Toxoplasma gondii: prevalence and characterization of new genotypes in free-range chickens from south Brazil

Toxoplasma gondii infection in European brown hares (Lepus europaeus) in Brazil

Toxoplasmosis is a worldwide zoonosis that affects warm-blooded animals, including humans. Wild animals can act as intermediate hosts of this pathogen; thus, this study aims to detect Toxoplasma gondii infection in invasive European brown hares in Brazil. For this, 72 wild European brown hares were captured from July 2020 to June 2022 in three Brazilian states: São Paulo, Paraná, and Rio Grande do Sul. The diagnostic of Toxoplasma gondii infection was performed by bioassay in mouse, histopathology in Hematoxylin-Eosin-stained tissue sections (brain, liver, lungs, kidneys, and small intestine), serology by IFAT, and molecular techniques by conventional PCR and qPCR. The combined prevalence of the different diagnostic methods was 51.4% (37/72, CI= 40.1 - 62.6 %), and there was no statistical difference between sexes, age range, or geographical region of the hosts. Mouse bioassay was the technique that detected more positive hares. To our knowledge, this is the first confirmation of Toxoplasma gondii infection in invasive European brown hares in Brazil. These animals act as reservoirs and potential infection source for carnivores and other wild and domestic animals, including humans, thus contributing to perpetuate the disease cycle in São Paulo, Paraná, and Rio Grande do Sul States. Research such as the present study is necessary to raise awareness about the role of animals in the disease cycle.

Genetic diversity of Toxoplasma gondii in South America: occurrence, immunity, and fate of infection

Toxoplasma gondii is an intracellular parasite with a worldwide distribution. Toxoplasma gondii infections are of great concern for public health, and their impact is usually most severe in pregnant women and their foetuses, and in immunocompromised individuals. Displaying considerable genetic diversity, T. gondii strains differ widely according to geographical location, with archetypal strains predominantly found in the Northern Hemisphere and non-archetypal (atypical) strains, with highly diverse genotypes, found mainly in South America. In this review, we present an overview of the identification and distribution of non-archetypal strains of T. gondii. Special attention is paid to the strains that have been isolated in Brazil, their interaction with the host immunological response, and their impact on disease outcomes. The genetic differences among the strains are pivotal to the distinct immunological responses that they elicit. These differences arise from polymorphisms of key proteins released by the parasite, which represent important virulence factors. Infection with divergent non-archetypal strains can lead to unusual manifestations of the disease, even in immunocompetent individuals.

Seroprevalence and risk factors of Toxoplasma gondii infection in slaughtered chickens in Tripoli, Lebanon

Toxoplasma gondii is a cosmopolitan protozoan parasite that has a wide range of intermediate hosts. It infects all warm-blooded animals, including humans and birds. The latter typically pick up the infection by ground feeding, and people can contract the parasite from eating undercooked chicken meat. In recent years, investigations into T. gondii infection in poultry have been reported worldwide. However, there is no epidemiological data regarding the seroprevalence of anti-T. gondii antibodies in chicken in Lebanon. Thus, the current investigation was carried out to determine the seroprevalence and associated risk factors of T. gondii infection in chicken destined for human consumption in the Tripoli district of Lebanon. For this, a cross-sectional study was carried out between April 2021 and February 2022. Blood samples were collected from 400 chickens in four poultry abattoirs in Tripoli. The modified agglutination test (MAT) was used to test sera for T. gondii antibodies. The association of T. gondii seroprevalence with potential risk factors was assessed using the Chi-square test. Multivariate analysis was used to confirm the association. The seroprevalence of T. gondii antibodies reported in this study was 13% (52/400); it was higher in the free-range chicken group (19.3%, 29/150) than in the caged group (9.2%, 23/250) (OR = 2.365; 95% CI: 1.311-4.267) (P = 0.004). The wet season and the presence of cats in the poultry farms were significantly associated with an increased seropositivity to T. gondii infection (P ≤ 0.0001). Given the occurrence of T. gondii antibodies in slaughtered chicken in this area, the consumption of raw or undercooked chicken meats may pose a serious threat to public health and highlight the need to implement appropriate precautionary strategies to halt the spread of T. gondii to humans.

