Effect of rodent control on Toxoplasma gondii infections in animal friendly pig farms with a rodent problem.

Livestock farming can be prone to rodent infestations as it provides unlimited amounts of shelter, water and food to commensal rodents. Besides economic losses and structural damages, these rodents may transmit pathogens directly to farmers or via livestock to consumers of livestock products. Hygienic standards in intensive pig production systems have largely eliminated the contact between rodents and livestock. The introduction of animal-friendly production sytems may however lead to an increased contact between livestock and small mammals (both rodents & insectivores). This has led to a demand for rodent control methods that are in line with ecologic principles. To underline the necessity of appropriate rodent control in animal-friendly farming systems we used the tranfer of an important food-borne pathogen, Toxoplasma gondii, as an example. Using lightcycler PCR methods we showed that rodents on animal-friendly farms indeed harbored Toxoplasma gondii. Subsequently three farms with a rodent problem were chosen to investigate the effect of an intense rodent control campaign on the seroprevalence of Toxoplasma infection of slaughtered pigs. During the time period July 2006 to January 2007 rodent control campaigns were started on these three farms and all consecutive slaughtered pigs were tested for the presence of Toxoplasma antibodies. Toxoplasma seroprevalence on all three farms dropped during the rodent control campaign. Further research is needed to exactly find out which rodent or insectivore species form the largest risk for transfer of Toxoplasma infection and which control method is most appropriate to target these species. This project thus shows that rodent control needs extensive attention in animal friendly farming systems. Although extermination of rodents is possible using methods that are in line with organic principles we would like to stress the importance of prevention. Rodent prevention includes measures such as making the direct environment of the barns unattractive for rodents, closing cracks and openings of the barn to limit access of rodents, closing feed storage and using natural predators in the vicinity of the farm (predatory birds). Inappropriate rodent control is not only a problem that concerns organic farming, but should be addressed in any livestock system where increased contact between wildlife and farm animals is possible

The effect of infection with Toxoplasma gondii strains on the IFN-g production and parasitic load in tissues of experimentally infected pigs

Objectives: Toxoplasma gondii is an intracellular parasite of humans and animals. The infection with this pathogen causes severe diseases in humans and has an important economic impact in domestic animals. One of the main sources of infection in humans is the consumption of raw or undercooked meat. The objective of this study was to determine the influence of subsequent infections of pigs with different T. gondii strains on the parasitic load of tissues, and to study the accompanying immune response. Parasitic load after infection with different T. gondii strains The parasitic load in tissues of experimentally infected pigs was determined after a consecutive infection with two T. gondii strains: Gangji (type I/II) and LR (type II). Seronegative 6-weeks old pigs were simultaneously inoculated with 6000 tissue cysts of the IPB-Gangji strain (group 1, n=3) or the IPB-LR strain (group 2, n=3). Sixty days later both groups were re-infected with 6000 tissue cysts of the two respective strains (group 1: Gangji/LR and group 2: LR/Gangji). A third group of animals (n=3) were inoculated with 6000 tissue cysts of the IPB-Gangji strain at day 60 PI (group 3: Gangji). The animals (group 1, 2 and 3) were euthanized to determine the parasitic load by qPCR in the following tissues: brain, heart, spleen, skeletal muscles and diaphragm. In all groups brain and heart samples showed the highest parasitic load. In group 1 (Gangji/LR) most skeletal muscles tested contained parasitic DNA, while in group 2 (LR/Gangji) only few muscle samples tested positive. Moreover, the amount of DNA found in these muscles was remarkably lower than in positive tissues of group 1. Group 3 (Gangji ½ t) showed a very high and a moderate parasitic load in brain and two muscle samples, respectively. Interestingly, these positive tissues contained less parasite-derived DNA than the same tissues of group 1 but more than those of group 2, suggesting a clearance (effect of IPB-Gangji infection on IPB-LR-infection). Involvement of T cells in the immune response: The production of IFN-g by T lymphocytes was determined by qPCR. Hereto, PBMCs were isolated from blood samples taken every 14 days, and subsequently cultured for 48 hours in the presence of total lysate antigen (TLA) or ConA as a positive control. IFN-g detection showed an increased production in all infected animals compared to control animals, which correlated with the inoculation time point,and was independent from the inoculation strain. This elevated production did not reach the maximum level in group 3, as observed in group 1 and 2. The involvement of different T-cell subpopulations in the cellular response after infection with two strains of T. gondii was analysed by flow cytometry. Hereto, two groups of 6-weeks old pigs were inoculated with 6000 tissue cysts of the IPB-Gangji strain (group 4, n=3) or the IPB-LR strain (group 5, n=3). The PBMCs were isolated and cultured as described above. The T-cell populations (CD3+, CD4+, CD8+) and the intracellular IFN-g production were detected by flow cytometry. Infection by both strains induced IFN-g production, which was positively correlated with the time point of the inoculation and was brought about by CD3+CD4+ and CD3+CD8+ proliferating T lymphocytes. In group 4 and 5 mainly the CD3+CD8hi T-cells and, to a lesser extent, the CD3+CD4+ population produced IFN-g, whereas the CD3+CD8int showed the fewest IFN-g positive cells. Conclusions: This study and previous data suggest that the IPB-Gangji strain can induce a clearance of the infected tissues, irrespective of the strain of the initial inoculation. The cellular response to parasitic infection was demonstrated by the time-dependent and strain-independent increased production of IFN-g by mainly CD3+CD8hi T cells

