Toxoplasma gondii seroprevalence in ringed seals (Pusa hispida) from the Canadian Arctic

Toxoplasmosis is a significant public health threat for Inuit in the Canadian Arctic. This study aimed to investigate arctic seals as a possible food-borne source of infection. Blood samples collected from 828 seals in 7 Canadian Arctic communities from 1999 to 2006 were tested for Toxoplasma gondii antibodies using a direct agglutination test. Polymerase chain reaction (PCR) was used to detect T. gondii DNA in tissues of a subsample of seals. Associations between seal age, sex, species, diet, community and year of capture, and serological test results were investigated by logistic regression. Overall seroprevalence was 10.4% (86/828). All tissues tested were negative by PCR. In ringed seals, seroprevalence was significantly higher in juveniles than in adults (odds ratio = 2.44). Overall, seroprevalence varied amongst communities (P = 0.0119) and by capture year (P = 0.0001). Our study supports the hypothesis that consumption of raw seal meat is a significant source of infection for Inuit. This work raises many questions about the mechanism of transfer of this terrestrial parasite to the marine environment, the preponderance of infection in younger animals and the natural course of infection in seals. Further studies to address these questions are essential to fully understand the health risks for Inuit communities.

Growth of Toxoplasma gondii is inhibited by aryloxyphenoxypropionate herbicides targeting acetyl-CoA carboxylase

Aryloxyphenoxypropionates, inhibitors of the plastid acetyl-CoA carboxylase (ACC) of grasses, also inhibit Toxoplasma gondii ACC. Clodinafop, the most effective of the herbicides tested, inhibits growth of T. gondii in human fibroblasts by 70% at 10 μM in 2 days and effectively eliminates the parasite in 2–4 days at 10–100 μM. Clodinafop is not toxic to the host cell even at much higher concentrations. Parasite growth inhibition by different herbicides is correlated with their ability to inhibit ACC enzyme activity, suggesting that ACC is a target for these agents. Fragments of genes encoding the biotin carboxylase domain of multidomain ACCs of T. gondii, Plasmodium falciparum, Plasmodium knowlesi, and Cryptosporidium parvum were sequenced. One T. gondii ACC (ACC1) amino acid sequence clusters with P. falciparum ACC, P. knowlesi ACC, and the putative Cyclotella cryptica chloroplast ACC. Another sequence (ACC2) clusters with that of C. parvum ACC, probably the cytosolic form.

Time-Lapse Video Microscopy of Gliding Motility in Toxoplasma gondii Reveals a Novel, Biphasic Mechanism of Cell LocomotionV⃞

Toxoplasma gondii is a member of the phylum Apicomplexa, a diverse group of intracellular parasites that share a unique form of gliding motility. Gliding is substrate dependent and occurs without apparent changes in cell shape and in the absence of traditional locomotory organelles. Here, we demonstrate that gliding is characterized by three distinct forms of motility: circular gliding, upright twirling, and helical rotation. Circular gliding commences while the crescent-shaped parasite lies on its right side, from where it moves in a counterclockwise manner at a rate of ∼1.5 μm/s. Twirling occurs when the parasite rights itself vertically, remaining attached to the substrate by its posterior end and spinning clockwise. Helical gliding is similar to twirling except that it occurs while the parasite is positioned horizontally, resulting in forward movement that follows the path of a corkscrew. The parasite begins lying on its left side (where the convex side is defined as dorsal) and initiates a clockwise revolution along the long axis of the crescent-shaped body. Time-lapse video analyses indicated that helical gliding is a biphasic process. During the first 180o of the turn, the parasite moves forward one body length at a rate of ∼1–3 μm/s. In the second phase, the parasite flips onto its left side, in the process undergoing little net forward motion. All three forms of motility were disrupted by inhibitors of actin filaments (cytochalasin D) and myosin ATPase (butanedione monoxime), indicating that they rely on an actinomyosin motor in the parasite. Gliding motility likely provides the force for active penetration of the host cell and may participate in dissemination within the host and thus is of both fundamental and practical interest.