Screening of apical membrane antigen-1 (AMA1), dense granule protein-7 (GRA7) and rhoptry protein-16 (ROP16) antigens for a potential vaccine candidate against Toxoplasma gondii for chickens

Toxoplasmosis is a zoonotic disease caused by the protozoan parasite, Toxoplasma gondii known to infect almost all animals, including birds and humans globally. This disease has impacted the livestock industry and public health, where infection of domestic animals increases the zoonotic risk of transmission of infection to humans, threatening public health. Hence the need to discover novel and safe vaccines to fight against toxoplasmosis. In the current study, a novel multiepitope vaccine was designed using immunoinformatics techniques targeting T. gondii AMA1, GRA7 and ROP16 antigens, consisting of antigenic, immunogenic, non-allergenic and cytokine inducing T-cell (9 CD8⁺ and 15 CD4⁺) epitopes and four (4) B-cell epitopes fused together using AAY, KK and GPGPG linkers. The tertiary model of the proposed vaccine was predicted and validated to confirm the structural quality of the vaccine. The designed vaccine was highly antigenic (antigenicity = 0.6645), immunogenic (score = 2.89998), with molecular weight of 73.35 kDa, instability and aliphatic index of 28.70 and 64.10, respectively; and GRAVY of -0.363. The binding interaction, stability and flexibility were assessed with molecular docking and dynamics simulation, which revealed the proposed vaccine to have good structural interaction (binding affinity = -106.882 kcal/mol) and stability when docked with Toll like receptor-4 (TLR4). The results revealed that the Profilin-adjuvanted vaccine is promising, as it predicted induction of enhanced immune responses through the production of cytokines and antibodies critical in blocking host invasion.

Genetic diversity of Toxoplasma gondii isolates from birds in the world: A systematic review

Toxoplasma gondii (T. gondii) is one of the most important foodborne pathogens that infects a large number of vertebrate species and has a cosmopolitan distribution. Birds as intermediate hosts are very important in the life cycle of T. gondii and they can be a main source of infection for humans and felids, as well as other animals. Most species of birds feed from the ground and are the best indicator for soil contamination with T. gondii oocysts. Hence, T. gondii strains isolated from birds can represent different genotypes circulating in the environment and their main predators and consumers. The recent systematic review tries to represent the population structure of T. gondii in birds around the world. Six English language databases were searched from 1990 to 2020 to find the related studies and overall, 1275 isolates of T. gondii were separated from the analyzed samples in birds. The results of our study revealed that atypical genotypes were predominant (58.8%, 750 out of 1275). Types II, III, and I had less frequency with prevalence rates of 23.4%, 13.8%, and 2%, respectively. No isolates of Type I were reported from Africa. Summarizing ToxoDB genotypes circulating in birds around the world manifested that ToxoDB #2 was the most common (101/875), followed by ToxoDB #1 (80/875), and #3 (63/875). Totally, the results of our review represented the high genetic diversity of T. gondii with circulating non-clonal strains in birds from South and North America, while clonal parasites with low genetic diversity were predominant in Europe, Asia, and Africa.

Prevalence and molecular characterization of Toxoplasma gondii in different types of poultry in Greece, associated risk factors and co-existence with Eimeria spp

