Low predictive value of seroprevalence of Toxoplasma gondii in cattle for detection of parasite DNA

Observational longitudinal study on Toxoplasma gondii infection in fattening beef cattle: serology and associated haematological findings

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is a globally distributed zoonotic infection with significant implications for human and animal health. This study investigated the prevalence of T. gondii infection in a population of beef cattle at three different stages of their productive lifespan and examined the impact of T. gondii serological status on blood parameters. A commercial beef fattening unit in Italy was the setting for this research, which involved a biosecurity assessment upon cattle arrival, blood sampling at three time points and Toxoplasma-specific serological testing using indirect fluorescent antibody tests (IFAT). Results revealed a dynamic pattern of T. gondii seropositivity in cattle, with an initial prevalence of 30.6% at arrival (T0) that increased to 44.6% at 14 days (T1) and then decreased slightly to 39.3% at slaughter after 5 months (T2). Interestingly, seroconversion was observed during the study, indicating ongoing infections, and antibody waning occurred in some animals. In terms of blood parameters, seropositive cattle exhibited significantly lower mean corpuscular volume (MCV) and a higher neutrophil-lymphocyte (N/L) ratio, suggesting an activation of the innate immune response. Furthermore, cattle with higher antibody titres displayed higher neutrophil counts. However, all blood parameters with a statistical significance were within the reference range. This study provides for the first time a longitudinal investigation on the serological status for T. gondii in naturally exposed beef cattle. These findings provide valuable insights into the clinico-pathological aspects of natural T. gondii exposure in cattle and underscore the importance of monitoring and managing T. gondii infection in livestock production systems.

Fluctuations of antibody serum titers for Toxoplasma gondii and Neospora caninum in naturally infected crossbred cows during gestation

This study aimed to assess the fluctuations of antibody serum titers for Toxoplasma gondii and Neospora caninum in naturally infected crossbred cows during gestation and to investigate transplacental transmission of T. gondii; 51 cows were monitored during pregnancy by monthly serologic testing by indirect fluorescent antibody test. 33 cows were seronegative for both N. caninum and T. gondii, 10 were seropositive only for N. caninum, 5 were seropositive only for T. gondii, and 3 were seropositive for both N. caninum and T. gondii. In both protozoan infections, great variation in antibody levels in pregnant cows was observed, and there was significant increase (p<0.05) in the comparison between the averages of serological titration per trimester. There was a significant correlation (p<0.05) between month and probability of seropositivity for T. gondii. We conclude that pregnancy influences antibody titers of crossbred cows naturally infected with N. caninum and/or T. gondii, and that serologic testing for T. gondii in pregnant cows from the sixth month of gestation onward may decrease the number of false negative results.

A Review of Toxoplasma gondii in Animals in Greece: A FoodBorne Pathogen of Public Health Importance

Toxoplasma gondii is a zoonotic protozoon with a complex life cycle and the second most important foodborne pathogen in Europe. Surveillance of toxoplasmosis is based on national considerations since there are no mandatory controls along the food chain in the European Union, and underreporting of meat is still a problem in many countries like Greece. The current review provides an overview of T. gondii prevalence, associated risk factors, and surveillance in animals in Greece, focusing on the transmission role of meat and highlighting the control measures that should be adopted by consumers. Sows, wild boars, hares, equines, and cats had lower, while sheep and goats generally had higher seroprevalence than their respective pooled European and global values. Seroprevalence in chickens was similar between Greece and Europe, while there was high variation in cattle studies, with no data regarding dairy products. Though a comprehensive meat safety assurance system is the most effective approach to control the principal biological hazards associated with meat, such as T. gondii, the prerequisite risk categorisation of farms and abattoirs based on EFSA's proposed harmonised epidemiological indicators has not materialised as yet in Greece. Therefore, comprehensive control strategies are still required to ensure food safety and safeguard public health.

Migratory Wild Birds as Potential Long-Distance Transmitters of Toxoplasma gondii Infection

Toxoplasma gondii is a worldwide distributed zoonotic protozoan capable of infecting a wide range of mammals (including humans) and birds as intermediate hosts. Migratory wild birds, through interconnecting countries along their flyways, can play a role in the spatial spread of T. gondii and could contribute to its sylvatic cycle. Additionally, hunted wild birds used for meat consumption could represent a further source of human infection. To determine the presence of T. gondii in wild birds, a total of 50 individuals belonging to the Anseriformes and Charadriiformes orders were sampled during the 2021–2022 hunting season in Northern Italy. Cardiac muscle samples of three Northern shovelers (Anas clypeata), two wild mallards (A. platyrhynchos), one Eurasian teal (A. crecca), and one Northern lapwing (Vanellus vanellus) were positive for the molecular detection of T. gondii based on a targeted amplification of the B1 gene. A 14% (7/50) overall positivity was observed in the sampled population. Results from this study suggest a moderate exposure of wild aquatic birds to T. gondii, highlighting the importance of a further characterization of T. gondii in its wildlife hosts.

A Case of Bovine Eosinophilic Myositis (BEM) Associated with Co-Infection by Sarcocystis hominis and Toxoplasma gondii

Bovine eosinophilic myositis (BEM) is a specific inflammatory myopathy, often associated with Sarcocystis spp., with multifocal gray-green lesions leading to carcass condemnation with considerable economic losses. Here is described a peculiar case of BEM that occurred in an adult (16 month) cattle, born in France, bred, and slaughtered in Italy at the end of 2021. On inspection, muscles showed the typical multifocal gray-green lesions that were sampled for, cytological, histological, and molecular investigations, while meat juice was subjected to IFAT for Toxoplasma IgG. Genomic DNA was extracted from lesions, portions of healthy muscle and from meat juice pellet and analyzed by PCR targeting 18S rDNA, COI mtDNA and B1 genes, and sequenced. The cytology showed inflammatory cells mostly referable to eosinophils; at histology, protozoan cysts and severe granulomatous myositis were observed. A BEM lesion and meat juice pellet subjected to PCR showed, concurrently, sequences referable both to S. hominis and T. gondii. Meat juice IFAT resulted negative for T. gondii IgG. Our findings highlight the first detection of T. gondii DNA in association with S. hominis in a BEM case, suggesting a multiple parasite infection associated with this pathology, although the actual role of T. gondii infection in the pathophysiology of the diseases should be clarified.

