Toxoplasma gondii: Pig seroprevalence, associated risk factors and viability in fresh pork meat

Combination of an enzyme-linked immunosorbent assay and an indirect fluorescence assay for a nationwide sero-survey of Toxoplasma gondii infection in pig herds in Taiwan

Toxoplasma gondii is a zoonotic pathogen that can infect farm animals, companion animals, and humans, sometimes causing public health issues. In Taiwan, the pig industry is a vital agricultural industry, with a self-sufficiency rate of 91 %, and pigs are also food-producing animal reservoirs of Toxoplasma gondii. Infected pigs are usually asymptomatic, and abortions and death may occur in severe cases. We combined an enzyme-linked immunosorbent assay (ELISA) and an indirect fluorescence assay (IFA) to investigate the seroprevalence of Toxoplasma gondii among pig populations in Taiwan. A stratified sampling approach to determine the number of sample farms proportional to the number of pig farms in each county was employed, with 15 blood samples collected at each farm between July and September 2017. With the tested results, empirical Bayesian smoothing was utilized to assess the proportion of Toxoplasma-positive farms at the county level. Bayesian mixed-effects logistic regression models, incorporating farm and county as random effects, were employed to investigate associations between Toxoplasma test results and potential risk factors. A total of 930 serum samples from 62 pig farms were collected and tested. An overall herd prevalence of 27.4 % was shown with the seroprevalence in northern Taiwan being greater than that in southern Taiwan. The sampling month and companion dog density in 2017 were significantly associated with Toxoplasma infections in pigs. With every increase in the number of companion dogs per km² at the county level, the odds of Toxoplasma infection in pigs increased by 4.7 % (95 % CI: 1.7-8.9 %). This study demonstrated that combining ELISA for screening with IFA for confirmation is a cost-effective and time-saving method for conducting a large-scale sample investigation. This was also the first nationwide, cross-sectional study in Taiwanese pig herds to investigate Toxoplasma gondii infection.

Seroepidemiological and biomolecular survey on Toxoplasma gondii in Sardinian wild boar (Sus scrofa)

Toxoplasma gondii is a zoonotic parasite able of infecting all warm-blooded animals. Toxoplasmosis is one of the major foodborne diseases globally. The consumption of wild boar (Sus scrofa) meat from recreational hunting has been linked to outbreaks of human toxoplasmosis. The island of Sardinia (Italy) contains a large wild boar population, thus providing an opportunity to assess the distribution of Toxoplasma in this species and the associated risks of transmission to humans. A total of 562 wild boars were screened: heart and meat juice samples were tested for T. gondii DNA via nested-PCR and IgG anti-Toxoplasma by commercial ELISA. Anti-Toxoplasma IgG were detected in 24.6% (138/562) of animals, while 37.2% (209/562) of the heart samples were PCR positive. The prevalence of T. gondii antibodies and DNA highlights the potential role of wild boar as an important reservoir for this parasite. The study suggests that wild boar could play a significant role in spreading the parasite to humans. As wild boar numbers are increasing throughout their range, their potential role in transmitting toxoplasmosis should be communicated to stakeholders, and the impact of different population control methods on disease transmission should be thoroughly assessed to mitigate potential threats effectively.

Toxoplasma gondii infection in pig intended for human consumption: seroprevalence, risk factors and influence of biosecurity measures

A serologic and epidemiologic study was carried out in order to determinate herd and animal seroprevalence and associated factors for Toxoplasma gondii in commercial pigs from Espírito Santo state, Brazil. Blood samples were collected from 416 pigs from 55 producer farms in 27 municipalities. An indirect immunofluorescent assay (IFA) was performed to estimate the seroprevalence of T. gondii and identify the associated risk factors using a questionnaire. The T. gondii antibody prevalence rate in commercial swine herds was 15.4% (64/416) using a cutoff of 1:64. The seropositivity for T. gondii was related to the presence of cats, water origin and age of swine in the increase of seroprevalence, and the existence of internal isolation fences and use of composting chambers as protective factors. To the best of our knowledge, this is the first study to report anti- T. gondii antibodies in the serum of pigs in the state of Espírito Santo, Brazil. This finding is important to public health because seropositive pigs can harbor tissue cysts in their meat, thereby representing a zoonotic risk for consumers of raw or undercooked porcine meat or its products.