Toxoplasma gondii is a protozoan parasite of public health importance, infecting all warm-blooded animals, including chickens. Undercooked chicken meat or relevant products such as sausages could lead to human infections. In free-range, organic and slow-growth farming systems where the susceptibility period for chickens is extended, more knowledge about potential risk factors is essential. This study is the first seroepidemiological survey in different regions and types of chicken farms in Greece, using a major tachyzoite surface antigen-based ELISA (TgSAG1), combined with magnetic-capture PCR (mc-PCR) and bioassay for the isolation of strains from the chickens' tissues. Potential risk factors for T. gondii infection in these hosts were also investigated. Additionally, the co-existence of T. gondii and Eimeria spp. infections was assessed to elucidate epidemiological links between these two protozoan infections. Overall T. gondii seroprevalence was 9.5%. Of the backyard chickens sampled, 41.2% were seropositive and 70% of the organic and free-range layer farms had at least one T. gondii seropositive hen. No serologically positive broilers were found, although mc-PCR revealed a positive sample, highlighting the importance of accurate early-infection direct detection of T. gondii infections to ensure public health. T. gondii isolates obtained by mouse bioassay were genotyped. All belonged to type II (ToxoDB#3) as confirmed also by microsatellite typing. Production system, type of nutrition, and feeding system automation were identified as the most significant risk factors, while no association was found between the presence of cats and T. gondii seropositivity as calculated on both a farm level and per individual bird sampled.

First report on the isolation and genotyping of Toxoplasma gondii strains from free-range chickens in the state of Mato Grosso, Midwestern Brazil

In the present study, 51 strains of Toxoplasma gondii (T. gondii) were isolated from free-range chickens in the state of Mato Grosso, Midwestern Brazil, upon conducting bioassays in mice, and genotyped them using PCR-restriction fragment length polymorphism (PCR-RFLP) and 11 markers, including SAG1, SAG2 (5'3'SAG2 and alt. SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico, and CS3. Fifty isolates were completely genotyped revealing 17 genotypes of T. gondii as follows: 12 matched using ToxoDB PCR-RFLP with the previously reported genotypes, including #6 type BrI (n = 4), #8 type BrIII (n = 7), #11 type BrII (n = 3), #14 (n = 1), #19 (n = 1), #41 (n = 1), #99 (n = 1), #109 (n = 4), #116 (n = 1), #140 (n = 2), #166 (n = 9), #190 (n = 1); and five genotypes have not been described before [#313 (n = 6), #314 (n = 1), #315 (n = 1), #316 (n = 1), #317 (n = 1)]. Moreover, mixed infections were identified in five isolates (TgCkBrMT8, TgCkBrMT9, TgCkBrMT33, TgCkBrMT38, and TgCkBrMT41). Additionally, genotype #190 was reported for the first time in chickens from Brazil. Our results corroborate with previous studies on T. gondii isolates identified in chickens from Brazil, thereby confirming their diversity, a typicality, and possibility of co-infection due to different T. gondii strains present in the country.

Evaluation of quantitative polymerase chain reaction for the detection of Toxoplasma gondii oocysts shed by cats

Felines are definitive hosts of Toxoplasma gondii and can shed oocysts in their feces, contaminating the environment. Sporulated oocysts are highly resistant to the environment and have higher infectivity, which are attributed to many toxoplasmosis outbreaks. The aim of the present study was to evaluate a quantitative polymerase chain reaction (qPCR) technique for the detection of T. gondii oocysts shed by cats. Twelve cats from a previous vaccine experiment were challenged orally with 600 cysts of the TgDoveBr8 strain on day 72. Fecal samples were collected daily using the centrifugal flotation technique, with microscopic examination (Sheather technique) and qPCR for 20 days after the challenge. Cats from all groups shed oocysts in their feces. Five negative cats in the Sheather were positive according to qPCR on the 3rd day post-inoculation (dpi). Oocysts were detected on the 4th dpi using the Sheather; however, there was no statistical difference between the two methods (p=0.1116). In addition, there was no statistically significant difference in oocyst shedding between the groups according to the Sheather technique (p=0.6534) and qPCR (p=0.9670). In conclusion, these results demonstrate that qPCR can be used as an alternative to the Sheather to detect and quantify T. gondii oocysts.

