PubMed Health⌕ Search

Biomedical subjects

J A Wagenaar

Publications and source records attributed to J A Wagenaar.

At least 19 recordsLinked to original sources
PubMed2006

Presence of Salmonella and Campylobacter spp. in wild small mammals on organic farms.

The presence of Salmonella and Campylobacter spp. in rodents and insectivores (n = 282) was investigated on organic farms. Infections were encountered in house mice (8 of 83 Campylobacter positive and 1 of 83 Salmonella sp. strain Livingstone positive) and brown rats (1 of 8 Campylobacter positive) but not in other species. No shared Campylobacter genotypes were found between rodent and pig manure isolates. Effective on-farm rodent management is recommended.

Animal Husbandry↗
PubMed2006

Campylobacter in primary animal production and control strategies to reduce the burden of human campylobacteriosis.

Campylobacteriosis is one of the most important bacterial food-borne illnesses in humans. One significant source of infection is the handling and consumption of poultry meat, although other sources also contribute considerably. Controlling Campylobacter in broilers reduces the human burden of illness. Broilers can easily become colonised with Campylobacter and preventive measures in primary production have a limited and unpredictable effect. Vaccination, competitive exclusion, bacteriophage therapy and the use of bacteriocins are not yet commercially available. However, measures in the slaughterhouse can reduce contamination in the final product. At present, the most promising control strategy is to keep colonised and non-colonised flocks separate during slaughter ('scheduled processing'). The virtually Campylobacter-free meat can supply the fresh poultry meat market, while the meat from infected flocks can be treated to reduce the Campylobacter concentration. Meat from infected flocks can be treated by freezing but chemical decontamination appears to be more cost effective. A variant of this scenario is to treat only highly contaminated meat. The authors conclude that, until new techniques become commercially available, scheduled processing is the most cost-effective approach. Finally, the authors describe trends in antimicrobial resistance in Campylobacter.

Animals↗
PubMed2005

[Campylobacter as a venereal disease in cattle].

Since the introduction of AI, venereal diseases caused by Tritrichomonas fetus and Campylobacter fetus subsp. venerealis haved been eradicated in The Netherlands. Campylobacter fetus subsp. fetus can cause sporadic abortion and early embryonic death. When natural breeding is practised, venereal diseases must be included in the list of differential diagnoses of fertility problems. A case study of a Campylobacter fetus subsp. fetus infection is described.

Abortion, Veterinary↗
PubMed2005

Global detection and identification of Campylobacter fetus subsp. venerealis.

Bovine genital campylobacteriosis caused by Campylobacter fetus subsp. venerealis (Cfv) is a genital infection that threatens the cattle industry. Detection and identification of Cfv are key factors in control programmes. Trade regulations should be based on scientifically and internationally accepted methods of detection and identification of Cfv. Such methods are described in the World Organisation for Animal Health (OIE) Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. A study was conducted to determine which methods are in use in OIE Member Countries and to get an overview of new or improved tests. A questionnaire was sent to OIE Member Countries, and 26 out of 166 were returned. Globally, a diversity of methods for the detection and identification of Cfv are in use. The authors conclude that there is a lack of harmonisation that may have consequences for the description of the health status of countries and may lead to disputes with respect to trade regulations.

Abortion, Veterinary↗
PubMed2004

Effect of acidified feed on susceptibility of broiler chickens to intestinal infection by Campylobacter and Salmonella.

