Quality control of Toxoplasma gondii in meat packages: standardization of an ELISA test and its use for detection in rabbit meat cuts

Detection of Toxoplasma gondii in artisanal salted meat products sold in street markets of the Ilhéus-Itabuna microregion

This study aimed to detect Toxoplasma gondii in artisanal salted meat products sold in street markets in the Ilhéus-Itabuna microregion and to assess the salt concentration used in their preparation and its influence on the parasite's viability. A total of 125 samples of various artisanal meat products sold in street markets located in the Ilhéus-Itabuna microregion were collected during 2021. Serological analysis using indirect hemagglutination (HAI) and molecular analysis (PCR) were performed on these samples to detect the presence of the parasite. Möhr's method was utilized to determine the sodium chloride concentration in the samples. Of all samples, 21 were subjected to a bioassay in albino mice to verify the viability of possible tissue cysts. Among the 125 meat products, 10 (8%) tested positive in the serological analysis including four cured pork sausages, five beef sun-dried meats, and one mixed fresh sausage (pork and chicken). None of 125 samples tested positive in the molecular analysis. On bioassay, all mice tested negative for the presence of the parasite. The NaCl concentration in the positive samples ranged from 2.9% to 8%. The results demonstrated that the salt concentration in the collected samples was sufficient to inactivate the parasite T. gondii.

Use of stable isotopes to reveal trophic relationships and transmission of a food-borne pathogen

Predators in food webs are valuable sentinel species for zoonotic and multi-host pathogens such as Toxoplasma gondii. This protozoan parasite is ubiquitous in warm-blooded vertebrates, and can have serious adverse effects in immunocompromised hosts and foetuses. In northern ecosystems, T. gondii is disproportionately prevalent in Inuit people and wildlife, in part due to multiple routes of transmission. We combined data on T. gondii infection in foxes from Nunavik (northern Québec, Canada) with stable isotope data tracking trophic relationships between foxes and several of their main prey species. Red (Vulpes vulpes) and Arctic fox (Vulpes lagopus) carcasses were collected by local trappers from 2015 to 2019. We used magnetic capture PCR to detect DNA of T. gondii in heart and brain tissues, and enzyme-linked immunosorbent assay to detect antibodies in blood. By linking infection status with diet composition, we showed that infected foxes had a higher probability of consuming aquatic prey and migratory geese, suggesting that these may be important sources of T. gondii transmission in the Arctic. This use of stable isotopes to reveal parasite transmission pathways can be applied more broadly to other foodborne pathogens, and provides evidence to assess and mitigate potential human and animal health risks associated with T. gondii in northern ecosystems.

Meat Juice and Oral Fluid as Alternatives to Serum for Aujeszky Disease Monitoring in Pigs

Aujeszky Disease Virus (ADV) is a double-stranded DNA virus with a lipoprotein envelope. The natural hosts of the infection are Suidae, but the virus can infect many other mammals. The gold-standard method identified by the WOAH for the diagnosis of Aujeszky disease is the ELISA method. The objective of this study was to compare the performance of meat juice and oral fluid matrices using a commercial ELISA kit designed for serum. A total of 80 blood and oral fluid samples were collected from four pig farms selected for this study. Diaphragm muscle samples of about 100 g and blood samples were collected from 213 animals at the abattoir. These biological matrices were collected from the same animals and tested using a competitive ELISA kit to detect antibodies against ADV. The relative accuracy of the meat juice compared to that of the serum was 96.7% (95% CI: 93.3-98.7%), with 206 correct results out of 213. The relative accuracy of the oral fluid compared to that of the serum was 61.3% (95% CI: 49.7-71.9%), with 58 correct results out of 80. Meat juice has a better combination of sensitivity and specificity than oral fluid. The usage of meat juice in routine diagnostic examinations could be achieved after further investigations to optimize the procedure.

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.

Are foxes (Vulpes spp.) good sentinel species for Toxoplasma gondii in northern Canada?