Direct detection and quantification of Toxoplasma gondii in meat samples from feral raccoons (Procyon lotor) in Germany by magnetic-capture real-time PCR

Because the number of wild raccoons in Germany is increasing constantly, it appears to be economic reasonable to use their meat as food. For this purpose, it is essential to generate data regarding the pathogen load of the meat to be consumed and handled. It is known that raccoons, particularly in Germany, show a high seroprevalence of Toxoplasma gondii. Because serological data only indicates contact of a host to a parasite additional direct detection is needed to prove presence of parasitic stages in particular tissues. Therefore, a total of 150 samples from raccoons with known serostatus were tested and quantified using magnetic-capture real-time PCR for Toxoplasma gondii. As it represents potentially consumption-relevant parts of raccoons, meat from forelimb and hindlimb was examined. Samples were stratified into three groups based on the animals' serostatus (each 50 negative, low positive, and high positive). All samples from seronegative animals were found negative by MC-PCR as well. In a total of 56 meat samples from 100 seropositive animals, T. gondii DNA was detected. Statistically significant more samples were positive by MC-PCR in the high positive than in the low positive serostatus group (38/50 vs. 18/50, p < 0.0001). Furthermore, samples from the former group were also found to have statistically significant higher DNA equivalent values compared to samples from the low positive serostatus group (p < 0.0001). These results suggest that meat from seropositive raccoons may contain considerable numbers of T. gondii presenting a potential public health risk for humans whilst handling and consumption.

Toxoplasma gondii contamination at an animal agriculture facility: Environmental, agricultural animal, and wildlife contamination indicator evaluation

Toxoplasma gondii is a parasite of significant public health importance. We attempted to detect T. gondii contamination and assess advantages and disadvantages of contamination indicators through surveilling soil, wildlife, cats (Felis catus), and cows (Bos taurus) on a farm in Tennessee, U.S. in 2016 and 2017. Twenty-two soil samples were collected from the farm and subjected to oocyst flotation, DNA extraction, and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) targeting 18S ribosomal RNA (18S rRNA) gene to detect and identify T. gondii. Three samples (13.6%) were positive for the parasite; however, T. gondii DNA was not consistently detected from repeated tests. Blood samples were collected from small mammals, cats, and mesopredators live-trapped on the farm, and serum from 30 of the farm's cows were obtained. Serological testing by the modified agglutination test (MAT; cutoff 1:50) found 2.5% (1/40) of small mammals, 52.9% (9/17) of raccoons (Procyon lotor), and 50% (1/2) of domestic cats were seropositive for T. gondii antibodies. No antibodies were found in 16 opossums (Didelphis virginiana), two skunks (Mephitis mephitis), and 30 cows. Small mammal tissue samples were subjected to PCR-RFLP detection. Four out of 29 (13.7%) tissue samples were positive for T. gondii; however, T. gondii DNA was not consistently detected during repeated PCR-RFLP testing. Our results indicate the ability to detect T. gondii varies greatly by contamination indicator. We found detection of soil oocysts to be challenging, and results suggest limited utility of the method performed. The ability to detect T. gondii in animals was highly variable among species. Our research emphasizes the importance of a holistic approach when surveilling for T. gondii to compensate for shortcomings of each contamination indicator. Future research should be conducted to further investigate the most effective T. gondii surveillance methods and species with increased sample sizes at other agricultural facilities.

Seroprevalence, spatial distribution and risk factors associated with Toxoplasma gondii infection among cattle in a quilombola community in the Brazilian cerrado

Little is known about Toxoplasma gondii infection among cattle living in the Cerrado (Brazilian savanna) biome in Brazil. In particular, there is no epidemiological data relating to infection in quilombo lands, i.e. areas settled by Afro-descendants of escaped slaves. The aim of this study was to determine the prevalence, spatial distribution and risk factors associated with T. gondii infection among cattle in the Kalunga quilombo, in the Cerrado biome. Blood samples were collected from 1533 cattle for antibody detection using the indirect fluorescence antibody test (IFAT). The study area was subdivided into five macroregions to determine the spatial distribution of infection. An objective questionnaire was applied to the cattle owners to evaluate risk factors, which were analyzed using univariate analysis and logistic regression. The prevalence of T. gondii infection among cattle was 8.93% (137/1533), and antibodies were found in 49.6% of the herds (66/133), in all macroregions. The risk factors associated with T. gondii infection in cattle were the following: number of animals in the herd (OR: 30.56), purchase of cattle (OR: 2.57), age group (OR: 1.95) and average annual temperature (OR: 1.77). Thus, the occurrence rate, spatial distribution and risk factors associated with T. gondii infection among cattle in the Kalunga quilombola community are documented here, for the first time.

Public Health Significance of Toxoplasma gondii Infections in Cattle: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The ingestion of food or water contaminated with oocysts excreted by infected cats or ingesting uncooked or undercooked meat containing tissue cysts of T. gondii are the 2 major modes of transmission of T. gondii. Viable T. gondii is more prevalent in pork and lamb than in beef. In the past decade, there have been many articles on the high seroprevalence in cattle, particularly from China. There is a report of an outbreak of acute toxoplasmosis in humans suspected to be linked to the ingestion of Artisan fresh cheese from cow's milk. There are conflicting reports concerning the rate of congenital transmission of T. gondii in cattle, especially from Brazil. In a report from Brazil, viable T. gondii was isolated from the blood of 1 of 60 pregnant cows slaughtered at an abattoir and from 1 fetus. The role of beef in the epidemiology of T. gondii infections is still not clear. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and public health risks of T. gondii infections in cattle from beef and cow's milk worldwide for the past decade.

Toxoplasmosis: stages of the protozoan life cycle and risk assessment in humans and animals for an enhanced awareness and an improved socio-economic status

Toxoplasma gondii is a protozoan parasite distributed globally. It causes toxoplasmosis, which is prevalent in animals, birds, and soil. T. gondii infection leads to severe pathological impacts in immunodeficient patients and congenital cases. This review indicated that high prevalence groups had close contact with cats, dogs, consumed uncooked raw fruits, meat, or vegetables and the socio-economic level noted to be one of the crucial factors that influence toxoplasmosis. Toxoplasmosis infection is high in low-income countries and low in developed European countries. Immunosuppressed groups and pregnant women were the highly vulnerable groups. The epidemiology of the parasite enumerated various routes of infections; but consumption of T. gondii contaminated food was the major route of disease transmission. However, the role of meat and meat-producing animals on disease transmission remained unclear. Unfiltered water acts as the primary reservoir of toxoplasmosis transmission. The diagnostic methods for determining T. gondii infection are not the gold standard, and different approaches have been prescribed to analyze the infected populations based on the organs affected. Although toxoplasmosis was reported before 70 years, no appropriate solution noted to be recommended to treat this disease. Based on the present analyses, it concluded that the eradication of toxoplasmosis would be challenging from the world until people's socio-economic level is improved. The main aim of the present study was to analyze and update the disease transmission, epidemiology, and possible clinical interventions of toxoplasmosis.

