Natural Resolution of Air Sac Lesions Caused by Mycoplasma meleagridis in Turkeys

Lesions caused by Mycoplasma meleagridis were followed in one hatch of turkeys from one day to 20½ weeks of age. Air sac lesion incidence increased from 20% at one day to 44% at six weeks of age with a slow decline to 10% at 10 weeks of age. Lesions were detectable on careful examination at 10-20% level to 20 weeks of age on laboratory examination, but at 20½ weeks only 0.07% lesions were found in 1000 turkeys from the same hatch.

Air sac lesion severity, based on an arbitrary 0.5,1,2,3,+scale, increased in intensity and spread of air sac involvement from a mean of 1.5 at day old to 2.5 at five weeks of age. This declined to 1.0 at 10 weeks of age and lesions became progressively more faint until careful examination was necessary to detect them in birds 15 weeks and older. The latter would not be considered as a cause of total condemnation.

The percentage of Mycoplasma isolations from the respiratory tissues were much higher in birds exhibiting air sac lesions than those in which no typical air sac lesions were visible, as follows. air sacs 51.6 vs. 2.9, lungs 43.3 vs. 4.0, trachea 47.2 vs. 4.6, sinus 38.5 vs. 19.0.

     

Mycoplasma hyopneumoniae infection in pigs: Duration of the disease and evaluation of four diagnostic assays

200 SPF pigs were infected by aerosol with Mycoplasma hyopneumoniae and the development of clinical signs, serological and pathological reactions were studied. Mean time to onset of coughing was 13 days. A mean delay of 9 days was observed from onset of coughing until seroconversion against M. hyopneumoniae as measured by ELISA. At an individual level, the sensitivity for this ELISA was estimated to 98–100% and the specificity to 93–100%. Pasteurella multocida was isolated from the majority of the lungs 4 weeks post inoculation with M. hyopneumoniae and the lung lesions in pigs were significantly larger when P. multocida was present as compared to pigs with M. hyopneumoniae alone. An evaluation of cultivation, immunofluorescence, ELISA and polymerase chain reaction for demonstration of M. hyopneumoniae in lungs showed that all four methods have a high sensitivity in the acute stages of pneumonia. In the later stages the sensitivity of cultivation was superior to the other methods. No differences in specificity were observed between the methods. The antigen-ELISA OD values and the immunofluorescence scores revealed a strong positive correlation. Nasal swabs were additionally used for demonstration of M. hyopneumoniae and the polymerase chain reaction was found superior to the other methods.     

Larval Distribution and Histopathology of Experimental Strongyloides ransomi Infection in Young Swine

Necropsy at various intervals of three week old pigs following experimental infection with larvae of Strongyloides ransomi showed distribution of the larvae through the body during the first 24 hours. Quiescent larvae at the 24 hour necropsy, as indicated by higher recovery before and after this period may be an indication of physiological changes preceding a moult. Whether or not a moult occurs in the lung prior to migration of the larvae to the intestine has not been determined. At the 72 hour necropsy, larvae were largely confined to the lung and juvenile worms were beginning to appear in the small intestine. Migration to the small intestine was completed by the 96 hour necropsy. Lesions were observed in the skin and lungs up to the 96 hour necropsy, and lymphocytic accumulations were observed in the skin and lungs to this point and lymphocytic accumulations were observed in the liver to the 72 hour necropsy. At 28 days post-application lung lesions were still evident and the duodenum and jejunum were heavily parasitized.

Egg passage began on the sixth day post-application and peaked on the 12th day.

     

Adaptation of a latex agglutination tube test for diagnosis of Mycoplasma hyopneumoniae swine pneumonia

A tube latex agglutination test (LAT) for diagnosis of Mycoplasma hyopneumoniae swine pneumonia was developed. In pigs inoculated with M. hyopneumoniae, LAT antibodies were generally detected 2–3 weeks post-inoculation, which was 1 week or more before complement-fixing antibodies were first detected in the corresponding pigs. Correlation of LAT results and gross and microscopic lung lesions of corresponding pigs revealed that LAT titers persisted after the pneumonic lesions had resolved.Latex agglutination titers in pigs exposed by contact with M. hyopneumoniae inoculated pigs were demonstrated 4–12 weeks post-contact.Latex agglutination antibodies were detected up to 48 weeks post-inoculation in pigs inoculated with M. hyopneumoniae and this was similar to the duration of detectable indirect hemagglutination titers. Complement-fixation titers, however, were demonstrated no longer than 28 weeks post-inoculation in corresponding pigs.Evaluation of repeatability of LAT results revealed some variation of LAT titers of sera titered on four different occasions.Sera from pigs inoculated with other swine mycoplasmas, including M. hyosynoviae and M. hyorhinis, did not react in the M. hyopneumoniae LAT. In addition, no detectable titers were demonstrated in the M. hyopneumoniae LAT using sera from pigs infected with Metastrongylus spp., Ascaris suum, or in sera from pigs vaccinated with any of four commonly used swine vaccines.     