BACKGROUND

In changing northern ecosystems, understanding the mechanisms of transmission of zoonotic pathogens, including the coccidian parasite Toxoplasma gondii, is essential to protect the health of vulnerable animals and humans. As high-level predators and scavengers, foxes represent a potentially sensitive indicator of the circulation of T. gondii in environments where humans co-exist. The objectives of our research were to compare serological and molecular assays to detect T. gondii, generate baseline data on T. gondii antibody and tissue prevalence in foxes in northern Canada, and compare regional seroprevalence in foxes with that in people from recently published surveys across northern Canada.

METHODS

Fox carcasses (Vulpes vulpes/Vulpes lagopus, n = 749) were collected by local trappers from the eastern (Labrador and Québec) and western Canadian Arctic (northern Manitoba, Nunavut, and the Northwest Territories) during the winters of 2015-2019. Antibodies in heart fluid were detected using a commercial enzyme-linked immunosorbent assay. Toxoplasma gondii DNA was detected in hearts and brains using a magnetic capture DNA extraction and real-time PCR assay.

RESULTS

Antibodies against T. gondii and DNA were detected in 36% and 27% of foxes, respectively. Detection of antibodies was higher in older (64%) compared to younger foxes (22%). More males (36%) than females (31%) were positive for antibodies to T. gondii. Tissue prevalence in foxes from western Nunavik (51%) was higher than in eastern Nunavik (19%). At the Canadian scale, T. gondii exposure was lower in western Inuit regions (13%) compared to eastern Inuit regions (39%), possibly because of regional differences in fox diet and/or environment. Exposure to T. gondii decreased at higher latitude and in foxes having moderate to little fat. Higher mean infection intensity was observed in Arctic foxes compared to red foxes. Fox and human seroprevalence showed similar trends across Inuit regions of Canada, but were less correlated in the eastern sub-Arctic, which may reflect regional differences in human dietary preferences.

CONCLUSIONS

Our study sheds new light on the current status of T. gondii in foxes in northern Canada and shows that foxes serve as a good sentinel species for environmental circulation and, in some regions, human exposure to this parasite in the Arctic.

Epidemiological and Public Health Significance of Toxoplasma gondii Infection in Wild Rabbits and Hares: 2010-2020

Toxoplasmosis is a zoonosis of global distribution, and Toxoplasma gondii infections are common in humans and animals worldwide. Hares and rabbits are important small game species, and their meat is consumed by humans in many countries. Demand for rabbit meat for human consumption is increasing; therefore, toxoplasmosis in rabbits and hares is of epidemiological significance. Viable T. gondii has been isolated from rabbits. The present review summarizes worldwide information on the seroprevalence, parasitological investigations, clinical cases, isolation, and genetic diversity of T. gondii in wild rabbits, free domestic rabbits, hares, and other rabbits from 2010 to 2020. Differences in prevalence, susceptibility, genetic variants, and clinical implications of T. gondii infection in rabbits and hares are discussed. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers. Additional studies are needed to increase our knowledge of genetic variants and the population structure of T. gondii in rabbits and hares and to understand the differences in susceptibility to T. gondii in hares in different areas.

Comparison of a commercial modified direct agglutination test and a commercial enzyme-linked immunosorbent assay for screening for antibodies against Toxoplasma gondii in naturally exposed domestic cats

Domestic cats and other felids are definitive hosts for the zoonotic protozoan parasite Toxoplasma gondii. Serology is widely used in epidemiological studies conducted to estimate the proportion of domestic cats that have encountered the parasite. However, a limited number of such studies are available from some regions, including eastern parts of Europe and Russia. Various serological tests have been applied for T. gondii serology for feline samples. Seropositivity indicates previous exposure, and seropositive cats are presumed to have shed oocysts of the parasite earlier and to be chronically infected. In this study, we included a random sample of 200 sera and plasma samples from a larger sampling frame comprising samples from domestic cats from Estonia, where T. gondii is common. The samples, which had been previously screened for anti-T. gondii immunoglobulin G antibodies using a commercial modified direct agglutination test (DAT: Toxo-Screen DA; bioMérieux SA, Marcy-l'Étoile, France), were screened using a commercial enzyme-linked immunosorbent assay (ELISA: VectoToxo-antibodies [VektoTokso-antytila], VectorBest, Novosibirsk, Russian Federation). The cut-off for seropositivity with DAT was titer of 40. Of the 200 samples, 120 (60.0%) tested positive with DAT and 114 (57.0%) tested positive with ELISA; 112 samples (56.0%) tested positive with both tests. Percent agreement of 95.0% and Kappa 0.8971 indicated an almost perfect agreement between the screening results using the two methods. The results of this study can be useful for comparison, evaluation, and interpretation of results obtained with these two tests in seroepidemiological studies and may encourage more studies on the topic from eastern parts of Europe and Russia.