Spatial distribution of Toxoplasma gondii in cows and associated risk factors

The aim of the present study was to evaluate the spatial distribution of the prevalence of T. gondii in cows using the indirect immunofluorescence assay and determine associated risk factors. Serum samples were collected from 2970 cows on 263 rural farms in 223 municipalities. A questionnaire was administered to herd owners to collect data for the evaluation of risk factors associated with this disease. Mean seroprevalence of T. gondii in cows was 8.48% (95% CI: 7.48 to 9.49). The microregions with the greatest likelihood (p ≤ 0.05) of having infected animals were Anápolis, Ceres, São Miguel do Araguaia, the Federal District, Anicuns, and Vão do Paraná. The purchase of females or males for reproductive/breeding purposes was significantly associated (p ≤ 0.05) with the prevalence of T. gondii in these regions. A positive correlation (0.7618; p = 0.047) was found between the prevalence of T. gondii and total area in hectares of forests in these regions, suggesting that wild cats may be disseminating T. gondii at these sites. The present results highlight the importance of considering the meat from these animals to be an important infection route for humans who eat raw or undercooked food.

Foodborne transmission of Toxoplasma gondii infection in the last decade. An overview

Toxoplasmosis is a zoonotic disease of global distribution and importance. It is caused by the protozoan parasite Toxoplasma gondii, the only species in the Toxoplasma genus. This parasite can infect most warm-blooded animals, including humans and livestock. Main routes of transmission are by ingestion of tissue cysts in raw or undercooked meat of infected animals, ingestion of raw vegetables or water contaminated with T. gondii oocysts from cat feces, and transplacental. Around one-third of human beings are chronically infected with T. gondii. Most infections appear to be asymptomatic in immunocompetent persons, but toxoplasmosis can be fatal to the fetus and immunocompromised adults. Water and foodborne outbreaks have been caused by this parasite worldwide, but few are well documented. Importantly, T. gondii is a parasite of high importance in animal health, causing reproductive failure, particularly in small ruminants, and clinical toxoplasmosis in many species. This overview discusses the knowledge of T. gondii infections in the last decade focusing on the foodborne transmission of this parasite.

Toxoplasma gondii seroprevalence in beef cattle raised in Italy: a multicenter study

Toxoplasmosis represents an important public health issue, with the consumption of raw or undercooked meat being a major way of human infection. The role of beef in the transmission of the parasite to humans is questioned due to lower quantity of tissue cysts compared with other meat-producing species. However, the habit of consuming raw beef is regionally diffused, and the risk posed by Toxoplasma gondii infection in cattle should not be overlooked. Therefore, to update information on T. gondii in cattle reared in Italy, a multicentric seroepidemiological survey was designed and implemented in four Northern regions (Liguria, Lombardy, Piedmont, and Trentino Alto Adige) and Sardinia. Overall, a convenience sampling was performed, collecting 1444 serum samples from 57 beef cattle herds. Thirteen beef breeds were sampled, besides cross-breed; bovines age varied from 3 months to over 12 years. Sera were tested with a commercial ELISA for the detection of anti-T. gondii antibodies. Individual and herd data were analyzed by binary logistic regression analysis. A T. gondii seroprevalence of 10.2% was recorded, with differences among regions and values ranging from 5.3% in Liguria to 18.6% in the Piedmont region (p value = 0.0001). Both young and adult animals and males and females tested positive, without any significant difference (age and gender: p value > 0.05). Lower seroprevalence values were recorded in cattle born in Italy (8.7%) if compared with animals imported from abroad (13.4%) (p value = 0.046). The spread of T. gondii in beef cattle destined to Italian consumers is confirmed, suggesting the need of continuous monitoring of the infection.

Detection of Toxoplasma gondii in retail meat samples in Scotland

Toxoplasma gondii is a globally important zoonotic parasite ranked as one of the most significant causes of disease burden among the major foodborne pathogens. Consumption of undercooked meat is a well-known risk factor for infection so the aim of this study was to investigate the presence of T. gondii in meat samples from retail outlets in Scotland. In Sampling Period 1, 300 meat samples (39 beef, 21 chicken, 87 lamb, 71 pork and 82 venison) were purchased from butchers', farmers' markets, farm shops and supermarkets, and in Sampling Period 2, 67 pure venison samples only were purchased from farmers' markets, farm shops and supermarkets. DNA was extracted and screened for T. gondii using a quantitative PCR targeting the 529 bp repeat element, and any positive samples were genotyped using PCR-RFLP targeting 10 markers. Meat juice was screened for T. gondii antibodies using a commercial ELISA or modified agglutination assay. Toxoplasma gondii DNA was detected in 0/39 (0%) beef samples, 1/21 (4.8%) chicken samples, 6/87 (6.9%) lamb samples, 3/71 (4.2%) pork samples and 29/82 (35.4%; Sampling Period 1) and 19/67 (28.4%; Sampling Period 2) venison samples. Partial PCR-RFLP genotyping revealed both clonal and non-clonal genotypes. Antibodies to T. gondii were detected in the meat juice of 2/38 (5.3%) beef samples, 3/21 (14.3%) chicken samples, 14/85 (16.5%) lamb samples, 2/68 (2.9%) pork samples and 11/78 (14.1%; Sampling Period 1) and 8/50 (16%; Sampling Period 2) venison samples. This is the first study to report the presence of T. gondii in retail meat products in Scotland and has highlighted venison as a potentially high risk meat. Further work is required to determine viability of parasites in this particular meat product.

Seroepidemiology of Toxoplasma gondii in Dairy Cows in Southeastern Brazil: Seropositive Cows on All Farms Investigated

PURPOSE

This study aimed to estimate the prevalence and identify the risk factors associated with the higher in-herd T. gondii seroprevalence in dairy cows in 37 farms in southern Minas Gerais, Southeastern Brazil.

METHODS

Serum samples from 1,105 dairy cows were subjected to an indirect fluorescence antibody test (IFAT 1:64) for anti-T. gondii IgG. The association existing between possible risk factors at the herd level and the seroprevalence were verified through Generalized Estimating Equation (GEE) multiple logistic regression models.

RESULTS

Anti-T. gondii antibodies were observed in 31.4% of the cows (347; 95% CI= 28.7-34.2) and on 100% of the farms (37; 95% CI= 90.6-100.0%), indicating that all properties possessed at least one seropositive animal. For univariate analysis, herds with seroprevalence were categorized as greater and less than 30% as the outcome. The "breeding of Holstein Friesian cows" (p= 0.016, OR= 6.667, 95% CI= 1.500-29.628) and in an "intensive system" (p= 0.013, OR= 6.120, 95% CI= 1.394-26.876) increased the chance of the herd seroprevalence being greater than 30% by approximately six-fold. However, these variables did not exhibit a significant association (p >0.05) in the Generalized Estimating Equations (GEE) logistic regression model.