An Abattoir Survey of the Incidence of Pneumonia in Saskatchewan Swine and an Investigation of the Microbiology of Affected Lungs

The lungs of 15 409 pigs, mostly from Saskatchewan, slaughtered at an abattoir were examined over a one year period. The incidence of lesions was 36.7% for “enzootic” pneumonia and 2.1% for pleurisy unassociated with pneumonia. Seasonal variations were recorded and compared with the results of similar surveys carried out in Australia, Belgium and England. Mycoplasmological examination of lungs from 347 animals was consistently negative for Mycoplasma hyopneumoniae. Pasteurella multocida was the commonest bacterial isolate, a result which agrees with those of other workers.     

Enzootic pneumonia in feeder pigs: Association with transmissible gastroenteritis virus infection

Infection with transmissible gastroenteritis virus (TGEV) was present in some pigs on arrival at a feeder pig farm and was well established three weeks later. TGE infection preceded Mycoplasma hyopneumoniae infection, which was not detected until three weeks after arrival. Severe lesions of enzootic pneumonia were observed at the end of the fattening period.     

Swine Enzootic Pneumonia: Age Susceptibility and Treatment Schemata

Pigs were found to be susceptible to Mycoplasma hyopneumoniae-induced swine enzootic pneumonia (SEP) when four hours old. Chlortetracycline was incapable of preventing transmission of SEP from infected pigs on the drug to susceptible, untreated pigs. When continuous medication was started at one or two weeks postinoculation, chlortetracycline partially or completely inhibited formation of SEP lesions but did not clear M. hyopneumoniae from inoculated pigs. Chlortetracycline administered orally was capable of completely suppressing the formation of SEP lesions in inoculated pigs if given prophylactically and if milk was withheld for several hours after each treatment; lesion suppression was incomplete if milk was given ad libitum. In either case treated animals remained infected with M. hyopneumoniae.     

The serological response of pigs experimentally infected with a species of Taenia from Taiwan

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibody in pigs infected with a possibly new species of Taenia isolated in Taiwan is described. The test antigen ThFAS was fractionated from the cyst fluod of a heterologous cestode Taenia hydatigena. In lightly infected pigs ( 4 recovered cysts at necropsy 17 weeks post-inoculation), antibody was detected as early as 3 weeks post-inoculation. In more heavily infected pigs (6–72 recovered cysts at necropsy 32 weeks post-inoculation), antibody was still detectable at the time of necropsy. Cysterci were found only in the livers of the infected pigs. This ELISA should be highly useful for detecting infection of pigs with this larval cestode in regions where the presence of Taenia solium is unlikely.     

Experimental reproduction of porcine respiratory disease complex in pigs inoculated porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae and followed by inoculation with porcine circovirus type 2

The aim of this study was to reproduce severe pneumonic lesions, similar to those during naturally-occurring porcine respiratory disease complex, in pigs dually inoculated with porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae at 6 weeks of age, followed by inoculation with porcine circovirus type 2 at two weeks after. Time and sequence of infection with three pathogens mirror Asian field conditions. Microscopically, interstitial pneumonia and peribronchiolar lymphoid hyperplasia are considered the most characteristic lung lesions in infected pigs. The results of the present study demonstrate that inoculation of pigs with these three pathogens can lead to severe interstitial pneumonia with peribronchial or peribronchiolar lymphoid hyperplasia and fibrosis.     