Prevalence and Haplotypes of Toxoplasma gondii in Native Village Chickens and Pigs in Peninsular Malaysia

Toxoplasma gondii is an important zoonotic foodborne parasite capable of infecting almost all warm-blooded animal species worldwide. Toxoplasmosis is usually acquired via ingestion of undercooked infected animal tissues resulting in life-threatening consequences for unborn foetus and immunocompromised individuals. A cross-sectional study was carried out to determine the prevalence of T. gondii infection, its associated risk factors in farms, and haplotypes isolated from the native village chicken and pig populations in Peninsular Malaysia. The seroprevalence of T. gondii in village chickens at the animal level was low at 7.6% (95% CI: 4.60-11.60), while at the farm level, it was 52.0% (95% CI: 31.30-72.20). For pigs, the animal-level seroprevalence of T. gondii was 3.0% (95% CI: 1.60-5.10), while the farm-level, it was 31.6% (95% CI: 12.60-56.60). The PCR-based DNA detection on meat samples from chickens (n = 250) and pork (n = 121) detected 14.0% (95% CI: 9.95-18.9) and 5.8% (95% CI: 2.4-11.6) positive, respectively. Six unique T. gondii haplotypes were isolated from the tissue samples. Multivariable logistic regression analysis showed that feeding the chickens farm-produced feeds and allowing wild animals access to pig farms were significant determinants for farm-level seropositivity. Providing hygienic and good quality feeds to chickens and increasing biosecurity in pig farms through prevention of access by wildlife may reduce the risk of transmission of T. gondii infection in the local chickens and pig farms.

Molecular Survey of Toxoplasma gondii in Wild Mammals of Southern Italy

Systematic wildlife surveillance is important to aid the prevention of zoonotic infections that jeopardize human health and undermine biodiversity. Toxoplasma gondii is an opportunistic zoonotic protozoan that can infect all endothermic vertebrates, causing severe disease in immunocompromised humans and cases of congenital transmission. Humans can be infected by ingestion of raw meat containing bradyzoites or water contaminated by oocysts. In our study, we assessed the potential circulation of Toxoplasma gondii in wild mammals by performing surveillance in the Campania region (southern Italy) and surveyed its presence from 2020 to 2022 within the framework of the Regional Plans for Wildlife Surveillance. In detail, 211 individuals belonging to five wild mammals (wolf, fox, wild boar, badger, and roe deer) underwent necropsy and the organs were analyzed by real-time PCR for the detection of the parasite. Toxoplasma gondii was found in 21.8% (46/211) of the subjects examined. No statistically significant differences were noticed between the prevalence and the host’s trophic level or age, rejecting the hypotheses that Toxoplasma gondii will have a higher prevalence in top predators and adult individuals, respectively. Our work emphasized the high circulation of Toxoplasma gondii in wildlife and remarked on the critical role of anthropized areas where domestic cats and wildlife may come into contact, urging a systematic surveillance.

Seroprevalence and associated risk factors of Toxoplasma gondii infection among slaughterhouse workers in Yangon Region, Myanmar: A cross-sectional study

BACKGROUND

Toxoplasmosis, having the significant consequences affecting mortality and quality of life, is still prevalent in various places throughout the world. The major gap in surveillance for Toxoplasma gondii infection among high-risk population, slaughterhouse workers, is an obstacle for the effective policies formulation to reduce the burden of toxoplasmosis in Myanmar. Therefore, this study aimed to assess the seroprevalence of toxoplasmosis and associated factors of seropositivity among slaughterhouse workers in Yangon Region, Myanmar.

METHODS

A cross-sectional study that was conducted from June to November 2020 included 139 slaughterhouse workers involving at five main slaughterhouses under Yangon City Development Committee, Myanmar. The presence of IgG and IgM anti-T. gondii antibodies in serum was detected using the OnSite Toxo IgG/IgM Combo Rapid Test. A face-to-face interview was also performed using pretested structured questionnaires to obtain the detail histories: sociodemographic characteristics, level of knowledge, occupational factors, and environmental factors related to T. gondii infection. Bivariate logistic regression was used to determine the factors associated with T. gondii infection.

RESULTS

Of all participants, the overall seroprevalence of anti-T. gondii was 43.9% (95% CI: 35.5-52.5%), of whom 98.4% (95% CI: 91.2-100.0%) were reactive only for IgG antibody and 1.6% (95% CI: 0.0-8.8%) were reactive for IgG and IgM antibodies. The significant factors associated with the seropositivity of T. gondii antibodies were blood transfusion history (OR: 5.74, 95% CI: 1.17-28.09), low level of knowledge (OR: 2.91, 95% CI: 1.46-5.83), contact with animal organs, muscles or blood (OR: 14.29, 95% CI: 1.83-111.51), and animals most frequently slaughtered (cattle) (OR: 3.22, 95% CI: 1.16-8.93).

