Salmonella typhimurium DT104 septicaemia with meningitis in neonatal piglets.

Clinical salmonellosis in pigs in the Netherlands usually manifests itself as diarrhoea. In finishing pigs this is sometimes accompanied by peracute mortality, mainly in the last month of the finishing period. This is the first report describing Salmonella Typhimurium DT104 infection of 1-week-old suckling piglets in the Netherlands. The piglets showed nervous symptoms and died. The clinical symptoms, gross pathology, histopathological, bacteriological and phagetyping results are presented as well as the antimicrobial resistance pattern. This case is not only important as an extension of the clinical syndrome of salmonellosis in pigs in the Netherlands, but also because of the risk of human infection after consumption of pork or pork products contaminated with this pathogenic and multiple resistant Salmonella clone.

[Sero-monitoring of notifiable diseases in wild boar in the Netherlands 1999-2001]. / Resultaten van seromonitoring van veewetziekten bij wilde zwijnen in Nederland 1999-2001.

Within the framework of a sero-monitoring system, in operation since 1996. blood samples from wild boar shot during the hunting seasons 1999-2000 and 2000-2001 in The Netherlands were screened for the presence of antibodies against classical swine fever virus (CSFV), swine vesicular disease virus (SVDV), and Anjeszky's disease virus (ADV). The results indicate that CSFV, SVDV, and ADV are uncommon in the wild boar population in the Netherlands. Because of the recent foot-and-mouth disease (FMD) epidemic in the Netherlands in 2001, blood samples (approximately 200 samples) from wild boar shot in the Netherlands during the hunting season 2001/2002 were examined for antibodies against FMD. To date, antibodies against FMD have not been detected.

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.

Return to oestrus after first insemination in sow herds (incidence, seasonality, and association with reproductivity and some blood parameters).

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were: 1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level; 2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics in order to get an impression of the economic importance of reproductive failure. These objectives were investigated by using the reproduction results of 240 swine breeding herds in the Southern Netherlands in 1987. This information was obtained from CBK plus computerized herd management records. The average incidence rate of return to oestrus after first insemination at a herd level was 16.9 per 100 first inseminations. The occurrence of return to oestrus after first insemination was distinctly higher in the insemination months July and August compared to the rest of the year. An increased incidence, with 10 returns per 100 first inseminations corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 live born piglets/sow/year. A prospective longitudinal study was started in 1988 and 1989 in 37 sow herds. Individual sows were monitored from weaning to first insemination, to the occurrence of return to oestrus, or not, after first insemination, and to farrowing. The investigation focused in particular on the relationship between return to oestrus after first insemination and seroconversion against porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava).(ABSTRACT TRUNCATED AT 250 WORDS)

[Doxycycline poisoning in veal calves]. / Doxycycline-vergiftiging bij witvleeskalveren.

Several veal calves that had received doxycycline died suddenly. Post mortem examination revealed pulmonary oedema, myocardial degeneration, and myocarditis. It is possible that hitherto unknown interactions between doxycycline and other compounds may have played a role.

[Return to estrus following first insemination in sow herds (incidence and association with reproductivity and various blood parameters)]. / Terugkomen na eerste inseminatie op zeugenbedrijven (incidentie en associatie met reproduktiviteit en een aantal bloedparameters).

As no systematic study has been done to get an accurate estimate of the incidence of return to oestrus after first insemination in sows in the Netherlands, the objectives of this investigation were: 1) to obtain an estimate of the incidence of return to oestrus after insemination at the herd level; 2) to investigate the association between incidence of return to oestrus after first insemination and reproduction characteristics to get an impression of the economic importance. These objectives were investigated using the reproduction results of 240 swine breeding herds in The Southern Netherlands in 1987, using their CBK plus computerized herd management records. The average incidence of return to oestrus after first insemination on a herd level was 16.9 per 100 first inseminations. An increase of incidence with 10 returns per 100 first inseminations, corrected for confounders in a multiple linear regression model, was associated with a decrease of approximately 0.3 liveborn piglets/sow/year. Thereupon individual sows were followed in 1988 and 1989 prospectively in 37 sow herds from weaning to insemination, returning to oestrus or not after first insemination to farrowing. The investigation focused in particular on the relationship between returning to oestrus after first insemination and incident infection with porcine parvovirus (PPV) and Leptospira interrogans serovar bratislava (L. bratislava). During a number of consecutive farm visits sows were blood sampled at weaning and again a blood sample was taken 6 weeks later. The final dataset that was analysed consisted of 161 animals that did not return to oestrus after first insemination and 158 animals that returned to oestrus after first insemination.(ABSTRACT TRUNCATED AT 250 WORDS)

A subclinical infection of bulls with bovine herpesvirus type 1 at an artificial insemination centre.