Porcine respiratory disease complex after the introduction of H1N1/2009 influenza virus in Brazil

From 2009 to 2015, 74 lungs from suckling (6.8%), nursing (70.3%), fattening (20.3%) pigs and pregnant sows (2.7%) with respiratory signs from pig farms in Southern Brazil were submitted to a diagnostic laboratory for necropsy and/or histologic examination and screening for respiratory agents by RT‐qPCR, immunohistochemistry (IHC), virus isolation (VI) and subtyping for influenza A virus (IAV), IHC and nested PCR for Mycoplasma hyopneumoniae (Mhyo), PCR for porcine circovirus 2 (PCV2), RT‐qPCR for porcine reproductive and respiratory syndrome virus (PRRSV) and bacterial culture. All lung samples were positive for IAV using RT‐qPCR. Seventy‐two lungs had histologic lesions associated with acute to subacute IAV infection characterized by necrotizing bronchiolitis/bronchitis or bronchointerstitial pneumonia with lymphocytic peribronchiolitis and bronchiolar/bronchial hyperplasia, respectively. Forty‐nine lungs (66.2%) were positive by IHC for IAV nucleoprotein. The H1N1/2009 was the most common subtype and the only IAV detected in 58.1% of lungs, followed by H1N2 (9.5%) and H3N2 (6.8%). Coinfection of IAV and Mhyo was seen in 23 (31%) cases. Although 14.9% of the lungs were positive for PCV2 using PCR, no suggestive lesions of PCV2 disease were observed. Porcine reproductive and respiratory syndrome virus (PRRSV) was not detected, consistent with the PRRS‐free status of Brazil. Secondary bacterial infections (8/38) were associated with suppurative bronchopneumonia and/or pleuritis. Primary IAV infection with Mhyo coinfection was the most common agents found in porcine respiratory disease complex (PRDC) in pigs in Southern Brazil.     

Naturally Occurring Histoplasmosis in Guinea Pigs

Histoplasmosis naturally occurring in laboratory guinea pigs is described in its clinical, necropsy, histological and mycological aspects.

The animals if adult show a chronic disease with progressive emaciation and lameness of the hind legs. The young below three months of age died in 2 to 4 weeks presenting ruffled fur, great dorsal curvature and sometimes closed eyelids and catarrhal conjunctivitis.

At necropsy the principal lesions were ulcerative gastritis, hemorrhagic and catarrhal enteritis, enlarged spleen and mesenteric lymph nodes. Sometimes the liver, lungs, mediastinal lymph nodes and other organs showed lesions.

Histological and mycological demonstration of the fungus completed the diagnosis and the surviving animals were burned and sanitation measures instituted.

Histological evidence of histoplasmosis in a cow's lung from the area from which the grass was obtained for the feeding of the guinea pigs suggests an epidemiological link. Efforts will be made to isolate and demonstrate H. capsulatum in wild animals on the same area.

     

Serological response to Actinobacillus pleuropneumoniae serovar 7 infection in a commercial pig herd

Serological responses to Actinobacillus pleuropneumoniae serovar 7 infection were monitored by enzyme-linked immunosorbent assay in a cohort of 66 pigs between weaning and market. Antibody concentrations were high (63/65 seropositive) at 4 weeks of age but declined to low levels from 8 to 12 weeks. Mean antibody concentrations rose significantly (p less than 0.001) between 12 and 23 weeks. Between 8 and 23 weeks of age, 33 (51.5%) of 64 surviving pigs seroconverted to A pleuropneumoniae serovar 7. Peak antibody concentrations in the seroconverting pigs usually (28/33) occurred at 23 weeks. Seroconversion to A pleuropneumoniae during the grower/finisher phase was not significantly associated (p greater than 0.05) with passive antibody concentrations at 4 weeks of age, lack of vaccination against Mycoplasma hyopneumoniae, or weaning weight. Pleuropneumonic lesions were evident at slaughter in 4 (6.3%) of 64 pigs. A pleuropneumoniae serovar 7 was isolated from 2 of 4 lungs with pleuropneumonia and from another lung with lesions considered typical of enzootic pneumonia.     

A multiplex PCR to identify porcine mycoplasmas present in broth cultures

Mycoplasma hyopneumoniae, Mycoplasma hyorhinis and Mycoplasma flocculare can be present in the lungs of pigs at the same time. These three mycoplasma species all require similar growth conditions and can be recovered from clinical samples using the same media. We have developed a multiplex PCR as a helpful tool for rapid differentiation of these three species in the course of isolation. Based on the 16S ribosomal DNA sequences, three different forward primers and a single reverse primer were selected. Each forward primer was compared to available mycoplasma sequences, showing the primers to be specific. The three amplification products observed of 1129 bp (M. hyorhinis), 1000 bp (M. hyopneumoniae) and 754 bp (M. flocculare) were clearly distinguishable on a 1% agarose gel. In addition, no cross-reaction with Mycoplasma hyosynoviae, another porcine mycoplasma, was noted. This multiplex PCR using the proposed set of primers is the first reported assay that allows the simultaneous identification of the different Mycoplasma species isolated from the lungs of pigs.     