CONCLUSIONS

A high seroprevalence of toxoplasmosis was detected among slaughterhouse workers in Yangon Region and it raises a significant public health concern. Therefore, providing health education regarding toxoplasmosis, enforcement of personal hygiene practices in workplaces, the establishment of training for occupational hygiene, and commencement of the risk assessment and serological screening for toxoplasmosis are crucial to curtail the prevalence of T. gondii infection among slaughterhouse workers.

Detection of Sarcocystis spp. and Toxoplasma gondii in swine and detection of DNA of these protozoa in tissues and sausages

The seroprevalence of Sarcocystis spp. and Toxoplasma gondii was researched in swine raised in Santa Maria, RS, Brazil. Serum samples from 84 pigs from 31 farms were tested using indirect immunofluorescence assay (IFA) for both agents. Additionally, 53 samples of pork sausages and tissues destined for human consumption, including: salami, sausage, black pudding, heart, tongue, brain, and rib muscle, were submitted to PCR to detect DNA for each agent. The frequency of anti-Sarcocystis spp. antibodies was 36.9% (31/84), with titers ranging from 32 to 1024, and 25% (21/84) for anti-T. gondii antibodies, with titers ranging from 64 to 2048. Sarcocystis spp. and T. gondii DNA were detected in 67.9% (36/53) and 13.2% (7/53) of samples, respectively. The presence of antibodies and the detection of DNA from Sarcocystis spp., and T. gondii suggests that the pigs were infected and may serve as an important reservoir for both parasites. The infection by these protozoa in the swine population is relevant to public health due to their zoonotic potential.

Seroprevalence, Direct Detection and Risk Factors for Toxoplasma gondii Infection in Pigs in Serbia, and Influence of Biosecurity Measures

Consumption of Toxoplasma gondii contaminated pork is a major risk factor for human infection. We thus conducted a cross-sectional survey on the seroprevalence of T. gondii infection in a representative sample of slaughter pigs from throughout Serbia and examined the influence of farm biosecurity-related risk factors on infection. In addition, direct detection of the parasite (by mouse bioassay) or its DNA was performed in the hearts of a subset of seropositive sows. The overall seroprevalence in the sample of 825 pigs as determined by the modified agglutination test (MAT) was 16.5%. Older age and inadequate rodent control were independent infection risk factors for pigs. In a subset of 581 pigs with complete biosecurity-related data, in addition to older age, smallholders’ finishing type farms (as opposed to farrow-to-finish), multispecies farming, and origin from Western and Central and South-Eastern Serbia (vs. the Northern region), all increased the risk of infection, while the absence of disinfection boot-dips in front of each barn and Belgrade district origin (vs. the Northern region) were associated with a 62% and 75% lower risk of infection, respectively. Evidence of viable parasites was obtained in 13 (41.9%) of the 31 bioassayed sow hearts, of which by isolation of brain cysts in seven, by detection of T. gondii DNA in an additional four, and by serology in another two. Recovery of brain cysts mostly (5/7) from sows with a MAT titre of ≥1:100 indicates the risk for consumers. These results highlight the public health risk from pork consumption and point to mandatory use of professional rodent control services, abstaining from multispecies farming, keeping disinfection boot-dips clean and freshly refilled, as well as strict implementation of zoo-hygienic measures on smallholders’ farms as specific farm biosecurity measures needed for its reduction.

Epidemiological investigation and reinfection evaluation of Toxoplasma gondii in chickens in Shandong Province, China

Toxoplasma gondii infects almost all warm-blooded animals, and toxoplasmosis is a common zoonotic parasitic disease worldwide. A nested PCR with high specificity and sensitivity was developed in this study based on the data collected on the infection rate of toxoplasmosis in chickens in Shandong province, and the effect of low temperature on the infectivity of tachyzoites was investigated. The sampling data showed that the total prevalence of T. gondii in Shandong province was 12.3%, and the positive rate varied in different regions, ranging from 6.7% to 21%. Chickens were infected with T. gondii under laboratory conditions, and positive chicken hearts were stored under various cold conditions to infect mice for reinfection evaluation. The results demonstrated that the parasites maintained high infectivity in mice even after 6 h of storage at -20 °C ambient temperature, indicating that short-term cryopreservation is not effective in reducing the risk of T. gondii transmission. These results form the basis for assessing the risk of toxoplasmosis contamination in consumed chicken products and provide information on the prevention of parasite transmission from animals to humans.

