Development of an in vivo model for Toxoplasma gondii infections in chickens and turkeys simulating natural routes of infection

Molecular characterization and epidemiology of Toxoplasma gondii isolates from free-range chickens in the southwest region of Goiás: new genotypes

The purpose of this study was to isolate Toxoplasma gondii from tissues of free-range chickens in the southwestern region of Goiás, to detect and molecularly characterize the genetic material of the parasite, and to determine the seroprevalence of the protozoan parasite in these animals. A seroprevalence of T. gondii antibodies of 76% (19/25) was found among the chickens, while genetic material from their tissues was detected in 56% (14/25). A total of 14 isolates was obtained in the bioassay, ten of which were considered acute, eight were considered isolates of high virulence lethal to mice, and four of low virulence, considered non-lethal but with the ability to chronify the infection. Seven of the ten isolates showed significant morphometric differences from the RH strain, in terms of nucleus-complex-apical distance, length and width. Genotyping of the acute isolates was performed by RFLP-PCR, using 11 genetic markers: SAG1, SAG2 (3'SAG2 and 5'SAG2), alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and APICO. The results were compared and classified according to the genotypes listed on the ToxoDB Platform, where different profiles were observed indicating the presence of two known genotypes (#7 and #63) and five new genotypes (NEW 3, NEW4, NEW5, NEW6, NEW 7). The results showed high seroprevalence, isolation rate, molecular detection and genotypic variations of T. gondii in free-range chickens in the southwestern region of Goiás.

Factors Associated with Toxoplasma gondii Seroprevalence in Pregnant Women: A Cross-Sectional Study in Belgrade, Serbia

Toxoplasmosis, caused by the cosmopolitan protozoan Toxoplasma gondii, has particular implications during pregnancy due to the possible transmission of infection to the fetus. Very few studies have assessed seroprevalence and the risk factors for toxoplasmosis in healthy pregnant women. The aim of this study was to examine the seroprevalence of T. gondii infection in healthy pregnant women and to identify the associated risk factors for toxoplasmosis. The cross-sectional study involved 300 healthy pregnant women who came to the Institute for Blood Transfusion in Belgrade between November 2018 and February 2019 for routine blood group and Rh factor testing before delivery, who were also tested using serological screening for the presence of specific antibodies. Positives were further examined using enzyme immunoassay. Of the total sera of participants analyzed, 38 were positive for specific IgG, resulting in a seroprevalence rate of 12.7% (95% Confidence Interval (CI) 9.1-17.0%). All pregnant women presented negative anti-T. gondii IgM antibodies. The multivariate logistic regression analysis revealed that living in a house with a garden was independently associated with the risk of T. gondii infections, while eating chicken meat was connected with a lower risk compared to eating other types of meat with an odds ratio (OR) of 2.5 (95% CI 1.21-5.02) and an OR of 0.3 (95% CI 0.09-0.83), respectively. Although the prevalence of anti-T. gondii IgG antibodies is relatively low, it is essential to maintain and adapt evidence-based preventive measures for toxoplasmosis continually.

Seroepidemiology of Toxoplasma gondii infection and parasite DNA in free-range chickens in Aguascalientes, Mexico

The objectives of the study were to estimate the prevalence of anti-Toxoplasma gondii antibodies in free-range chickens in Aguascalientes, Mexico, its association with certain risk factors, and the frequency of parasite DNA in the heart. Eighty-one small rural family farms were included, and blood and heart samples were taken from 150 clinically healthy, adult, free-range chickens. Serum samples were processed by indirect immunofluorescence antibody test considering a dilution of 1:16 as a positive reaction, while the DNA detection was done by PCR. The correlation between the presence of antibodies and the potential risk factors was estimated with logistic regression. The overall seroprevalence in the examined populations was 67%, with a range from 33% to 100% among municipalities, and 78% of the farms having at least one seropositive bird. The PCR test identified the presence of parasite DNA for one case only. Among the variables, the presence of cats and the presence of other animal species on the farm were the ones that had the highest values, while the presence of feral cats and the presence of noxious fauna were also identified as potential risk factors. The results indicate high soil contamination by T. gondii oocysts, which implies the active role of cats living on the farms.

Comparison of serological and molecular techniques to detect Toxoplasma gondii in free-range chickens (Gallus gallus domesticus)

The present study aimed to compare different indirect and direct diagnostic techniques to diagnose Toxoplasma gondii in free-range chickens. Samples of 386 chickens obtained from 24 Paraná properties were used for serological analysis by indirect fluorescent antibody test (IFAT), modified agglutination test (MAT), and enzyme-linked immunosorbent assay (ELISA). Animals positive by IFAT and/or MAT had their tissues submitted to the mouse bioassay, and those who were positive in this technique had their blood, tissues, and acidic pepsin tissue digestion submitted to PCR (conventional, nested, and quantitative-PCR (qPCR)). One hundred and nineteen chickens (30.8 %) were positive in at least one of the serological tests, being 102 (26.4 %) in the IFAT, 64 (16.6 %) in the MAT, and 62 (16.0 %) in the ELISA. The IFAT was used as a gold standard, and the MAT showed higher sensitivity (46.0 %) and specificity (94.0) compared to ELISA (43.5 % and 93.6 %, respectively). Ninety samples of eighteen chickens positive in the mouse bioassay were subjected to PCR, and according to molecular tests, the conventional PCR detected the T. gondii DNA in 30 % (27/90) of the samples, in 38.8 % (35/90) with nested-PCR and 40.0 % (36/90) with real-time. According to molecular analyzes, the sensitivity was higher in ITS1 nested-PCR (69.4 %) and specificity in conventional PCR-529bp (90.7 %), using the qPCR as the gold standard. MAT and ELISA had similarities in concordance analyzes. The IFAT was the serological technique with the highest agreement with the mouse bioassay, and serological tests in parallel showed to be a good screening option for the isolation of T. gondii in chick tissues. The PCR markers effectively detected the parasite DNA, and the heart was the tissue with the highest number of positives samples. The conventional PCR had sensitivity similar to nested-PCR and qPCR and could be a cheaper alternative to diagnose T. gondii infection in chicken tissues.