A microbiological study of pneumonic calf lungs.

BITSCH, V., N. F. FRIIS and H. V. KROGH: A microbiological study of pneumonic calf lungs. Acta vet. scand. 1976, 17, 32–42.–Fifty pneumonic calf lungs were subjected to microbiologic screening with regard to bacteria, mycoplasmas, and viruses.Of bacteria the species most commonly found were Pasteurella multocida (eight lungs), Pasteurella hemolytica (eight lungs), and Corynebacterium pyogenes (13 lungs). Of special interest was the demonstration of Neisseria spp. in five lungs. Mycoplasma dispar was found in 31 lungs, Mycoplasma bovirhinis in 16 lungs, and Urea-plasma in 26 lungs. Cytopathogenic agents were demonstrated in 14 lungs. Four isolates were found to be bovine respiratory syncytial virus, three were bovine viral diarrhea virus, and two were bovine parainfluenza 3 virus. The remaining five cytopathogenic agents were not identified.     

Protection against enzootic pneumonia of pigs: intraperitoneal inoculation with live LKR strain of Mycoplasma hyopneumoniae

Pigs obtained from a mycoplasma-free piggery were randomised into 4 groups of 9. Groups 1 and 2 were injected by the intraperitoneal route with liquid culture of the LKR strain of Mycoplasma hyopneumoniae. Group 1 was injected once and group 2 twice. Group 3 was made up of pigs inoculated by the intranasal route with the virulent Beaufort strain of M. hyopneumoniae; they served as the source of infection for the challenge. Group 4 were uninfected, uninjected controls. Six weeks after the last injection, groups from 1 to 4 were placed in contact. Seven of the pigs in the 1-dose group and 6 in the 2-dose group were free of lesions at necropsy 6 weeks after challenge. Of the two pigs with lesions in the 1-dose group one had only a small lesion but the other had extensive lesions; it had not shown an antibody response after injection of culture. The lesions in the 3 pigs in the 2-dose group were all small. All 9 control pigs had lesions which varied from medium to large in size. The difference in the incidence of pneumonia between the injected and control groups was significant (P less than 0.05) and the proportion of severely affected pigs in the vaccinated groups was significantly lower (P greater than 0.01). There was no difference between those given one dose of vaccine and those receiving 2 doses.     

An Investigation of Ovine Pneumonia in Four Herds from Central Norway: I. Prevalence of Pneumonia and Microbiological Findings

In a study of 4 sheep herds, 1 apparently healthy and 3 having respiratory problems, lesions typical of subacute or chronic pneumonia were found in 3–36 % of slaughtered lambs. Occurrence appeared to be related to certain environmental factors such as pasture, whereas moderate lungworm invasion was not found to contribute to subacute or chronic pneumonia. Relation between pneumonia and low carcass weight was established only in 1 herd.Lungs were subjected to microbiological examination. Mycoplasma ovipneumoniae was isolated from both normal and pneumonic lungs from all 4 herds. The prevalence was far higher in pneumonic (98 %) than in normal ones (28 %). Bacteria, mostly Pasteurella haemolytica, were also found in both pneumonic (49 %) and normal (18 %) lungs from all 4 herds. These results confirm the conclusions of a previous study that M. ovipneumoniae is of etiological significance in subacute or chronic pneumonia, whereas bacteria mainly occur as secondary invaders. M. ovipneumoniae appears, however, only to be a potential pathogen. Examinations for Mycoplasma arginini and virus were negative and these agents are considered to be of less significance in subacute or chronic pneumonia under Norwegian conditions.     

Efficacy of tilmicosin in the control of experimentally induced Actinobacillus pleuropneumoniae infection in swine

The efficacy of tilmicosin administered in the feed to control Actinobacillus pleuropneumoniae infections in pigs was evaluated through a multisite, multitrial study. For each of 6 trials, 48 pigs (stratified by weight and sex) were randomly assigned to 6 to 8 pens. Medicated feed containing tilmicosin (200 g/t) and unmedicated feed were randomly assigned at the pen level and were provided ad libitum from day −7 to trial termination (day 14). Seeder pigs (inoculated intranasally with A. pleuropneumoniae serotype 1 and showing signs of clinical disease) were introduced to each pen on day 0. Rates of death, gross lesions, and culture of A. pleuropneumoniae at necropsy, clinical scores, average daily gain in weight, and average body temperature were compared between the medicated and unmedicated pigs. Compared with the unmedicated pigs, significantly fewer (P < 0.05) pigs given tilmicosin had lesions typical of A. pleuropneumoniae or had A. pleuropneumoniae isolated from their tissues at necropsy. Together with a significant reduction (P < 0.05) in the average percentage of pneumonic lung involvement (both visually and by weight), there were reductions in the numbers of pigs with moderate and severe pneumonic lung lesions and with A. pleuropneumoniae associated mortality. With tilmicosin treatment, the average daily weight gain, daily temperature, abdominal appearance, attitude, and respiration were also significantly better (P < 0.05). The results of this study demonstrate the in vivo effectiveness of tilmicosin (200 g/t) in controlling pleuropneumonia among swine experimentally infected with A. pleuropneumoniae.     