Consumption of poultry meat is associated with human Campylobacter and Salmonella infections. One way to control the presence of these bacteria in broiler flocks is to make chickens less susceptible for colonisation. Acidification of feed may be a tool to reduce the Campylobacter and Salmonella carriage in broiler chickens. In the present experiments an acidified feed with high levels of organic acid, 5.7% lactic acid and 0.7% acetic acid, was applied. In an in vitro experiment the reduction or growth of Campylobacter and Salmonella was measured after addition of 10(7)cfu of these bacteria into a conventional broiler feed, acidified feed and fermented feed, whereas the numbers of Salmonella increased in non-acidified feed. The number of Campylobacter decreased 2-3 (10)log cfu. In the acidified and fermented feed a complete reduction of Campylobacter was observed within 20 min, and a total Salmonella reduction started after 1h, and was complete after 2h. Subsequently, an in vivo experiment with 100 individually housed broiler chickens showed that chickens fed acidified feed were less susceptible to an infection with Campylobacter than were chickens fed conventional feed. The size of reduction was however limited. The susceptibility for Salmonella colonisation was not affected by acidified feed. It is concluded that the role for acidified feed in the control of Campylobacter and Salmonella is limited.

Animal Feed↗
PubMed2004

Transmission of Salmonella between broiler chickens fed with fermented liquid feed.

In the light of food safety and the control of Salmonella at chicken farms, fermented liquid feed (FLF) was studied. This moistened feed reduced the susceptibility of chickens for Salmonella. To assess the effect of the fermented feed on the transmission of Salmonella between chickens, a transmission experiment was performed. Salmonella shedding was followed within groups of two susceptible chickens together with two previously inoculated chickens. The between-chicken transmission was quantified by calculating a reproduction ratio (R0) and a transmission rate parameter (beta). R0 and beta in the FLF-treated groups were reduced, but a typical infectious chicken fed with FLF, could on average still infect more than one new infectious case. FLF can therefore reduce the transmission of Salmonella in chicken flocks, but it will not prevent the occurrence of major outbreaks.

Animal Feed↗
PubMed2004

Simultaneous presence of multiple Campylobacter species in dogs.

The prevalence of coinfection of Campylobacter species in dogs was determined using four isolation methods. In 26% of the positive-testing stools, multiple Campylobacter species were identified. The use of multiple isolation methods as well as the time lapse between sampling and processing are important for detection of coinfection.

Animals↗
PubMed2003

Entry and survival of Salmonella enterica serotype Enteritidis PT4 in chicken macrophage and lymphocyte cell lines.

Various leukocytes are involved in the reaction to counter Salmonella infection in chicken. The various leukocyte types react differently after an infection, since some clear the infection while others may cause dissemination of Salmonella throughout the chicken. Therefore, we investigated in vitro the entry and survival of Salmonella enterica serotype Enteritidis in chicken cell lines of various cell types, including two macrophage cell lines, HD11 and MQ-NCSU (NCSU), two B-cell lines LSCC-1104-X5 (1104) and LSCC-RP9 (RP9), and a T-cell line MDCC-MSB-1 (MSB-1). The macrophages were able to internalize high numbers of S. Enteritidis. In contrast and as expected, cells of the T-cell line MSB-1 and the B-cell line RP9 internalized bacteria at a much lower level. After S. Enteritidis entered the macrophages, the number of intracellular S. Enteritidis decreased over time, so that after 48h no more than 20% of the bacteria, which had entered, survived intracellularly. In contrast to macrophages, the number of S. Enteritidis in cells of the T-cell line MSB-1 and the B-cell line RP9 increased rapidly within 12h post-inoculation. Thereafter the number of intracellular S. Enteritidis decreased only slowly. In conclusion, all three different cell types were able to control and to start clearing S. Enteritidis, although macrophages were far more effective compared to T- and B-cells. However, none of the cell lines were able to clear S. Enteritidis fully within 48h. These results suggest that the three cell types play an important but different role in the dissemination and elimination of S. Enteritidis throughout the animal.

Animals↗
PubMed2003

Comparison of natural resistance in seven genetic groups of meat-type chicken.