A facile isoelectric focusing of myoglobin and hemoglobin used as markers for screening of chicken meat quality in China

A novel analytical protocol was developed for general quality screening of chicken meat based on IEF and protein extraction. To demonstrate the developed protocol, 24 chickens were divided into three groups; each had eight chickens. The chickens in Group 1 were slaughtered by exsanguination, Group 2 asphyxiated in water, and that in Group 3 were infected by new castle disease virus. Proteins were extracted from the meat samples by using pure water as an extractant, separated by IEF, verified by western blot, and quantified via imaging analysis. The relevant experiments demonstrated that two myoglobin (Mb) bands were detected at pI 6.8 and 7.04 for all samples of Groups 1, 2, and 3, but there were additional hemoglobin (Hb) bands at pI 7.09 and 7.13 (P < 0.05) for the samples of Groups 2 and 3. The results implied that Hb bands might be a potential biomarker for the screening of chicken meat quality. The RSD values of two Mb bands (pI 6.8 and 7.04) in Group 1 were respectively 4.08 and 3.63%, the ones of two Hb bands (pI 7.09 and 7.13) in Group 2 were 3.66 and 2.10%, and those in Group 3 were 2.17% and 2.77%, respectively. All the RSD values indicated high stability and reliability of the developed protocol. Additionally, the protocol had a direct readout of protein bands in IEF without staining. However, it was time-consuming and had high cost. Even so, the relevant general method and finding have potential for screening of chicken meat quality.

The One Health Approach to Toxoplasmosis: Epidemiology, Control, and Prevention Strategies

One Health is a collaborative, interdisciplinary effort that seeks optimal health for people, animals, plants, and the environment. Toxoplasmosis, caused by Toxoplasma gondii, is an intracellular protozoan infection distributed worldwide, with a heteroxenous life cycle that practically affects all homeotherms and in which felines act as definitive reservoirs. Herein, we review the natural history of T. gondii, its transmission and impacts in humans, domestic animals, wildlife both terrestrial and aquatic, and ecosystems. The epidemiology, prevention, and control strategies are reviewed, with the objective of facilitating awareness of this disease and promoting transdisciplinary collaborations, integrative research, and capacity building among universities, government agencies, NGOs, policy makers, practicing physicians, veterinarians, and the general public.

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.

Avaliação da técnica de ELISA para pesquisa de IgG anti-Toxoplasma gondii em exsudatos de carnes de sol

Resumo Toxoplasmose é uma importante zoonose de veiculação hídrica e alimentar, cujo agente é o Toxoplasma gondii. A toxoplasmose acomete seres humanos e animais de produção. É uma zoonose cosmopolita e sua prevalência está relacionada ao consumo de carne crua ou mal cozida, sendo este hábito considerado um dos principais fatores de risco. O controle do potencial de transmissão da toxoplasmose pela carne é relevante, principalmente em produtos artesanais, como as carnes de sol, que são processadas artesanalmente e podem ser consumidas cruas ou mal passadas. Neste estudo, propomos a avaliação da presença de imunoglobulinas da classe IgG anti-T. gondii pela técnica de imunoensaio ELISA, padronizando uma diluição do exsudato cárneo obtido pelo descongelamento das carnes de sol produzidas a partir de músculos de animais experimentais e também de carnes de sol comercializadas em “Casas do Norte”. Nossos resultados demonstram que o potencial do exsudato cárneo como um material biológico é limitado em carnes processadas, possibilitando o ensaio somente das amostras que obtiveram uma absorbância em densidade óptica (DO) igual ou superior a 0,116, faixa que garante a presença de sangue suficiente para o ensaio da ELISA, permitindo aferir imunoglobulinas específicas anti-T. gondii. Dentre as 32 amostras de carne de sol obtidas de cortes de bovinos experimentais, somente nove (28%) apresentaram sangue suficiente para ser ensaiadas, mensuradas pela DO igual ou superior a 0,116, sendo sete positivas, obtidas de cortes de animais infectados, e duas negativas, confeccionadas com cortes de animais controle. Dentre as 42 amostras de exsudatos de carne de sol obtidas no varejo, somente seis (14,28%) apresentaram sangue suficiente para serem ensaiadas e somente uma apresentou imunoglobulinas anti-T. gondii, concordante com dados da literatura. Nossos resultados são promissores e demonstram a importância do desenvolvimento de pesquisa e novas abordagens no controle sanitário dos alimentos ofertados à população.

