Carrier Animals Research Articles

Detection of a major gene for litter size in Thoka Cheviot sheep using Bayesian segregation analyses

AbstractSegregation analyses were applied to data from an experimental sheep flock to investigate the presence of a major gene affecting litter size. The data set contained 14 years of litter size data, with up to five parities per ewe, from Cheviot sheep carrying the putative Thoka fecundity gene from Icelandic sheep. Segregation analyses were performed using a Markov chain Monte Carlo method implemented using Gibbs sampling. Uniform priors were initially used for estimating variance components, the gene effect and fixed effects in the data. Genotypes in the base generation were assumed known based on the use of the imported Icelandic donor semen from the founder rams. The use of alternative priors (naïve and inverse-gamma distributions) for the variance components did not significantly affect the results, demonstrating the data to be sufficiently powerful for the analyses used. Segregation analyses detected a major gene for litter size in the Thoka Cheviot flock increasing litter size by 0·70 lambs per ewe lambing for a single copy of the gene. When the analysis was repeated without fixing the genotypes in the base population, the analyses predicted a different genotype than that previously used for one of the founder rams and suggested the major gene to be segregating in the Cheviot founder animals prior to the introduction of the Thoka rams. A liability threshold analysis was also applied to the data. As identified in other studies, the threshold analysis overestimated the heritability, but the estimated major gene effect was not significantly different from other analyses. The results confirm the segregation of the Thoka gene in a Cheviot flock and highlight the statistical method as a useful tool for identifying carrier animals to be used for future matings.

Identification of foot and mouth disease virus carrier and subclinically infected animals and differentiation from vaccinated animals.

Countries that are free of foot and mouth disease (FMD) are reluctant to use vaccine in the event of an outbreak because of the difficulties this can cause in re-establishing freedom from FMD status to the satisfaction of trading partners. The problem does not lie in distinguishing between vaccinated and recovered animals as vaccinated animals can be tagged or otherwise marked to show that they have been vaccinated; the difficulty is in identifying vaccinated animals that have had contact with live virus and become carriers. The traditional probang test is not sufficiently sensitive and is labour- and laboratory-intensive, but alternative serological tests such as those for antibodies to non-structural proteins (NSPs), or specific immunoglobulin A (IgA) are also not 100% sensitive. However, these newer tests do provide increased security by reducing the likelihood of trading carrier animals and can be used to help define the limits of an outbreak; the use of vaccine to help control an outbreak of FMD in a previously free country still has significant consequences on trade in FMD susceptible animals and their products.

Evaluation of serology, bacteriological isolation and polymerase chain reaction for the detection of pigs carrying Actinobacillus pleuropneumoniae in the upper respiratory tract after experimental infection

Pigs, asymptomatically infected with Actinobacillus pleuropneumoniae in their upper respiratory tract, can transmit the infection. Detection of such animals is indispensable to prevent the intake of the disease in a herd. This study was conducted to evaluate bacteriology, polymerase chain reaction (PCR) and serology for the detection of subclinically infected pigs. Pigs were inoculated onto the tonsils with an A. pleuropneumoniae serotype 9 strain ( n=12, group 1) or phosphate buffered saline solution (PBSS) ( n=5, group 2). To prevent infection of the lungs, pigs of group 1 were treated three times with sodium ceftiofur as an aerosol. A third group ( n=5) was inoculated intranasally with the same strain. All animals were euthanized 30 days post-inoculation (dpi). In pigs of group 1, clinical signs were not observed. A small lung lesion was found in only one pig and A. pleuropneumoniae was isolated from this lesion. The bacterium was not isolated from the lungs of animals that did not develop lung lesions. A. pleuropneumoniae was demonstrated in tonsils of 9/12 animals using bacteriological isolation, whereas it was demonstrated in mixed bacterial cultures from tonsils of all 12 animals by PCR. In non-infected animals (group 2), clinical signs were not observed and A. pleuropneumoniae was not demonstrated in any sample. All intranasally infected animals (group 3) developed disease signs and lung lesions. High antibody titers against ApxI, ApxII and heat-stable antigens were detected in animals that developed lung lesions. Antibody titers against these antigens were low or absent in all other pigs. It was concluded that pigs carrying A. pleuropneumoniae in the upper respiratory tract generally do not show measurable antibodies in serum. Therefore, sensitive methods for the detection of the etiological agent such as PCR are required to identify carrier animals, while serological methods are not suitable.