A systematic review of Toxoplasma gondii genotypes in Gallus gallus domesticus worldwide: The focus is Brazil

Toxoplasma gondii was initially classified in three main lineages related to its virulence: Types I, II, and III. The recombination of genes during sexual cycle in felids gut led to more than 200 genotypes, found in ToxoDB database, using 11 RFLP markers. Free-range chickens are good bioindicators of soil contamination with T. gondii oocysts. In this sense, there are systematic reviews regarding data of genetic characterization of this parasite in felines and ruminants, but not in chickens heretofore, what makes this work necessary. A systematic review of the literature was performed with papers published prior to September 21, 2020. The main inclusion criteria were the presence of T. gondii genotypes, isolated strictly from free-range chickens, in experimental works. Initially, a total of 1,343 studies related to the terms were identified on databases and 30 studies were selected to be systematically reviewed. A total of 561 isolates of T. gondii from 6,356 free-range chickens were analyzed for genotyping, revealing 190 genotypes. ToxoDB #59 and #2 were the most frequent in America, #1 was the most frequent in Africa and three atypical isolates from genotype ToxoDB #9 were found in Asia. There is no data from Europe and Oceania. The majority of studies were Brazilian (16/30). A total of 68 RFLP genotypes were recognized among the 561 isolates' DNAs analyzed from the 30 studies. Some studies showed new genotypes never described before, which reinforces the idea that in some years even more new genotypes will be identified, due to gradual genetic recombination. A large number of undefined genotypes makes it necessary to perform Nested PCR technique when genotyping. Moreover, the lack of data in Continents such as Europe, Asia, and Oceania makes it necessary to perform new isolating and genotyping studies in these places.

Genetic and histopathological characterization of Toxoplasma gondii genotypes isolated from free-range chickens reared in the metropolitan region of Rio de Janeiro state, Brazil

This study aimed to genetically characterize Toxoplasma gondii isolates obtained from free-range chickens reared in the metropolitan region of the state of Rio de Janeiro, Brazil, and to evaluate the morbidity and histological changes associated with these isolates in mice. A mouse bioassay was used to isolate T. gondii from a pool of tissue samples (brain, heart, and thigh muscles) collected from 163 chickens. The 36 isolates obtained were genetically characterized by restriction fragment polymorphism (PCR-RFLP) analysis of the SAG1, 5'-3'SAG2, aSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico, and CS3 genomic regions. Seventeen atypical genotypes were identified and nine of them were reported for the first time. All identified genotypes caused clinical signs and histological changes in mice, with the majority being associated with high cumulative morbidity (65%) and severe or very severe histological changes (76%). The exclusive identification of atypical genotypes, with a predominance of new genotypes, indicates great genetic diversity of T. gondii in the region studied. In addition, the finding that all identified genotypes caused clinical signs and often severe histological changes in mice suggests potentially relevant virulence of these strains.

Ocular Disease in Mice Inoculated with Pork Heart Samples Infected with Toxoplasma gondii

PURPOSE

We analyzed the frequency, viability, and genetic characteristics of T. gondii in pork heart samples.Methods: Thirty-five fresh pork samples were purchased in a slaughterhouse in Erechim city. The DNA was extracted and qPCR was performed. T. gondii genotyping was performed using PCR-RFLP analysis. Positive samples were digested and inoculated in mice for viability analysis.Results: Our results showed that T. gondii DNA was detected in 25.7% of the pork heart samples and genotyping revealed one new atypical strain. The viability analyses demonstrated that 40% of mice presented clinical signs of T. gondii infection. qPCR was positive in the lung, liver, and brain of mice that presented clinical signs of T. gondii infection. Also, the histopathology analysis showed retinal disorganization, retinal detachment, inflammatory cell infiltration, and fibrosis in the eyes analyzed.Conclusion: Our findings have shown that pork eat from southern Brazil may contain live T. gondii that could be associated with toxoplasmosis.

Occurrence of Atypical and New Genotypes of Toxoplasma Gondii in Free-Range Chickens Intended for Human Consumption in Brazil

Purpose

The aim of the present study was to detect and genotype T. gondii in free-range chickens destined to human consumption in Alagoas state, Brazil.

Methods

Two hundred blood samples were collected from free-range chickens and submitted to indirect immunofluorescence antibody test (IFAT). Brain tissue from 14 animals randomly selected were subjected to mouse bioassay. Positive samples in mouse bioassay were submitted to PCR and genotyped by PCR–RFLP.

