Gondii Tissue Cysts Research Articles

Evaluating uncertainty and variability associated with Toxoplasma gondii survival during cooking and low temperature storage of fresh cut meats

Toxoplasmosis is an infection caused by the protozoan parasite, Toxoplasma gondii. It has been reported as the fourth leading cause of hospitalization and second leading cause of death among 31 major foodborne pathogens in the United States. Humans are infected through consumption of raw or undercooked meat containing T. gondii tissue cysts or ingestion of food, soil, or water contaminated by T. gondii oocysts. People often lack knowledge about how to prevent T. gondii infection, especially the risks associated with eating or handling raw or undercooked meat. Current available data on cooking or low temperature storage for whole cuts of meat are not sufficient to validate inactivation of T. gondii. The objectives of the present study were to estimate the relationship of time and temperature with the survival rate of T. gondii during cooking and low temperature storage of fresh cut meats. We used different statistical sampling techniques such as bootstrap resampling and Gibbs sampling to establish those relationships. Monte Carlo simulation was used to estimate the safe temperature for cooking and storing meats. The results showed no detection of T. gondii in fresh meats when the internal temperature reached above 64 °C (147.2 °F) and below −18 °C (0 °F). The tissue cysts can remain viable at least up to 30 days at 4 °C (39 °F) and about 3.3% cysts survived at 62.8 °C (145 °F). This study can provide helpful information in improving the risk models to further mitigate the public health burden of toxoplasmosis.

Antibody kinetics and exposure to Toxoplasma gondii in cats: a seroepidemiological study

Domestic cats are the most important definitive hosts for Toxoplasma gondii, the agent of an important global zoonosis. Serial sera from cats orally inoculated either withT. gondii tissue cysts (n = 3) or sporulated oocysts (n = 3) and from 65 client-owned cats, plus sera from 1,757 client-owned cats presented to veterinarians in Switzerland were analysed for an antibody response to T. gondii by ELISA. Risk factors for seropositivity and prevalence were estimated with a generalised linear and beta regression model. The first model examined the association of an OD405 value as the dependent variable, with gender, age, and outside access as possible independent variables. In the second model, we first analysed the data assuming a bimodal distribution representing two overlapping distributions of OD405 values from positive and negative cats, enabling the assignment of a probability of true infection status to each cat. Mean probabilities of true infection status across groups represent an estimate of true prevalence. These probabilities were then regressed against age, gender and outside access. Antibody kinetics in cats orally inoculated with tissue cysts, shedding oocysts, did not differ significantly from those of cats inoculated with sporulated oocysts without detectable oocyst excretion, suggesting extraintestinal parasite invasion and exposure to tachyzoites in both situations at an early stage of infection. Analysis of serial serum samples suggested a persisting long-term humoral immune response. Of the client-owned cats, 42.4% (95% confidence interval (CI): 40.1–44.6) had a positive true infection status. This was higher (56.3% (95% CI: 53.2–59.6)) in cats with outside access than in those without (22.1% (95% CI: 18.9–25.4)). In the first model, the factors age (P < 0.0001), gender (male: P = 0.046), and outside access (P < 0.0001) were independently associated with significantly higher OD405 values. In the second model, the probability of having a positive true infection status increased with age (P < 0.0001), was higher with outside access (P < 0.0001) and in outdoor male cats (P = 0.0006).

Key Limitations and New Insights Into the Toxoplasma gondii Parasite Stage Switching for Future Vaccine Development in Human, Livestock, and Cats.

Toxoplasmosis is a parasitic disease affecting human, livestock and cat. Prophylactic strategies would be ideal to prevent infection. In a One Health vaccination approach, the objectives would be the prevention of congenital disease in both women and livestock, prevention/reduction of T. gondii tissue cysts in food-producing animals; and oocyst shedding in cats. Over the last few years, an explosion of strategies for vaccine development, especially due to the development of genetic-engineering technologies has emerged. The field of vaccinology has been exploring safer vaccines by the generation of recombinant immunogenic proteins, naked DNA vaccines, and viral/bacterial recombinants vectors. These strategies based on single- or few antigens, are less efficacious than recombinant live-attenuated, mostly tachyzoite T. gondii vaccine candidates. Reflections on the development of an anti-Toxoplasma vaccine must focus not only on the appropriate route of administration, capable of inducing efficient immune response, but also on the choice of the antigen (s) of interest and the associated delivery systems. To answer these questions, the choice of the animal model is essential. If mice helped in understanding the protection mechanisms, the data obtained cannot be directly transposed to humans, livestock and cats. Moreover, effectiveness vaccines should elicit strong and protective humoral and cellular immune responses at both local and systemic levels against the different stages of the parasite. Finally, challenge protocols should use the oral route, major natural route of infection, either by feeding tissue cysts or oocysts from different T. gondii strains. Effective Toxoplasma vaccines depend on our understanding of the (1) protective host immune response during T. gondii invasion and infection in the different hosts, (2) manipulation and modulation of host immune response to ensure survival of the parasites able to evade and subvert host immunity, (3) molecular mechanisms that define specific stage development. This review presents an overview of the key limitations for the development of an effective vaccine and highlights the contributions made by recent studies on the mechanisms behind stage switching to offer interesting perspectives for vaccine development.