A new model of hepatitis B virus reinfection: liver transplantation in the woodchuck1.

Reinfection of liver grafts with hepatitis B virus (HBV) is a pertinent problem in clinical liver transplantation, requiring the development of new treatment strategies. However, no animal model is currently available to study the course and mechanism of hepatitis B reinfection. This was the reason to establish the technique of liver transplantation in the woodchuck, which is a widely used animal model for HBV infection. For the reinfection study, woodchuck hepatitis virus (WHV)-negative animals were selected as donors, whereas chronic carriers served as recipients (n=3). Immunosuppression consisted of cyclosporine in a daily dose of 5 mg/kg. Blood and liver samples were obtained before and 8 hr, 3 weeks, and 10 weeks after transplantation. Virological markers included serological testing for WHV DNA, WHV surface antigen (WHsAg), core antigen (WHcAg), and their antibodies (anti-WHs and anti-WHc). WHV DNA replication intermediates and viral RNA were detected by Southern blot hybridization and Northern blot, respectively. Viral proteins in the liver were visualized by immunohistochemistry for WHsAg and WHcAg. Early after transplantation membranous but no intracytoplasmic staining for WHsAg was detected in the liver graft, which was negative for WHcAg as well as WHV-DNA and RNA. Nearly all hepatocytes in the liver grafts of animals killed at 3 weeks and 10 weeks posttransplant showed strong membranous (WHsAg) and intracytoplasmic (WHsAg and WHcAg) staining, which was higher in frequency and intensity than in carriers before transplantation. The apparently reduced level of WHV replication intermediates and viral RNA in the reinfected liver grafts compared with the carrier animals was caused by the severe morphological changes leading to a replacement of hepatocytes by extended portal infiltrates. The woodchuck proved to be a suitable model to study WHV reinfection after liver transplantation, because the operative procedure was well tolerated. The first sign of viral presence in the graft was WHsAg detected exclusively in the sinusoids. Reinfection was proven by heavy intracytoplasmic staining for WHsAg and WHcAg in the majority of hepatocytes and detection of viral DNA and RNA in the graft.

An interferon-gamma assay for diagnosis of Corynebacterium pseudotuberculosis infection in adult sheep from a research flock

The optimal method of control of caseous lymphadenitis of sheep caused by Corynebacterium pseudotuberculosis is eradication of infection by identification and removal of infected carrier animals. Current serological approaches to identification of infected sheep are generally hampered by low sensitivity and specificity of available tests. The objective of this study was to develop a whole blood assay for detection of C. pseudotuberculosis-infected sheep, based on detection of IFN-γ response to whole cell C. pseudotuberculosis antigens, and to determine the reliability of the assay. A commercially available bovine interferon-γ assay enzyme-linked immunosorbent assay was used and the test optimised using experimentally infected sheep. The assay was also tested on known CLA-negative sheep. Setting a IFN-γ optical density cut-off at 0.100 as positive under the conditions used, the test detected C. pseudotuberculosis experimentally infected sheep over a 450-day period with a reliability of 95.7%. It identified known non-infected sheep with a reliability of 95.5%. Repeated vaccination of three uninfected sheep with a commercially available bacterin-toxoid vaccine did not interfere with the assay. The IFN-γ response of sheep whole blood to C. pseudotuberculosis antigens offers promise for use in a test-and-removal approach to eradication of CLA in sheep.