Results

Out of two hundred blood samples from chickens, 72 (36%) samples were considered positive by IFAT. Two T. gondii strains were isolated, both being characterized as atypical and classified as #146 and a new genotype, named #279 in ToxoDB database.

Conclusions

Our results showed a sero-occurrence of T. gondii in free-range chickens intended for humans, and the genetic diversity of the parasite in Brazil, with a new genotype described.

Epidemiologic significance of Toxoplasma gondii infections in chickens (Gallus domesticus): the past decade

Toxoplasma gondii infections are common in humans and animals worldwide. Domestic free-range chickens (Gallus domesticus) are excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Chickens can be easily infected with T. gondii; however, clinical toxoplasmosis is rare in these hosts. Chickens are comparatively inexpensive and thus are good sentinel animals for T. gondii infections on the farms. Here, the authors reviewed prevalence, the persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from chickens worldwide for the past decade. Data on phenotypic and molecular characteristics of 794 viable T. gondii strains from chickens are discussed, including new data on T. gondii isolates from chickens in Brazil. This paper will be of interest to biologists, epidemiologists, veterinarians and parasitologists.

Toxoplasma gondii infection in backyard chickens (Gallus domesticus): Seroprevalence and associated risk factors in Northwest Ethiopia

Limited data is accessible about the seroprevalence of Toxoplasma gondii infection in backyard (free-range) chickens in Ethiopia. This cross-sectional study was carried out from November 2018 to April 2019 to estimate the seroprevalence and assess associated risk factors of T. gondii infection in backyard chickens in Northwest Ethiopia. Serum samples were collected from 384 backyard chickens. Toxoplasma gondii antibodies were assayed using Toxo-Latex slide agglutination test. Seropositivity for T. gondii antibodies was confirmed in 72.4% of 384 birds. Altitude, presence of cat and dog around the house, age, breed and water source were considered as potential risk factors (p < .05) associated with Toxoplasma seropositivity in this study. But, sex was not identified as a predictor for Toxoplasma infection even though higher seroprevalence was observed in females (73.7%) than males (69.3%). In conclusion, this study indicates a high prevalence of T. gondii infection in backyard chickens in Northwest Ethiopia. Therefore, further works on epidemiology, bioassay, isolation and genetic characterization of the pathogen are imperative. It also warrants an action to prevent and control T. gondii infection in backyard chickens that could serve as an important intermediate host and pose a potential threat for consumers.

Prevalence of Toxoplasma gondii Infections in Chicken Hearts from Farmers' Markets and Supermarkets in the Tai'an Region of China

ABSTRACT

The detection of Toxoplasma gondii in quick-frozen chickens is a good indicator of the possible transmission risk that this parasite poses to human consumers. The aim of this study was to investigate the occurrence of T. gondii in quick-frozen chicken hearts using a nested PCR assay. Heart samples (n = 720) from farmers' markets and supermarkets in the Tai'an region, People's Republic of China, were collected, and the DNA extracted was analyzed for the presence of T. gondii. The overall prevalence of T. gondii in all samples was 10.7%, but the rates for samples from farmers' markets (19.2%) and supermarkets (2.2%) were significantly different (P < 0.01). Nested PCR restriction fragment length polymorphism genotyping was performed on the 77 positive samples based on the T. gondii SAG3 and GRA6 gene loci. SAG3 genotyping revealed a mixed infection rate of 89.6% for type I and type I/II strains, and GRA6 genotyping revealed an infection rate of 98.7% for type I strains. Our results revealed a high prevalence of T. gondii in chicken hearts from farmers' markets, and most strains were mainly type I strains. Further studies are needed to determine whether quick-frozen chicken hearts are involved in disease transmission to human consumers in this area.

