detecting mycobacterial DNA in feces) in 65 animals. Of which, positive results recorded in animals were; Johnin test 21 (32%), biosensor 26 (40%) and fecal PCR detected mycobacterial DNA in 28 (43%) animals. Though the nanobioelectronics sensor was slightly less sensitive (not statistically significant) compared to absorbed ELISA and fecal nested PCR for mycobacterial DNA but it was simple to perform in field conditions and requires less time. The speed of detection and the equipment involved would support its application toward the various point-of-care opportunities aimed at control and management of Johne's disease in goats.     

Isolation of Mycobacterium avium subsp. paratuberculosis from free-ranging birds and mammals on livestock premises

Surveys for Mycobacterium avium subsp. paratuberculosis infection in free-ranging mammals and birds were conducted on nine dairy and beef cattle farms in Wisconsin and Georgia. Specimens were collected from 774 animals representing 25 mammalian and 22 avian species. Specimens of ileum, liver, intestinal lymph nodes, and feces were harvested from the larger mammals; a liver specimen and the gastrointestinal tract were harvested from birds and small mammals. Cultures were performed by using radiometric culture and acid-fast isolates were identified by 16S/IS900/IS1311 PCR and mycobactin dependency characteristics. M. avium subsp. paratuberculosis was cultured from tissues and feces from 39 samples from 30 animals representing nine mammalian and three avian species. The prevalence of infected wild animals by premises ranged from 2.7 to 8.3% in Wisconsin and from 0 to 6.0% in Georgia. Shedding was documented in seven (0.9%) animals: three raccoons, two armadillos, one opossum, and one feral cat. The use of two highly polymorphic short sequence repeat loci for analysis of 29 of the 39 strains identified 10 alleles. One allelic pattern broadly shared in domestic ruminants ("7,5") appeared in approximately one-third of the wildlife M. avium subsp. paratuberculosis isolates studied. Given the few cases of shedding by free-ranging animals compared to the volume of contaminated manure produced by infected domestic ruminant livestock, contamination of the farm environment by infected wildlife was negligible. Wildlife may, however, have epidemiological significance for farms where M. avium subsp. paratuberculosis recently has been eliminated or on farms free of M. avium subsp. paratuberculosis but located in the geographic vicinity of farms with infected livestock.     

Testing for Mycobacterium avium subsp. paratuberculosis infection in asymptomatic free-ranging tule elk from an infected herd

Forty-five adult tule elk (Cervus elaphus nannodes) in good physical condition were translocated from a population located at Point Reyes National Seashore, Marin County (California, USA), to a holding pen 6 mo prior to release in an unfenced region of the park. Because infection with Mycobacterium avium subsp. paratuberculosis (Mptb) had been reported in the source population, the translocated elk underwent extensive ante-mortem testing using three Johne's disease assays: enzyme linked immunosorbent assay (ELISA); agar gel immunodiffusion assay (AGID), and fecal culture. Isolation of Mptb was made from fecal samples in six of 45 elk (13%). All AGID results were negative while ELISA results for 18 elk (40%) were considered elevated. Elevated ELISA results or Mptb isolation from fecal samples were obtained for 22 of 45 elk (49%); these elk were euthanized and necropsied. Mycobacterium avium subsp. paratuberculosis was isolated from tissue in 10 of 22 euthanized elk (45%); of these 10 cases of confirmed infection, eight had elevated ELISA results (80%) and four were fecal culture positive (40%). One of 10 cases had histopathologic lesions consistent with Mptb infection. Mycobacterium avium subsp. paratuberculosis was also isolated from tissue from one of eight fetuses sampled. The number of tule elk found to be infected was unexpected, both because of the continued overall health of the source herd and the normal clinical status of all study animals.     

Corynebacterium Pseudotuberculosis Infection in Goats V.

In 2 goat herds, one infected with Gorynebacterium pseudo-tuberculosis and one free from the infection,, goats were examined for superficial swellings on the shoulder and chest. All animals in this study had been vaccinated against paratuberculosis before the age of 4 weeks. The vaccine had been applied subcutaneously behind the shoulder. Twenty-two of 40 (55 %) and 31 of 45 (69 %) goats had such lesions in the infected and non-infected herds, respectively. The difference between the herds was not significant, P > 0.05. Swellings found behind the shoulder in 19 goat carcasses derived from 4 herds in which G. pseudotuberculosis infection occurred were examined bacteriologically. No bacteria could be isolated from such lesions in 15 animals, while G. pseudotuberculosis in pure culture was isolated from 3 carcasses, and a mixed bacterial flora from the re-maining carcass. Bacteria could not be isolated from lesions situated behind the shoulder in 7 carcasses from 3 herds free from G. pseudo-tuberculosis infection. It is concluded that most swellings on the shoulder and chest in goats were granulomas resulting from vaccination against paratuber-culosis.     

