Toxoplasma gondii infection and toxoplasmosis in farm animals: Risk factors and economic impact

The protozoan parasite Toxoplasma gondii is a zoonotic parasite that can be transmitted from animals to humans. Felids, including domestic cats, are definitive hosts that can shed oocysts with their feces. In addition to infections that occur by accidental oral uptake of food or water contaminated with oocysts, it is assumed that a large proportion of affected humans may have become infected by consuming meat or other animal products that contained infective parasitic stages of T. gondii. Since farm animals represent a direct source of infection for humans, but also a possible reservoir for the parasite, it is important to control T. gondii infections in livestock. Moreover, T. gondii may also be pathogenic to livestock where it could be responsible for considerable economic losses in some regions and particular farming systems, e.g. in areas where the small ruminant industry is relevant. This review aims to summarize actual knowledge on the prevalence and effects of infections with T. gondii in the most important livestock species and on the effects of toxoplasmosis on livestock. It also provides an overview on potential risk factors favoring infections of livestock with T. gondii. Knowledge on potential risk factors is prerequisite to implement effective biosecurity measures on farms to prevent T. gondii infections. Risk factors identified by many studies are cat-related, but also those associated with a potential contamination of fodder or water, and with access to a potentially contaminated environment. Published information on the costs T. gondii infections cause in livestock production, is scarce. The most recent peer reviewed reports from Great Britain and Uruguay suggest annual cost of about 5–15 million US $ per country. Since these estimates are outdated, future studies are needed to estimate the present costs due to toxoplasmosis in livestock. Further, the fact that T. gondii infections in livestock may affect human health needs to be considered and the respective costs should also be estimated, but this is beyond the scope of this article

Phenotypic characterisation of the cellular immune infiltrate in placentas of cattle following experimental inoculation with Neospora caninum in late gestation

Abstract Despite Neospora caninum being a major cause of bovine abortion worldwide, its pathogenesis is not completely understood. Neospora infection stimulates host cell-mediated immune responses, which may be responsible for the placental damage leading to abortion. The aim of the current study was to characterize the placental immune response following an experimental inoculation of pregnant cattle with N. caninum tachyzoites at day 210 of gestation. Cows were culled at 14, 28, 42 and 56 days post inoculation (dpi). Placentomes were examined by immunohistochemistry using antibodies against macrophages, T-cell subsets (CD4, CD8 and γδ), NK cells and B cells. Macrophages were detected mainly at 14 days post inoculation. Inflammation was generally mild and mainly characterized by CD3+, CD4+ and γδ T-cells; whereas CD8+ and NK cells were less numerous. The immune cell repertoire observed in this study was similar to those seen in pregnant cattle challenged with N. caninum at early gestation. However, cellular infiltrates were less severe than those seen during first trimester Neospora infections. This may explain the milder clinical outcome observed when animals are infected late in gestation.The authors acknowledge the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS), UK, and Instituto Nacional de Tecnología Agropecuaria (INTA), Argentina, for funding this study and Dr Alex Schock from Animal Health and Veterinary Laboratories Agency and Prof. Gary Entrican from Moredun Research Institute for useful and constructive discussion.Peer Reviewe

Placental thrombosis in acute phase abortions during experimental Toxoplasma gondii infection in sheep

43 p.After oral administration of ewes during mid gestation with 2000 freshly prepared sporulated oocysts of T. gondii isolate M4, abortions occurred between days 7 and 11 in 91.6% of pregnant and infected ewes. Afterwards, a further infection was carried out at late gestation in another group of sheep with 500 sporulated oocysts. Abortions happened again between days 9 and 11 post infection (pi) in 58.3% of the infected ewes. Classically, abortions in natural and experimental ovine toxoplasmosis usually occur one month after infection. Few experimental studies have reported the so-called acute phase abortions as early as 7 to 14 days after oral inoculation of oocysts, and pyrexia was proposed to be responsible for abortion, although the underline mechanism was not elucidated. In the present study, all placentas analysed from ewes suffering acute phase abortions showed infarcts and thrombosis in the caruncullar villi of the placentomes and ischemic lesions (periventricular leukomalacia) in the brain of some foetuses. The parasite was identified by PCR in samples from some placentomes of only one sheep, and no antigen was detected by immunohistochemical labelling. These findings suggest that the vascular lesions found in the placenta, and the consequent hypoxic damage to the foetus, could be associated to the occurrence of acute phase abortions. Although the pathogenesis of these lesions remains to be determined, the infectious dose or virulence of the isolate may play a role in their developmentS

Caracterización lesional y etiológica de neumonías en vacuno de cebo sacrificado en matadero