A serological survey of Toxoplasma gondii in polish pigs from organic farms, other housing systems and in pigs of different age groups

Background

The consumption of raw or undercooked meat, especially pork, and offal containing infective tissue cysts is suspected to be a significant route of infection with Toxoplasma gondii. Although the use of “animal-friendly pig production systems” ensuring direct contact with the natural environment offers ethical benefits, it limits the ability to ensure animal health; it may also increase the probability of infections by pathogens such as T. gondii, and thus their entry into the food chain. This study determines the seroprevalence of T. gondii in pigs from different housing systems and farms with different hygiene standards in Poland, as well as among pigs of different age groups from farms with high hygiene standards. In total 760 pig serum samples were examined for the presence of specific antibodies using the PrioCHECK^® Toxoplasma Ab porcine commercial ELISA test (Prionics, Switzerland).

Results

Test results with PP ≥ 20% were regarded as positive, as indicated by the manufacturer. Antibodies to T. gondii were found in 193 of 760 (25.4%) tested sera. Regarding different housing systems, antibodies were found in 117 pigs: of these, 52.6% (61/116) were from organic farms, 40.9% (47/115) from farms with low hygiene standards, 5.4% (9/167) from farms with high hygiene standards and 0% (0/40) from a farm with a high level of biosecurity. Regarding age groups, antibodies were found in 76 animals on farms with high hygiene standards: 11.1% (7/63) were pigs younger than 3 months, 0% (0/60) aged 3–4 months, 12.3% (7/57) aged 5–6 months (final fattening stage) and 43.7% (62/142) were sows aged 9 months and older.

Conclusions

Antibodies to T. gondii were most often found in pigs from organic and low-hygiene farms, as well as in pigs aged 9 months and older. Meat derived from seropositive animals can pose a potential source of infection for humans. As maternal antibodies to T. gondii can be present in the blood of piglets aged up to 3–4 months, serological examination is unjustified in piglets up to this age.

Toxoplasma gondii Infection in Swine: Implications for Public Health

Toxoplasmosis, due to Toxoplasma gondii, is a parasitic disease with global importance. Among livestock, chronic T. gondii infection has been reported in higher rates in pigs and small ruminants, but with subclinical infections in case commonly encountered in pigs. Seroprevalence in the global pig population ranges according to the age or species of pigs, geographical distribution, production programs, and systems. Generally, T. gondii infections are noticed in low prevalence rates in conventional pig farms with high hygiene standards. In contrast, higher prevalence is common on free-ranging farms, outdoor or backyard small pig fams, as well as in farmed or hunted wild boars. The T. gondii average worldwide seroprevalence in pigs is reported to be 13% in Europe, 21% in Africa, 25% in North America, 21% in Asia, and 23% in South America. Human toxoplasmosis outbreaks have been correlated with the consumption of raw or undercooked meat, especially from infected pigs or wild boars, as well as of contaminated drinking water. The risk of infection in processed pork products is lower compared with fresh pork, as meat processing can reduce or inactivate T. gondii tissue cysts. Hence, the prevalence of T. gondii in the pig population may be a useful indicator of the risk of human toxoplasmosis associated with the consumption of pork products. The lack of obligatory screening methods at farm level for the detection of antibodies in farmed animals or the viable T. gondii in carcasses at slaughterhouse level increases the risk of contaminated pork or meat products. For this reason, the application of biosecurity and surveillance programs at farm level is very important to prevent a T. gondii infection.

Seroprevalence and risk factors of Toxoplasma gondii in cattle from Unai, Minas Gerais state, Brazil

Toxoplasma gondii is a widespread protozoan parasite that causes infections in animals and humans. The presence of tissue cysts in cattle musculature evidences their epidemiological significance in transmission to humans. The present study aimed to evaluate the seroprevalence of and risk factors of T. gondii seropositivity in beef cattle in the municipality of Unaí, Minas Gerais state, Brazil. Bovine blood samples (n = 612) were collected from 31 herds. Risk factors associated with the animal-level and herd-level seroprevalence were analysed using a questionnaire that investigates the epidemiological aspects of toxoplasmosis. A search for anti-T. gondii antibodies was performed by means of an indirect fluorescent antibody test (IFAT). Analysis of 612 samples showed 369 animals positive for anti-T. gondii antibodies (IFAT ≥64), with a seroprevalence of 60.29% (95% confidence interval (CI): 56.35-64.10). The herd-level seroprevalence was 96.77% (95% CI: 79.00-99.58). Applying a multivariate logistic regression analysis, a test of the association between seroprevalence of T. gondii infection and the potential predictors showed that cats (domestic or wild) with access to the drinking water of cattle were a significant (P = 0.001) predictor. The seroprevalence of T. gondii in cattle destined for human consumption is widely distributed throughout the entire study area. Thus, integrated control measures and strategies are suggested to prevent T. gondii infection in cattle.