Computational image analysis reveals the structural complexity of Toxoplasma gondii tissue cysts

Toxoplasma gondii is an obligate intracellular parasite infecting up to one third of the human population. The central event in the pathogenesis of toxoplasmosis is the conversion of tachyzoites into encysted bradyzoites. A novel approach to analyze the structure of in vivo-derived tissue cysts may be the increasingly used computational image analysis. The objective of this study was to quantify the geometrical complexity of T. gondii cysts by morphological, particle, and fractal analysis, as well as to determine if it is impacted by parasite strain, cyst age, and host type. A total of 31 images of T. gondii brain cysts of four type-2 strains (Me49, and local isolates BGD1, BGD14, and BGD26) was analyzed using ImageJ software. The parameters of interest included diameter, circularity, packing density (PD), fractal dimension (FD), and lacunarity. Although cyst diameter varied widely, its negative correlation with PD was observed. Circularity was remarkably close to 1, indicating a perfectly round shape of the cysts. PD and FD did not vary among cysts of different strains, age, and derived from mice of different genetic background. Conversely, lacunarity, which is a measure of heterogeneity, was significantly lower for BGD1 strain vs. all other strains, and higher for Me49 vs. BGD14 and BGD26, but did not differ among Me49 cysts of different age, or those derived from genetically different mice. The results indicate a highly uniform structure and occupancy of the different T. gondii tissue cysts. This study furthers the use of image analysis in describing the structural complexity of T. gondii cyst morphology, and presents the first application of fractal analysis for this purpose. The presented results show that use of a freely available software is a cost-effective approach to advance automated image scoring for T. gondii cysts.

Distribution of Toxoplasma gondii Tissue Cysts in Shoulder Muscles of Naturally Infected Goats and Lambs

Toxoplasmosis has been recognized as a major public health problem worldwide. The consumption of uncooked or undercooked meat infected with Toxoplasma gondii tissue cysts is one of the main means of transmission of this parasite. Although sheep, goats, and pigs are commonly infected with T. gondii, little information is available on the distribution of T. gondii tissue cysts in naturally infected meat. In this study, we investigated the distribution of viable T. gondii tissue cysts in shoulder muscles of naturally infected lambs and goats. Hearts and shoulders of 46 lambs and 39 goats from a local grocery store were tested for T. gondii infection. Animals were evaluated for the presence of anti-T. gondii antibodies in heart blood and clots by the modified agglutination test. Fourteen of the 85 animals (seven lambs and seven goats) were seropositive. Six to 12 samples weighing 5, 10, and 50 g were obtained from shoulder muscles of each seropositive animal and used for bioassay in mice. The distribution of viable T. gondii differed according to the size of the sample analyzed, but in general larger sample sizes resulted in higher isolation rates (P < 0.05). Results of the study revealed an uneven distribution of T. gondii in muscle samples of lambs and goats and that T. gondii can be transmitted by consumption of very small servings (5 and 10 g) of meat when it is consumed raw or is undercooked.

Histopathological and Serological Analysis of Aborted Ewes and Neonatal Death with Toxoplasma gondii in Duhok City, Kurdistan-Iraq.