El Complejo Respiratorio Bovino constituye una importante enfermedad en bovinos de cebo. Los agentes etiológicos principalmente implicados en este síndrome incluyen virus (BoHv1,PI-3, BVDv, bRSV), bacterias (Mannheimia haemolytica, Pasteurella multocida, Histophilussomni, Trueperella pyogenes) y Mycoplasma bovis. Dentro de este síndrome, la neumonía es la lesión más relevante. Este estudio se ha realizado en animales de cebo sacrificados en matader

Inflammatory infiltration into placentas of Neospora caninum challenged cattle correlates with clinical outcome of pregnancy

International audienceInfection with Neospora caninum stimulates host cell-mediated immune responses, which may be responsible for placental damage leading to bovine abortion. The aim of this study was to compare immune responses in the bovine placenta, following experimental infection in different stages of pregnancy. Placentomes were examined by immunohistochemistry and inflammation in early gestation was generally moderate to severe, particularly in the placentas carrying non-viable foetuses, whereas it was milder in later stages, mainly characterised by the presence of CD3+, CD4+ and γδ T-cells. This distinctive cellular immune response may explain the milder clinical outcome observed when animals are infected in later gestation

Efectos de la vacunación frente a la paratuberculosis antes o después de la infección. Estudio experimental en la especie caprina

La vacunación es el procedimiento más eficaz para el control de la paratuberculosis El objetivo de este estudio es valorar la eficacia de la vacunación tras su administración antes y después de la infección, en un modelo experimental en cabras. Se empleó un total de 35 cabritos de 1-2 meses de edad, ocho de los cuales fueron vacunados y posteriormente infectados con la cepa K-10 de Mycobacterium avium subsp paratuberculosis (Map). Parte de los animales se sacrificaron a los 150 días post-infección (dpi) para comprobar el establecimiento de la infección, y posteriormente 5 cabritos previamente infectados se vacunaron a los 180 dpi. A los 360 dpi se sacrificaron todos los animales, en los que se realizaron estudios histopatológicos, de valoración de la respuesta inmune periférica y aislamiento de Map de heces y tejidos. La vacuna indujo la producción de niveles elevados de IFN-γ, pero menores en los animales vacunados tras la infección (IV). Se observó una reducción en el número y gravedad de las lesiones en el grupo de cabras vacunadas antes de la infección (VI), que fue progresiva a lo largo del estudio. Sin embargo, los animales vacunados tras la infección (IV) mostraron una variabilidad individual marcada, apareciendo cabras sin lesiones, con formas focales e incluso una con lesión difusa, siendo en conjunto la intensidad lesional superior a la del grupo infectado. Solo se aisló Map de dos animales, uno del grupo IV y otro infectado. La vacunación frente a paratuberculosis tendría un efecto claramente protector en cabras si se aplica previamente a la infección, mientras que si se hace después, su efecto terapéutico no tendría lugar en todos los animales, existiendo diferencias individuales en la respuesta

Cytokine expression in the placenta of pregnant cattle after inoculation with Neospora caninum

13 páginas, 4 tablas, 2 figuras.Neospora caninum is recognized as a major cause of reproductive losses worldwide but its pathogenesis is not completely understood. Immune mediated placental pathology has been reported as being responsible for compromising pregnancy probably due to the adverse effects of exacerbated Th1 type response at the maternal-foetal interface. Different clinical outcomes are known to occur following experimental infections of cattle at different stages of gestation, with foetal death being the most common finding during early gestation, and the birth of live congenitally infected calves following infection later in gestation. The aim of the current study was to characterize the cytokine expression in the placenta of cattle experimentally challenged with tachyzoites of the Nc-1 strain during early, mid and late gestation. Moderate to severe infiltration of IL-12, IFN-γ and TNF-α expressing cells was observed in the placentas collected at early gestation and this infiltration was more pronounced in the samples collected from challenged dams carrying non-viable foetuses, compared with the mothers carrying viable foetuses. In contrast, the infiltration of Th1 cytokine expressing-cells was mild following N. caninum infection in mid gestation and scarce during infection in late gestation. Scarce expression of IL-4 was observed in the placentas from N. caninum-challenged and negative control animals throughout gestation. The milder Th1 immune response observed during later stages of gestation following Nc-1 infection could partially explain the less severe clinical outcome when compared to early pregnancy. © 2014 Elsevier B.V.The authors acknowledge the Scottish Government's Rural and Environment Science and Analytical Services Division (RESAS), UK, and Instituto Nacional de Tecnología Agropecuaria (INTA), Argentina.Peer Reviewe