Characterization of the carrier state in porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome (PRRS) virus infection results in clinically normal, but persistently infected animals. An understanding of the carrier state is necessary for prevention, control and/or elimination of PRRS virus. The objective of this experiment was to estimate the proportion of PRRS virus carriers over time and determine which combination of sample and diagnostic assay could most effectively identify persistently infected animals. Sixty 3-week-old pigs were inoculated with PRRS virus ATCC VR-2332 and followed for up to 105 days post-inoculation (PI). Sixty age-matched animals served as uninoculated controls. Samples (serum, peripheral blood leukocytes, oropharyngeal scrapings, tonsil, bronchoalveolar lavage, lung tissue and tracheobronchial lymph nodes) were collected periodically and tested for evidence of PRRS virus infection by virus isolation (VI), swine bioassay and reverse transcriptase-nested polymerase chain reaction (RT-nPCR). The PRRS virus-specific antibody response was monitored with a commercial enzyme-linked immunosorbent assay (ELISA). Overall, PRRS virus was found in 51 of the 59 (84%) necropsied animals by VI or swine bioassay between 63 and 105 days PI, including 10 of the 11 (91%) of animals at day 105 PI. RT-nPCR on oropharyngeal scrapings was the most effective combination of assay and sample for detecting carriers. There was no significant difference in the antibody response of carrier vs. non-carrier animals. Infectious PRRS virus is present in most pigs the first 105 days following infection. Antibody response, as measured by a commercial ELISA, cannot be used to determine carrier status. RT-nPCR is a useful tool for detection of carriers, but diagnostic sample selection is critical if false negative results are to be avoided.

Detection of Actinobacillus pleuropneumoniae in cultures from nasal and tonsillar swabs of pigs by a PCR assay based on the nucleotide sequence of a dsbE-like gene

A PCR assay for the detection of Actinobacillus pleuropneumoniae was developed based on the amplification of a dsbE-like gene. All of 157 field isolates of A. pleuropneumoniae reacted in the PCR by the amplification of a 342 bp product. No reaction was observed with related bacterial species or other bacterial species isolated from pigs, except for A. lignieresii. The lower detection limit of the PCR was 10 2 CFU per PCR test tube and was not affected by the addition of 10 6 CFU Escherichia coli. The PCR was evaluated on mixed bacterial cultures from nasal and tonsillar swabs as well as suspensions of nasal conchae and tonsils obtained from specific pathogen-free (SPF) pigs, experimentally infected pigs, and pigs from farrow-to-finish herds. The results of the new PCR were compared with a PCR based on the detection of the omlA gene coding for an outer membrane protein, with a commercially available PCR (Adiavet™APP, Adiagène, Saint-Brieuc, France), and with conventional culturing. No positive reactions were observed with any of the PCR methods in samples of SPF animals. In samples of the other animals, no or low significant differences between nasal swabs and suspensions as well as tonsillar swabs and suspensions were observed in any method. In general, more positive results were obtained from tonsillar samples in comparison to nasal samples. Interassay sensitivity and specificity values were assessed for each test by pair wise comparisons between assays. The agreement between tests was evaluated by calculating Cohen’s κ coefficient. From these analyses the three PCR assays showed a good agreement. The dsbE-based PCR proved to be highly sensitive (95 and 93%) and specific (82 and 74%) in comparison to the omlA-based PCR and the commercially available PCR, respectively. It was concluded that the dsbE-like gene-based PCR is a reliable diagnostic assay for demonstration of A. pleuropneumoniae. Furthermore, it was demonstrated that tonsillar swabs can be used for the detection of the pathogen in healthy carrier animals.

Study of Theileria annulata population structure during bovine infection and following transmission to ticks.

