Schmallenberg virus outbreak in the Netherlands: routine diagnostics and test results.

At the end of 2011, a new Orthobunyavirus was discovered in Germany and named Schmallenberg virus (SBV). In the Netherlands malformations in new-born ruminants were made notifiable from the 20th of December 2011. After a notification, malformed new-borns were necropsied and brain tissue was sampled for reverse transcription-polymerase chain reaction (RT-PCR). In addition, blood samples from mothers of affected new-borns were tested for antibodies in a virus neutralization test (VNT). The aim of this study was to summarize and evaluate the diagnostic data obtained and to gain insight into the possible regional differences. In total 2166 brains were tested: 800 from lambs, 1301 from calves and 65 from goat kids. Furthermore 1394 blood samples were tested: 458 from ewes, 899 from cows and 37 from goats. Results showed that 29% of the lamb brains, 14% of the calf brains, and 9% of the goat kid brains were RT-PCR positive. The number of malformed and RT-PCR positive lambs decreased over time while the number of malformed and RT-PCR positive calves increased. In the VNT 92% of the ewes, 96% of the cows and 43% of the goats tested positive. Combining RT-PCR and VNT results, 18% of all farms tested positive in both the RT-PCR and VNT. The relative sensitivity and specificity of the RT-PCR are 19% and 97% respectively, and of the VNT 99% and 6%. The results show a widespread exposure to SBV and the regional evaluation seems to indicate an introduction of SBV in the central/eastern part.

Salmonella infections in finishing pigs in The Netherlands: bacteriological herd prevalence, serogroup and antibiotic resistance of isolates and risk factors for infection.

Salmonellae are wide spread in man and animals world wide and are of increasing significance as causative agents of foodborne diseases in man. The European Union, national authorities and the pig industry are therefore more and more interested in the Salmonella status of the pig population. The aim of this study was to estimate the bacteriological prevalence of Salmonella in finishing pig herds, the serogroup and the resistance to antibiotics of the isolated Salmonellae and a preliminary risk analysis of factors associated with infection. For this, 317 finishing pig herds were randomly selected from a database containing 1500 herds in the southern part of the Netherlands. In each herd 24 samples of fresh faeces were collected from two compartments with pigs close to market weight. Per compartment 12 samples of faeces were pooled into one pooled sample. Pooled samples were cultured in duplicate. Salmonella spp. were recovered from 71 out of 306 herds (23%) in which two compartments could be sampled. A total of 108 isolated Salmonella's were serotyped: 71 serogroup B, 3 serogroup C1, 6 serogroup C2, 22 serogroup D1, and 6 isolates neither serogroup B, C or D1. Of a total of 115 Salmonella isolates tested, none were resistant to colistin, enrofloxacin, flumequin or gentamicin. Automated liquid feeding of by-products, and membership of an Integrated Quality Control (IQC) production group were associated with a decreased risk of infection, while use of trough feeding was associated with an increased risk of infection. It is necessary to test these presumed risk factors in intervention studies to evaluate their potency to reduce the Salmonella prevalence in finishing pigs and thereby reduce the risk of Salmonellosis in people consuming pork.

Survey of infectious agents involved in acute respiratory disease in finishing pigs.

Outbreaks of respiratory disease constitute a major health problem in herds of finishing pigs and their aetiology often remains unclear. In this study, 16 outbreaks of respiratory disease with acute clinical signs in finishing pigs were investigated to determine which infectious agents were involved. From each herd four diseased and two clinically healthy pigs were examined pathologically and for the presence of viruses, bacteria and mycoplasmas. In addition, paired blood samples from 10 groupmates of the diseased pigs were tested for antibodies against commonly known causal agents of respiratory disease. A clear diagnosis was possible in 12 of the 16 outbreaks. Seven were due to an infection with influenza virus and five were due to an infection with Actinobacillus pleuropneumoniae. A combination of influenza virus and A pleuropneumoniae may have caused one other outbreak, but no clear cause could be established for the other three outbreaks.

Incidence of clinical mastitis in a random sample of dairy herds in the southern Netherlands.