Comparison of the effect of pneumonia detected during lifetime with pneumonia detected at slaughter on growth in swine

Pneumonia in swine has been studied mainly at slaughter or necropsy. However, when performing slaughter or postmortem examinations, assessment of the true prevalence or lifetime extent of pneumonia is at best speculative. Radiography was used to evaluate lungs from pigs 21 to 150 days old. Follow-up slaughter examination was performed on pigs 180 days old. Individual percentage of pneumonia observed over the life of each pig and at slaughter were added to yield lifetime pneumonia scores. A significant (P = 0.0001) negative effect of lifetime pneumonia on growth rate was found. By comparison, slaughter examination proved to be a poor indicator of lifetime pneumonia; lesions were found to progress and regress dynamically throughout the life of pigs.     

Evaluation of the ELISA and comparison to the complement fixation test and radial immunodiffusion enzyme assay for detection of antibodies against Mycoplasma hyopneumoniae in swine serum

An enzyme-linked immunosorbent assay (ELISA) was evaluated for detection of antibodies (Ab) against Mycoplasma hyopneumoniae and M. flocculare in sera from swine experimentally infected with these agents. In addition, the ELISA was compared with the complement fixation test (CFT), and radial immunodiffusion enzyme assay (RIDEA) for the demonstration of Ab against M. hyopneumoniae. Twenty two 6-week-old swine from a respiratory disease-free herd were divided into five groups. Two or three pigs from each of the four groups were inoculated, respectively, with M. hyopneumoniae or with M. flocculare while two pigs in each group were contact exposed to the inoculated penmates. A fifth group, consisting of three pigs, served as inoculated controls. Pigs inoculated with M. hyopneumoniae began coughing 13 days post inoculation (PI). Antibodies were first detected 2 weeks PI with the CFT, 3 weeks PI with the ELISA, and 5 weeks PI with the RIDEA. With the ELISA and RIDEA, Ab were still detectable one year PI at a very low level. With the CFT, Ab were not detectable in sera from any swine beyond 5 months PI. At necropsy 1 year PI, no lesions were detected in lungs of any of the animals nor were mycoplasmas detected. M. flocculare inoculated or contact-exposed pigs never evidenced clinical signs. Antibodies against M. flocculare were first detected 5 to 12 weeks PI with CFT, and 6 to 12 weeks PI with the ELISA. Peak optical density (OD) values obtained in the ELISA with M. flocculare Ab were as high as the values obtained with peak M. hyopneumoniae Ab titers. Levels of Ab against M. flocculare were at relatively higher OD at 1 year PI than Ab against M. hyopneumoniae. Sera with high levels of Ab against M. flocculare cross-reacted slightly with M. hyopneumoniae antigen in immunoblotting and ELISA.     

Mycoplasmosis in green iguanas (Iguana iguana).

Mycoplasma iguanae was the suspected etiology of spinal disease in feral iguanas (Iguana iguana) from Florida. In an experimental infection study, juvenile iguanas were inoculated with M. iguanae intravenously or by instillation into the nares. Blood samples obtained at intervals postinoculation were all culture negative for mycoplasma. Gross anatomic and histologic findings at necropsy 12 wk postinoculation were unremarkable. Mycoplasmas were cultured in high numbers from the posterior choanae and upper trachea of some inoculated and control iguanas at necropsy. The 16S rDNA gene sequence of these isolates revealed they were all a previously undescribed strain, Mycoplasma insons proposed species nova. M. iguanae. Mycoplasma iguanae was not recovered from the conjunctivae, choanae, trachea, lung, coelomic cavity, blood, heart, liver, spleen, limb joints, brain, or spinal cord of inoculated iguanas, and the iguanas did not seroconvert. We conclude that M. iguanae is unlikely to be an agent of acute disease in iguanas and that M. insons can be considered as normal flora in the respiratory tract of iguanas.