Tams1 is the polymorphic immunodominant merozoite-piroplasm surface protein of Theileria annulata. Evidence for selection of divergent forms of Tams1 has been obtained recently. This study was performed to address whether selection takes place during persistent infection of the bovine host or during passage through the Hyalomma tick vector. Four calves were infected with a T. annulata isolate representing multiple parasite genotypes. The development of the parasite population was analysed by denaturing gradient gel electrophoresis (DGGE) using the Tams1 gene as a marker. In addition, the parasitaemia was measured by a semi-quantitative reverse line blot hybridization assay in order to correlate Tams1 variation to changes in parasitaemia. It was found that both parasitaemia and parasite population displayed limited variation during persistent infection. Ticks were allowed to acquire T. annulata during 2 periods of the bovine infection. Tams1 alleles detected in ticks fed during acute infection were identical to the population in the bovine host. However, ticks fed during the carrier status acquired parasites showing a single Tams1 isotype that represented, in several cases, a minor population in the bovine host at the time of infestation. Although only a limited number of ticks were studied, these preliminary data suggest that specific parasite genotypes may be selected during tick transmission from a carrier animal.

Mycoplasma infection in cattle

Mycoplasma spp. have been associated with many disease entities in cattle including mastitis, keratoconjunctivitis, otitis media, decubital abscesses, meningitis, reproductive problems and the pneumonia-arthritis symdrome. Since there are no pathognomonic signs to aid in making a clinical diagnosis, diagnosis of Mycoplasma infections presents a challenge to practitioners. Culture with identification of the organism and other ancillary tests are required for definitive diagnosis. Failure to respond to treatment is common. Isolation/segregation and culling infected or carrier animals are the best recommendations for control and prevention of Mycoplasma infections in a herd. In a companion paper, the pneumonia-arthritis syndrome was discussed. This paper reviews other disease entities caused by Mycoplasma spp.

Detection of new hosts for white spot syndrome virus of shrimp using nested polymerase chain reaction

The presence of white spot syndrome virus (WSSV) of shrimp in various marine crustaceans was studied by using polymerase chain reaction (PCR). The incidence of the virus in non-cultured crustaceans from shrimp farms was also studied. The results indicate that wild-caught asymptomatic marine shrimp such as Metapenaeus dobsoni, Parapenaeopsis stylifera, Solenocera indica and Squilla mantis carry WSSV. This virus could be detected in apparently healthy marine crabs Charybdis annulata, C. cruciata, Macrophthalmus sulcatus, Gelasimus marionis nitidus and Metopograpsus messor. The virus could also be detected in asymptomatic Macrobrachium rosenbergii cultured inland far away from coast. Detection of carrier animals required two-step nested PCR.

The control of VTEC in the animal reservoir

A great diversity of VTECs exist but only in the case of Escherichia coli O157:H7, a common human foodborne pathogen, has sufficient research been done to allow generalizations about the ecology. The key features are as follows: lack of host specificity such that indistinguishable isolates can be found in a variety of species; near-ubiquitous distribution in cattle (and perhaps other ruminant) farms; transient residence in the gastrointestinal flora of individual animals that is not associated with clinical disease; temporal clustering at the population level such that most fecal shedding is confined to sharp bursts in a high percentage of animals separated by much longer periods of very low prevalence; a higher prevalence in young animals in comparison to older ones; a higher prevalence in animals with floral disturbance such as that caused by transit, feed changes or antimicrobial dosing; and a markedly higher prevalence during warm months. Molecular epidemiological studies of E. coli O157:H7 have demonstrated that subtypes of the organism can persist on cattle farms for years, thus supporting a conclusion that cattle farms represent a reservoir. Yet on such farms, common subtypes are often found in environmental niches and in other species of animals; thus, it is not completely clear that cattle themselves are the reservoir. New subtypes are periodically observed on particular farms, and indistinguishable subtypes can be found on farms that are separated by hundreds of kilometers even in the absence of any obvious animal movements between them. The number of subtypes found on a farm does not appear to be qualitatively correlated with cattle movements (e.g., purchases) into the farm. Commercial feeds are sometimes contaminated with E. coli O157:H7, and it seems likely that feeds represent an important route of dissemination for this agent and other VTEC. Mixed feeds collected from feeding troughs are commonly positive for E. coli O157:H7, as are cattle watering troughs, and feed and water likely represent the most common means of infection. Environmental replication in feeds and in sediments of watering troughs occurs and may account for the higher level of fecal shedding in the warm months. Since E. coli O157:H7 has been found to persist and remain infective for at least 6 months in water trough sediments, this may be an important environmental niche where the organism survives during periods when it cannot be detected in cattle, especially during cold months. Traditional means of controlling infectious agents, such as eradication or test and removal of carrier animals, do not appear to be feasible for VTECs. Nevertheless, certain farm management practices—especially those related to maintenance and multiplication of the agent in feed and water—may provide practical means to substantially reduce the prevalence of these agents in cattle on farms and in those arriving at slaughter plants.