Occurrence of Toxoplasma gondii in domestic rabbits of Northeastern Brazil

The present study aimed to conduct a serosurvey of toxoplasmosis in domestic rabbits of Northeastern Brazil. Blood samples and tissue fragments (brain, heart and diaphragm) were collected from 150 and 54 rabbits from the state of Pernambuco, Brazil, respectively. The serum samples were subjected to serological analysis (Modified Agglutination Test - MAT) and the tissue samples were assessed by PCR and histopathological analysis. Data collected through questionnaires were subjected to analysis of risk factors. According to the MAT and the PCR results, 6.7% (10/150; CI 3.2%-11.9%) of the rabbits were positive for anti-T. gondii antibodies and 9.25% (5/54) of the tissue fragments were positive for T. gondii DNA, respectively. Lesions associated with T. gondii infection, mainly characterized by granuloma, mononuclear cell infiltrates, degeneration areas and necrosis in brain and heart, were detected in the histopathological analysis. The risk factors associated with T. gondii infection identified in the present study were homemade food (odds ratio = 39.00) and contact between cats and rabbits (odds ratio = 52.00). This is the first report of toxoplasmosis in rabbits of Northeastern Brazil. The management problems identified in the present study must be corrected to reduce the frequency of positive animals in herds of rabbits.

Toxoplasma gondii coinfection with diseases and parasites in wild rabbits in Scotland

In wild rabbits (Oryctolagus cuniculus) on an estate in Perthshire, central Scotland, the seroprevalence of Toxoplasma gondii was 18/548 (3·3%). The wild rabbit could be a T. gondii reservoir and it has potential value as a sentinel of T. gondii in environmental substrates. Toxoplasma gondii was associated with female sex (P < 0·001) and with relatively heavy infections by Eimeria stiedae (P = 0·036). It was not associated with the intensity of coccidial oocysts, the severity of myxomatosis caused by the virus Myxomatosis cuniculi, the intensity of roundworm eggs, the year or season, rabbit age or distance from farm buildings. Coinfections could have been affected by gestational down regulation of type 1 T helper cells. A sudden influx or release of T. gondii oocysts might have occurred. This is the first report of T. gondii in any wild herbivore in Scotland and also the first report of lapine T. gondii as a coinfection with E. stiedae, M. cuniculi and helminths.

"Meat juice" is not a homogeneous serological matrix

Meat juice samples are used in serological assays to monitor infectious diseases within the food chain. However, evidence of inferior sensitivity, presumably due to low levels of antibodies in the meat juice compared to serum, has been presented, and it has been suggested that adjusting the dilution factor of meat juice in proportion to its blood content could improve sensitivity. In the present study, the agreement between Toxoplasma gondii-specific immunoglobulin G (IgG) levels in meat juice and serum was evaluated, and whether the level of immunoglobulins in meat juice was dependent on its blood content. Serum and meat juice from diaphragm, heart, tongue, Musculus triceps brachii and M. semitendinosus were collected from 20 pigs experimentally infected with T. gondii. Analysis of total IgG, heme-containing proteins (hematin), and hemoglobin (Hb) revealed significant differences between samples from different muscles, with the highest levels in samples from heart and tongue, and the lowest in samples from leg muscles. Comparison of T. gondii-specific antibody titers in meat juice and serum revealed a strong positive correlation for meat juice from heart (rs=0.87; p<0.001), while it was lower for M. semitendinosus (rs=0.71; p<0.001) and diaphragm (rs=0.54; p=0.02). Meanwhile, the correlation between total IgG and T. gondii titer ratio (meat juice/serum) was highest in diaphragm (rs=0.77; p<0.001) followed by M. semitendinosus (rs=0.64; p=0.005) and heart (rs=0.50; p=0.051). The correlation between Hb and T. gondii titer ratio was only significant for diaphragm (rs=0.65; p=0.008), and for hematin no significant correlation was recorded. In conclusion, the specific IgG titers in meat juice appeared to depend on the total IgG level, but the correlation to blood (Hb or hematin) was poor. Importantly, large significant differences in total IgG levels as well as in specific antibody titers were recorded, depending on the muscle the meat juice had been extracted from.