This study was carried out on seven flocks of ewes suffered from late abortion and neonatal mortality with the prevalence rate of infection reported as 13.95%. The blood and tissue samples were collected from the aborted ewes in several flocks of Duhok province, Kurdistan Region, Iraq. Serological analysis indicated that all the aborted ewes were confirmed positive for agglutination to Toxoplasma gondii (T. gondii)antibody. The investigation of the aborted fetuses showed the blood-stained fluid in the thoracic and abdominal cavity. Most of the aborted fetuses had also enlarged, congested, and friable livers and lungs. The placenta was swollen, reddish, and friable, and its cotyledons also spotted with whitish foci. T. gondii tachyzoites were also demonstrated in the placental sections of some aborted ewes. Severe congestion, necrosis, and infiltration of multinucleated cells were the most predominant histopathological changes of the aborted fetuses, as well as presented tissue cysts, tachyzoites, and bradyzoites in the liver, brain, heart, and lung. There were also several clusters of dark purple banana-shaped T. gondii tachyzoites within the brain and heart tissues in most of the examined aborted fetuses in different flocks. T. gondii tachyzoites were also detected from the peritoneal ascites of mice inoculated experimentally 12 days following the infection. Moreover, T. gondii tissue cysts were detected from the impression smears of the mice brains 32 days after the infection. Accordingly, the demonstration of T. gondii in Giemsa-stained impression smears associated with characteristic histopathological changes of different organs is a great fundamental method for the diagnosis of T. gondii in aborted cases.

Methods to assess the effect of meat processing on viability of Toxoplasma gondii: towards replacement of mouse bioassay by in vitro testing

Consumption of meat containing viable tissue cysts is considered one of the main sources of human infection with Toxoplasma gondii. In contrast to fresh meat, raw meat products usually undergo processing, including salting and mixing with other additives such as sodium acetate and sodium lactate, which affects the viability of T. gondii. However, the experiments described in the literature are not always performed in line with the current processing methods applied in industry. It was our goal to study the effect of salting and additives according to the recipes used by industrial producers. Mouse or cat bioassay is the ‘gold standard’ to demonstrate the presence of viable T. gondii. However, it is costly, time consuming and for ethical reasons not preferred for large-scale studies.Therefore, we first aimed to develop an alternative for mouse bioassay that can be used to determine the effect of processing on the viability of T. gondii tissue cysts. The assays studied were (i) a cell culture method to determine the parasite’s ability to multiply, and (ii) a propidium monoazide (PMA) dye-based assay to selectively detect DNA from intact parasites. Processing experiments were performed with minced meat incubated for 20 h with low concentrations of NaCl, sodium lactate and sodium acetate. NaCl appeared to be the most effective ingredient with only one or two out of eight mice infected after inoculation with pepsin-digest of portions processed with 1.0, 1.2 and 1.6% NaCl. Results of preliminary experiments with the PMA-based method were inconsistent and did not sufficiently discriminate between live and dead parasites. In contrast, the cell culture method showed promising results, but further optimization is needed before it can replace or reduce the number of mouse bioassays needed. In future, standardised in vitro methods are necessary to allow more extensive testing of product-specific processing methods, thereby providing a better indication of the risk of T. gondii infection for consumers.

Chronic Toxoplasma gondii infection contributes to decreasing of perineuronal nets surrounding neurons in the Corpus striatum of mice.

Recent advances in chronic toxoplasmosis understanding became the focus of discussion about behavioral abnormalities, which could be explained by cyst location and neuronal impairment in specific brain areas. Perineuronal nets (PNNs) are specialized extracellular matrices that surround the neuronal body and proximal dendrites and play key roles in neuronal circuitry maintenance and stabilization. Its impairment can lead to abnormal synaptic functioning with behavioral repercussions. In this context, we analyzed the impact of Toxoplasma gondii infection on neuronal integrity in the Corpus striatum of chronically infected mice. C57BL/6 and Balb/c female mice were infected with T. gondii ME49 cysts. Brain sections were submitted to immunohistochemistry with Wisteria floribunda agglutinin (WFA) for PNN labeling followed by quantification of tissue cyst and labeled neuronal cells 30days after infection. Our results revealed that C57BL/6 exhibited a significant decrease in PNN-positive (WFA+) labeled neurons and an expressively higher number of tissue cysts than Balb/c mice. It was also possible to observe that the number of T. gondii tissue cysts and the number of WFA+ neurons were inversely correlated for C57BL/6-infected mice. However, no correlation was observed for Balb/c mice. These data suggest how the impact of parasite dissemination in the brain and host characteristics can influence neuronal integrity impairment during infection by decreasing WFA+ neurons. This might be a plausible pathway in which the presence of T. gondii contributes to behavioral changes in the infected host.