Infecção concomitante experimental de Rattus norvegicus por Toxocara canis e Toxoplasma gondii: estudo comportamental e histopatológico

A hipótese de \"manipulação comportamental\" supõe que um parasito pode alterar o comportamento de seu hospedeiro visando aumentar a probabilidade de completar seu ciclo evolutivo. Tais alterações aumentariam a taxa de transmissão hospedeirohospedeiro, assegurando ao parasito ou a seus propágulos o encontro de novo hospedeiro. A possibilidade de infecções parasitárias provocarem mudanças comportamentais em seus hospedeiros e a elevada frequência com que o acometimento de seres humanos por larvas de Toxocara e cistos de Toxoplasma ocorre, têm chamado à atenção de pesquisadores interessados no estudo das relações hospedeiro-parasita. Na infecção por Toxoplasma gondii e Toxocara canis, cistos e larvas estão presentes em diversos locais anatômicos incluindo musculatura, coração, pulmões, olhos e cérebro. A presença de parasitos no cérebro dá oportunidade de manipulação do comportamento do hospedeiro. Entretanto, não se sabe qual ou quais mecanismos estão envolvidos no processo de manipulação do comportamento. Os objetivos do presente estudo foram verificar alterações na ansiedade, medo, memória e aprendizagem de Rattus norvegicus experimentalmente infectados por Toxocara canis e/ou Toxoplasma gondii em dois períodos após infecção, bem como a localização das larvas e cistos e presença de placas beta amiloide ( A) na região do hipocampo no tecido cerebral desses roedores corado pela técnica de Hematoxilina e Eosina (HE), e Vermelho de Congo, respectivamente. Foram utilizadas 40 exemplares fêmeas da espécie Rattus norvegicus, com seis a oito semanas. Os animais foram divididos em quatro grupos: Toxocara - 10 ratos infectados com 300 ovos de Toxocara canis, Toxoplasma -10 ratos infectados com 10 cistos de Toxoplasma gondii, Infecção dupla - 10 ratos infectados com 300 ovos de Toxocara canis e 10 cistos de Toxoplasma gondii, e controle - 10 ratos sem infecção. Nos dias 40, 41, 70 e 71 após a infecção, os animais dos grupos infectados e controle foram submetidos à avaliação no Labirinto em Cruz Elevado e Campo aberto. Aos 120 após infecção foi feita avaliação da memória, aprendizado e aversão a urina de gato dos animais no Labirinto de Barnes. No final das análises comportamentais os animais foram levados a eutanásia para retirada do cérebro e confecção dos cortes histológicos preparados em HE e Vermelho de Congo. Os resultados mostraram efeito ansiolítico para ambas as infecções, principalmente para Toxoplasma gondii. Não houve comprometimento da memória e aprendizado no LB, porém os animais infectados por Toxocara canis ou Toxoplasma gondii apresentaram menor tempo para encontrar a toca com urina e entrar nela. A leitura dos cortes histológicos corados com HE mostraram larvas de Toxocara canis e cistos de Toxoplasma gondii em regiões do sistema nervoso central dos animais relacionadas com memória e aprendizado. As lâminas coradas com Vermelho de Congo apresentaram placas beta amiloides ( A) em metade dos animais infectados por Toxoplasma gondii. Conclui-se que a infecção por ambos os parasitos apresenta efeito ansiolítico quando ocorre infecção única. Quando a Infecção ocorre concomitantemente há modulação no comportamento. Além disso, ratas infectadas com infecção única apresentam-se menos aversivas à urina de gatos.

Enrofloxacina e toltrazuril reduzem a infecção por Toxoplasma gondii em células trofoblásticas humanas e em explantes de vilos placentários humanos de terceiro trimestre