CONCLUSIONS

The results demonstrate that T. gondii infection is widespread among dairy cows in the south of Minas Gerais, with a wide environmental dispersion of the parasite on farms in this region.

Toxoplasma gondii infection in slaughtered pigs and cattle in Poland: seroprevalence, molecular detection and characterization of parasites in meat

Background

Toxoplasma gondii infection may pose a severe medical problem especially in a congenital form and as an acquired infection in immunocompromised persons. Raw and undercooked meat of slaughtered animals is regarded as an important source of parasite infection; however, data concerning this issue in Poland are still insufficient. The aim of this study was to estimate the prevalence of T. gondii infection in pigs and cattle slaughtered for human consumption in Poland using serological and molecular methods.

Methods

Sera of 3111 pigs and 2411 cattle from 16 regions (voivodeships) of the country were examined for the presence of anti-T. gondii IgG using the direct agglutination test (DAT). Pepsin-digested samples of diaphragm and heart of seropositive animals were examined for the presence of T. gondii DNA (B1 gene) by nested PCR and real-time PCR, while non-digested samples were only examined by nested PCR. The B1 gene DNA samples were genotyped at 11 genetic markers using multilocus nested PCR-RFLP (Mn-PCR-RFLP) and sequencing.

Results

Seropositive DAT results were found in 11.9% of pigs and 13.0% of cattle. The highest seroprevalence was found in pigs from Podkarpackie (32.6%) and in cattle from Mazowieckie (44.6%). Data analysis showed that cattle > 5–10 years-old, as well as cattle and pigs from small farms, and pigs from farms with open production systems, had higher odds of testing seropositive (P < 0.05). Among the examined tissue samples, positive PCR results were found in samples from 12.2% and 10.2% of seropositive pigs and cattle, respectively. Among the samples successfully genotyped by Mn-PCR-RFLP and sequenced, four samples were identified as T. gondii type II and one sample as type I.

Conclusions

The presence of T. gondii antibodies in a substantial proportion of examined pigs and cattle as well as the detection of parasite DNA in their tissues highlight a potential health risk to the consumers in Poland.

Toxoplasma gondii in cattle in Brazil: a review

Toxoplasma gondii is an apicomplexan protozoan that is frequently found in both humans and animals worldwide. The aim of this review was to list important aspects of Toxoplasma gondii infection in cattle in Brazil. The frequency of occurrence of T. gondii antibodies in Brazilian cattle ranges from 1 to 89.1%, depending on the region evaluated, based on data from 1978 to 2018. However, some characteristics of T. gondii infection in cattle remain uncertain, such as the role of meat intake in transmitting the parasite to humans. Most information regarding T. gondii infection among Brazilian cattle is limited to evaluations of the frequency of occurrence of antibodies. About 70% of the diagnoses of infection in these ruminants in Brazil are made via the indirect fluorescence antibody test (IFAT). Nevertheless, little is known about the population structure of this protozoan in cattle. It is necessary to expand the studies on toxoplasmosis in cattle, in order to better understand T. gondii infection in these animals and its implications for Brazilian public health.

Toxoplasma gondii in beef consumed in France: regional variation in seroprevalence and parasite isolation

In France, the consumption of cattle and sheep meat appears to be a risk factor for infection of pregnant women with Toxoplasma gondii. Several nation-wide surveys in France have investigated the prevalence of T. gondii in sheep and pig meat, but little is known at present about the prevalence of the parasite in beef. The main objective of the present cross-sectional survey was to estimate the seroprevalence of T. gondii infection in beef consumed in France. A secondary objective was to attempt to isolate T. gondii from cattle tissues and to study the geographical and age variations of this seroprevalence. The overall estimate of seroprevalence of T. gondii in bovine carcasses (n = 2912), for a threshold of 1:6 was 17.38%. A strong age effect was observed (p < 0.0001) with a seroprevalence of 5.34% for calves (<8 months) and 23.12% for adults (>8 months). Seroprevalence estimates given by area of birth and area of slaughtering for adults showed that the areas with the highest seroprevalence were not the same between these two variables. Only two strains, corresponding to genotype II, were isolated from heart samples, indicating that there is a limited risk of human infection with T. gondii, which needs to be correlated with the food habit of consuming raw or undercook (bleu or saignant) beef. However, new questions have emerged, especially concerning the isolation of parasites from beef and the precise role of bovines, generally described as poor hosts for T. gondii, in human infection.

Cross-Sectional Survey on Toxoplasma gondii Infection in Cattle, Sheep, and Goats in Algeria: Seroprevalence and Risk Factors

A cross-sectional study aimed at assessing the seroprevalence and identifying the risk factors for Toxoplasma gondii infection in cattle, sheep, and goats in eight provinces located in two main Algerian agro-ecological zones was carried out from October 2015 to March 2018. Blood sera from 4074 animals of both sexes were tested for the presence of anti-T. gondii IgG antibodies, using the indirect, enzyme-linked, immunosorbent assay technique (ELISA). Moreover, to identify the potential risk factors of T. gondii infection, a survey through a breeders' questionnaires was conducted. Nearly one-fourth of the total number of animals tested (1024/4074)-i.e., 25.1%--were seropositive. The seroprevalence in cattle, sheep, and goats was 28.7%, 25.6%, and 11.9%, respectively. The area, sex, age, and herd size were identified as risk factors for T. gondii infection. Higher seropositivity rates were recorded in cows and goats (odds ratio (OR) = 1.63 and 6.4), in old animals (cattle, OR = 2.1; sheep, OR = 1.9; and goat, OR = 3.9), and in small size herds (cattle, OR = 2.5; sheep, OR = 1.9; goat, OR = 2.2). In conclusion, there is widespread T. gondii infection in cattle, sheep, and goats in these two strategic agricultural areas. The identification of the risk factors determines the type of measures and strategies to be undertaken to reduce, control, and prevent T. gondii infection in domestic animals, and thereby reduce human infection.