Induction of partial protection against infection with Toxoplasma gondii genotype II by DNA vaccination with recombinant chimeric tachyzoite antigens36838

Infection with the obligate intracellular parasite Toxoplasma gondii is a significant source of parasitic infections worldwide. In adults, infections may often lead to severe retinochoroiditis. Infection of the foetus causes abortion or congenital pathology that may lead to neurological complications. Although several strategies have been suggested for making a vaccine, none is currently available. Here, we investigate the protection conferred by DNA vaccination with two constructs, pcEC2 (MIC2-MIC3-SAG1) and pcEC3 (GRA3-GRA7-M2AP), encoding chimeric proteins containing multiple antigenic sequences from T. gondii. After challenge with a T. gondii genotype II, but not a genotype III strain, a significant decrease in cerebral cyst load was found compared to the controls. The immune protection involved a cell-mediated immune response with the synthesis of the cytokines IFN-? and IL-10. In silico structure analysis and the expression profile of EC2, suggest an association between antigen stability, the degree of protein secondary structure and induction of cellular immune responses. Intracellular protein degradation is an important step in the pathway leading to presentation of antigenic peptides on Major Histocompatibility Complex molecules. We suggest that degradation of this chimeric protein may have contributed to the induction of a cellular immune response via enhanced presentation of antigenic peptides on Major Histocompatibility Complex class I molecules</p

Molecular Study of Toxoplasma gondii Isolates Originating from Humans and Organic Pigs in Belgium

International audienceToxoplasma gondii is a worldwide prevalent, zoonotic parasite of major importance for public health, which can infect any warm-blooded animal species, including humans. Humans can get infected by consumption of meat from a chronically infected animal, by ingestion of sporulated oocysts (resulting from the sexual replication in felids), via contaminated water, soil, or vegetables, and by vertical transmission via the placenta. Infection through meat consumption is estimated to be one of the main sources of human toxoplasmosis cases in developed countries, and more specifically pork is considered to be responsible for 41% of foodborne human toxoplasmosis cases in the United States. To better assess the role of pork as a source of T. gondii infection in humans in Belgium, parasites were isolated from pigs to compare with human clinical isolates in a molecular epidemiological study. A positive result was obtained by magnetic capture-quantitative polymerase chain reaction for T. gondii in 14 out of the 92 hearts sampled during 2016 and 2017 from pigs raised in organic farms. From 9 of these 14 samples, parasites were isolated by mouse bioassay, demonstrating the presence of viable T. gondii in animals intended for human consumption. When genotyped and compared with 15 human isolates obtained during 2015 and 2016, a highly related structured population was demonstrated. Overall, these findings demonstrate the presence of infectious T. gondii in pigs intended for human consumption. Therefore, a potential transmission of T. gondii strains from pigs to humans could occur. However, both species could also be infected via a common source of infection such as oocysts. Furthermore, Belgium does not have an official surveillance program for T. gondii in human cases or food-producing animals; as a consequence, the detection of the infection source of a patient is very rare. Overall, this study reinforces the identification of pork as a potential risk for the consumers