Quantitative risk assessment of meat-borne Toxoplasma gondii infection in the mainland of China

Toxoplasma gondii, a protozoan zoonotic parasite, has a worldwide distribution. It can cause severe pathological damage to the fetus in primary infected pregnant women and life-threatening encephalitis in immunocompromised patients. One of the main transmission routes to humans is consumption of raw or undercooked meat containing viable T. gondii tissue cysts. In China, the lack of quantitative information on the risk and incidence of infection due to consumption of meat hampers the development of prevention strategies to reduce the burden of toxoplasmosis. The aim of this study was to set up a quantitative microbial risk assessment (QMRA) model to estimate the relative attribution of different types of meat (i.e., pork, beef, lamb and mutton, chicken and duck) to human T. gondii infections in China. The model was built based on the structure of the first meat-borne T. gondii infection QMRA model developed in the Netherlands and applied for seven regions of mainland China. Data on the prevalence of T. gondii in livestock and consumption were obtained from China, however information on preparation habits was lacking. Consumption data were available as average consumption amounts per day collected over three days. The results calculated from the QMRA model were at least thousand-fold higher compared to the incidence rate obtained from an epidemiological susceptible-infected (SI) type model. In general, pork and chicken meat contributed more to the estimated number of infections than beef, small ruminant and duck meat. Cooking temperature was identified as one of the parameters that most strongly affected the estimated incidence rate in the QMRA model. Sensitivity analysis showed that the estimated incidence rate from the QMRA model would be comparable to the results obtained from the SI model if final cooking temperatures are around 1.7 times higher than the temperatures based on a dataset for American consumers. Scenario analysis demonstrated that it is important to know portion size and frequency of consumption in addition to total consumed amounts to calculate incidence of infection. Due to uncertainties present in the input data and the at least thousand-fold overestimated incidence rates, the results merely give an indication of the relative importance of different types of meat. However, the QMRA model clearly identified the key knowledge gaps for future research and can subsequently support cost-effective decisions to reduce the disease burden of human toxoplasmosis.

The effect of salting on Toxoplasma gondii viability evaluated and implemented in a quantitative risk assessment of meat-borne human infection

The protozoan parasite Toxoplasma gondii can infect all warm-blooded animals and it causes the disease toxoplasmosis. Meat containing viable T. gondii tissue cysts is considered one of the main sources of human infection. The relative importance of the different types of meat depends, not only on the prevalence of T. gondii infection in the different livestock species, but also on consumed volumes and preparation habits. To take these factors into account and to estimate the relative contribution of different meat products to human infection, a quantitative risk assessment model for meat-borne T. gondii infection was previously developed. However, at the time, the effect of salting on parasite viability was estimated based on a single experiment. In recent years, data using salting methods that are more in line with processing of meat products have come available. Literature data on the effect of salting on T. gondii viability were collected and used to fit a predictive model. In addition to the new salting model, a lower concentration of bradyzoites in cattle, more specific heating profiles, and more recent consumption data were implemented in the QMRA model for meat-borne T. gondii infection in the Netherlands. Results show that beef remains the most important source, as it contributed 84% of the total number of predicted infections in the Dutch population, followed by pork (12%), mutton (3.7%), lamb (0.2%) pork/beef mixed products (0.1%), and veal (0.01%). The predicted number of T. gondii infections is reasonably in line with epidemiological data. At the product level, filet americain (a raw beef spread) alone contributed 80% of the total predicted infections in the base model, but scenario analyses demonstrate that its contribution is highly dependent on the salting parameters. A clear identification of the most risky meat products is important, as interventions focussing on these products could have a great impact on reducing T. gondii disease burden in the Netherlands. For that reason, it is important that the effects of salting and other processing methods are evaluated in line with industrial processing and incorporated in quantitative risk assessment models for meat-borne toxoplasmosis.