Antigenic variation of Anaplasma marginale: major surface protein 2 diversity during cyclic transmission between ticks and cattle.

The rickettsial pathogen Anaplasma marginale expresses a variable immunodominant outer membrane protein, major surface protein 2 (MSP2), involved in antigenic variation and long-term persistence of the organism in carrier animals. MSP2 contains a central hypervariable region of about 100 amino acids that encodes immunogenic B-cell epitopes that induce variant-specific antibodies during infection. Previously, we have shown that MSP2 is encoded on a polycistronic mRNA transcript in erythrocyte stages of A. marginale and defined the structure of the genomic expression site for this transcript. In this study, we show that the same expression site is utilized in stages of A. marginale infecting tick salivary glands. We also analyzed the variability of this genomic expression site in Oklahoma strain A. marginale transmitted from in vitro cultures to cattle and between cattle and ticks. The structure of the expression site and flanking regions was conserved except for sequence that encoded the MSP2 hypervariable region. At least three different MSP2 variants were encoded in each A. marginale population. The major sequence variants did not change on passage of A. marginale between culture, acute erythrocyte stage infections, and tick salivary glands but did change during persistent infections of cattle. The variant types found in tick salivary glands most closely resembled those present in bovine blood at the time of acquisition of infection, whether infection was acquired from an acute or from a persistent rickettsemia. These variations in structure of an expression site for a major, immunoprotective outer membrane protein have important implications for vaccine development and for obtaining an improved understanding of the mechanisms of persistence of ehrlichial infections in humans, domestic animals, and reservoir hosts.

Isolation of Actinobacillus pleuropneumoniae serotype 2 by immunomagnetic separation

In Denmark porcine pleuropneumonia is most frequently caused by Actinobacillus pleuropneumoniae serotype 2 (60%). Isolation of A. pleuropneumoniae from nasal cavities or tonsils from carrier animals is complicated due to the mixed bacterial flora present. An immunomagnetic separation technique (IMS) using immunomagnetic beads (Dynabeads ®) was developed for isolation of A. pleuropneumoniae serotype 2 from pure cultures and from heterogeneous suspensions. Different coating and washing procedures were evaluated in pure and mixed cultures using polyclonal (PAb) and monoclonal antibodies. The highest reisolation yield was achieved when the beads were coated with 1.5 μg PAb IgG/10 7 beads. After washing the beads for four times 9–24% of the bacteria could be reisolated depending on the amount of IgG attached to the beads and the number of beads used. The recovery was increased to 19–61% when only two washing steps were performed. The IMS was further evaluated using dilutions of A. pleuropneumoniae with added Pasteurella multocida (10 9 CFU/ml). After two washing steps 15% of the A. pleuropneumoniae cells and no P. multocida was reisolated. A detection limit of 10 CFU/ml was found in this heterogeneous suspension. No significant difference was observed when comparing the recovery of A. pleuropneumoniae from pure culture, from mixed cultures and from artificially inoculated tonsils. From 12 pigs inoculated with an aerosol of A. pleuropneumoniae serotype 2 the bacterium could not be detected from the nasal cavity or tonsils by cultivation or PCR 6 weeks later. By using IMS A. pleuropneumoniae serotype 2 could be reisolated from the tonsils of three pigs. The IMS method represents a valuable tool for isolation of A. pleuropneumoniae from tissue samples.

Detection of feline coronavirus infection in captive cheetahs (Acinonyx jubatus) by polymerase chain reaction.

