Toxoplasma gondii y Neospora caninum son dos protozoarios apicomplexos de distribución mundial y potenciales causantes de enfermedades neuromusculares en canes. Sin embargo, en el Perú son escasos los estudios sobre la implicancia de estos agentes en la especie canina. Así, el objetivo de este estudio fue determinar la frecuencia de anticuerpos IgG contra Neospora caninum y Toxoplasma gondii en canes con alteraciones neuromusculares y observar el tipo de asociación que existe entre la presencia de anticuerpos y la afección neuromuscular. Para el estudio fueron examinados 96 sueros de canes con signos clínicos de afección neuromuscular y 120 sueros de canes sin presencia de signos neuromusculares. Todas las muestras fueron obtenidas en la Clínica de Animales Menores de la FMV – UNMSM. Luego, el diagnóstico se realizó a través de la prueba de Inmunofluorescencia Indirecta (IFI) para la detección de anticuerpos IgG, considerándose positivos los sueros que presentaron fluorescencia completa del taquizoíto en la dilución 1:50. En los canes con afección neuromuscular, la frecuencia para Toxoplasma gondii fue de 23.96 ± 8.5% (23/96) y para Neospora caninum fue de 5.21 ± 4.4 (5/96), mientras que en los canes sin afección neuromuscular la frecuencia para Toxoplasma gondii fue de 3.34 ± 3.1 (4/120) y para Neospora caninum fue de 1.67 ± 2.5 (2/120). Finalmente, se observó que existe asociación entre la afección neuromuscular y la presencia de anticuerpos anti-Toxoplasma gondii, mientras que no se halló asociación entre tal afección y la presencia de anticuerpos anti-Neospora caninum. / Toxoplasma gondii and Neospora caninum are two apicomplex protozoans that can cause neuromuscular diseases in dogs. In Peru, are only a few studies on the implication of these agents in the canine species. The target of this investigation was to find the association between IgG antibodies and neuromuscular diseases. In this study, 96 sera of dogs with clinical signs of neuromuscular disease and 120 sera of dogs without neuromuscular signs were examinated. All the samples were obtained at the Small Animal Clinic of the FMV – UNMSM. The diagnosis was performed by means of indirect immunofluorescence test (IFI) for the detection of IgG antibodies, considering positive the sera that showed complete fluorescence of the tachyzoite in the dilution 1:50. In the dogs with neuromuscular disease, the frequency for Toxoplasma gondii was 23.96 ± 8.5% (23/96) and for Neospora caninum was 5.21 ± 4.4 (5/96), meanwhile, in the dogs without neuromuscular disease the frequency for Toxoplasma gondii was 3.34 ± 3.1 (4/120) and for Neospora caninum was 1.67 ± 2.5 (2/120). Finally, it was observed association between the neuromuscular disease and the presence of anti-Toxoplasma gondii antibodies, while did not find association between such disease and the presence of anti-Neospora caninum antibodies.

Toxoplasma gondii es un patógeno intracelular obligatorio dentro del Phylum Apicomplexa, con un amplio rango de hospederos incluyendo muchas aves y mamíferos en el mundo. El objetivo del estudio fue determinar la seroprevalencia de anticuerpos anti-Toxoplasma gondii en alpacas de la Unidad de Producción de Cuyo de la SAIS Pachacútec, ubicada en el distrito de Marcapomacocha, Provincia de Yauli, Departamento de Junín. Para tal fin se recolectaron en el mes de enero del 2003, sueros sanguíneos de 258 alpacas hembras para la detección de anticuerpos de Toxoplasma gondii; mediante la técnica de Inmunofluorescencia Indirecta (IFI), encontrándose que el 8.53±3.41% (22/258) de las muestras, presentaban anticuerpos contra el parásito; siendo estos menores en proporción con los hallados en alpacas de otras zonas ganaderas del país, por lo tanto se hace necesario la continuar con estudios similares a fin de determinar el verdadero rol de este parásito con los problemas reproductivos en alpacas. / --- Toxoplasma gondii is an obligate intracellular pathogen within the phylum Apicomplexa, with a broad host range including many birds and mammals in the world. The objective of this study was determine the seroprevalence of antibodies against Toxoplasma gondii in alpacas in the United of Production of Cuyo at the SAIS Pachacutec, located in the district of Marcapomacocha, Province of Yauli, Departament of Junin. In order to do this, 258 sera from female alpacas were collected in the month of January of 2003. Sera was tested against Toxoplasma gondii antibodies using Indirect Immunoflorescence (IFI), being that 8.53±3.41% (22/258) of the samples showed antibodies against the parasite. These results show a lower proportion compared to those findings in alpacas from other zones of the country; therefore, it is necessary to continue with similar studies, which will determine the real pathological role of this parasite in alpacas.