The incidence of clinical mastitis and distribution of pathogens in dairy cows was estimated in 171 randomly selected dairy herds in the southern Netherlands. A total of 1103 quarter cases were reported. The average annual incidence rate was 12.7 quarter cases per 100 cows per year. The most frequent isolates from clinical cases were Escherichia coli (16.9 per cent), Staphylococcus aureus (14.4 per cent), Streptococcus uberis (11.9 per cent) and Streptococcus dysgalactiae (8.9 per cent). Most cases were reported in early lactation: 25.4 per cent in the first month of lactation for all cows, and 39.1 per cent in the first month for first lactation cows. The rear quarters had a significantly higher incidence rate than the front quarters. Cows with an E coli infection showed more general clinical signs than cows infected with S aureus, S uberis and S dysgalactiae. A significantly higher incidence was observed in herds with a low (< 150,000 cells/ml) bulk milk somatic cell count than in herds with a count above 250,000 cells/ml.

Antimicrobial resistance of Escherichia coli isolates from the faecal flora of veterinarians with different professional specialties.

The prevalence of antibiotic resistant Escherichia coli isolates from faecal samples from 110 veterinarians with different specialties (predominantly working with cattle, swine, poultry, or small animals or working as a non-practitioner, e.g. in government or industry) was investigated. In 22% and 13% of the veterinarians E. coli isolates showed a high level of resistance to oxytetracycline and ampicillin respectively. A significantly higher percentage of cattle practitioners had a high level of antibiotic resistance against ampicillin than did swine practitioners. Furthermore, a significantly higher percentage of poultry practitioners had a high level of antibiotic resistance against oxytetracycline than did swine practitioners and non-practitioners. A significantly higher percentage of practitioners recently (within last 6 months) used antibiotics for personal intake than did the group of non-practitioners. There was no evidence for a relationship between personal intake of antibiotics and the occurrence of a high level of resistance to ampicillin or oxytetracycline. The prevalence of E. coli isolates, that were resistant to several antibiotics was highest in cattle and poultry practitioners and the lowest in swine practitioners. A possible explanation for the observed differences in high level resistance to oxytetracycline and ampicillin between veterinary specialty groups is a difference in exposure to antibiotics during practice.

Incidence of paratuberculosis after vaccination against M. paratuberculosis in two infected dairy herds.

Vaccination against paratuberculosis of all newborn animals has been performed since April 1984 in two dairy herds with a high incidence of clinical cases of paratuberculosis, using a vaccine containing heat-inactivated M. paratuberculosis in a water/mineral oil emulsion. Animals slaughtered between April 1984 and January 1991 were included in the study. Histology, bacterioscopy and culture on Smith and modified Löwenstein-Jensen media were performed using jejunum, ileum and draining lymph nodes. The animals present on the farm in April 1984 constituted a retrospective non-vaccinated group, giving an indication of the initial infection rate. After vaccination, the percentage of animals culled for clinical paratuberculosis decreased significantly (7.8 to 1.8%; P < 0.005), as did the percentage of animals with positive histology (11.8% to 5%). The incidence of infected animals, defined by positive results in histology and or bacterioscopy and/or culture, however, increased from 21.8% to 25.9%.

[Respiratory problems, growth retardation and arthritis in turkeys and broilers caused by a Pasteurella-like organism: Ornithobacterium rhinotracheale or 'Taxon 28']. / Ademhalingsproblemen, groeivertraging en gewrichtsontsteking bij kalkoenen en vleeskuikens door een Pasteurella-achtige bacterie: Ornithobacterium rhinotracheale of 'Taxon 28'.

Since August 1993 moderate to serious respiratory problems with necrotic pneumonia, growth depression and fast increasing mortality are seen in commercial turkeys (2-8 weeks of age) and broilers (4-6 weeks of age). An unidentified pleiomorphic Gram-negative rod was isolated from affected tissues. This Pasteurella-like organism, with yet unknown taxonomy, is recently named Ornithobacterium rhinotracheale gen. nov. sp. nov. or 'Taxon 28'. Experimentally severe growth depression and arthritis could be evoked in commercial turkeys and chickens. Respiratory signs caused by O. rhinotracheale could not (yet) be reproduced experimentally. This is the first report of the isolation of this organism in poultry in the Netherlands findings.

Relationship between negative skin test with Johnin after vaccination and post mortem findings.

One hundred and seventy-six cattle, vaccinated against paratuberculosis in the first month of life with a whole-cell inactivated vaccine, containing Mycobacterium paratuberculosis suspended in a water/oil emulsion, were tested with intradermal Johnin between the ages of five and 14 months. Negative results in the skin test occurred more frequently in animals found positive in post mortem examinations (P = 0.008) using histological, microscopical and cultural techniques.