The classical treatment for congenital toxoplasmosis is based on combination of sulfadiazine and pyrimethamine plus folinic acid. Due to teratogenic effects and bone marrow suppression caused by pyrimethamine, the establishment of new therapeutic targets is indispensable to minimize the undesirable effects and improve the control of the infection. Previous studies demonstrated that enrofloxacin and toltrazuril were able to control the infection triggered by Neospora caninum and Toxoplasma gondii. Therefore, the aim of this present study was evaluate the efficacy of enrofloxacin and toltrazuril in the control of T. gondii proliferation in human trophoblast cells (BeWo lineage) and in human villous explants from third trimester. BeWo cells and villous were treated with several concentrations of enrofloxacin, toltrazuril, sulfadiazine, pyrimethamine or association (sulfadiazine + pyrimethamine) in other to verify their viability by MTT or LDH assay, respectively. Next, BeWo cells were infected with T. gondii RH (2F1 clone) or ME49 strain, whereas villous were infected only with RH strain (2F1 clone), after, both cells and villous were treated or not with the same antibiotics and analyzed to T. gondii intracellular proliferation by beta-galactosidase assay (for RH strain) or blue toluidine staining (for ME49 strain). ELISA was performed in the supernatant to evaluate the cytokine profile. Enrofloxacin and toltrazuril did not change strongly the viability in cells and villous. Furthermore, the drugs decreased the parasite intracellular proliferation regardless T. gondii strain in BeWo cells and villous explants when compared to untreated and infected conditions. In BeWo cells infected by RH, enrofloxacin induced high levels of IL-6 low levels of MIF, while both cytokines were upregulated by enrofloxacin and toltrazuril in BeWo cells infected by ME49 strain. Additionally, in villous explantes, enrofloxacin induced high MIF production. Thus, enrofloxacin and toltrazuril were able to control the parasitism in BeWo cells and villous explants, and probably it occurs by modulation of immune response in these cells or tissues and direct action on parasite, but future experiments are necessary to verify this hypothesis.

Toxoplasma gondii seropositive rates of animals living on Svalbard

Samples (blood or tissue fluid) from 594 arctic foxes (Alopex lagopus), 390 Svalbard reindeer (Rangifer tarandus platyrhynchus), 361 sibling voles (Microtus rossiaemeridionalis), 17 walruses (Odobenus rosmarus), 149 barnacle geese (Branta leucopsis), 58 kittiwakes (Rissa tridactyla), and 27 glaucous gulls (Larus hyperboreus) from Svalbard and nearby waters were assayed for antibodies against Toxoplasma gondii using a direct agglutination test. The proportion of seropositive animals was 43% in arctic foxes, 7% in barnacle geese, and 6% (1 of 17) in walruses. There were no seropositive Svalbard reindeer, sibling voles, glaucous gulls, or kittiwakes. The prevalence in the arctic fox was relatively high compared to previous reports from canid populations. There are no wild felids in Svalbard and domestic cats are prohibited, and the absence of antibodies against T gondii among the herbivorous Svalbard reindeer and voles indicates that transmission of the parasite by oocysts is not likely to be an important mechanism in the Svalbard ecosystem. Our results suggest that migratory birds, such as the barnacle goose, may be the most important vectors bringing the parasite to Svalbard. In addition to transmission through infected prey and carrion, the age-seroprevalence profile in the fox population suggests that their infection levels are enhanced by vertical transmission.

PREVALENCE, ISOLATION, AND GENETIC CHARACTERIZATION OF TOXOPLASMA GONDII IN CHICKEN

Toxoplasma gondii (T. gondii) is one of the most successful parasites in the world because of its capability of infecting all warm-blooded animals. It has been reported that up to one third of the world population is infected with this parasite. Chickens are recognized as good indicators of the environmental T. gondii oocysts contamination because they obtain food from the ground. Thus, the prevalence of T. gondii in chicken provides more insight related to public health concern from T. gondii. Previous studies have shown a high isolation rate from free-range chickens raised in the United States. The objectives of this study were to evaluate the microbial safety and infection of T. gondii in free-range chickens available at the grocery stores and farms for the consumers to purchase and genotype T. gondii isolates. Chicken hearts were obtained from the local markets and also from the farms raising free- range chickens. Heart juice was obtained from cavities of each heart. Modified agglutination test (MAT) for detection of IgG antibodies was conducted with those heart juice samples with titer of 1:5, 1:25, and 1: 100. Each seropositive heart was pepsin digested and bioassayed into a group of two mice. Six weeks post inoculation (p.i.) mice were bled and euthanized to examine the infection of T. gondii. In addition, multiplex multilocus nested PCR-RFLP was performed to genetically characterize T. gondii isolates with eleven PCR-RFLP markers including SAG1, SAG2, altSAT2, SAG3, BTUB, GRA6, c22-8, c29-a, L358, PK1, and Apico. One hundred fifty from a total of 997 samples (15.0%) were found seropositive for T. gondii. No viable T. gondii was isolated from chicken hearts that were sampled. A total of four genotypes were identified, including one new genotype and three previously identified genotypes. The results suggest that T. gondii oocysts could present in the environment and infect the food animals. T. gondii prevalence in chicken hearts could reflect the environmental contamination of T. gondii and prevalence information can be used to manage T. gondii infection risk.

