Clostridial co-infection episodes in commercial laying hens.

The present report describes two outbreaks of serious enteritis in commercial laying hens where Clostridium perfringens and Clostridium colinum were simultaneously detected. At the age of 44 and 31 weeks, two laying hen flocks showed an increase of the mortality rate and a worsening of productive performance. Post-mortem examination revealed intestinal necrotic-haemorrhagic ulcerations and hepatic focal necrosis. The bacteriological examination yielded the isolation of C. colinum and C. perfringens toxin type A, NetB positive. In one outbreak, C. colinum was detected also by polymerase chain reaction in all the intestines of affected birds. In laying hens, C. colinum has never been isolated but only suspected as the causative agent of a slight enteric disease called duodenal focal necrosis. The present case report was characterized by severe enteritis presumably due to the synergistic effect of C. colinum and C. perfringens.

Kinetics and intrapulmonary disposition of tilmicosin after single and repeated oral bolus administrations to rabbits.

Tilmicosin (TIM, Pulmotil) was administered to eight rabbits by oral gavage at a dose of 12.5 mg/kg body weight for 2, 5, and 7 days, and its plasma kinetics and intrapulmonary disposition were investigated. TIM concentrations in plasma samples collected after days 1 and 6 of treatment were measured by high-performance liquid chromatography with ultraviolet detection. The pharmacokinetic parameters, obtained by non-compartmental analysis of TIM plasma concentrations, did not show any significant variations between days 1 and 6. From the second day of treatment, TIM concentrations attained in lung tissue and pulmonary alveolar macrophages (PAM) exceeded those in plasma by 7- and 400-fold, respectively, and high levels were maintained in lung tissues during the entire treatment duration. After the first day of withdrawal, a fast decline in TIM levels in both plasma and lung tissue was observed, but in PAM, much higher concentrations were maintained after 3 days of TIM withdrawal.

Prevalence, disease associations and risk factors for colonization with intestinal spirochaetes (Brachyspira spp.) in flocks of laying hens in north-eastern Italy.

The present study investigated the occurrence of anaerobic intestinal spirochaetes of the genus Brachyspira in laying hen flocks in Treviso province, north-eastern Italy, with respect to prevalence, spirochaete species present, disease associations and risk factors for colonization. A total of 450 faecal samples from 45 sheds on 29 laying hen farms were cultured for intestinal spirochaetes. Nineteen sheds on 12 farms contained chickens with symptoms consistent with avian intestinal spirochaetosis, including reduced egg production, wet litter and/or pasty vents. Spirochaetes were isolated from 157 (34.8%) samples from 21 (72.4%) farms, and from 32 (71.1%) sheds. From these positive samples, 189 spirochaetal isolates were speciated using three polymerase chain reaction assays and a restriction fragment polymorphism analysis of 16S rDNA polymerase chain reaction products. Overall, 52 (27.5%) isolates were identified as pathogenic Brachyspira intermedia, 26 (13.8%) as pathogenic Brachyspira pilosicoli, 93 (49.7%) as non-pathogenic (Brachyspira innocens/Brachyspira murdochii), and 18 (9.6%) were unidentified. Faeces from 14 sheds (31%) on 10 farms (34.5%) contained B. intermedia and/or B. pilosicoli, and disease consistent with avian intestinal spirochaetosis was observed in nine of these sheds on seven farms. There was a significant association (P=0.042) between the presence of spirochaetes and using deep pits rather than conveyor belts for manure disposal. Sheds housing chickens >40 weeks of age were significantly more likely to contain spirochaetes (P=0.048) and pathogenic species (P=007) than sheds housing younger chickens. A significant association (P=0.02) was found between infection with pathogenic spirochaetes and reduced egg production.

Diagnosis of rabbit haemorrhagic disease (RHD) and European brown hare syndrome (EBHS) by indirect sandwich polyclonal ELISA.

The establishment of two indirect sandwich polyclonal ELISAs for the virological diagnosis of rabbit haemorrhagic disease (RHD) and European brown hare syndrome (EBHS) is described. Each assay uses rabbit and guinea pig antisera raised to RHD or EBHS purified virus particles. The tests are sensitive and specific, but cross-reactions between rabbit haemorrhagic disease virus (RHDV) and European brown hare syndrome virus (EBHSV) are observed. Most rabbit liver homogenates identified as RHDV-positive by ELISA do not haemagglutinate human red blood cells at room temperature.

Characterization of some parameters of non-specific immunity in beef cattle (II).

Serum protein, immunoglobulins, complement, lysozyme, serum bactericidal activity and blast transformation of peripheral blood lymphocytes were tested in beef cattle in different herds and age groups. These parameters were evaluated in their time-kinetics, in comparison with age-matched groups of dairy cattle. Like dairy calves, beef calves up to 4 months of age were shown to have low levels of serum bactericidal activity and haemolytic complement; besides, a worse profile was detected in serum protein and gamma 2 globulin levels. Al(OH)3 and oil-adjuvanted vaccines had a favourable influence on immunoglobulin and lysozyme synthesis. An acute stressing event like transportation was shown to decrease mitogen-driven lymphocyte stimulation for at least 10 days after arrival.