Conventional and alternative housing systems for poultry--point of view of infectious disease medicine

The use of conventional battery cages for hens will be prohibited in Germany in 2007. Only few studies, however, have considered the differences between battery cages and alternative systems with regard to infectious diseases. The existing gaps in the current knowledge need to be closed by research and measures must be developed that will prevent the spread of viral, bacterial, and parasitic infections in alternative poultry housing systems.With regard to virus infections, avian influenza requires particular attention. Since wild birds, particularly anseriformes, represent a reservoir for avian influenza viruses, free-ranging poultry is much more at risk of infection than birds in closed hen-houses. Appropriate measures must prevent direct contact with wild birds and transmission via contaminated water, feed, or equipment. Several bacterial infections of poultry represent zoonoses. Salmonella and Campylobacter are considered as particularly important. To avoid a potential increase in the risk of infection for consumers due to poultry keeping systems that might favour infections with bacterial zoonotic agents, there is a special need for research in this area. With regard to parasitic infections, coccidioses may cause problems in alternative poultry housing systems, and lead to considerable economic consequences. The epidemiological situation concerning infections with Histomonas meleagridis needs to be analysed. Since all compounds that had been used for prophylactic or therapeutic purposes in the past have been banned, there is a need to develop new drugs which are safe for animals and humans.     

Development of two real-time PCR assays for the detection of Mycoplasma hyopneumoniae in clinical samples

In order to improve the diagnosis of enzootic pneumonia (EP) in pigs two real-time polymerase chain reaction (rtPCR) assays for the detection of Mycoplasma hyopneumoniae in bronchial swabs from lung necropsies were established and validated in parallel. As a gold standard, the current "mosaic diagnosis" was taken, including epidemiological tracing, clinical signs, macro- and histopathological lesions of the lungs and immunofluorescence. One rtPCR is targeting a repeated DNA element of the M. hyopneumoniae genome (REP assay), the other a putative ABC transporter gene (ABC assay). Both assays were shown to be specific for M. hyopneumoniae and did not cross react with other bacteria and mollicutes from pig. With material from pigs of defined EP-negative farms the two assays showed to be 100% specific. When testing lungs from pig farms with EP, the REP assay detected 50% and the ABC assay 90% of the farms as positive. Both tests together detected all positive farms. Within a positive herd the two assays tested similarly with on average over 90% of the lung samples analysed from a single farm showing positive scores. A series of samples with suspicion of EP and samples from pigs with diseases other than respiratory taken from current routine diagnostic was assayed. None of the assays showed false positive results. The sensitivities in this sample group were 50% for the REP and 70% for the ABC assays and for both assays together 85%. The two assays run in parallel are therefore a valuable tool for the improvement of the current diagnosis of EP.     

Aplastic articular facets in a dog with intervertebral disk rupture of the 12th to 13th thoracic vertebral space

A 6-year-old, female spayed Pomeranian was presented with acute hind-limb paraplegia with the presence of deep pain perception and urinary incontinence. Myelography showed a Hansen type I herniation of the12th to 13th thoracic intervertebral space (T(12-13)). Articular facets of the T(12-13) and T(13) to first lumbar vertebra (L(1)) were absent. The spinal cord was decompressed using a bilateral T(12-13) modified lateral hemilaminectomy (pediculectomy). The aplastic sites were associated with minimal instability of the vertebral column, and stabilization of the vertebral column was not required. Familiarity with this condition is important, because articular facet aplasia may cause vertebral instability and may require an adjusted surgical approach or vertebral reduction and fusion following decompression.     

Distribution of Brachyspira hyodysenteriae and Lawsonia intracellularis in healthy and diarrhoeic pigs