Nanosilver Colloid Inhibits Toxoplasma gondii Tachyzoites and Bradyzoites in Vitro

Toxoplasma gondii, the coccidian protozoan parasite with worldwide distribution, is the agent of toxoplasmosis. The disease is life threatening in congenital form and in immunocompromised patients. The present study was carried out in 2016 to evaluate the in vitro effects of nanosilver colloid on tachyzoites and bradyzoites of T. gondii, RH and Tehran strains. Different concentrations (5, 10, 20 ppm) of nanosilver colloid were added to tachyzoites of T. gondii, RH strain (type I) and bradyzoites and tissue cysts of T. gondii, Tehran strain (type II) and incubated for 30, 60, 90 and 120 minutes. The mortality rates of tachyzoites and bradyzoites were evaluated by trypan blue dye and MTT assay. Then SEM carried out to show the changes between control and exposed parasites. The greatest mortality rate was seen in 20 ppm concentration and after 120 minutes of exposure. By electron microscopy, the structural changes were seen in tachyzoites of RH and tissue cyst of Tehran strain in comparison with control groups. Nanosilver colloid was effective on both tachyzoites and bradyzoites of T. gondii, RH and Tehran strains.

The impact of dry ageing vacuum-packed pork on the viability of Toxoplasma gondii tissue cysts

The present study evaluated the viability of Toxoplasma gondii tissue cysts in dry-aged pork loins (m. longissimus) after 14, 21 and 28 days under controlled temperature (0 °C ± 1 °C). The pigs (n = 9) were orally inoculated with 3,000 T. gondii oocysts. The right loin of each pig was aged for a predetermined period, and the left loin was kept unprocessed as a control. Two experiments were performed. In Experiment 1, the loins of three pigs were aged for 14 days and then bioassayed in both cats and mice. In Experiment 2, the loins of six pigs were bioassayed only in mice, and the ageing periods were 14, 21, and 28 days. Toxoplasma gondii tissue cysts remained viable in loins aged up to 14 days, as confirmed by bioassays in cats and mice. Viable T. gondii was not recovered by bioassays in mice from loins that were aged for 21 or 28 days. These results demonstrate that T. gondii remained viable in vacuum-packed dry-aged pork loins for 14 days at controlled temperature but not for 21 days or longer.

Toxoplasma gondii: How an Amazonian parasite became an Inuit health issue.

Toxoplasma gondii is a protozoan parasite that originated in the Amazon. Felids (mammals in the cat family) are the only definitive hosts. These animals shed large numbers of infectious oocysts into the environment, which can subsequently infect many intermediate hosts, including birds, mammals and, possibly, fish. Human T. gondii seroprevalence is high in some parts of the Canadian Arctic and is associated with adverse health consequences among Inuit population. Since the range of felids does not extend to the Arctic, it is not immediately obvious how this parasite got from the Amazon to the Arctic. The objectives of this overview are to summarize the health impacts of T. gondii infection in Inuit in Canada's North and to consider how this infection could have reached them. This article reviews the prevalence of T. gondii infection in terrestrial and marine animals in the Canadian Arctic and discusses their potential role in the foodborne transmission of this parasite to humans. Two distribution factors seem plausible. First, felids in more southern habitats may release infectious oocysts into waterways. As these oocysts remain viable for months, they can be transported northward via rivers and ocean currents and could infect Arctic fish and eventually the marine mammals that prey on the fish. Second, migratory terrestrial and marine intermediate hosts may be responsible for carrying T. gondii tissue cysts to the Arctic, where they may then pass on the infection to carnivores. The most likely source of T. gondii in Inuit is from consumption of traditionally-prepared country foods including meat and organs from intermediate hosts, which may be consumed raw. With climate change, northward migration of felids may increase the prevalence of T. gondii in Arctic wildlife.

The relationship between the presence of antibodies and direct detection of Toxoplasma gondii in slaughtered calves and cattle in four European countries

In cattle, antibodies to Toxoplasma gondii infection are frequently detected, but evidence for the presence of T. gondii tissue cysts in cattle is limited. To study the concordance between the presence of anti-T. gondii IgG and viable tissue cysts of T. gondii in cattle, serum, liver and diaphragm samples of 167 veal calves and 235 adult cattle were collected in Italy, the Netherlands, Romania and the United Kingdom. Serum samples were tested for anti-T. gondii IgG by the modified agglutination test and p30 immunoblot. Samples from liver were analyzed by mouse bioassay and PCR after trypsin digestion. In addition, all diaphragms of cattle that had tested T. gondii-positive (either in bioassay, by PCR on trypsin-digested liver or serologically by MAT) and a selection of diaphragms from cattle that had tested negative were analyzed by magnetic capture quantitative PCR (MC-PCR). Overall, 13 animals were considered positive by a direct detection method: seven out of 151 (4.6%) by MC-PCR and six out of 385 (1.6%) by bioassay, indicating the presence of viable parasites. As cattle that tested positive in the bioassay tested negative by MC-PCR and vice-versa, these results demonstrate a lack of concordance between the presence of viable parasites in liver and the detection of T. gondii DNA in diaphragm. In addition, the probability to detect T. gondii parasites or DNA in seropositive and seronegative cattle was comparable, demonstrating that serological testing by MAT or p30 immunoblot does not provide information about the presence of T. gondii parasites or DNA in cattle and therefore is not a reliable indicator of the risk for consumers.