Isolation, Genotyping, and Mouse Virulence Characterization of Toxoplasma gondii From Free Ranging Iberian Pigs

The present study aimed to isolate and perform molecular and phenotypic characterization of Toxoplasma gondii strains infecting Iberian pigs bred under semi-free conditions and destined for human consumption. Blood and heart tissue samples from 361 fattening pigs from 10 various herds selected in the main areas of Iberian pig production were collected at a slaughterhouse; the sera were tested for anti-T. gondii antibodies using a commercial indirect ELISA kit, and a mouse bioassay was carried out using heart muscle of seropositive individual representatives from each geographical location. Seventy-nine (21.9%) of the 361 animals tested positive for anti-T. gondii antibodies according to the serology test. Fifteen samples of myocardial tissue were subjected to bioassay and 5 isolates (TgPigSp1 to TgPigSp5) were obtained. The isolates were characterized by using 11 PCR-RFLP genetic markers; three isolates had a ToxoDB #3 genotype (3/5) and two isolates had a ToxoDB #2 genotype (2/5). The TgPigSp1 and TgPigSp4 isolates were selected for virulence in mice characterization as instances of each different RFLP-genotype found. The TgPigSp1 isolate (#2 genotype) was virulent in mice with notable cumulative mortality (87.5%) and morbidity rates (100%); the TgPigSp4 (#3) was nonvirulent and triggered mild clinical signs in 42.1% of seropositive mice. Infection dynamics and organ distribution of both isolates were analyzed; the data revealed significant differences, including substantially higher parasite load in the lung during the acute phase of infection, in mice infected with TgPigSp1 than in the case of TgPigSp4 (median parasite load 7.6 vs. 0 zoites/mg, respectively; p < 0.05). Furthermore, degrees of severity of detected histopathological lesions appeared to be related to higher parasite burdens. Taking into account the unexpectedly high mortality rate and parasite load associated with the clonal genotype III, which is traditionally considered nonvirulent in mice, the need for further investigation and characterization of the T. gondii strains circulating in any host in Europe is emphasized.

All about Toxoplasma gondii infections in pigs: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasma gondii infection in pigs continues to be of public health concern. Pigs are important for the economy of many countries, particularly, USA, China, and European countries. Among the many food animals, pigs are considered the most important for T. gondii transmission in USA and China because viable parasites have rarely been isolated from beef or indoor raised chickens. Besides public health issues, T. gondii causes outbreaks of clinical toxoplasmosis in pigs in China, associated with a unique genotype of T. gondii (ToxoDB genotype #9 or Chinese 1), rarely found in other countries. The safety of ready to eat pork products with respect to T. gondii infection is a matter of recent debate. Here, we review in detail seroprevalence, prevalence of viable and nonviable T. gondii, epidemiology, risk assessment, diagnosis, and curing of pork products containing T. gondii for the past decade. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

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.

Seroepidemiology of Toxoplasma gondii in domestic cattle, sheep, goats and pigs from São Tomé and Príncipe

Abstract Despite the global importance of the zoonotic parasite Toxoplasma gondii, little is known regarding its infection in the Democratic Republic of São Tomé and Príncipe (DRSTP). This is the first report of antibodies to T. gondii in cattle, sheep, goats and pigs from the DRSTP. Antibodies were assessed by the modified agglutination test (MAT), with a cut-off titer of 100 for cattle and 20 for sheep, goats and pigs. The present study revealed an overall seroprevalence of 55.8%; 27.1% in 48 cattle, 68.4% in 98 sheep, 70.1% in 97 goats and 43.7% in 103 pigs. The south geographical area for cattle, the central area for sheep, and adult age and living in the central region for goats were found to be risk factors for seropositivity to T. gondii. These results support the scenario of a considerable presence of sporulated oocysts as well as of infected intermediate hosts in the local environment. Consumption of raw or undercooked meat should be considered as an important potential source of infection for animals and humans in the DRSTP.