Cross-Sectional Survey on Toxoplasma gondii Infection in Cattle, Sheep, and Goats in Algeria: Seroprevalence and Risk Factors

A cross-sectional study aimed at assessing the seroprevalence and identifying the risk factors for Toxoplasma gondii infection in cattle, sheep, and goats in eight provinces located in two main Algerian agro-ecological zones was carried out from October 2015 to March 2018. Blood sera from 4074 animals of both sexes were tested for the presence of anti-T. gondii IgG antibodies, using the indirect, enzyme-linked, immunosorbent assay technique (ELISA). Moreover, to identify the potential risk factors of T. gondii infection, a survey through a breeders' questionnaires was conducted. Nearly one-fourth of the total number of animals tested (1024/4074)-i.e., 25.1%--were seropositive. The seroprevalence in cattle, sheep, and goats was 28.7%, 25.6%, and 11.9%, respectively. The area, sex, age, and herd size were identified as risk factors for T. gondii infection. Higher seropositivity rates were recorded in cows and goats (odds ratio (OR) = 1.63 and 6.4), in old animals (cattle, OR = 2.1; sheep, OR = 1.9; and goat, OR = 3.9), and in small size herds (cattle, OR = 2.5; sheep, OR = 1.9; goat, OR = 2.2). In conclusion, there is widespread T. gondii infection in cattle, sheep, and goats in these two strategic agricultural areas. The identification of the risk factors determines the type of measures and strategies to be undertaken to reduce, control, and prevent T. gondii infection in domestic animals, and thereby reduce human infection.

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.

A one health approach to vaccines against Toxoplasma gondii

Toxoplasmosis is a serious disease with global impact, now recognised as one of the most important food borne diseases worldwide and a major cause of production loss in livestock. A one health approach to develop a vaccination programme to tackle toxoplasmosis is an attractive and realistic prospect. Knowledge of disease epidemiology, parasite transmission routes and main risk groups has helped to target key host species and outcomes for a vaccine programme and these would be to prevent/reduce congenital disease in women and sheep; prevent/reduce T. gondii tissue cysts in food animal species and to prevent/reduce T. gondii oocyst shedding in cats. Most animals, including humans, develop good protective immunity following infection, involving cell mediated immune responses, which may explain why live vaccines are generally more effective to protect against T. gondii. Recent advances in our knowledge of parasite genetics and gene manipulation, strain variation, key antigenic epitopes, delivery systems and induction of immune responses are all contributing to the prospects of developing new vaccines which may be more widely applicable. A key area in progressing vaccine development is to devise standard vaccine efficacy models in relevant animal hosts and this is where a one health approach bringing together researchers across different disciplines can be of major benefit. The tools and technologies are in place to make a real impact in tackling toxoplasmosis using vaccination and it just requires a collective will to make it happen.

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.

Serological and molecular detection of Toxoplasma gondii in terrestrial and marine wildlife harvested for food in Nunavik, Canada

BACKGROUND

Toxoplasma gondii, a zoonotic protozoan parasite, infects mammals and birds worldwide. Infection in humans is often asymptomatic, though illnesses can occur in immunocompromised hosts and the fetuses of susceptible women infected during pregnancy. In Nunavik, Canada, 60% of the Inuit population has measurable antibodies against T. gondii. Handling and consumption of wildlife have been identified as risk factors for exposure. Serological evidence of exposure has been reported for wildlife in Nunavik; however, T. gondii has not been detected in wildlife tissues commonly consumed by Inuit.

METHODS

We used a magnetic capture DNA extraction and real-time PCR protocol to extract and amplify T. gondii DNA from large quantities of tissues (up to 100 g) of 441 individual animals in Nunavik: 166 ptarmigan (Lagopus lagopus), 156 geese (Branta canadensis and Chen caerulescens), 61 ringed seals (Pusa hispida), 31 caribou (Rangifer tarandus) and 27 walruses (Odobenus rosmarus).

RESULTS

DNA from T. gondii was detected in 9% (95% CI: 3-15%) of geese from four communities in western and southern Nunavik, but DNA was not detected in other wildlife species including 20% (95% CI: 12-31%) of ringed seals and 26% (95% CI: 14-43%) of caribou positive on a commercial modified agglutination test (MAT) using thawed heart muscle juice. In geese, tissue parasite burden was highest in heart, followed by brain, breast muscle, liver and gizzard. Serological results did not correlate well with tissue infection status for any wildlife species.

CONCLUSIONS

To our knowledge, this is the first report on the detection, quantification, and characterization of DNA of T. gondii (clonal lineage II in one goose) from wildlife harvested for food in Nunavik, which supports the hypothesis that migratory geese can carry T. gondii into Nunavik where feline definitive hosts are rare. This study suggests that direct detection methods may be useful for detection of T. gondii in wildlife harvested for human consumption and provides data needed for a quantitative exposure assessment that will determine the risk of T. gondii exposure for Inuit who harvest and consume geese in Nunavik.

Seroprevalence of Toxoplasma gondii in domestic pigs, sheep, cattle, wild boars, and moose in the Nordic-Baltic region: A systematic review and meta-analysis

Background

Toxoplasma gondii is an important foodborne zoonotic parasite. Meat of infected animals is presumed to constitute a major source of human infection and may be a driver of geographical variation in the prevalence of anti-T. gondii antibodies in humans, which is substantial in the Nordic-Baltic region in northern Europe. However, data on seroprevalence of T. gondii in different animal species used for human consumption are scattered.

Methods

We conducted a systematic review of seroprevalence studies and meta-analysis to estimate the seroprevalence of T. gondii in five animal species that are raised or hunted for human consumption in the Nordic-Baltic region: domestic pigs (Sus scrofa domesticus), sheep (Ovis aries), cattle (Bos taurus), wild boars (Sus scrofa), and moose (Alces alces). We searched for studies that were conducted between January 1990 and June 2018, and reported in articles, theses, conference abstracts and proceedings, and manuscripts. Subgroup analyses were performed to identify variables influencing the seroprevalence.

Findings

From a total of 271 studies identified in the systematic review, 32 were included in the meta-analysis. These comprised of 13 studies on domestic pigs, six on sheep, three on cattle, six on wild boars, and four on moose. The estimated pooled seroprevalence of T. gondii was 6% in domestic pigs (CI_95%: 3–10%), 23% in sheep (CI_95%: 12–36%), 7% in cattle (CI_95%: 1–21%), 33% in wild boars (CI_95%: 26–41%), and 16% in moose (CI_95%: 10–23%). High heterogeneity was observed in the seroprevalence data within each species. In all host species except wild boars, the pooled seroprevalence estimates were significantly higher in animals >1 year of age than in younger animals. Not all studies provided information on animal age, sensitivity and specificity of the serological method employed, and the cut-off values used for defining an animal seropositive.

