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

ABSTRACT 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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    • "The difficulties with conception represent a serious and growing public health problem in most of developed countries. Toxoplasmosis is the most widespread human parasitic infectious disease that affects about one third of the human population worldwide (Tenter et al. 2000). Currently, no method of treatment of latent toxoplasmosis is available. "
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    ABSTRACT: Several studies have investigated the association between infection with Toxoplasma gondii (Nicolle et Manceaux, 1908), pregnancy and fertility, but the results of studies focused on the fertility are rather ambiguous. Here we report results of four new cross-sectional studies. The studies were performed in the General University Hospital, Prague (study A with n = 1 165, and study C with n = 317), in private clinics of the Centre of Reproductive Medicine, Prague (study B with n = 1 016), and in a population of Czech and Slovak volunteers from the Facebook page 'Guinea Pigs' willing to participate in various basic science studies (study D with n = 524). In studies A and B, the clinical records were used to assess the fertility problems, whereas in studies C and D, the women were asked to rate their fertility problems using a six-point scale. Pregnant T. gondii-infected women were older than T. gondii-free women (study A: 33.1 vs 31.2, P < 0.001; study B: 30.6 vs 29.6, P = 0.012) and more often used assisted reproductive technology to conceive (study A: 17.2% vs 12.4%, P = 0.041; study B: 13.4% vs 9.2%, P = 0.317). Pregnant T. gondii-infected primiparous women were older than T. gondii-free primiparas (study A: 31.1 vs 29.5, P < 0.001; study B: 29.7 vs 28.9, P = 0.064) and more often used assisted reproductive technology to conceive (study A: 24.7% vs 14.4%, P = 0.010; study B: 15.9% vs 15.5%, P = 0.888). T. gondii-infected women reported to take a longer time to conceive than T. gondii-free women (P = 0.015). They also claimed to have more fertility problems than T. gondii-free women (P < 0.0001). Our results suggest that 'asymptomatic' latent toxoplasmosis could be a more serious source of fertility problems and health-associated burden than more severe but far rarer congenital toxoplasmosis.
    Folia parasitologica 08/2015; 62. DOI:10.14411/fp.2015.041 · 1.15 Impact Factor
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    • "This demonstrates that there is a need to apply appropriate technologies to the realities of sheep farming in the semiarid region. Absence of technification, such as practicing regular cleaning of the installations and reproductive management during the postpartum period, may facilitate the contact with T. gondii oocysts present in the environment (TENTER et al., 2000). In the risk factor analysis, the variables of purpose of rearing (P = 0.164), technified rearing (P = 0.066), flock size (P = 0.066) and occurrences of abortions (P = 0.081) were selected from the univariable analysis (Table 1). "
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    ABSTRACT: The aims of this survey were to determine the flock-level and animal-level prevalences of anti-Toxoplasma gondii antibodies in sheep in the State of Paraíba, Northeastern Brazil, and to identify risk factors. Blood samples were collected from 540 sheep in 63 flocks in 14 municipalities in the Sertão mesoregion. To serologically diagnose T. gondiiinfection, the indirect immunofluorescent antibody test (IFAT) was used. Flocks with at least one seropositive animal were considered positive. Among the 63 flocks, 28 (44.44%) were positive, and 60 (11.11%) of the 540 animals were seropositive. Variable flock size > 25 animals was identified as a risk factor (odds ratio = 3.2; 95% CI = 1.09 - 9.34; P = 0.033). The results from this survey demonstrate that T. gondii is spread among sheep in the State of Paraíba.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 08/2015; DOI:10.1590/S1984-29612015043 · 0.87 Impact Factor
    • "For humans, other forms of infection are epidemiologically important such as ingestion of raw or undercooked meat from infected animals. Thus, it is estimated that about one third of the world population is seropositive for toxoplasmosis [4]. The treatment of choice for toxoplasmosis in humans has been sulfadiazine, a drug that has "
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    ABSTRACT: The aim of this study was to investigate the effects of resveratrol on its free form and complexed with 2-hydroxypropyl-β-cyclodextrin (HPβCD) when associated with sulfamethoxazole-trimethoprim (ST) on cytokines levels of mice (n = 60) experimentally infected by Toxoplasma gondii. Groups A and E were used as controls (untreated): negative and positive, respectively. The onset of treatment started 20 days post-infection (PI), and it lasted for 10 consecutive days. ST was administered orally in doses of 0.5 mg kg(-1) for groups B and F, while 100 mg kg(-1) was the dose for resveratrol in its free form (groups C - G), inclusion complex (groups D and H), and on free and inclusion complex together (groups I - J). On day 31 PI, blood samples were collected in order to evaluate the cytokine profile. The mice that received drug combination (I and J) showed a significant (P < 0.05) reduction in the number of cysts in the brain compared to other infected groups (E - H). The results showed that mice from the Group E had increased (P < 0.001) levels of pro-inflammatory cytokines, while IL-10 levels were reduced when compared to the Group A. Additionally, there were increased levels of IL-4 and IFN-γ in animals of groups C and D, respectively (P < 0.05). Animals of the Group B showed reduced levels of IL-1, IL-4, IL-6, TNF-α, and IFN-γ (P < 0.05). Mice infected and treated (groups F - J) showed increased levels of pro-inflammatory cytokines along with a reduction of IL-10. Treatment with the combination of drugs (the Group J) led to a protective effect, i.e. reduction in pro-inflammatory cytokines. Therefore, resveratrol associated with ST was able to modulate seric cytokine profile and moderate the tissue inflammatory process caused by T. gondii infection, as well as to reduce parasite multiplication. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Microbial Pathogenesis 07/2015; 87. DOI:10.1016/j.micpath.2015.07.013 · 1.79 Impact Factor
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