Toxoplasma gondii: From animals to humans

Institut für Parasitologie, Tierärztliche Hochschule Hannover, Bünteweg 17, D-30559, Hannover, Germany.
International Journal for Parasitology (Impact Factor: 3.87). 11/2000; 30(12-13):1217-58. DOI: 10.1016/S0020-7519(00)00124-7
Source: PubMed


Toxoplasmosis is one of the more common parasitic zoonoses world-wide. Its causative agent, Toxoplasma gondii, is a facultatively heteroxenous, polyxenous protozoon that has developed several potential routes of transmission within and between different host species. If first contracted during pregnancy, T. gondii may be transmitted vertically by tachyzoites that are passed to the foetus via the placenta. Horizontal transmission of T. gondii may involve three life-cycle stages, i.e. ingesting infectious oocysts from the environment or ingesting tissue cysts or tachyzoites which are contained in meat or primary offal (viscera) of many different animals. Transmission may also occur via tachyzoites contained in blood products, tissue transplants, or unpasteurised milk. However, it is not known which of these routes is more important epidemiologically. In the past, the consumption of raw or undercooked meat, in particular of pigs and sheep, has been regarded as a major route of transmission to humans. However, recent studies showed that the prevalence of T. gondii in meat-producing animals decreased considerably over the past 20 years in areas with intensive farm management. For example, in several countries of the European Union prevalences of T. gondii in fattening pigs are now <1%. Considering these data it is unlikely that pork is still a major source of infection for humans in these countries. However, it is likely that the major routes of transmission are different in human populations with differences in culture and eating habits. In the Americas, recent outbreaks of acute toxoplasmosis in humans have been associated with oocyst contamination of the environment. Therefore, future epidemiological studies on T. gondii infections should consider the role of oocysts as potential sources of infection for humans, and methods to monitor these are currently being developed. This review presents recent epidemiological data on T. gondii, hypotheses on the major routes of transmission to humans in different populations, and preventive measures that may reduce the risk of contracting a primary infection during pregnancy.

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    • "Toxoplasma gondii is an apicomplexan ubiquitary intracellular parasite that can infect all warmblooded animals, including humans (Tenter et al., 2000; Dubey et al., 2012; Franco et al., 2015). The infection caused by this parasite is usually asymptomatic for immunocompetent individuals, but it causes severe consequences for immunocompromised individuals, like HIV–AIDS patients. "

    Frontiers in Microbiology 11/2015; 6(e108329-1305). DOI:10.3389/fmicb.2015.01305 · 3.99 Impact Factor
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    • "FAO (2014) considers T. gondii as one of the most important foodborne parasites in the world. Wild boar has an important role in the epidemiological cycle of this protozoan parasite as an intermediate host that can potentially infect humans if the meat is consumed raw or undercooked (Tenter et al. 2000; Dubey and Jones 2008, Dubey 2010). Under this assumption, the detection of infected animal carcasses from the food chain is an important public health issue (Cook et al. 2000; Hill et al. 2006). "
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    ABSTRACT: Toxoplasmosis is a global zoonosis caused by the protozoan parasite Toxoplasma gondii. Detection of antibodies to T. gondii in serum samples from hunted animals may represent a key step for public health protection. It is also important to assess the circulation of this parasite in wild boar population. However, in hunted animals, collection of blood is not feasible and meat juice may represent an alternative sample. The purpose of the present study was to evaluate heart meat juice of hunted wild boars as an alternative sample for post-mortem detection of antibodies to T. gondii by modified agglutination test (MAT). The agreement beyond chance between results from meat juice assessed with Cohen's kappa coefficient revealed that the 1:20 meat juice dilution provided the highest agreement. McNemars's test further revealed 1:10 as the most suitable meat juice dilution, as the proportion of positive paired samples (serum and meat juice from the same animal) did not differ at this dilution. All together, these results suggest a reasonable accuracy of heart meat juice to detect antibodies to T. gondii by MAT and support it as an alternative sample in post-mortem analysis in hunted wild boars.
    EcoHealth 11/2015; DOI:10.1007/s10393-015-1073-9 · 2.45 Impact Factor
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    • "Additionally, T. gondii infection causes economic losses due to the abortion and neonatal loss in livestock, especially in sheep and goats. Even worse than this is the fact that human can be infected by ingesting undercooked or raw meat containing tissue cysts, or by ingesting food or water contaminated with oocysts [3] [4] [5]. At present, prevention and treatment of toxoplasmosis mainly depends on chemotherapeutics that acting on the acute phase of the infection. "
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    ABSTRACT: Toxoplasma gondii (T. gondii) is an obligate, intracellular, protozoan parasite that infects large variety of warm-blooded animals including humans, livestock, and marine mammals, and causes the disease toxoplasmosis. Although T. gondii infection rates differ significantly from country to country, it still has a high morbidity and mortality. In these circumstances, developing an effective vaccine against T. gondii is urgently needed for preventing and treating toxoplasmosis. The aim of this study was to construct a multi-epitopes DNA vaccine and evaluate the immune protective efficacy against acute toxoplasmosis in mice. Therefore, twelve T- and B-cell epitopes from SAG1, GRA2, GRA7 and ROP16 of T. gondii were predicted by bioinformatics analysis, and then a multi-epitopes DNA vaccine was constructed. Mice immunized with the multi-epitopes DNA vaccine gained higher levels of IgG titers and IgG2a subclass titers, significant production of gamma interferon (IFN-γ), percentage of T lymphocyte subsets, and longer survival times against the acute infection of T. gondii compared with those of mice administered with empty plasmid and those in control groups. Furthermore, a genetic adjuvant pEGFP-RANTES (pRANTES) could enhance the efficacy of the multi-epitopes DNA vaccine associating with humoral and cellular (Th1, CD8(+) T cell) immune responses. Above all, the DNA vaccine and the genetic adjuvant revealed in this study might be new candidates for further vaccine development against T. gondii infection.
    Vaccine 10/2015; DOI:10.1016/j.vaccine.2015.10.077 · 3.62 Impact Factor
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