1. Several studies have shown that genetic variation exists in response to various Salmonella strains in mammals and poultry. In the current study immunocompetence traits related to natural resistance to Salmonella were measured in 7 genetic groups of meat-type chickens (in total 296 chickens involved). 2. Variables were measured of both innate (phagocytic activity) and adaptive immune responses that are important after a natural or experimental Salmonella enteritidis infection. Two traditional Old Dutch Breeds (groups 1 and 2), four commercial broiler groups (groups 3 to 6), and one experimental broiler group (group 7) were used. In two periods, birds of each group were killed for examination at ages between 14 and 35 d post hatch. 3. Significant differences between groups were found for most immune variables measured, with significant correlations between several of them. All groups produced an adequate immune response, of either the innate or the adaptive type. 4. In the current study, group 2 showed the highest overall natural resistance, though none of the groups was uniformly superior with respect to all traits measured. 5. In conclusion, for reliable measurements of general immunocompetence or resistance to Salmonella, for example, it is important to measure several aspects of the immune system.

Aging↗
PubMed2003

Fermented liquid feed reduces susceptibility of broilers for Salmonella enteritidis.

The presence of Salmonella in chickens is a problem because poultry meat is recognized as a source of human salmonellosis. Fermented feed has characteristics like a high number of lactobacilli and high concentration of lactic acid, which could make chickens less susceptible for infection with Salmonella. Fermented feed might therefore prevent the colonization of chickens with Salmonella. Two studies were performed to quantify the effect of fermented liquid feed on the susceptibility of broilers for Salmonella. The fermented feed was prepared by fermenting a dry broiler feed supplemented with 1.4 parts of water. Lactobacillus plantarum was used for fermentation. The fermented liquid feed (FLF) contained 10(9) to 10(10) cfu lactobacilli per gram, and the pH was 4. Individually housed control chickens and FLF-fed chickens were inoculated with 10(2) to 10(7) cfu Salmonella enteritidis (SE). Colonization was estimated by cloacal swabs and quantitative caecal culture. The proportion of SE-shedding chickens was decreased in FLF-fed chickens. FLF-fed chickens required a longer time after inoculation or a higher inoculation dose to get the same proportion of infected chickens in comparison with dry feed-fed chickens. The level of cecal colonization with Salmonella in the ceca was not different at the end of the experimental period. The results indicate that FLF can hamper the introduction of Salmonella in broiler flocks because the chickens are less susceptible for infection. Fermented liquid feed might therefore be a new hurdle in the strategy to control Salmonella in chicken flocks.

Animal Feed↗
PubMed2002

Resistance of broiler outbred lines to infection with Salmonella enteritidis.

Salmonella infections originating from poultry are one of the major causes of food-borne disease. For the control of salmonella in poultry a multifactorial approach is more likely to be effective, and the genetic resistance of poultry breeds to salmonella infections may be a valuable contribution. Experimental Salmonella enteritidis infections were examined in three different broiler outbred lines: the FC line, which had been selected for feed conversion efficiency; the R line, which had been selected for growth rate; and the C line, a commercially available line. The FC line had the highest mortality rate after intramuscular inoculation with 5 x 10(6) colony forming units (CFU) of S. enteritidis at 2 weeks of age (40% versus 21 and 20% in the other lines). However, at slaughter age, the number of birds carrying salmonella in caecal contents, and the concentration of salmonella in the caecal contents, was lowest in the FC line. The FC and R lines were compared by inoculation with doses ranging from 10(2) to 10(7) CFU S. enteritidis. At sublethal doses (10(5) CFU or less), the FC line carried significantly less salmonella in caecal contents and the rate of systemic infection was lower. The start of shedding was also delayed compared with the R line. At doses of 10(6) CFU S. enteritidis or higher, there were no differences in salmonella carriage between the lines, and the FC line showed higher mortality. In conclusion, resistance to mortality and resistance to the carriage of S. enteritidis do not necessarily coincide within lines, as the FC line showed high mortality but low carriage, both in survivors of high infection doses and in all birds at lower infection doses.

Animals↗
PubMed2001

Characterization of the innate and adaptive immunity to Salmonella enteritidis PT1 infection in four broiler lines.