Burden and regional distribution of Toxoplasma gondii cysts in the brain of COBB 500 broiler chickens following chronic infection with 76K strain

Toxoplasmosis is a worldwide zoonosis caused by the obligate intracellular apicomplexan parasite Toxoplasma gondii (T. gondii). Chickens are ground-feeders and represent, especially if free-range, important intermediate hosts in the epidemiology of toxoplasmosis and are used as sentinels of environmental contamination with T. gondii oocysts. Until now, little is known about the burden and regional distribution of T. gondii cysts in the chicken brain. It was therefore the aim of this study to investigate the abundance and specific distribution of T. gondii cysts within the chicken brain following chronic infection with a type II strain (76 K) of T. gondii. A total of 29 chickens were included in the study and divided into control group (n = 9) and two different infection groups, a low dose (n = 10) and a high dose (n = 10) group, which were orally inoculated with 1500 or 150,000 T. gondii oocysts per animal, respectively. Seroconversion was detected in the majority of chickens of the high dose group, but not in the animals of the low dose and the control group. Moreover, T. gondii DNA was detected most frequently in the brain and more frequently in the heart than in liver, spleen, thigh and pectoral muscle using qPCR analysis. The number of T. gondii cysts, quantified in the chicken brain using histological analysis, seems to be considerably lower as compared to studies in rodents, which might explain why T. gondii infected chickens very rarely, if at all, develop neurological deficits. Similar to observations in mice, in which no lateralisation for T. gondii cysts was reported, T. gondii cysts were distributed nearly equally between the left and right chicken brain hemispheres. When different brain regions (fore-, mid- and hindbrain) were compared, all T. gondii cysts were located in the forebrain with the overwhelming majority of these cysts being present in the telencephalic pallium and subpallium. More studies including different strains and higher doses of T. gondii are needed in order to precisely evaluate its cyst burden and regional distribution in the chicken brain. Together, our findings provide insights into the course of T. gondii infection in chickens and are important to understand the differences of chronic T. gondii infection in the chicken and mammalian brain.

The presence of Toxoplasma gondii in soil, their transmission, and their influence on the small ruminants and human population: A review

The ecosystem approach has been developed since the 1940s. An ecosystem is a community of living organism and their interaction and conjugation with abiotic factors of the environment. The ecosystem is not endemic to the aquatic environment only but, the terrestrial environment is also considered to be a part of an ecosystem. Soil act as mother role for the survival of different microorganism. The Toxoplasma gondii oocysts stay survive for a long time in the soil. This presence of these oocysts might critically enhance the success of this parasite in two ways. First, this parasite can widespread; second, it can create a lot of consequences regarding animals and their economic value. Soil contamination caused by Toxoplasma gondii Y is a significant and profound issue for animals and public health. Therefore, the current study was aimed to summarize and correlate the soil and parasite, their transmission, infection, and some aspects related to T. gondii. The small animals are pose at a high risk therefore, it was concluded that some preventive measures should be taken to keep secure itself from zoonotic diseases.

Experimental infection with Toxoplasma gondii in broiler chickens (Gallus domesticus): seroconversion, tissue cyst distribution, and prophylaxis

Toxoplasma gondii is a widespread zoonotic protozoan that infects most species of mammals and birds, including poultry. This study aimed to investigate the course of T. gondii infection and the efficacy of diclazuril and Artemisia annua in preventing infection in experimentally infected chickens. Seventy-five 1-month-old chickens, female and male, were randomly divided into five groups (n = 15 each) as follows: (1) uninfected untreated (negative control, NC); (2) infected with T. gondii genotype II/III isolated from a wild cat (group WC); (3) infected with T. gondii genotype II isolated from a domestic cat (group DC); (4) infected with T. gondii domestic cat strain and treated with the anticoccidial diclazuril (group DC-D); and (5) infected with T. gondii domestic cat strain and treated with the medicinal plant Artemisia annua (group DC-A). Clinical signs, body temperature, mortality rate, weight gain, feed conversion ratio, hematological parameters, and the presence of T. gondii-specific IgY antibodies were recorded in all groups. Five chickens per group were euthanized 28 days post-infection (p.i.) and their brains, hearts, and breast muscle tested for T. gondii by mouse bioassay and polymerase chain reaction (PCR). No clinical signs related to the experimental infection were observed throughout the study period. T. gondii-specific antibodies were detected by day 28 p.i., but not in all infected chickens. Overall, T. gondii DNA was detected (bioassay or tissue digests) in all infected and untreated chickens (10/10), while viable parasite (bioassay) was isolated from 7 out of 10 chickens. The parasite was most frequently identified in the brain (7/10). There were no differences in the T. gondii strains regarding clinical infection and the rate of T. gondii detection in tissues. However, higher antibody titers were obtained in chickens infected with T. gondii WC strain (1:192) comparing with T. gondii DC strain (1:48). A. annua reduced replication of the parasite in 3 out of 5 chickens, while diclazuril did not. In conclusion, broiler chickens were resistant to clinical toxoplasmosis, irrespective of the strain (domestic or wild cat strain). The herb A. annua presented prophylactic efficacy by reduced parasite replication. However, further studies are required aiming at the efficacy of diclazuril and A. annua for the prevention of T. gondii infection in chickens using quantitative analysis methods.

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.