Toxoplasma gondii tissue cyst formation and density of tissue cysts in shoulders of pigs 7 and 14 days after feeding infected mice tissues

Among the meat sources of Toxoplasma gondii, pork is considered important in the epidemiology of toxoplasmosis in the USA. How soon after infection T. gondii forms tissue cysts in pork is unknown. In the present study, eight serologically negative ˜3 months old pigs were fed mouse tissues infected with VEG (Type III) strain of T. gondii and euthanized 7 (4 pigs) and 14 days (4 pigs) post-inoculation (p.i.). Meat from the right shoulder of each pig was bioassayed in mice for T. gondii tissue cysts by peptic digestion. From each pig, the shoulder muscle was cut at random spots into 5 g, 10 g and 50 g portions. Extreme care was taken to use different scalpels and forceps to minimize cross contamination among 17 samples (6 replicates of each 5 g and 10 g portions and 5 replicates of 50 g). From the four pigs euthanized at 7 days p.i., a composite of ˜200 g of leftover meat from each shoulder was bioassayed in cats and their feces were tested for oocyst excretion. All eight pigs developed T. gondii antibodies (modified agglutination test, MAT, 1: 80 or higher) and viable T. gondii was isolated from shoulder meat of each pig. All four cats fed pork from excreted T. gondii oocysts. The density of T. gondii, based on mouse infectivity, varied within 5–50 g samples each pig, and between pigs within the same group, day 7 versus day 14 p.i. There were no significant differences in mouse bioassay results obtained with day 7 versus day 14 infected pigs. Overall, the rate of isolation of T. gondii increased with sample size of meat bioassayed. Results demonstrate that tissue cysts are formed early in infection and they are unevenly distributed.

Retrospective Serological Evidence of High Exposure of Globally Relevant Zoonotic Parasite Toxoplasma Gondii in The Latvian Population

Abstract Toxoplasmosis is an important infection caused by the single-celled parasite Toxoplasma gondii, which is a zoonotic parasite causing widespread human and animal diseases, mostly involving the central nervous system. Humans can acquire toxoplasmosis by ingestion of raw or undercooked meat containing T. gondii tissue cysts, ingestion of oocysts shed by infected felids via contaminated food or water, and by vertical transmission to the fetus through the placenta from the mother during pregnancy. The aim of the present study was to determine the seroprevalence of specific anti-T. gondii IgG and IgM antibodies using a large set of clinical diagnostic laboratory data obtained over a 14-year period. In total, 25 069 unique patients were included in the present study. The overall specific anti-T. gondii IgG prevalence were 36.3%, which was significantly (p &lt; 0.01) higher than IgM prevalence (2.4%). Mean age for IgG antibody-positive patients was 33.7 ± 12.2 years. A significant positive correlation (r = 0.99; p &lt; 0.01) was observed between age group and anti-T. gondii IgG antibody prevalence, which ranged from 4.2% to 66.7%. The most prevalent (69.9%; 95% CI 69.2–70.7) comorbidities of patients tested for presence of anti-T. gondii IgG and IgM antibodies were classified as factors affecting health status which includes also monitoring of normal pregnancy.

Evidence of red panda as an intermediate host of Toxoplasma gondii and Sarcocystis species.

Toxoplasma gondii has been found to infect almost all warm-blooded animals; however, some hosts lack direct evidence of T. gondii infection. The red panda (Ailurus fulgens) is an endangered species that mainly lives in temperate forests of South Asia. Here, T. gondii infection in red pandas from zoos in China were reported. Antibodies to T. gondii were found in 14.3% (2/14) of red pandas via the modified agglutination test (MAT) with a cut-off titer of 1:25. One viable T. gondii strain was isolated from tissues of red panda and designated as TgRedpandaCHn1. DNA from tachyzoites obtained from cell culture was characterized by PCR-RFLP with 10 markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29–2, L358, PK1, and Apico) and virulence genes of ROP5 and ROP18. The results indicate that this isolate belonged to ToxoDB genotype #20. The ROP18/ROP5 genotype combination predicated that this strain is non-lethal to mice, which is supported by the infection in mice. T. gondii tissue cysts were readily formed and mice survived. Tissue cysts observed in the histopathological sections of the tongue and diaphragm of one red panda were speculated as sarcocysts, but not T. gondii base on morphological characteristics. To our knowledge, this study is the first to report on the isolation of T. gondii from red panda. Additionally, this report provides direct evidence of red panda as an intermediate host of T. gondii and Sarcocystis species.