Conclusions

A substantial proportion of animals raised or hunted for human consumption in the region had tested positive for T. gondii. This indicates widespread exposure to T. gondii among animals raised or hunted for human consumption in the region. Large variations were observed in the seroprevalence estimates between the studies in the region; however, studies were too few to identify spatial patterns at country-level.

Diversity of Toxoplasma gondii strains shaped by commensal communities of small mammals

Commensal rodent species are key reservoirs for Toxoplasma gondii in the domestic environment. In rodents, different T. gondii strains show variable patterns of virulence according to host species. Toxoplasma gondii strains causing non-lethal chronic infections in local hosts will be more likely to persist in a given environment, but few studies have addressed the possible role of these interactions in shaping the T. gondii population structure. In addition, the absence of validated techniques for upstream detection of T. gondii chronic infection in wild rodents hinders exploration of this issue under natural conditions. In this study, we took advantage of an extensive survey of commensal small mammals in three coastal localities of Senegal, with a species assemblage constituted of both native African species and invasive species. We tested 828 individuals for T. gondii chronic infection using the modified agglutination test for antibody detection in serum samples and a quantitative PCR assay for detection of T. gondii DNA in brain samples. The infecting T. gondii strains were genotyped whenever possible by the analysis of 15 microsatellite markers. We found (i) a very poor concordance between molecular detection and serology in the invasive house mouse, (ii) significantly different levels of prevalence by species and (iii) the autochthonous T. gondii Africa 1 lineage strains, which are lethal for laboratory mice, only in the native African species of commensal small mammals. Overall, this study highlights the need to reconsider the use of MAT serology in natural populations of house mice and provides the first known data about T. gondii genetic diversity in invasive and native species of small mammals from Africa. In light of these results, we discuss the role of invasive and native species, with their variable adaptations to different T. gondii strains, in shaping the spatial structure of T. gondii genetic diversity in Africa.

Low prevalence of antibodies against Toxoplasma gondii in dairy cattle from China's central region

Background

Toxoplasma gondii is an intracellular protozoan that can infect humans and other animals, including cattle. Cattle are one of the world’s main sources of meat, and people who consume raw or undercooked meat and milk of cattle infected with T. gondii can become infected. In this study, a total of 5292 dairy cattle serum samples, collected from 17 cities (Henan Province, China) from January 2015 to September 2017, were screened for antibodies against T. gondii.

Results

Antibodies to T. gondii were found in 1.93% (102/5292) (95% CI, 1.56–2.30) of dairy cattle using a modified agglutination test (cut-off 1:100). The results showed that geographic location and season may be risk factors for T. gondii infection of cattle (P < 0.05), and the seroprevalence of T. gondii in cattle along the Yellow River is higher than other areas.

Conclusions

This is the first large-scale investigation on the seroprevalence of T. gondii infection in cattle from Central China. This survey shows that the T. gondii infection rate of dairy cattle is low; however, these findings provide additional information on the epidemiology of Chinese T. gondii. The possibility of dairy cattle exposure to T. gondii in Central China can not be ignored, and the consumption of raw or undercooked beef or milk may pose a risk to human health.

Serological survey of cattle toxoplasmosis in Medea, Algeria

Toxoplasmosis is an important zoonotic disease transmitted to humans and warm-blooded animals by a ubiquitous parasite Toxoplasma gondii. One of the most common sources of human infection is the ingestion of tissue cysts through raw or undercooked meat. The present study was conducted to investigate a serological survey of Toxoplasma antibodies in cattle from Medea (North of Algeria). Serum samples were obtained from 295 clinically healthy cattle (261 females and 34 males). All cattle sera were tested for antibodies to T. gondii using the Modified Agglutination Test (MAT). According to MAT results, and taking 1:25 as the cut-off value, antibodies were found in 13 (4.4%) of 295 bovine sera. Five cattle had an antibody titer of 1:25; 6 of 1:50 and 2 of 1:100. More serological surveys are necessary to better understand the epidemiological status of toxoplasmosis in cattle and other ruminants.

Detection and dissemination of Toxoplasma gondii in experimentally infected calves, a single test does not tell the whole story

Background

Although the detection of Toxoplasma gondii in bovine tissues is rare, beef might be an important source of human infection. The use of molecular techniques, such as magnetic capture qPCR (MC-qPCR), in combination with the gold standard method for isolating the parasite (mouse bioassay), may increase the sensitivity of T. gondii detection in infected cattle. The risk of transmission of the parasite to humans from undercooked/raw beef is not fully known and further knowledge about the predilection sites of T. gondii within cattle is needed. In the current study, six Holstein Friesian calves (Bos taurus) were experimentally infected with 10⁶ T. gondii oocysts of the M4 strain and, following euthanasia (42 dpi), pooled tissues were tested for presence of the parasite by mouse bioassay and MC-qPCR.

Results

Toxoplasma gondii was detected by both MC-qPCR and mouse bioassay from distinct pools (100 g) of tissues comprising: liver, tongue, heart, diaphragm, semitendinosus (hindlimb), longissimus dorsi muscle (sirloin) and psoas major muscle (fillet). When a selection of individual tissues which had been used for mouse bioassay were examined by MC-qPCR, parasite DNA could only be detected from two animals, despite all calves showing seroconversion after infection.

Conclusions

It is apparent that one individual test will not provide an answer as to whether a calf harbours T. gondii tissue cysts. Although the calves received a known number of infectious oocysts and highly sensitive methods for the detection of the parasite within bovine tissues were applied (mouse bioassay and MC-qPCR), the results confirm previous studies which report low presence of viable T. gondii in cattle and no clear predilection site within bovine tissues.

Serological survey of Neospora caninum and Toxoplasma gondii in cattle (Bos indicus) and water buffaloes (Bubalus bubalis) in ten provinces of Brazil

The objective of this study was to determine the prevalence of antibodies to Neospora caninum and Toxoplasma gondii among 500 cattle (Bos indicus) and 500 buffaloes (Bubalus bubalis) using the indirect fluorescent antibody test (IFAT) technique. Blood samples from were collected from water buffalo and cattle in 10 municipalities in the northern region of Brazil. The frequency of cattle and water buffaloes seropositive for Neospora caninum in Pará state, Brazil, was 55% and 44%, respectively, and the frequency of cattle and water buffaloes seropositive for Toxoplasma gondii was 52% and 39%, respectively. Seropositivity for both N. caninum and T. gondii was detected in 10.6% of the cattle samples and 14.8% of the buffalo samples. The frequency of cattle positive for N. caninum and T. gondii was significantly (p<0.05) higher than that of buffalo in two and three provinces, respectively. Buffaloes had a lower seroprevalence for N. caninum or T. gondii in all of the provinces studied. These results suggest that both species, when exposed to the same risks for N. caninum and T. gondii infection, have a high serological prevalence. Cattle showed a higher probability of being seropositive when exposed to the same risks for N. caninum and T. gondii. Our study, which included an extensive number of blood samples, provides important epidemiological information pertinent to buffalo production in tropical countries that can be used as a basis for disease-management practices in Latin America.