Isolation and genotyping of viable Toxoplasma gondii from sheep and goats in Ethiopia destined for human consumption

International audienceBackground: Toxoplasma gondii is an obligate intracellular protozoan parasite that infects humans and a broad spectrum of warm-blooded vertebrates. The present study was undertaken with the objectives of isolation and determining the genotypes of T. gondii strains from sheep and goats slaughtered in East and West Shewa Zones of Oromia Regional State, Central Ethiopia. Methods: Hearts of 47 sheep and 44 goats that were seropositive in the Direct Agglutination Test (DAT) were bioassayed in mice. A multiplex PCR assay with 15 microsatellite markers was employed for genotyping of T. gondii isolates from sheep and goats. Results: Viable T. gondii were isolated from 47 (51.65%) animals, 27 sheep and 20 goats. Most isolates caused sub-clinical infections in mice, however, 2 sheep and 1 goat isolates were mouse-virulent, killing mice between 19–27 days post-inoculation. The success of T. gondii isolation in mice increased significantly (P = 0.0001) with higher DAT antibody titers in sheep and goats. Genotyping revealed that 29 (87.88%) of the 33 isolates were Type II, 3 (9.09%) were Type III and 1 (3.03%) was atypical. Three strains (one type II, one type III, and the atypical genotype) were virulent for mice. Conclusions: T. gondii tissue cysts in sheep and goats slaughtered for human consumption are widespread. This is the first report on isolation and genotyping of T. gondii from sheep and goats of Ethiopia

Isolation and genotyping of viable Toxoplasma gondii from sheep and goats in Ethiopia destined for human consumption

BACKGROUND: Toxoplasma gondii is an obligate intracellular protozoan parasite that infects humans and a broad spectrum of warm-blooded vertebrates. The present study was undertaken with the objectives of isolation and determining the genotypes of T. gondii strains from sheep and goats slaughtered in East and West Shewa Zones of Oromia Regional State, Central Ethiopia. METHODS: Hearts of 47 sheep and 44 goats that were seropositive in the Direct Agglutination Test (DAT) were bioassayed in mice. A multiplex PCR assay with 15 microsatellite markers was employed for genotyping of T. gondii isolates from sheep and goats. RESULTS: Viable T. gondii were isolated from 47 (51.65%) animals, 27 sheep and 20 goats. Most isolates caused sub-clinical infections in mice, however, 2 sheep and 1 goat isolates were mouse-virulent, killing mice between 19-27 days post-inoculation. The success of T. gondii isolation in mice increased significantly (P = 0.0001) with higher DAT antibody titers in sheep and goats. Genotyping revealed that 29 (87.88%) of the 33 isolates were Type II, 3 (9.09%) were Type III and 1 (3.03%) was atypical. Three strains (one type II, one type III, and the atypical genotype) were virulent for mice. CONCLUSIONS: T. gondii tissue cysts in sheep and goats slaughtered for human consumption are widespread. This is the first report on isolation and genotyping of T. gondii from sheep and goats of Ethiopia.status: publishe

Partial depletion of CD4(+)CD25(+)Foxp3(+) T regulatory cells significantly increases morbidity during acute phase Toxoplasma gondii infection in resistant BALB/c mice

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