After immunization of four calves with a live modified Mycobacterium paratuberculosis vaccine the course of the humoral and cell mediated immune reactions was studied during a 2-year clinical investigation. Furthermore, the possibility of shedding of the vaccine strain and the influence of the vaccination on the tuberculin skin test was determined. In addition to standard procedures recently developed diagnostic methods (antibody enzyme-linked immunosorbent assay, interferon-gamma test, polymerase chain reaction) were used. A cell-mediated immune reaction, reflected in an increased, specifically induced, interferon-gamma production developed much earlier (1-2 weeks post-immunization) than humoral immunity (8-16 weeks post-gamma immunization). While the increase in antibody titres was transient, declining to extremely low levels 48-60 weeks post-immunization, cell-mediated immunity remained detectable until the end of the investigation. Spread of the vaccine strain into the body and shedding were never detected during the whole course of the study except for one colon site in one calf. As late as 2 years after vaccine application positive or doubtful skin reactions against M. bovis purified protein derivative were measured, reflecting possible interference of the immunization with the diagnosis of bovine tuberculosis. At the end of the investigation, a positive cell-mediated immune reaction was detected the control animal although clinical, pathological and bacteriological examinations gave no indication for a mycobacterial infection.

In the present study, 132 selected faecal samples from clinically affected and subclinically infected cattle from dairy herds known to be affected by Johne's disease were investigated for the presence of Mycobacterium paratuberculosis using Ziehl-Neelsen staining, faecal culture and a commercially available DNAProbe ® test. The sensitivity was 36.4% for Ziehl-Neelsen staining, 85.6% for faecal culture and 47.7% for the DNA-Probe ® test. Proving the presence of acid-fast bacteria in 49.3% of the samples from clinically affected cattle and 19.3% of those from subclinically infected cattle, Ziehl-Neelsen staining had the lowest detection rate of the three tests under investigation. Faecal culture showed the highest detection rate of M. paratuberculosis in samples from both clinically affected (84.0%) and subclinically infected (87.7%) animals. The DNA-Probe ® test showed a positive result in 68.0% of the samples from clinically affected cattle and 21.1% of those from subclinically infected cattle. Ziehl-Neelsen staining proved unreliable in diagnosing Johne's disease. Faecal culture was the most sensitive method for detecting M. paratuberculosis both in clinically affected and subclinically infected cattle. The sensitivity of a commercially available DNAProbe ® test has to be enhanced to enable a quick and reliable diagnosis of Johne's disease.

No abstract

Zusammenfassung: Gegenstand und Ziel: Zur Schätzung der Neospora-caninum-Seroprävalenz in Milchvieh- und Mutterkuhherden erfolgte 2003 und 2004 eine Querschnittsstudie in Rheinland Pfalz. Material und Methoden: Einzelmilchproben von 4343 Kühen aus 100 zufällig ausgewählten Milchviehherden und 2680 Serumproben aus 106 Mutterkuhherden wurden im Milch- bzw. Serum-p38-ELISA auf Antikörper gegen N. caninum untersucht. Mittels Daten aus einer Befragung der an der Studie teilnehmenden Landwirte sowie Angaben zur Hundedichte und mittleren Lufttemperatur im Juli in den Landkreisen wurden mögliche Risikofaktoren für N. caninum-Infektionen in Rinderherden ermittelt. Ergebnisse: Es ergab sich eine Gesamtseroprävalenz von 4,0% (172/4343) für Milchvieh und 4,9% (131/2680) für Mutterkühe. Die Seroprävalenzen innerhalb der Milchviehherden lagen zwischen 0% und 43% mit einem Wert von ≥ 5% bei 35% (35/100) der Herden. Die Prävalenzen innerhalb der Mutterkuhherden lagen zwischen 0% und 55% mit einem Wert von ≥ 5% bei 37% (39/106) der Herden. Ein optimiertes logistisches Regressionsmodell zur Beschreibung möglicher Risikofaktoren für N.-caninum-Infektionen in Milchviehherden beinhaltete die Eingabevariablen “Hundedichte im Landkreis” und “Anwesenheit eines oder mehrerer Hofhunde bei der Herde” als potenzielle Risikofak- toren(p<0,05). Bei einervergleichbarenAnalyse der Daten fürMutterkuhherden ließ sich lediglich die Eingabevariable “mittlere Lufttemperatur im Juli im Landkreis” als potenzieller Risikofaktor identifizieren (p < 0,05). Schlussfolgerungen: Zahlreiche Milch- und Fleischrinderherden in Rheinland-Pfalz sind mit N. caninum infiziert. Bei Milchrinderherden spielen Hofhunde für die horizontale Übertragung offenbar eine wichtige Rolle. Nach den Ergebnissen der Risikofaktorstudie ist nicht auszuschließen, dass auch über in der Umgebung der Herde gehaltene Hunde Infektionen in Milchrinderherden gelangen. Klinische Relevanz: Bei ungeklärten Abortgeschehen in Rinderhaltungen sollte auch auf N.-caninum-Infektionen untersucht werden. Um eine Verbreitung von N.-caninum-Infektionen in Milchviehbeständen zu verhindern, sollte Hunden (vor allem Hofhunden) der direkte Kontakt zu Rindern und deren Futter verwehrt werden.

Environmental samples are considered to be a cost-effective method of identifying Mycobacterium avium subsp. paratuberculosis (MAP)-positive dairy herds, but evidence for beef cow-calf herds is weak. This study aims at evaluating this approach in a total of 20 German herds that were characterized by individual faecal samples (n = 2545) of all cows. For 14 MAP-positive herds having at least one MAP-positive animal, the within-herd prevalence was calculated from concurrent individual faecal culture-based testing. Six herds certified as 'MAP free' based on the negative results of previous years served as MAP-negative controls. On average, six environmental samples were taken at the end of winter from areas with high cow traffic and tested for MAP by faecal culture. According to the environmental samples, nine (64·3%) out of the 14 MAP-positive cow-calf herds were infected. The percentage of positive environmental samples and the apparent within-herd prevalence (Spearman's P = 0·73, P < 0·001) as well as the herd-level test results (positive and negative) and the herd's status based on individual testing (Fisher's exact test, P = 0·014) showed a positive association. Considering limitations in low-prevalence herds, MAP-positive beef cow-calf herds are detectable by environmental samples in temperate climate zones.