El Toxoplasma gondii, agente causal de la toxoplasmosis, es un parásito importante en la salud animal, por ser una de las principales infecciones parasitarias que ocasiona problemas reproductivos, y también constituye una zoonosis muy importante alrededor del mundo. El objetivo del presente estudio fue determinar la seroprevalencia de Toxoplasma gondii en alpacas de la Unidad de Producción de Cochas de la SAIS Túpac Amaru, ubicada en el distrito de Canchayllo, Provincia de Jauja, Departamento de Junín. Para tal fin, se recolectaron sueros sanguíneos procedentes de 200 alpacas entre hembras y machos, en el mes de diciembre de año 2000, para la detección de anticuerpos mediante la técnica de Hemaglutinación Indirecta (HAI). Los resultados generales indicaron que el 21 ± 5.64 % (42/200) de las muestras de alpacas presentaron anticuerpos con títulos que variaron desde 1/16 hasta 1/1024. La seroprevalencia hallada en machos 26.47 10.49 % (18/68) fue mayor que en hembras 18.18 6.57 % (24/132), y por rangos de edad desde los 8 a 12 meses, de 12 hasta 36 meses y más de 36 meses las seroprevalencias fueron 33.33 16.08 %, 15.38 9.81, 20 7.31 respectivamente. Al realizar el análisis estadístico respectivo mediante la Prueba de regresión Logística no se encontró relación estadística significativa entre la presencia de anticuerpos contra T. gondii y el sexo de las alpacas, pero si entre la edad del animal y la infección por T. gondii, siendo las alpacas más jóvenes (8 a 12 meses) aproximadamente 2,9 veces más susceptibles que los otros dos grupos etéreos, este resultado podría deberse a la presencia de anticuerpos maternales, manejo de los animales, factores ambientales y frecuencia del hospedero definitivo. La prevalencia encontrada en el presente estudio fue moderada, por lo tanto, se hace necesario la realización de más estudios a fin de determinar el verdadero rol de este parásito en los problemas reproductivos de las alpacas. / --- Toxoplasma gondii, causative agent of toxoplasmosis, is an important parasite in animal health because it is one of the major parasitic infections that produce reproductive problems, and also it is an important zoonosis worldwide. The objective of this study was to determine the seroprevalence of antibodies against Toxoplasma gondii in alpacas from the Unit of Production of Cochas of the SAIS Tupac Amaru, located in the district of Canchayllo, Province of Jauja, Departament of Junin, Perú. To this end, sera from 200 alpacas among females and male were gathered in the month of December of 2000, for the detection of antibodies by using the method of Indirect Hemaglutination (IHA). 21 5.64 % (42/200) of the samples showed antibodies, with titles ranging from 1/16 up to 1/1024. The seroprevalence found in males was 26.47 (10.47% (18/64), and it was greater than in females, 18.18 6.57 % (24/132), and for age groups, from the birth until 1 year old, more than 1 up to 2 years old and more than 3 years old; the seroprevalence found was 33.33 16.08%, 15.38 9.8, 20 7.31 respectively. The analysis by using The Logistic regression found that the genus did not represent a risk factor. The age did represent a risk factor, being younger alpacas (8 to 12 months) more susceptible than other age groups. These results are coherent with other studies obtained in different parts of world, however, it is observed that there are differences with recent studies obtained in Peru; this, this could be due to environmental factors, frequency of the definitive host. Prevalence found in the present study was moderate, should be done further studies to determine the real importance of T. gondii in the occurrence of abortion in alpacas.