Classification of lesions and comparison of immunohistochemical and acid fast staining in diagnosis of naturally occurring paratuberculosis in goats

Lesions associated with paratuberculosis and degrees of positivity by Ziehl-Neelsen (ZN) and Avidin–Biotin Complex peroxidase (ABC) techniques in 26 adult goats grossly or clinically suspected to paratuberculosis were studied. Of these, 17 (65.4%) had microscopic lesions associated with paratuberculosis which were classified into three categories. Diffuse multibacillary lesions (30.8%) characterized by a diffuse granulomatous enteritis with epithelioid macrophages infiltration as main inflammatory cells into lamina propria that arranged mosaic-like appearance, and filled with numerous acid fast bacilli in ZN and highly positive in ABC. Diffuse lymphocytic lesions (11.5%) composed of lymphocytes as main inflammatory infiltrate, with some epithelioid macrophages or giant cells containing few if any mycobacteria. Diffuse mixed lesions (23%) characterized by a diffuse granulomatous enteritis with infiltration of mixture of large numbers of lymphocytes and epithelioid macrophages with varying degrees of positivity in ZN and ABC. In all types of lesions, other lesions such as granulomatous lymphangitis and arteritis, lymphangiectasis, thrombi composed of degenerated epithelioid macrophages were observed. Caseous necrosis, calcification and fibrosis in mesenteric lymph nodes commonly, especially in diffuse lymphocytic form, were observed. In conclusion, the present study showed three categories of lesions in which diffuse multibacillary form was the commonest type. Both ABC and ZN methods can detect (ABC with more positivity) almost all the goats with diffuse multibacillary and mixed lesions; more cases with lymphocytic forms were positive by ABC than by ZN. ABC method seems to be an efficient diagnostic adjunct to conventional ZN staining for diagnosis of paratuberculosis in goats. The importance of sampling the ileum (especially ileocecal valve), jejunum and mesenteric lymph nodes to find microscopic lesions of paratuberculosis in goats is emphasized.     

Detection of Mycobacterium avium subsp. paratuberculosis in formalin- fixed,paraffin embedded tissues of goats by IS900 polymerase chain reaction

The objective of the present study was to optimise and evaluate a procedure for detection of Mycobacterium avium subsp. paratuberculosis in archived formalin-fixed, paraffin embedded tissue sections from cases of naturally occurring paratuberculosis in goats. A pilot study assessed 3 procedures for extraction of DNA for detection by PCR. The procedure that gave the most consistent results involved removal of paraffin by treatment with xylene and ethanol, disruption of tissue pellets by beating with zirconium/silica beads, extraction of DNA using a DNeasy kit (Qiagen) with overnight proteinase K digestion and final ethanol precipitation. This procedure was used to analyse 82 paraffin embedded tissues (44 small intestine, 38 mesenteric lymph node) with various grades of histological lesions of paratuberculosis and acid-fast bacilli (AFB) loads. The overall sensitivity of the PCR was about 72% of all samples including both paucibacillary and multibacillary lesions. The sensitivity of the assay was 87.5% (42/48) in all paraffin sections having clearly and easily demonstrable AFB. Fifty percent of the tissue sections with rarely detectable AFB were positive by PCR. There was no significant difference (<0.05) between the sensitivity of the PCR analyses carried out on intestinal and mesenteric lymph node tissues. The results of this study suggest that IS900 PCR on formalin-fixed, paraffin embedded histological sections is a practical and important tool for confirming diagnosis of paratuberculosis in goats, where fresh tissues for bacterial culture or PCR are not available due to problem of maintaining a cold chain system.     