HIGHLIGHTS

Prevalence and Genetic Diversity of Toxoplasma gondii in Free-Ranging Chickens from the Caribbean

Purpose

Toxoplasma gondii is a zoonotic parasite capable of infecting a wide range of hosts. Free-range chickens are important sentinels in the epidemiology of this parasite as they feed from the ground and are likely to ingest oocysts shed in the faeces of infected cats. Atypical strains of T. gondii are known to dominate in South America where they are associated with more severe disease in humans, yet relatively little is known about the strains circulating in neighbouring Caribbean islands.

Methods

In this study, hearts and brains were collected from free-range chickens in Antigua and Barbuda (n = 45), Dominica (n = 76) and Trinidad (n = 41), and DNA was extracted for nested ITS1 PCR and PCR–RFLP. Sera were collected and screened for antibodies using the modified agglutination test (MAT).

Results

Antibodies to T. gondii were detected in 20.5, 38.2 and 17.1% of chickens in Antigua and Barbuda, Dominica and Trinidad, respectively. Toxoplasma gondii DNA was also detected by PCR in 24.4, 17.1 and 17.1% of chickens, respectively, giving an overall prevalence of 31.1, 42.1, and 29.3% for each of the 3 island nations. Results of PCR–RFLP revealed 2 new atypical genotypes (designated ToxoDB #281 and #282) and one Type III (ToxoDB #2) in chickens from Antigua. Partial genotyping of a further 8 isolates (7 from Antigua and one from Trinidad) revealed different allele-types at five or more markers for 7 of the isolates, suggesting atypical genotypes.

Conclusions

This is the first study to report the prevalence of T. gondii in free-range chickens in Antigua and Barbuda, Dominica and Trinidad and Tobago. It is also the first to report the presence of atypical genotypes in Antigua and Barbuda and Trinidad and Tobago.

A new strain of Toxoplasma gondii circulating in southern Brazil

Recently, an outbreak of human toxoplasmosis was identified in Santa Maria city, Southern Brazil. However, the suspected vehicle of Toxoplasma gondii contamination in this region remains unclear. This study was conduct to analyze whether pork meat samples collected in supermarkets from Santa Maria city, RS, could be infected with T. gondii. Thus, we analyzed the presence of T. gondii DNA in 20 pork hearts, 20 pork tongues and 20 sausages. DNA was extracted from each sample and real-time PCR was performed using 529-bp and B1 markers. T. gondii genotyping was performed by PCR-RFLP analysis. T. gondii DNA was detected in 2 of 20 (10%) heart samples and in 1 of 20 (5%) tongue samples using 529-bp marker. Besides, those 2 (10%) heart samples also were positive for T. gondii using B1 marker. All sausage samples were negative for both markers. Genotyping revealed a new atypical genotype in the pork meat. Our findings were not able to confirm whether these food samples were involved in some outbreak. However, we can conclude that food samples containing T. gondii can be displayed in Santa Maria supermarkets. In addition, a new T. gondii genotype was identified circulating in southern Brazil.

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.

Regional Differences in the Clinical Manifestation of Ocular Toxoplasmosis Between the Center and Northeast of Argentina

Purpose: To compare the clinical characteristics of patients with active episodes of ocular toxoplasmosis from three provinces, Misiones, Santa Fe, and Buenos Aires, Argentina. Methods: Patients with a diagnosis of ocular toxoplasmosis from three databases of four tertiary referral uveitis centers were reviewed. Collected data included presentation of the retinochoroiditis, location of the active lesions, associated inflammatory ocular signs and complications. Results: Three hundred thirty-four patients were included in this study. Bilateral involvement of the ocular disease occurred in 26 patients in Misiones (35.14%), 21 patients (12.8%) in Santa Fe, and 9 patients in Buenos Aires (9.4%) (p < 0.001). Extensive retinitis was observed in 49 patients (66.2%) in Misiones, 39 patients (23.8%) in Santa Fe, and 12 patients (12.5%) in Buenos Aires (p < 0.001). Conclusion: The results indicate that there are differences in the clinical characteristics of ocular toxoplasmosis in patients from Misiones, Santa Fe, and Buenos Aires.