Feline coronavirus genetic elements were detected by polymerase chain reaction from blood, fecal samples, and effusive fluid collected from 33 cheetahs in the U.S.A. Feline coronavirus-specific serum antibodies were also measured by indirect immunofluorescence. Ten cheetahs were positive for viral shedding by polymerase chain reaction, whereas 13 were seropositive by immunofluorescence. Results of serology did not consistently correlate with shedding of virus, and the capture antigen used for detection of feline coronavirus-specific antibodies had a significant impact on results. Testing of samples from one population over a 1-yr period indicated chronic infection in some animals. These relatively healthy carrier animals were a source of virus for contact animals. Screening programs in cheetah populations for feline coronavirus infection may be most reliable if a combination of serologic analysis and viral detection by polymerase chain reaction is used.

A vision of pig production in the UK

PreambleWhile preparing to write a vision of pig production in the UK, the fragility of crystal ball gazing became apparent, when in February 2001, the nightmare scenario of Foot and Mouth disease broke. The problem appears to have started on a pig farm using swill feed in Northumberland and within weeks, primarily associated with the farmer's failure to report a problem and legal but uncontrolled sheep movement, Foot and Mouth Disease spread throughout the West of England, Wales and the South West of Scotland as well as closing a major slaughterhouse for adult pigs. The disease then spread into continental Europe, causing instant havoc to export markets for the UK and then over the whole of the European Union. Had the problem prevented Denmark from exporting globally for any period, this would have resulted in severe price depression in pig production in Europe. And all this in the year following East Anglia's savaging with Classical Swine Fever.The Foot and Mouth epidemic in the UK is likely to have a long term impact on the country's export capabilities; already there are threats of five year bans from countries like the United States of America. Much will depend on whether natural wildlife, such as deer, have become infected and how effective we are at finding carrier animals.

Environmental and Food Safety Aspects of Escherichia coli O157:H7 Infections in Cattle

The presence of E. coli O157:H7 in cattle illustrates the complex, interrelated nature of the environment, livestock production practices, food safety, and the science of microbiology, particularly microbial ecology. Enterohemorrhagic E. coli, including E. coli O157:H7, can cause severe human diseases that can be debilitating and life threatening. Cattle are currently considered to be the definitive source for E. coli O157:H7 in the food supply, but this view may be simplistic and incomplete. E. coli O157:H7, appears widespread among U.S. cattle herds, while individual animal prevalence is low and transient. Most individual animals appear to be a transient reservoir for E. coli O157:H7 although the issue of carrier animals still remains unresolved. Epidemiological studies of the cattle production system have not clearly identified risk factors or management practices that affect E. coli O157:H7 prevalence in cattle feces. The problem of E. coli O157:H7 increases during the summer and fall months, but the environmental factors that contribute to this increase are poorly understood. Possible environmental factors that may influence E. coli O157:H7 shedding in cattle include livestock feed and waste handling practices as well as insects and microbial interactions in soil and water. Studies of E. coli O157:H7 ecology in cattle and the environment have been limited, but they suggest that a consideration of other independent, environmental sources of this microbe seems appropriate. The natural ecology of cholera may serve as a useful environmental model for pursuing additional environmental research on the occurrence and transmission of E. coli O157:H7 in nature.

Babesiosis (Babesia bovis) stability in unstable environments.