Occurrence and spatial distribution of Toggenburg Orbivirus in Switzerland

Recently, a new member of the Bluetongue virus (BTV) serogroup named Toggenburg Orbivirus (TOV) in goats from Switzerland has been described. The epidemiology and host range of TOV are currently unknown. Since TOV causes cross-reactions in laboratory tests used for BTV diagnosis, this study was carried out in order to determine the spatial and temporal spread of TOV. Therefore, serum samples from a national survey in goats, collected during winter and spring 2008 in Switzerland, were serologically examined. Additionally, cattle and sheep from holdings with seropositive goats were tested for the presence of viral RNA and antibodies against BTV and TOV. All goat samples analysed within routine diagnostics at the Institute of Virology and Immunoprophylaxis from 2008 to 2009 were also tested for the presence of TOV. Finally, goat sera collected 1998 in the Canton of Ticino (TI) were analysed.Although the TOV index cases had been identified in flocks north of the Alps, no additional TOV-positive herds were found by serological testing in this region. In contrast, south of the Alps, i.e. in the Canton of Ticino (TI), an apparent seroprevalence of 49% in goats was found at animal and 60% at herd level. In the eastern and western part of the Swiss Alps 15.2% and 10% of tested goats were serologically positive, respectively. A within-herd prevalence of up to 100% was found in some of the positive flocks. The positive flocks in TI were mainly found in three of the five districts, but seropositive animals were identified in each district. Certain selected seropositive flocks were investigated virologically. By RT-qPCR and genome sequencing, the presence of TOV could be confirmed in all investigated seropositive flocks.By testing the goats within routine diagnostics, TOV genome was detected in one goat showing BT-like clinical symptoms from the central Alps and in three healthy animals imported from Germany.Although 3.8% of the sheep from flocks with TOV-positive goats or in contact with these animals showed a positive antibody reaction, TOV-specific RNA was not found in any of the tested sheep and also not in cattle from flocks with TOV-positive goats.Serological and virological test results from archived Swiss goat samples collected in 1998 indicated the presence of TOV already at that time, prior to any Bluetongue disease outbreak in this part of Europe. The results of this study demonstrate that TOV is widespread in certain parts of Switzerland and suggests that this virus has been present in the goat population for at least a decade, albeit without causing any disease signs.     

Pathology of brucellosis in bison from Yellowstone National Park

Between February 1995 and June 1999, specimens from seven aborted bison (Bison bison) fetuses or stillborn calves and their placentas, two additional placentas, three dead neonates, one 2-wk-old calf, and 35 juvenile and adult female bison from Yellowstone National Park (USA) were submitted for bacteriologic and histopathologic examination. One adult animal with a retained placenta had recently aborted. Serum samples from the 35 juvenile and adult bison were tested for Brucella spp. antibodies. Twenty-six bison, including the cow with the retained placenta, were seropositive, one was suspect, and eight were seronegative. Brucella abortus biovar 1 was isolated from three aborted fetuses and associated placentas, an additional placenta, the 2-wk-old calf, and 11 of the seropositive female bison including the animal that had recently aborted. Brucella abortus biovar 2 was isolated from one additional seropositive adult female bison. Brucella abortus was recovered from numerous tissue sites from the aborted fetuses, placentas and 2-wk-old calf. In the juvenile and adult bison, the organism was more frequently isolated from supramammary (83%), retropharyngeal (67%), and iliac (58%) lymph nodes than from other tissues cultured. Cultures from the seronegative and suspect bison were negative for B. abortus. Lesions in the B. abortus-infected, aborted placentas and fetuses consisted of necropurulent placentitis and mild bronchointerstitial pneumonia. The infected 2-wk-old calf had bronchointerstitial pneumonia, focal splenic infarction, and purulent nephritis. The recently-aborting bison cow had purulent endometritis and necropurulent placentitis. Immunohistochemical staining of tissues from the culture-positive aborted fetuses, placentas, 2-wk-old calf, and recently-aborting cow disclosed large numbers of B. abortus in placental trophoblasts and exudate, and fetal and calf lung. A similar study with the same tissue collection and culture protocol was done using six seropositive cattle from a B. abortus-infected herd in July and August, 1997. Results of the bison and cattle studies were similar.     