Zoonoses parasitárias veiculadas por alimentos de origem animal: revisão sobre a situação no Brasil

O Brasil se destaca na produção mundial de alimentos de origem animal, sendo que cada vez mais os mercados consumidores buscam alimentos seguros e inócuos para a saúde. Nesse contexto, torna-se fundamental a prevenção das zoonoses, que podem ser transmitidas através dos alimentos de origem animal, que muitas vezes são consumidos sem o devido preparo ou por populações mais vulneráveis. Nesta revisão bibliográfica, serão abordadas importantes enfermidades parasitárias de caráter zoonótico que ocorrem atualmente pela via de transmissão alimentar: a toxoplasmose, o complexo teníase-cisticercose, criptosporidiose, anisacose, difilobotriose e triquinelose.

Risk factors for ocular toxoplasmosis in Brazil

The aim of this study was to investigate risk factors for ocular toxoplasmosis (OT) in patients who received medical attention at a public health service. Three hundred and forty-nine consecutive patients, treated in the Outpatient Eye Clinic of Hospital de Base, São José do Rio Preto, São Paulo state, Brazil, were enrolled in this study. After an eye examination, enzyme-linked immunosorbent assay (ELISA) was used to determine anti-Toxoplasma gondii antibodies. The results showed that 25·5% of the patients were seronegative and 74·5% were seropositive for IgG anti-T. gondii antibodies; of these 27·3% had OT and 72·7% had other ocular diseases (OOD). The presence of cats or dogs [odds ratio (OR) 2·22, 95% confidence interval (CI) 1·24–3·98, P = 0·009] and consumption of raw or undercooked meat (OR 1·77, 95% CI 1·05–2·98, P = 0·03) were associated with infection but not with the development of OT. Age (OT 48·2 ± 21·2 years vs. OOD: 69·5 ± 14·7 years, P < 0·0001) and the low level of schooling/literacy (OT vs. OOD: OR 0·414, 95% CI 0·2231–0·7692, P = 0·007) were associated with OT. The presence of dogs and cats as well as eating raw/undercooked meat increases the risk of infection, but is not associated with the development of OT.

Prevalence and genotypes of Toxoplasma gondii in pork from retail meat stores in Eastern China

Pork is known as one of the most important sources of Toxoplasma gondii infection in China. In the present study, 416 fresh pork samples were collected from different locations of Anhui province, Eastern China. Tissue fluid ELISA was conducted to detect the antibodies to T. gondii. Real-time PCR and bioassay were performed to identify the presence of T. gondii DNA and viable parasites, respectively. Seventy-five out of 416 samples (18.03%) demonstrated real-time PCR positive reaction and 42 out of 416 samples (10.1%) showed tissue fluid ELISA positive reaction. One isolate (Tgpkfx171) was obtained through bioassay in mice from 14 samples that demonstrated both PCR and ELISA positive reaction. The isolate and seven positive DNA samples were genotyped using 9 PCR-RFLP markers including SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. Among these, only the isolate and two positive DNA samples were genotyped with complete data for all loci, belonging to ToxoDB#9 (Chinese 1) and ToxoDB#213, respectively. This is the first report of the prevalence and genetic typing of T. gondii from pork in retail meat stores in China. The present results provide an accurate picture of the risk of exposure to T. gondii in retail pork in China.