Seroepidemiology of Toxoplasma gondii in extensively raised Iberian pigs in Spain

Pigs reared under extensive farming conditions are currently in high commercial demand because they are associated with high-quality products. Nevertheless, the risk of contact with different pathogens of animal and public health concern is also higher in extensive production systems. Toxoplasma gondii is a widely prevalent zoonotic pathogen and transmission by contaminated pork is likely one of the main routes of human toxoplasmosis. The aim of this study was to determine the seroprevalence, risk factors and spatial distribution of T. gondii on extensive Iberian pig herds in Spain. Sera from 2245 Iberian pigs from 114 herds were collected between 2015 and 2017 and analyzed using a commercial ELISA. The apparent individual prevalence of antibodies against T. gondii was 24.1 % (542/2245) and the estimated true seroprevalence was 24.3 % (CI95 %: 22.5-26.1). Seropositivity was detected in 86.0 % (98/114; CI95 %: 77.4-91.1) of 114 herds analyzed. A multi-level logistic regression model showed that T. gondii infection was significantly more frequent in sows than in fattening pigs (OR: 2.6; CI95 %: 1.5-4.8) and in herds with more than three cats compared to no cats (OR: 2.9; CI95 %: 1.1-8.7). Our results indicate a widespread but heterogenous distribution of T. gondii in extensively reared Iberian pig herds, which may have important implications for public health through the consumption of undercooked or improperly cured pork products.

The prevalence of Toxoplasma gondii in mice living in Danish indoor sow herds

Background

Toxoplasma gondii is found worldwide, and consumption of undercooked meat is considered a significant risk factor for human infections. In Denmark, little is known about the distribution of T. gondii, but a recent study revealed a seroprevalence of 34% in Danish indoor sows. The present cross-sectional study aimed to investigate the role of mice for the transmission of T. gondii in Danish indoor sow herds.

Results

In total, 56 sow herds were visited, 137 mice were caught by snap traps from 32 farms, and 52 cat faecal samples were collected from 22 farms. Eight percent of the mice were positive for T. gondii DNA, representing 11% of the farms. Significant associations were found between the presence of T. gondii-positive mice and both open feed systems (P= 0.041) and extra rodent control on the farm (P= 0.024). All cat faecal samples were deemed negative for T. gondii by light microscopy examination and real-time polymerase chain reaction analysis.

Conclusion

Mice captured inside Danish sow herds were found to be infected with T. gondii and may thus contribute to the transmission of T. gondii to sows, which may explain the high seroprevalence found in Danish pigs.

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.

Endemicity of Toxoplasma infection and its associated risk factors in Cebu, Philippines

Toxoplasma gondii is a single-celled intracellular apicomplexan parasite that causes toxoplasmosis. It is capable of infecting humans and nearly all warm-blooded animals including pigs, but cats are the only known definitive host. This ubiquitous zoonotic pathogen can cause abortion, stillbirth and fetal abnormalities, and has been associated with mental and behavioral changes in humans. Acute infection is potentially fatal in immunocompromised individuals. The present study aimed to assess the Toxoplasma seroprevalence in pigs, humans and cats after its initial reported detection in pigs about three decades ago in Cebu, Philippines. A total of 924 humans, 104 cats and 514 slaughter pigs were tested for antibodies against T. gondii using a commercial latex agglutination test. The results revealed positive detection rates of 26.3% (244/924) for humans, 42.3% (44/104) for cats and 13.4% (69/514) for slaughter pigs. Statistical analyses revealed that the area (P = 0.004), cat ownership (P = 0.020), the frequency of contact with cats (P < 0.0001) and consumption of street foods (P = 0.043) were significantly associated with seropositivity for T. gondii in humans. Meanwhile, the use of litter trays (P = 0.001) and contact with other animals (P = 0.007) were significantly associated with seropositivity in cats. The odds ratio for selected significant factors revealed that living in suburban areas (OR 1.66, 95% CI: 1.20–2.31), owning a cat (OR 1.482, 95% CI: 1.07–2.07) and eating street foods (OR 1.585, 95% CI: 1.01–2.48) were associated with an increased risk of T. gondii exposure in humans. In cats, the use of a litter tray (OR 4.5, 95% CI: 1.73–11.71) was associated with an increased risk of exposure. None of the profile parameters were found to be significantly associated with seropositivity in slaughter pigs (P > 0.05). This study is the first report of the serological detection of T. gondii in humans and cats in Cebu, Philippines, and the first assessment of the prevalence of the parasite in pigs in the area since its initial detection in 1982. This is also the first report documenting the seropositivity of T. gondii in pregnant women in the country. The confirmed seropositivity of T. gondii in Cebu, Philippines, in the present study implies the endemicity of toxoplasmosis in this area and highlights the need for routine testing and increased public awareness.

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.