Although Brachyspira (B.) hyodysenteriae and Lawsonia (L.) intracellularis are widely distributed in pigs in Germany, there exists limited information on their clinical relevance.To get more insight into their potential role in swine diarrhoeal disease, in 2002 and 2003 faecal specimens from healthy pigs (n=1445) as well as from diarrhoeic pigs (n=2002) were tested by polymerase chain reaction (PCR) for the presence of both agents. Of the specimens from healthy pigs L. intracellularis and B. hyodysenteriae were detected in 7.3% and 6.7%, respectively. In contrast, of the diarrhoeic pigs the ratios of positive samples amounted to 19.4% for L. intracellularis and 17.9% for B. hyodysenteriae. Concerning the age of the diseased animals, in growing pigs the detection rates of L. intracellularis and B. hyodysenteriae were nearly identical (16.4% and 14.2%, respectively). In fattening pigs a significant higher number of animals were affected with B. hyodysenteriae (35.8%) than with L. intracellularis (28.2%). On the other hand, in sows L. intracellularis (35.6% positive samples) was dominant compared to B. hyodysenteriae (21.2% positive samples). Considering the nearly threefold higher percentage rates of L. intracellularis and B. hyodysenteriae in diarrhoeic pigs in comparison to healthy pigs, it is concluded that both agents play an important role in swine diarrhoeal disease. The results further indicated that in fattening pigs B. hyodysenteriae and in sows L. intracellularis have a dominant role, respectively.     

T-helper cells from naive to committed

An endotoxin-induced mastitis model was used to study permeability changes associated with increased milk matrix metalloproteinase (MMP) activity in early inflammation. One quarter of two cows was inoculated with endotoxin (Escherichia coli 055:B5). Blood, milk, and whey were collected before and repeatedly after inoculation for 48 h. The profile and amounts of gelatinolytic MMPs were determined by zymography; gelatinase A (72 kD MMP-2) and gelatinase B (92 kD MMP-9) were identified by Western immunoblotting. Bovine serum albumin (BSA) and trypsin inhibitor capacity (TIC) were used as markers of capillary permeability with parallel examination of neutrophil penetration from blood to milk. Five clinical E. coli mastitis milk samples and five milk samples from cows with healthy udders were analyzed to detect whether increased levels of gelatinolytic MMP-2 and MMP-9 have a role in naturally occurring mastitis with endotoxin involvement. Milk MMP levels increased 2h after the endotoxin challenge. Both MMP-2 and MMP-9 were involved in this early proteolytic event. These increased MMP levels are associated with increased capillary permeability, evidenced first by the penetration of small molecular weight proteins, such as BSA and TIC. Later, 6-12h post endotoxin inoculation, neutrophilic leucocytes also entered the site, as they require larger tissue damage in basal membrane and interstitial tissue structures than BSA and TIC to extravasate. In naturally occurring disease, increased MMP-2 and MMP-9 levels were detected in milk. Thus, gelatinases, especially MMP-2, are involved in the early degradation of the blood-milk barrier, which precedes the penetration of blood-derived cellular components into milk in endotoxin-induced mastitis. In the future, measuring MMP in milk/whey might be a useful tool for diagnosing early mastitis.     

The use of the toxin binding inhibition test for potency testing of Clostridium novyi type B alpha toxoid vaccines

The toxin binding inhibition test (ToBI) were developed for potency testing of C. novyi type B alpha toxoid containing veterinary vaccines to replace the currently used toxin neutralisation test in mice (TNT). The antitoxin titres of rabbit sera (AN-, HV- and SP sera) were determined with ToBI using the international reference serum with known antitoxin titre. In order to show the validity of the methods, the results were compared with those of the manufacturers/regulatory authorities and correlation coefficients were calculated. The correlation coefficients were r = 0.93 (AN sera), r = 0.73 (HV sera) and r = 0.85 (SP sera). All correlations were statistically significant. The specificity of the methods could be proved using heterologous antisera. The results of the ToBI were reproducible. Thus, the ToBI offers a suitable in vitro method for the determination of the antitoxin titre of rabbit antisera as an alternative to the toxin neutralisation in mice for potency testing of vaccines containing C. novyi type B alpha toxoid.     

A phagocytosis test for the evaluation of the local immunity status during endometritis therapy with special regard to the use of uterofertil in cattle

After the influence of organic acids or peroxide acids with low concentration upon mucous membranes results a higher activity of the topical defence-situation. The application of a 0.2 per cent solution of peroxyethane acid (drug Uterofertil) into the uterus for endometritis-therapy directs an increase of phagocytosis-activity not only topical but also in the peripheric circulation of blood. The phagocytosis-activity was measured with a test by granulocytes. Other drugs were also tested, which will needed by endometritis-treatment of cattle.