A subclinical bovine herpesvirus type 1 (BHV1) infection affected bulls at an artificial insemination centre for at least six months. The virus was detected in semen samples from 43 out of 116 bulls examined; 27 of them shed virus during one consecutive period of up to 10 days and 16 shed the virus intermittently. The virus titres ranged between 10 and 100,000 TCID50/ml. Vaccinated bulls tended to excrete the virus less frequently than unvaccinated bulls. Approximately 50 per cent of the bulls that had an increase in neutralising antibody titre to BHV1 shed the virus in their semen.

[Comparison of antibody titers against Aujeszky's disease virus in pig blood collected on the farm and in the slaughterhouse]. / De vergelijking van antistoftiters tegen het virus van de ziekte van Aujeszky in bloed verzameld bij vleesvarkens op de boerderij en in het slachthuis.

Antibody titres against Aujeszky's disease virus (ADV) in the plasma of slaughter pigs were compared with respect to the site of sampling, namely on the farm (one day before delivery to the slaughterhouse) and in the slaughterhouse during slaughter. No significant differences were noted in the antibody titres against ADV with respect to the different sampling sites. Blood samples collected at the slaughterhouse can be used for monitoring and surveillance systems within the framework of organised pig health care.

Spread of bovine virus diarrhoea virus in a herd of heifer calves.

A calf persistently infected and immunotolerant to Bovine Virus Diarrhoea virus (BVD virus) was, on purpose, introduced to a herd of heifer calves over 4 months of age that had been reared as recipients for embryo transplantation. All calves were brought in contact with the persistently infected animal. In total, 240 calves were involved in this experiment, 22 of which were serologically negative when introduced. These serologically negative animals developed antibodies against BVD virus within 5 months after introduction. At short distances from the persistently infected BVD virus shedder, negative calves seroconverted within 2 months, but at greater distances the moment of seroconversion was unpredictable. The calves that had undergone a natural infection with BVD virus received embryos after transportation to an allied farm. In total, 14 calves were born after embryo transplantation, all of which were free of BVD virus, in spite of the presence of BVD-virus on the latter farm.

Determination of BHV1 specific immune reactivity in naturally infected and vaccinated animals by lymphocyte proliferation assays.

The in vitro BHV1-specific lymphocyte stimulation assay was used to investigate immune reactivity of cattle after natural infection or vaccination with BHV1. Proliferative responses to live virus were shown in tests with peripheral blood lymphocytes of seropositive field virus-infected animals and of vaccinated animals. Nineteen out of 36 seropositive field virus-infected animals did not show in vitro responses. Nine out of 12 animals showed, at least transient, responsiveness after vaccination. Antibody titers were maintained throughout the observation period. T cell activity is believed to play a role in protection against BHV1 infection. The in vitro proliferative assay, however, can not discriminate between BHV1 seropositive and seronegative field virus-infected animals. After vaccination, the BHV1-specific lymphocyte responses of at least one animal disappeared. Both observations may point to the fact that T cell memory is generated, or at least systemically present, to a limited extent.

Failure of an in vitro lymphoproliferative assay specific for bovine herpes virus type 1 to detect immunised or latently infected animals.

The in vitro lymphoproliferative assay specific for bovine herpes virus type 1 (BHV1) was tested for its ability to predict whether an animal was protected against challenge with virulent BHV1 and for its ability to identify animals latently infected with the virus. Three animals that had been in contact with a field strain of the virus, three that had been vaccinated with a modified live-virus vaccine seven weeks previously, six that had been vaccinated in the same way five months previously, and seven control animals that had had no previous contact with the virus were challenged with virulent BHV1. The 12 animals that had had previous contact with BHV1 all resisted the challenge well or fairly well, but six of them did not react positively in the in vitro lymphoproliferative assay. It was concluded that the assay did not give consistent evidence of the immune status of the animals. Four animals that had had previous contact with a field strain of BHV1 were treated with dexamethasone; they excreted BHV1 irrespective of whether they showed a positive response in the in vitro lymphoproliferative assay.

Pregnancy rate of heifers bred by an immunotolerant bull persistently infected with bovine viral diarrhoea virus.

Twenty four maiden heifers were bred by natural route by a specific immunotolerant bull, that was persistently infected with Bovine Viral Diarrhoea virus (BVD virus). The quality of the bull's semen was normal. Twelve heifers became pregnant in the first oestrus cycle and the remaining twelve in the second oestrus cycle. This leads to the conclusion that such persistently infected bulls may have good fertilisation results. Nevertheless, it is felt that bulls persistently infected with the BVD virus must be excluded from artificial insemination centres because of the risk of introducing BVD virus in a herd by the semen.

A case of chronic zinc poisoning in calves fed with zinc-contaminated roughage.