The global seroprevalence of Toxoplasma gondii in pigs: A systematic review and meta-analysis

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important disease with worldwide distribution. Infection can occur from ingesting raw or undercooked infected meat, and among food animal species, pork is known to be one of the main sources of meat-borne infection. Here, we present results of the first systematic review and meta-analysis on the global T. gondii seroprevalence in pigs. PubMed/MEDLINE, Scopus, and EMBASE databases were comprehensively searched for relevant studies published between January 1, 1990 and October 25, 2018. We used a random effects model to calculate pooled seroprevalence estimates with 95% confidence intervals (CI) and analyzed data from five continents. We also conducted subgroup and meta-regression analyses to evaluate the effects of geographical and climate variables on pooled seroprevalence rates. Among 1542 publications identified, 148 studies containing 150 datasets were included in the meta-analysis, and comprised 148,092 pigs from 47 countries. The pooled global T. gondii seroprevalence in pigs was estimated to be 19% (95%CI, 17-22%; 23,696/148,092), with the lowest seroprevalence in Europe (13%; 10-15%) and highest seroprevalence in Africa (25%; 17-34%) and North America (25%; 19-33%). The seropositivity rates in Asia and South America regions were (21%, 16-26%) and (23%; 17-30%), respectively. A significantly higher T. gondii seroprevalence was associated with higher mean annual temperature and lower geographical latitude. The presence of cats on farms was identified as a potential risk factor for T. gondii seropositivity (OR, 1.41; 95%CI, 1.00-2.02). Our findings highlight the importance of pigs as a possible source of human T. gondii infections.

Genotyping of Toxoplasma gondii isolated from pigs for human consumption

The present study aimed to isolate and genotype strains of T. gondii from pigs slaughtered for human consumption in South Brazil. Blood and tissues (heart, diaphragm, liver, tongue, and masseter) from 400 animals were collected at two slaughterhouses. Sera were obtained, and antibodies against T. gondii were detected by both indirect fluorescence antibody test (IFAT) and modified agglutination test (MAT). The tissues of animals that tested positive in MAT, IFAT, or both (cut-off ≥ 64) were bioassayed. Twenty-six (6.5%) of the 400 animals were positive by serology. A total of 18 (69.2%) out of those 26 were positive in the mouse bioassay. The isolates were characterized by using 10 PCR-RFLP genetic markers. Fourteen isolates were fully genotyped, and four isolates were genotyped using nine of the 10 markers. All isolates belonged to ToxoDB PCR-RFLP genotype #206. The present study reports on genotype #206 in pigs for the first time, and it confirms the atypical nature of the Brazilian T. gondii isolates. Additionally, even with low levels of antibodies detected in pig herds, pork presents a T. gondii infection risk for humans.

A review on inactivation methods of Toxoplasma gondii in foods

Toxoplasmosis is an infection caused by Toxoplasma gondii, a widespread zoonotic protozoan which poses a great threat to human health and economic well-being worldwide. It is usually acquired by ingestion of water contaminated with oocysts from the feces of infected cats or by the ingestion of raw or undercooked foodstuff containing tissue cysts. The oocyst can contaminate irrigation water and fresh edible produce. It is estimated that approximately one-third of the human population worldwide harbor this parasite. Infection with T. gondii is an important cause of diseases of the central nervous system and the eye in immunocompromised and immunocompetent individuals. The purpose of this study was to evaluate the efficacy and applicability of thermal (heating, cooking, freezing and low temperature), non-thermal (high pressure processing, ionizing irradiation and curing) and chemical and biochemical (disinfection, essential oils and biochemical methods such as enzymes, nanoparticles, antibiotics and immune response) treatments for the inactivation, inhabitation or to kill T. gondii in foodstuff intended for public consumption and under experimental conditions.

Prevalence, risk factors and genetic characterization of Toxoplasma gondii in sick pigs and stray cats in Jiangsu Province, eastern China

Toxoplasma gondii is an obligate intracellular parasitic protozoan with a worldwide distribution. The parasites in edible tissues of pigs and oocysts from cats are the major sources of T. gondii infection in humans. However, there are no data from sick pigs in veterinary clinics or from stray cats in Jiangsu Province, eastern China. In total, biological samples from 141 sick pigs and 64 stray cats were collected from this region. The rate of T. gondii infection in sick pigs was 46.81% using a polymerase chain reaction (PCR), and the overall prevalence of toxoplasmosis in stray cats was 34.38% by PCR and an enzyme-linked immunosorbent assay (ELISA). T. gondii was significantly more prevalent in lungs and heart than in liver and spleen (P < 0.05). Age and geographic region were considered to be the main risk factors associated with T. gondii infection in these pigs. The DNA samples from 17 sick pigs and seven stray cats, were successfully genotyped by multilocus PCR-restriction fragment length polymorphism (PCR-RFLP) with 10 genetic markers [SAG1, SAG2 (5'-3'SAG2, alt. SAG2), SAG3, GRA6, PK1, c22-8, c29-2, BTUB, L358 and Apico]. Six distinct genotypes were found, which were designated ToxoDB PCR-RFLP genotypes #9 (Chinese I), #10 (Type I), #213, and #89, and New 1 and New 2. Chinese I is the most prevalent T. gondii genotype in this region. The two new genotypes (designated New 1 and New 2) are reported and the ToxoDB PCR-RFLP genotype #89 is found for the first time in China. Such information will be useful for the prevention, diagnosis and treatment of porcine toxoplasmosis in Jiangsu Province, eastern China.