Epidemiological studies on foot and mouth disease and paratuberculosis in small ruminants in Tafelah and Ma’an,Jordan

A cross-sectional study was performed to investigate some epidemiological aspects of foot and mouth disease (FMD) and paratuberculosis in small ruminant flocks located in two governorates in Southern Jordan. A total of 320 sheep and 300 goats from 38 and 24, sheep and goat flocks, respectively, were randomly sampled and assayed for presence of antibodies against FMD virus and Mycobacterium paratuberculosis using commercially available kits. A structured pre-tested questionnaire was administered to collect information on flocks’ health and management. A multivariable logistic regression model was constructed to investigate risk factors associated with seropositivity to the two studied diseases. The individual prevalence of FMD and paratuberculosis in sheep was 10.4 and 22.1%, respectively. The sheep flock level seroprevalence for FMD and paratuberculosis was 44.7 and 50%, respectively. In goats, the individual prevalence of FMD and paratuberculosis was 6.3 and 18.1%, respectively. The goat flock level seroprevalence for FMD and paratuberculosis was 33.3 and 45.8%, respectively. The logistic regression model revealed mixed farming as a common risk factor for both FMD and paratuberculosis. Grazing in communal areas and addition of new animals were identified as risk factors for paratuberculosis.     

Isolation of Mycobacterium avium subsp paratuberculosis (Map) from feral cats on a dairy farm with Map-infected cattle

Paratuberculosis is an economically important disease of dairy cattle caused by Mycobacterium avium subsp. paratuberculosis (Map). The role of nonruminant, nondomestic animals in the epidemiology of paratuberculosis in cattle is unclear. To examine nonruminant, nondomestic animals for the presence of Map, 25 feral cats, nine mice (species unknown), eight rabbits (Sylvilagus floridanus), six raccoons (Procyon lotor), and three opossums (Didelphis virginiana) were collected from a mid-western dairy with known Map-infected cattle. Mycobacterium avium subsp. paratuberculosis was isolated from the mesenteric lymph node from seven of 25 (28%) feral cats. Ileum was culture-positive for three of these seven cats, and an isolation of Map was also made from the ileum of one of nine (11%) mice. Tissue samples from other species were negative as determined by Map culture; microscopic lesions consistent with paratuberculosis were not seen in any animal. Restriction fragment polymorphism analysis of isolates from cats and dairy cattle suggest interspecies transmission. The means by which interspecies transmission occurred may be through ingestion of Map-contaminated feces or waste milk or through ingestion of Map-infected prey. Shedding of Map from infected cats was not evaluated. The epidemiologic role of Map-infected feral cats on dairy farms requires further investigation.     

Visna Virus Meningoencephalomyelitis in Goats

A progressive paresis was encountered in herds of Swedish goats. The symptoms developed during a period of weeks or months, and were initially often seen as a weakness of the hind limbs before the animals became paralytic. The development and the histopathological lesions of the disease in the GNS and the lungs were similar to those of visna in sheep. In vitro grown choroid plexus cells, prepared from affected goats, showed foci of polykaryocytes. Electron microscopy revealed the presence of particles morphologically similar to those of sheep visna virus (SVV). Goats experimentally infected with the goat visna virus (GVV) developed GNS lesions similar to those of visna in sheep and became seropositive to SVV. The results of complement fixation tests, carried out on sera from 11 goat herds, showed a coincidence between seropositiveness and the occurrence of disease in one and the same herd. Using the ELISA method, an average of 80 % of the goats in 5 herds were found to be seropositive to GVV.     

Experimental Maedi Visna Virus Infection in sheep: a morphological, immunohistochemical and PCR study after three years of infection

A morphological, immunohistochemical and polymerase chain reaction (PCR) study was performed on eight ewes experimentally infected with an Italian strain of Maedi-Visna Virus (MVV) in order to evaluate the lesions and the viral distribution after three years of infection. At the moment of euthanasia, seven sheep were seropositive for MVV, while one sheep in poor body conditions was seronegative since one year. Lungs, pulmonary lymph nodes, udder, supramammary lymph nodes, carpal joints, the CNS, spleen and bone marrow of the eight infected sheep were collected for histology, for immunohistochemical detection of the MVV core protein p28 and for PCR amplification of a 218 bp viral DNA sequence of the pol region. The most common histological findings consisted of interstitial lymphoproliferative pneumonia and lymphoproliferative mastitis of different severity, while no lesions were observed in the CNS. MVV p28 antigen was immunohistochemically labelled in lungs, udder, pulmonary lymph nodes, spleen and bone marrow but not in the CNS of all the eight infected sheep. A 218 bp sequence of MVV pol region was detected in lung of a seropositive and of the seroconverted negative sheep. The results suggest that (i) MVV causes heterogeneous lesions in homogeneously reared ewes, (ii) MVV p28 antigen is detectable not only in inflammed target organs, but also in pulmonary lymph nodes, spleen and bone marrow, and (iii) immunohistochemistry and PCR are useful methods for Maedi-Visna diagnosis in suspected cases, also when serological tests are negative.