Toxoplasma gondii detection in cattle: A slaughterhouse survey

Toxoplasmosis is a zoonotic disease caused by the protozoan parasite Toxoplasma gondii. Ingestion of raw or undercooked meat containing viable cysts has been suggested to be a major source of T. gondii infection in humans. Suboptimal performance of serological assays in cattle has traditionally precluded accurate quantification of the extent to which cattle populations are infected and their meat harbour tissue cysts. In the absence of accurate estimates of the level of infection in the animal population, assessments of likely human exposure through the consumption of cattle meat remain highly speculative. Following the development of novel and sensitive molecular methods that can be applied to the relatively large numbers of samples required in observational studies, the first quantitative estimates of the frequency of T. gondii in meat samples from naturally infected cattle have become available recently. Such estimates are critical for the development of quantitative risk assessment models that could be used to inform food safety policies. The aim of this study was to generate the first estimates of the prevalence of T. gondii infection in a sample of cattle exposed to natural levels of infection and slaughtered for human consumption in the UK under commercial conditions. Such estimates provide great value to the global assessment of T. gondii burden given the scarcity of data available on the frequency of natural infection in cattle populations worldwide. Between October 2015 and January 2016 diaphragm samples were collected from 305 animals, slaughtered in ten commercial slaughterhouses across the UK. Movement histories showed that the animals sampled (41.6% females and 58.4% males) had passed through a total of 614 farms and 40 livestock markets across the country. Five animals (1.6%) were deemed positive for T. gondii following magnetic capture real-time PCR, confirmed by amplicon sequencing. The true prevalence of infection was estimated to be 1.79%. All positive animals were male, none of whom had been on the same farm and/or livestock market before slaughter and there was no apparent geographic pattern. The results from this study suggest a low level of infection in cattle raised and slaughtered in the UK and can be used to populate the first stages of formal risk assessments to quantify the likely extent of human exposure to T. gondii through the consumption of beef with relevance to the UK, EU and rest of the world.

Seroprevalence and epidemiology of Toxoplasma gondii in farm animals in different regions of Egypt

Toxoplasmosis is a cosmopolitan protozoan disease that has been recorded in a wide range of vertebrate hosts, including humans. In response to the paucity of available data, this study was undertaken to comprehensively establish the seroprevalence of Toxoplasma gondii among various farm animals in different localities of Egypt. The latex agglutination test and TgGRA7-based enzyme-linked immunosorbent assay were used to screen the investigated animals for anti-T. gondii IgG antibodies. When only samples with simultaneously positive results for both the latex agglutination test and the TgGRA7-based ELISA were considered positive, 174 (26.7%) of 652 serum samples from different animals were seropositive. The prevalence of antibodies according to species was: sheep 38.7%, goats 28.7%, cattle 23.6%, and donkeys 22.6%. Thus, prevalence rate was significantly higher in sheep than in cattle or donkeys. The prevalence was also significantly higher in Kafr El Sheikh than in the other governorates investigated (Qena, Sohag, Minoufiya, and Matrouh). No significant differences were observed in age, sex, locality, or breeding system when evaluated as predisposing factors for T. gondii infection in cattle. In conclusion, this study demonstrates the high prevalence for T. gondii-specific antibodies among different animal species in southern and northern localities of Egypt, and provides valuable new data on the prevalence of T. gondii in donkeys, which are used as a food for carnivorous animals, particularly in the feline family, at Giza Zoo, Egypt.

Investigating the Determinants of Toxoplasma gondii Prevalence in Meat: A Systematic Review and Meta-Regression

BACKGROUND

Toxoplasma gondii is one of the most widespread parasites in humans and can cause severe illness in immunocompromised individuals. However, its role in healthy people is probably under-appreciated. The complex epidemiology of this protozoan recognizes several infection routes but consumption of contaminated food is likely to be the predominant one. Among food, consumption of raw and undercooked meat is a relevant route of transmission, but the role of different meat producing animal species and meats thereof is controversial.

OBJECTIVES

The aim of the present work is to summarize and analyse literature data reporting prevalence estimates of T. gondii in meat animals/meats.

DATA SOURCES

We searched Medline, Web of Science, Science Direct (last update 31/03/2015).

ELIGIBILITY CRITERIA

Relevant papers should report data from primary studies dealing with the prevalence of T. gondii in meat from livestock species as obtained through direct detection methods. Meta-analysis and meta-regression were performed.

RESULTS

Of 1915 papers screened, 69 papers were included, dealing mainly with cattle, pigs and sheep. Pooled prevalences, based on random-effect models, were 2.6% (CI95 [0.5-5.8]) for cattle, 12.3% (CI95 [7.6-17.8]) for pigs and 14.7% (CI95 [8.9-21.5]) for sheep. Due to the high heterogeneity observed, univariable and multivariable meta-regression models were fitted showing that the geographic area for cattle (p = 0.032), the farming type for pigs (p = 0.0004) and the sample composition for sheep (p = 0.03) had significant effects on the prevalences of Toxoplasma detected/estimated. Moreover, the role of different animal species was dependent on the geographic location of animals' origin.

LIMITATIONS

Limitations were due mainly to a possible publication bias.

CONCLUSIONS AND IMPLICATIONS

The present work confirms the role of meat, including beef, as T. gondii sources, and highlights the need for a control system for this parasite to be implemented along the meat production chain. Moreover, consumer knowledge should be strengthened in order to reduce the impact of disease.

Major Parasitic Zoonoses Associated with Dogs and Cats in Europe

Some of the most important zoonotic infectious diseases are associated with parasites transmitted from companion animals to man. This review describes the main parasitic zoonoses in Europe related to dogs and cats, with particular emphasis on their current epidemiology. Toxoplasmosis, leishmaniosis, giardiosis, echinococcosis, dirofilariosis and toxocariosis are described from the animal, as well as from the human host perspectives, with an emphasis on parasite life cycle, transmission, pathogenicity, prevention and identification of knowledge gaps. In addition, priorities for research and intervention in order to decrease the risks and burden of these diseases are presented. Preventing zoonotic parasitic infections requires an integrated multidisciplinary 'One Health' approach involving collaboration between veterinary and medical scientists, policy makers and public health officials.