The European Union summary report on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks in 2016

This report of the European Food Safety Authority and the European Centre for Disease Prevention and Control presents the results of the zoonoses monitoring activities carried out in 2016 in 37 European countries (28 Member States (MS) and nine non-MS). Campylobacteriosis was the most commonly reported zoonosis and the increasing European Union (EU) trend for confirmed human cases since 2008 stabilised during 2012-2016. In food, the occurrence of Campylobacter remained high in broiler meat. The decreasing EU trend for confirmed human salmonellosis cases since 2008 ended during 2012-2016, and the proportion of human Salmonella Enteritidis cases increased. Most MS met their Salmonella reduction targets for poultry, except five MS for laying hens. At primary production level, the EU-level flock prevalence of target Salmonella serovars in breeding hens, broilers, breeding and fattening turkeys decreased or stabilised compared with previous years but the EU prevalence of S. Enteritidis in laying hens significantly increased. In foodstuffs, the EU-level Salmonella non-compliance for minced meat and meat preparations from poultry was low. The number of human listeriosis confirmed cases further increased in 2016, despite the fact that Listeria seldom exceeds the EU food safety limit in ready-to-eat foods. The decreasing EU trend for confirmed yersiniosis cases since 2008 stabilised during 2012-2016, and also the number of confirmed Shiga toxin-producing Escherichia coli (STEC) infections in humans was stable. In total, 4,786 food-borne outbreaks, including waterborne outbreaks, were reported. Salmonella was the most commonly detected causative agent - with one out of six outbreaks due to S. Enteritidis - followed by other bacteria, bacterial toxins and viruses. Salmonella in eggs continued to represent the highest risk agent/food combination. The report further summarises trends and sources for bovine tuberculosis, brucellosis, trichinellosis, echinococcosis, toxoplasmosis, rabies, Q fever, West Nile fever and tularaemia.

Experimental Porcine Toxoplasma gondii Infection as a Representative Model for Human Toxoplasmosis

Porcine infections are currently not the state-of-the-art model to study human diseases. Nevertheless, the course of human and porcine toxoplasmosis is much more comparable than that of human and murine toxoplasmosis. For example, severity of infection, transplacental transmission, and interferon-gamma-induced antiparasitic effector mechanisms are similar in pigs and humans. In addition, the severe immunosuppression during acute infection described in mice does not occur in the experimentally infected ones. Thus, we hypothesise that porcine Toxoplasma gondii infection data are more representative for human toxoplasmosis. We therefore suggest that the animal model chosen must be critically evaluated for its assignability to human diseases.

Toxoplasma gondii in raw and dry-cured ham: The influence of the curing process

The aim of this work was to analyze Toxoplasma gondii in raw hams by mouse bioassay and to evaluate the effect of curing on the viability of the parasite to assess the risk of infection from eating dry-cured ham. After a serology study of 1200 pigs in Aragón (Spain), forty-one naturally infected pigs with different serological titers against T. gondii were selected. Two cured periods (9 and 12 months) were evaluated as well as the influence of the physicochemical composition of hams on T. gondii survival. Although the parasite burden was low, a high number of seropositive pigs with Toxoplasma tissues cysts in raw hams were found (31.6%). Viability of T. gondii was influenced by the curing, with statistically significant differences between fresh and cured hams (p < 0.001). The viability was higher in hams cured for 9 months compared to those cured for 12 months. However, this period of curing resulted in the reduction but not in a complete elimination of the risk. Thus, from a public health point of view, under the conditions of this study it is safer to consume dry-cured ham with periods of curing higher than 12 months. Analysis of physicochemical results did not identify any variable with significant influence on the presence and viability of T. gondii in cured ham, but loss of viability of T. gondii was observed in hams with a lower fat content. Further research is required to validate combinations of salts concentration and time of curing that can be used as preventive measures in the HACCP system of dry-cured ham industry.