Als obligat intrazellulärer Parasit und Erreger von lebenslang persistierenden Infektionen in Mensch und Tier dürfte Toxoplasma gondii von der Integrität seiner Wirtszelle in besonderem Maße abhängig sein. Ziel der Arbeit war es, den Einfluss des Parasiten auf die Wirtszellapoptose zu untersuchen. T. gondii inhibiert die in vitro induzierte Apoptose in humanen HL-60- und U937-Zellen. Dabei muss der Parasit aktiv in die Zelle eindringen, jedoch nicht in dieser replizieren können. Er interferiert dabei mit mindestens zwei Komponenten der Apoptose-Signalkaskade: Erstens vermindert T. gondii die Herunterregulation der Mcl-1-Expression nach Apoptoseinduktion. Das führt dazu, dass trotz Apoptoseinduktion die Translokation von Cytochrom c aus den Mitochondrien in das Zytoplasma inhibiert wird und daraufhin die Caspasen 9 und 3 sowie deren Substrate weniger stark aktiviert werden. Zweitens wird die Expression der Poly-(ADP-Ribose)Polymerase (PARP) durch T. gondii inhibiert. Beide Mechanismen könnten an der Inhibierung der Wirtszellapoptose durch T. gondii beteiligt sein und dem Parasiten damit sein intrazelluläres Überleben sichern. / As an obligate intracellular parasite that causes persistent infections in humans and animals Toxoplasma gondii may rely on the integrity of its host cells. We investigated the effect of the parasite on host cell apoptosis. T. gondii inhibits the in vitro induced apoptosis in human-derived HL-60 and U937 cells. For this effect it is necessary that the parasite is able to invade its host cell actively but not to replicate. T. gondii interferes with at least two different components of the apoptosis-inducing signaling cascade: Firstly, it partially abrogates the down-regulation of Mcl-1 expression after induction of apoptosis. As a result, the translocation of cytochrome c from the mitochondria into the cytoplasm is inhibited and the activiation of caspases 9 and 3 and their substrates is diminished. Secondly, the expression of poly (ADP-ribose)polymerase (PARP) is down-regulated by the parasite. Both mechanisms may contribute to the inhibition of host cell apoptosis by T. gondii and may facilitate intracellular survival of the parasite.

T. gondii é um protozoário amplamente disseminado pelo mundo que pode causar doença em animais e humanos. A evolução e a gravidade da doença dependem de características genéticas do parasita e do hospedeiro. A prevalência varia geograficamente, em Erechim, RS, 88% da população é soropositiva e 18% destes apresentam toxoplasmose ocular (TO). A resposta imune humoral contra T. gondii é persistente em todas as fases da infecção. O objetivo deste retrospectivo estudo foi correlacionar a imunidade humoral e a resposta contra peptídeos cepa-específicos com a gravidade da TO em pacientes de Erechim. 327 amostras de soro foram testadas (ELISA) para a pesquisa dos isótipos específicos e contra peptídeos cepa-específicos de regiões polimórficas (GRA6 e GRA7) do parasita. Nossos resultados sugerem que IgG2 e IgG3 estão associados à infecção adquirida recente, porém não há associação entre os isótipos e a evolução clínica da TO. Entretanto, embora seis diferentes sorotipos infectem estes pacientes, a gravidade da TO está associada a um novo padrão sorotípico (Atípico D). / T. gondii is a widespread protozoan parasite that is associated with a large spectrum of diseases in both humans and animals. The progression and severity of disease is quite variable and presumably due to some combination of host and parasite genetics. Prevalence varies with geography. In Erechim, Brazil, it is 88% prevalent and is related with a high incidence (18%) of ocular toxoplasmosis (OT). Humoral immune response against the parasite is effective. The aim of this retrospective study was to correlate the humoral immunity and response against the strain-specific peptides with the severity of the TO in Erechim`s patients. 327 sera were evaluated by ELISA to isotypes, IgG avidity and serotyped using strain-specific polymorphic peptides (GRA6 and GRA7). Our results suggest that IgG2 and IgG3 were associated with recent acquired infection. However, there is no association between isotypes and clinical evolution of OT, and also 6 different serotype-strains were detected in this population, but only one of these (Atypical D) was strongly associated with severe OT.