Ocorrência da infecção por Toxoplasma gondii e avaliação da imunização em caprinos do sertão do cabugi, Rio Grande do Norte

Toxoplasmosis is one zoonosis caused by Toxoplasma gondii protozoan. Goats, amongst the production animals, are one of the species most susceptible to this parasite, being one them main involved agents in ovine and goat abortions, determining great economic losses and implications for public health, since the presence it parasite in the products of goat origin, consist in one of the main sources of infection for the man. In this study 244 blood samples in 8 farms situated in 4 cities from the Sertão do Cabugi region, Rio Grande do Norte State, northeast of Brazil and, tested by ELISA assay. The results had shown a prevalence of 47.13% for anti- T. gondii antibodies and a significant association between positivity and variable evaluated as age, locality and property. The IgG avidity assay evaluated in 115 positive samples was carried to discriminate acute and chronic infection. Twelve samples (10.4%) had presented antibodies of low avidity while 103 (89.6%) presented high avidity antibodies; indicating that most of the animals was precocious exposure to the parasite. Significant difference was verified only for the variable sex. We also evaluate the capacity of recombinant adenoviruses codifying SAG1, SAG2, SAG3 and CMV in inducing activation of specific immune response in goat. These 109 animals received 109 pfu of the AdSAG1, AdSAG2, AdSAG3, AdCMV or PBS in vaccine protocol with 3 immunizations. Serum samples of the each animal, before and after mmunization, had been submitted to the ELISA. The results demonstrate that the immunizations had induced the production of IgG antibodies specific against T. gondii proteins

Epidemiological studies on toxoplasma gondii infection in a one health perspective

The objective of the present Ph.D. thesis was to investigate with a One Health approach the epidemiological patterns of T. gondii infection in Italy, to better understand the transmission dynamics of the parasite, following different research lines. The results of a retrospective analysis in animals and human showed the widespread distribution of T. gondii in the study area, with specific antibodies found in various animal species and human populations, indicating its constant presence across diverse environments. The environment plays a significant role in T. gondii's epidemiology. Migratory aquatic birds, rodents, wolves, and wild boars were investigated as sentinels of their spread, highlighting the potential transmission across geographic areas and infection risks for wildlife in natural settings. The study also provided insights into seroprevalence in wolves. Dogs, subjected to serological investigations exhibited risk factors for T. gondii infection, such as cohabitation with cats, coprophagy behaviours, and continuous outdoor. Correlation between serological evidence of exposure to T. gondii and pathological anxiety in large-size dogs was observed, and the consumption of raw meat was associated with a higher risk of infection in these animals. Results of the investigations conducted in this thesis, demonstrate the dynamic nature of T. gondii infection in cattle, characterized by new infections and declining antibody levels over the production cycle. The study also describes a co-infection between T. gondii and Sarcocystis hominis in bovine eosinophilic myositis. In the final part of the Thesis, a comprehensive genotyping of T. gondii in Italy reveals the predominance of Type II strains, particularly in cases of ovine abortion and fatal toxoplasmosis among captive Lemur catta. This approach enhances our understanding of the parasite's genetic diversity and transmission patterns, vital for effective management of its impact on human and animal health in Italy.

Prevalence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies in swine from Northeastern Brazil

A serologic survey was conducted among 130 swine slaughtered in the public slaughterhouse of the city of Patos, Paraíba State, Northeastern Brazil, to determine the prevalence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies, and to verify possible associations between sex of the animals and antibody prevalence. The sera were analyzed by indirect antibody tests, considering 1:64 (T. gondii) and 1:50 (N. caninum) dilutions as cut-off points. The prevalence of anti-T. gondii antibodies was 36.2% (47/130) (95% CI = 27.9 - 45.0%) with reciprocal titers ranging from 64 to 2,048, and of anti-N. caninum antibodies was 3.1% (4/130) (95% CI = 0.8 - 7.7%) with reciprocal titers ranging from 50 to 6,400. Three of the four N. caninum-positive samples were also positive for T. gondii antibodies. All Neospora and Toxoplasma IFAT-positive animals were also positive for confirmatory immunoblotting techniques using total and purified N. caninum and T. gondii tachyzoite antigens, i.e., p38 (NcSRS2) and p30 (TgSAG1). There was no association between sex of animals and prevalence of anti-T. gondii and anti-N. caninum antibodies. This is the first indication of N. caninum natural infection in pigs from Brazil.