A case of zinc intoxication in young female cattle is described. The clinical signs consisted of reduced appetite, emaciation, submandibular oedema and diarrhoea. The source of zinc proved to be roughage harvested in the vicinity of a factory galvanizing steel tubes. In this roughage zinc levels between 3000 and 7300 mg/kg dry weight were found. In the liver of four animals zinc levels varied between 420 and 1600 mg/kg, and between 910 and 1680 mg/kg dry weight in the kidneys.

[Direct communication of both coronary arteries with the right ventricle in a calf]. / Een directe verbinding van beide coronaire arteriën (arteriae coronariae) met de rechter ventrikel bij het kalf.

Direct communication between the two coronary arteries and the right ventricle in a two-week-old bull calf is described. The descending branches of the coronary arteries were dilated. The pathophysiological features and the possible pathogenesis of this malformation are discussed.

[Field trials of a number of IBR vaccines in dairy cattle]. / Praktijkproeven met enkele IBR-vaccins bij melkkoeien.

Vaccination of ninety-six cows which showed titres of less than or equal to 1:2 on inoculation, using vaccines containing attenuated live IBR virus (Tracherine, Resbo. IBR PI3, Respacine 3) elicited a moderate serological response. Inoculation of these vaccines in 192 cows showing titres of greater than or equal to 1:3 on vaccination did not result in a significant increase in titre. Inactivated IBR vaccines (Iffavax and Ibeair H) induced a satisfactory serological response in 140 cows, regardless of the IBR virus titres of the animals on inoculation. Within five months after vaccination, four animals vaccinated with Ibeair H were found to be only moderately immune against intranasal infection using virulent IBR virus. The present authors prefer the use of vaccines containing attenuated live virus.

[Vaccination against IBR: a recommendation for dairy herds]. / Vaccinatie tegen IBR: een advies voor melkveekoppels.

In view of the results of previous serological studies on the presence of SN antibodies to IBR virus in a minimum of ten per cent of the herd, the following procedure is suggested: (1) Vaccination of serologically negative herds in areas menaced by IBR virus. (2) Vaccination of IBR-negative groups of animals in herds in which serologically IBR-positive animals are present. When sampling shows that IBR-negative animals are present in every age group, vaccination of the entire herd should be contemplated. (3) Vaccination of all animals which are added to dairy herds including animals showing antibodies to IBR virus.

[Aujeszky's disease: serological responsiveness after vaccination of 6-10-week-old piglets with maternal antibody (author's transl)]. / Ziekte van Aujeszky: entbaarheid van biggen met maternale antistoffen op een leeftijd van 6-10 weken.

Trials were made to study the extent to which 6-10-week-old piglets with and without virus-neutralizing (VN) antibodies are capable of a serological response to vaccination. The piglets were inoculated with three different vaccines: two live vaccines (Aescovac Aujeszky and MK25 vaccine) and an inactivated vaccine (Geskyvac). The titre of virus-neutralizing antibody in the blood was determined for each vaccine in approximately 200 piglets at the time of inoculation as well as within four and twelve weeks after inoculation. The maternal antibodies present at the time of inoculation were found to have an inhibitory action on the serological response following inoculation. Of those piglets in which a maternal VN titre was observed using the above technique, only 9 per cent showed an increase in titre after inoculation. This proportion was 74 per cent in the serologically negative piglets. Marked variations in serological response to the different vaccines were observed. the most positive response was that induced by Aescovac. There was an obvious relationship between the VN titre following inoculation and immunity against intracerebral challenge with 2,000 TCID50 of Aujeszky disease virus. Animals showing titres of 1:4 or over were immune to this challenge.

[Aujeszky's disease: maternal immunity of piglets born of sows inoculated with various vaccines (author's transl)]. / Ziekte van Aujeszky: maternale immuniteit van biggen, geboren uit met verschillende entstoffen geënte zeugen.

Studies on the maternal state of immunity were done in 4-10 week-old piglets born of vaccinated sows free from Aujeszky's disease. The sows were inoculated with three different vaccines: two live vaccines (Aescovac Aujeszky) and the MK25 vaccine) and an inactivated vaccine (Geskyvac). The maternal state of immunity of the piglets was assessed from the titre of the virus-neutralizing (VN) antibodies in the blood. To do so, samples were taken from 300-400 4-10-week-old piglets per vaccine inoculated in the sow. At the same time, the VN titre of the blood of the sow was determined. The VN titres were highest in those sows which were vaccinated with Geskyvac. There was an obvious correlation between the VN titre of the sow and the maternal VN titres of the piglets. As a result, the maternal state of immunity in the sows vaccinated with Geskyvac also was highest. The value of the maternal VN titres in the assessment of maternal immunity was tested by exposing 28-37-day-old piglets showing various maternal VN titres to intracerebral challenge with 2000 TCID50 of Aujeszky disease virus (Van Doorn strain). Piglets showing VN titres higher than 1:8 were usually found to be immune against this challenge.