Detection of Toxoplasma gondii DNA in horse meat from supermarkets in France and performance evaluation of two serological tests

In France, some cases of severe toxoplasmosis have been linked to the consumption of horse meat that had been imported from the American continent where atypical strains of Toxoplasma gondii are more common than in Europe. Many seroprevalence studies are presented in the literature but risk assessment of T. gondii infection after horse meat consumption is not possible in the absence of validated serological tests and the unknown correlation between detection of antibodies against T. gondii and presence of tissue cysts. We performed magnetic-capture polymerase chain reaction (MC-PCR) to detect T. gondii DNA in 231 horse meat samples purchased in supermarkets in France and evaluated the performance and level of agreement of the modified agglutination test (MAT) and enzyme-linked immunosorbent assay (ELISA) in the meat juices. The serological tests lacked sensitivity, specificity, and agreement between them, and there was no correlation with the presence of T. gondii DNA in horse meat, raising concerns about the reliability of T. gondii seroprevalence data in horses from the literature. T. gondii DNA was detected in 43% of horse meat samples but the absence of strain isolation in mice following inoculation of more than 100 horse meat samples suggests a low distribution of cysts in skeletal muscles and a low risk of T. gondii infection associated with horse meat consumption. However, to avoid any risk of toxoplasmosis, thorough cooking of horse meat is recommended.

Prevalence and risk factors for Toxoplasma gondii infection in meat animals and meat products destined for human consumption

Toxoplasma gondii is a protozoan parasite that is responsible for approximately 24% of all estimated deaths attributed to foodborne pathogens in the United States. Human infection results from accidental ingestion of oocysts from the environment, in water, or on insufficiently washed produce or from consumption of raw or undercooked meat products that contain T. gondii tissue cysts. This review focused on studies of T. gondii in meat because many human T. gondii infections are acquired through consumption of raw or undercooked meat. Prevalence of T. gondii is higher in conventionally reared pigs, sheep, and poultry than in cattle and is greater in meat products from organic than from conventionally reared meat animals because of outdoor access, which poses substantially greater opportunities for exposure to infected rodents, wildlife, and oocyst-contaminated feed, water, or environmental surfaces. Risk factors related to T. gondii exposure for livestock include farm type, feed source, presence of cats, methods of rodent and bird control, methods of carcass handling, and water quality. This review serves as a useful resource and information repository for informing quantitative risk assessment studies for T. gondii infection in humans through meat consumption.

Intervention strategies to reduce human Toxoplasma gondii disease burden

Infection with Toxoplasma gondii is acquired through consumption of undercooked infected meat, or by uptake of cat-shed oocysts. Although congenital toxoplasmosis is generally considered to contribute most to the disease burden of T. gondii, ocular disease from acquired infection was recently shown to add substantially to the burden. In addition, toxoplasmosis in immune-compromised individuals usually results from reactivation of an infection acquired earlier in life. Nevertheless, prevention of toxoplasmosis commonly targets mainly pregnant women. We summarize current prevention strategies of congenital toxoplasmosis and evaluate options to improve protection of the general population (including pregnant women). To protect the general population, freezing of meat destined for raw or undercooked consumption is the most readily applicable option, especially when limited to meat from animals originating from nonbiosecure husbandry systems. In the long term, more health benefits are expected from cat vaccination; therefore, development of a cat vaccine and evaluation of its implementation is a research priority.

Animals are key to human toxoplasmosis

Toxoplasma gondii is an extremely sucessfull protozoal parasite which infects almost all mamalian species including humans. Approximately 30% of the human population worldwide is chronically infected with T. gondii. In general, human infection is asymptomatic but the parasite may induce severe disease in fetuses and immunocompromised patients. In addition, T. gondii may cause sight-threatening posterior uveitis in immunocompetent patients. Apart from few exceptions, humans acquire T. gondii from animals. Both, the oral uptake of T. gondii oocysts released by specific hosts, i.e. felidae, and of cysts persisting in muscle cells of animals result in human toxoplasmosis. In the present review, we discuss recent new data on the cell biology of T. gondii and parasite diversity in animals. In addition, we focus on the impact of these various parasite strains and their different virulence on the clinical outcome of human congenital toxoplasmosis and T. gondii uveitis.

Veterinary vaccines against toxoplasmosis

Toxoplasma gondii is a cosmopolitan protozoan parasite that infects a wide range of mammal and bird species. Common infection leads to high economic (e.g., abortions in sheep) and human (e.g., congenital toxoplasmosis or neurotoxoplasmosis in humans) losses. With one exception (Toxovax for sheep), there are no vaccines to prevent human or animal toxoplasmosis. The paper presents the current state and challenges in the development of a vaccine against toxoplasmosis, designed for farm animals either bred for consumption or commonly kept on farms and involved in parasite transmission. So far, the trials have mostly revolved around conventional vaccines and, compared with the research using laboratory animals (mainly mice), they have not been very numerous. However, the results obtained are promising and could be a good starting point for developing an effective vaccine to prevent toxoplasmosis.

Real-time PCR detection of the HhaI tandem DNA repeat in pre- and post-patent Brugia malayi Infections: a study in Indonesian transmigrants

BACKGROUND

Lymphatic filariasis caused by Wuchereria bancrofti or Brugia spp. is a public health problem in developing countries. To monitor bancroftian filariasis infections, Circulating Filarial Antigen (CFA) test is commonly used, but for brugian infections only microfilariae (Mf) microscopy and indirect IgG4 antibody analyses are available. Improved diagnostics for detecting latent infections are required.

METHODS

An optimized real-time PCR targeting the brugian HhaI repeat was validated with plasma from microfilariae negative Mongolian gerbils (jirds) infected with B. malayi. Plasma samples from microfilaremic patients infected with B. malayi or W. bancrofti were used as positive and negative controls, respectively. PCR results of plasma samples from a transmigrant population in a B. malayi endemic area were compared to those of life-long residents in the same endemic area; and to IgG4 serology results from the same population. To discriminate between active infections and larval exposure a threshold was determined by correlation and Receiver-Operating Characteristics (ROC) curve analyses.

RESULTS

The PCR detected HhaI in pre-patent (56 dpi) B. malayi infected jirds and B. malayi Mf-positive patients from Central Sulawesi, Indonesia. HhaI was also detected in 9/9 elephantiasis patients. In South Sulawesi 87.4% of the transmigrants and life-long residents (94% Mf-negative) were HhaI PCR positive. Based on ROC-curve analysis a threshold for active infections was set to >53 HhaI copies/μl (AUC: 0.854).

CONCLUSIONS

The results demonstrate that the HhaI PCR detects brugian infections with greater sensitivity than the IgG4 test, most notably in Mf-negative patients (i.e. pre-patent or latent infections).