Four broiler lines were inoculated orally with Salmonella enteritidis phage type 1 at the age of 7 days (experiment A: lines 1 and 2) and at the age of 1 day (experiment B: lines 3 and 4). At various days post-infection chickens were sacrificed and the number of Salmonella in the caeca, liver, and spleen were determined. Furthermore, phagocytic activity, cellular immune responses, and humoral responses were determined using, respectively, single-cell suspensions of spleen or intestine and serum. In both experiments, similar trends were seen. Increased numbers of S. enteritidis were found in the caeca of lines 1 and 3, whereas at the same time a decreased colonization was found in the spleen and in the liver, as compared to lines 2 and 4. In the latter two lines, the phagocytic activity of the phagocytes was higher and the humoral responses were lower. Observations from this study suggest that lower activity of phagocytes and higher humoral activity prevent systemic S. enteritidis infection.

Animals↗
PubMed2001

Evidence for a genetically stable strain of Campylobacter jejuni.

The genetic stability of selected epidemiologically linked strains of Campylobacter jejuni during outbreak situations was investigated by using subtyping techniques. Strains isolated from geographically related chicken flock outbreaks in 1998 and from a human outbreak in 1981 were investigated. There was little similarity in the strains obtained from the different chicken flock outbreaks; however, the strains from each of three chicken outbreaks, including strains isolated from various environments, were identical as determined by fla typing, amplified fragment length polymorphism (AFLP) analysis, and pulsed-field gel electrophoresis, which confirmed the genetic stability of these strains during the short time courses of chicken flock outbreaks. The human outbreak samples were compared with strain 81116, which originated from the same outbreak but has since undergone innumerable laboratory passages. Two main AFLP profiles were recognized from this outbreak, which confirmed the serotyping results obtained at the time of the outbreak. The major type isolated from this outbreak (serotype P6:L6) was exemplified by strain 81116. Despite the long existence of strain 81116 as a laboratory strain, the AFLP profile of this strain was identical to the profiles of all the other historical P6:L6 strains from the outbreak, indicating that the genotype has remained stable for almost 20 years. Interestingly, the AFLP profiles of the P6:L6 group of strains from the human outbreak and the strains from one of the recent chicken outbreaks were also identical. This similarity suggests that some clones of C. jejuni remain genetically stable in completely different environments over long periods of time and considerable geographical distances.

Animals↗
PubMed2001

Genomic relatedness within five common Finnish Campylobacter jejuni pulsed-field gel electrophoresis genotypes studied by amplified fragment length polymorphism analysis, ribotyping, and serotyping.

Thirty-five Finnish Campylobacter jejuni strains with five SmaI/SacII pulsed-field gel electrophoresis (PFGE) genotypes selected among human and chicken isolates from 1997 and 1998 were used for comparison of their PFGE patterns, amplified fragment length polymorphism (AFLP) patterns, HaeIII ribotypes, and heat-stable (HS) serotypes. The discriminatory power of PFGE, AFLP, and ribotyping with HaeIII were shown to be at the same level for this selected set of strains, and these methods assigned the strains into the same groups. The PFGE and AFLP patterns within a genotype were highly similar, indicating genetic relatedness. The same HS serotypes were distributed among different genotypes, and different serotypes were identified within one genotype. HS serotype 12 was only associated with the combined genotype G1 (PFGE-AFLP-ribotype). These studies using polyphasic genotyping methods suggested that common Finnish C. jejuni genotypes form genetic lineages which colonize both humans and chickens.

Animals↗
PubMed2001

Comparative study using amplified fragment length polymorphism fingerprinting, PCR genotyping, and phenotyping to differentiate Campylobacter fetus strains isolated from animals.

A collection of Campylobacter fetus strains, including both C. fetus subsp. fetus and C. fetus subsp. venerealis, were phenotypically identified to the subspecies level and genotypically typed by PCR and amplified fragment length polymorphism (AFLP) analysis. Phenotypic subspecies determination methods were unreliable. Genotyping of the strains by PCR and AFLP showed a clear discrimination between the two subspecies.

Animals↗