Occurrence of anti-Neospora caninum and anti-Toxoplasma gondii antibodies in dogs with visceral leishmaniasis

Uninfected dogs and those naturally infected with Leishmania chagasi exhibiting different clinical forms of disease were evaluated for the presence of anti-Neospora caninum and anti-Toxoplasma gondii antibodies. Blood samples were collected from 110 mongrel dogs. Sera were tested using the indirect fluorescent antibody test (IFAT), and the animals with visceral leishmaniasis (VL) (n=60) were classified clinically. Out of the 110 sera investigated, 5 (4.5%) were positive for N. caninum (IFAT≥50) and 36 (32.7%) for T. gondii (IFAT≥16). Anti-L. chagasi antibody titers in asymptomatic dogs (n=10) were found to be significantly lower (P<0.05) than those in oligosymptomatic ones (n=22), which were in turn significantly lower (P<0.05) than those in symptomatic ones (n=28). No association between Leishmania and N. caninum infections was observed. Among dogs infected with L. chagasi, a tendency (P=0.053) towards an association between the infection with T. gondii and the appearance of VL symptoms was observed, suggesting that the clinical manifestation of VL in dogs may enhance their susceptibility to T. gondii. The possible influence of the immunosuppressive status of canine leishmaniasis in the different clinical forms of the disease is discussed.

Avaliação da ocorrência de anticorpos anti-Toxoplasma gondii, em soros de caprinos do estado de São Paulo, e associação com variáveis epidemiológicas, problemas reprodutivos e riscos à saúde pública

Objetivando avaliar a ocorrência de anticorpos anti-Toxoplasma gondii, em caprinos leiteiros do estado de São Paulo, e verificar possíveis associações com idade, sexo, presença de gatos, problemas reprodutivos e potenciais riscos à saúde pública, foram considerados soros de 923 caprinos, de ambos os sexos e idade acima de três meses, provenientes de 17 propriedades de diferentes municípios. Para o diagnóstico, utilizou-se a reação de imunofluorescência indireta (RIFIe"16) e, também, um inquérito sobre saúde, a fim de se coletarem informações epidemiológicas e de esfera reprodutiva de todos os capris. Os resultados foram discutidos no nível de 5% de significância. Do total das 17 propriedades, foram diagnosticados 15 focos de T. gondii, com positividade entre 2,70% e 81,25%. Não foram verificadas associações entre freqüência de soropositividade e sexo dos animais nem ocorrência de falhas reprodutivas, nos capris. Constatou-se influência positiva na taxa de anticorpos anti-T. gondii pelo aumento da idade dos caprinos e presença de gatos, nos capris. Além de a enfermidade encontrar-se amplamente difundida no estado de São Paulo, o risco eminente de transmissão de T. gondii à saúde pública também deve ser considerado, uma vez que se encontraram focos onde se comercializavam produtos "in natura", como leite e carne.

Presence of antibodies against Toxoplasma gondii, Neospora caninum and Leishmania infantum in dogs from Piauí

This study aimed to evaluate the presence of antibodies against Neospora caninum, Toxoplasma gondii and Leishmania infantum in dogs attended at the Veterinary Hospital of the Federal University of Piauí, Northeastern Brazil, where there are no reports of the occurrence of N. caninum and T. gondii in dogs. Serum samples from 530 dogs of genders, different ages and breeds from the municipality of Teresina and nearby towns were analyzed using three indirect fluorescent antibody tests, each one targeting one of the three agents. The associations between the parasites and gender, breed and age of the dogs were assessed by the chi-square test (p > 0.05). The occurrence of antibodies to N. caninum, T. gondii and L. infantum was 3.2, 18.0 and 78.1%, respectively. Toxoplasma gondii was more frequently found in older dogs (p < 0.05) whereas L. infantum was more common in animals aged between 1 to 3 years (p < 0.05). In order to evaluate potential associations between the presence of anti-N. caninum and anti-T. gondii antibodies and Leishmania infection, 240 dogs were selected (120 positive and 120 negative for Leishmania spp.), based on serological and parasitological diagnoses. No association was found between Leishmania spp. and the coccidian parasites (p > 0.05). The results confirm the exposure of dogs to these parasites in the State of Piauí.