Enzootic stability (herd immunity) in bovine babesiosis occurs when the rate of transmission (inoculation rate) of Babesia spp by the tick vector is sufficient to immunize a majority of susceptible calves before the loss of calfhood resistance. The effect of three tick (Boophilus microplus) control strategies (none, threshold, and strategic) on enzootic stability and the likelihood of babesiosis (Babesia bovis) outbreaks was studied using a spreadsheet age-class computer simulation model. The model was driven by weekly bovine tick counts from Brazil and Uruguay. The Eldorado do Sul, RS, Brazil bovine population (30 degrees 05' South latitude) was found to be in a naturally occurring state of enzootic stability, corresponding to an inoculation rate exceeding 0.005 throughout the year. Threshold dipping strategies should not increase the risk of babesiosis in cattle so managed. Strategic dipping resulted in an extended period of enzootic instability lasting 30 weeks, which requires protection of the herd through immunization. Because of the more prolonged low winter temperature conditions, the Tacuarembó, Uruguay bovine population (31 degrees 40' South latitude) was found to be in a naturally occurring state of enzootic instability, characterized by a 28 week period in which the inoculation rate was below 0.005. Strategic dipping should lead to eradication of the babesial parasite from tick and bovine populations, but would not result in eradication of the tick vector. This could lead to subsequent outbreaks if Babesia carrier animals were to be introduced into the herd. In both populations, strategic tick control could be accompanied by concurrent babesiosis vaccination.

Production of bovine herpesvirus type 1-seronegative latent carriers by administration of a live-attenuated vaccine in passively immunized calves.

The consequences of the vaccination of neonatal calves with the widely used live-attenuated temperature-sensitive (ts) bovine herpesvirus type 1 (BHV-1) were investigated. The ts strain established acute and latent infections in all vaccinated calves either with or without passive immunity. Four of seven calves vaccinated under passive immunity became clearly BHV-1 seronegative by different serological tests, as did uninfected control calves after the disappearance of maternal antibodies, and they remained so for long periods. A cell-mediated immune response was detected by a BHV-1 gamma interferon assay, but this test failed to detect the seronegative latent carriers (SNLCs). While they are not detected, SNLCs represent a threat for BHV-1-free herds or countries. This study demonstrates that SNLCs can be easily obtained by inoculation with a live-attenuated BHV-1 under passive immunity and that latent carrier animals without any antibody do exist. Consequently, this situation could represent a good model to experimentally produce SNLCs.

Disease caused by Mycoplasma mycoides subspecies mycoides LC in Hungarian goat herds.

The occurrence of a goat disease caused by Mycoplasma mycoides subsp. mycoides LC in Hungary is reported. The disease occurred in two goat herds in the spring of 1999. In one herd 25% of the 4-12 weeks old kids (10 animals) while in the other herd 33% of the 6-12 weeks old kids (20 animals) became affected. The goat kids developed polyarthritis. The most severe lesions developed in the carpal joints. All animals died after 3-8 days of disease. Four dead kids were necropsied. All of them had serofibrinous and purulent polyarthritis, and in two animals bronchopneumonia, fibrinous pleuritis and meningitis were also found. In the articular exudates the presence of mycoplasmas was detected by PCR using a general mycoplasma primer. Mycoplasmas were cultured from the joints of all animals, from the abdominal parenchymal organs of two kids and from the lungs of one animal. The cultured mycoplasmas grew in strikingly large colonies, proved to be glucose positive, arginine negative and phosphatase positive, and liquefied the coagulated serum. They survived incubation at 45 degrees C for more than 24 h. Based upon their biochemical properties, the results of the immunofluorescence (IF) and growth inhibition tests and the sequence analysis of the PCR product, the cultured strains were identified as M. mycoides subsp. mycoides LC. Animals purchased in the previous autumn had been introduced to both farms. The disease may have been introduced with asymptomatic carrier animals, as earlier no similar disease had been observed at either farm.

Assessment of the long-term shedding pattern of Salmonella serovar choleraesuis following experimental infection of neonatal piglets.

In the United States, swine salmonellosis is most often attributed to infections by Salmonella serovar choleraesuis. As a host-adapted pathogen rarely found in nonswine sources, S. choleraesuis is thought to be spread primarily via horizontal transmission, with carrier animals playing an important role. Little has been reported regarding infection of neonatal piglets, particularly regarding their potential to become carriers. Evidence reported herein demonstrates that piglets experimentally infected by S. choleraesuis at 2 days of age were capable of shedding the pathogen for up to 85 days postinfection, at which time the study was concluded. This study also presents findings supporting the use of GN-Hajna as a preenrichment medium for the isolation of S. choleraesuis.