Isolation of viable Toxoplasma gondii from organs and Brazilian commercial meat cuts of experimentally infected pigs.

The present study evaluated the distribution and viability of Toxoplasma gondii tissue cysts in the organs and Brazilian commercial cuts of experimentally infected pigs. The pigs were infected with 3 × 103 oocysts of the T. gondii isolate TgCkBr57 (Type BrII). Mouse bioassays were performed on the brain, retina, tongue, diaphragm, and heart as well as the following muscle cuts: loin (longissimus), coppa (longissimus, spinalis dorsi, rhomboideus), tenderloin (psoas major), outside flat (biceps femoris), topside (semimembranosus), and top sirloin (gluteus medius). Toxoplasma gondii was isolated from the coppa, heart, diaphragm, and tongue of three pigs; from the tenderloin, outside flat, and brain of two pigs; and from the top sirloin and loin of one pig. Thus, the viability of T. gondii cysts was observed in all of the organs and cuts evaluated (except for the topside and retina), demonstrating the broad distribution of this parasite in pig organs and commercial meat cuts, and the importance of this species as a source of human infection.

Performance of three molecular methods for detection of Toxoplasma gondii in pork

Comparison of epidemiological data on the occurrence of Toxoplasma (T.) gondii tissue cysts in meat is hampered by the lack of standardization and a great variety of methods for molecular detection. Therefore, this study aimed to compare and validate three different polymerase chain reaction (PCR) methods for detection of T. gondii DNA in pork. Analytical performance characteristics of two real time PCRs (qPCRs; Tg-qPCR1, Tg-qPCR2) and one conventional endpoint PCR (cPCR), all targeting the 529 repeated element, were assessed using genomic DNA of three clonal T. gondii types prevailing in Europe and North America. qPCR efficiencies for all three clonal types ranged between 93.8 and 94.4% (Tg-qPCR1) and 94.3–95.6% (Tg-qPCR2). Tg-qPCR1 and Tg-qPCR2 showed an overall PCR performance score of 85% and displayed a similar 95% detection limit of 1.067 and 1.561 genome equivalents per PCR reaction (GE/PCR), respectively. However, T. gondii DNA could be detected at concentrations as low as 0.1 GE/PCR. Reliable quantification is possible over 4 log ranges from 105 to 100 GE/PCR with mean repeatability relative standard deviations of ≤11% and reproducibility relative standard deviations of ≤12.7%. Presumably, both qPCRs are similarly suitable for sensitive and specific detection of T. gondii DNA in pork. In contrast, the cPCR using primer pair TOX5/Tox-8 proved to be highly sensitive with a detection limit of 1.41 GE/PCR, but not suitable for detection of T. gondii DNA in pork as unspecific amplification of porcine DNA was observed resulting in bands with similar size to the desired T. gondii-specific PCR product.

Comparative Study in detection of Toxoplasma Gondii on Soil Sample from Baghdad and Kut Cities by Using PCR

Toxoplasma gondii caused a widely distributed protozoan disease called Toxoplasmosis. “The infective stage of T. gondii is capable of infecting variety of vertebrates including humans, domestic animals and wild felids are capable of serving as definitive hosts and T. gondii Oocyst are excreted in their feces”. “Toxoplasmosis is caused by ingestion T. gondii Oocyst from contaminated soil or water or foodstuff or by consuming T. gondii tissue cysts from infected hosts”. “The present study was designed to develop methods for detection of Oocyst from soil by nested PCR using Toxoplasma gene B1 primers”. The results in this study noted that the contamination was highest prevalence in gardens with T. gondii, schools and “backyards of homes” that is in Baghdad city (21.42%, 17.4%, 16.66%) respectively and in the Kut city is (6%, 5.5%, 4%) respectively. rural area infection with T. gondii was highest in the two cities Baghdad and Kut.