Thesis advisor: Marc Jan Gubbels / Thesis advisor: Thomas Chiles / The length of the tachyzoite cell cycle, in particular G1, is an important virulence factor in Toxoplasma gondii. Cdk and Cyclin activities ultimately control the cell cycle; however, the checkpoint control mechanisms diverge from higher eukaryotes and are poorly understood. In order to elucidate these mechanisms, temperature sensitive (ts) mutants were generated by chemical mutagenesis. One of these mutants, called FV-P6, dies within one cell cycle in the G1 phase upon transfer from the permissive (35°C) to the restrictive temperature (40°C). Cosmid complementation identified the gene responsible for this G1 arrest as a `Cactin' ortholog. A single point mutation in this gene that resulted in an amino acid substitution from Tyrosine to Histidine at position 661 in the highly conserved C-terminus was shown to underlay the temperature sensitive effect. Cactin is highly conserved across eukaryotes and plays a role in embryonic development of metazoa although its mechanism of action is poorly understood. In agreement with the predicted nuclear localization signal in the N-terminus, expression of a fluorescent reporter gene fusion resulted in nuclear localization. Genome-wide expression profiling analysis of mutant and wild type at the permissive and restrictive temperatures confirmed the G1 arrest and furthermore demonstrated up-regulation of bradyzoite and Toxoplasma cat life cycle stage genes, hinting at TgCactin's role as a repressor. Since DNA binding domains or enzymatic domains are absent in TgCactin, TgCactin must act in a complex. Native blue gel electrophoresis demonstrated that TgCactin is present in large complexes of 720 and 800 kDa. A yeast two-hybrid screen (YTH) identified 40 potential TgCactin-interacting proteins of which 10 were selected for further validation. Eight out of these ten candidates are involved in DNA/RNA processes pertaining to transcription and translation, respectively. One-on-one YTH interactions between mutated and N-terminal deletion mutants of TgCactin and the above 10 interactors were abolished except for a single RNA helicase. Studies in Toxoplasma of four of these interactors demonstrated that only the RNA helicase localized to the nucleus; however, co-immunoprecipitation experiments to demonstrate that this protein is present in a complex with TgCactin were inconclusive. Furthermore, TgCactin self interactions identified domains necessary for TgCactin-TgCactin binding. Taken together, these findings indicate that TgCactin likely functions as a repressor of gene expression, possibly through an epigenetic mechanism reminiscent of an RNA/DNA helicase- based system in plants. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.

Mais de 2 bilhões de pessoas em todo o mundo encontram-se infectadas com Toxoplasma gondii. Na região endêmica de Erechim, RS, cerca de 90% da população é soropositiva e cerca de 18% destes indivíduos apresentam lesões oculares com manifestações clínicas. A estrutura genética das populações do T. gondii tem sido bastante investigada, a despeito da infecção ter se espalhado pelo mundo, do grande número de hospedeiros intermediários e da capacidade do parasita de se reproduzir sexualmente. Linhagens de T. gondii com atípica ou nova combinação de alelos têm sido isoladas de animais não domésticos ou em outros continentes, como América do Sul e África, e de pacientes com apresentações clínicas incomuns. Em modelos murinos, as linhagens com o genótipo tipo I são altamente virulentas, em contraste às cepas tipo II e tipo III que são menos virulentas. Este trabalho propõe a caracterização fenotípica da resposta imune do hospedeiro frente a infecção por diferentes cepas de T. gondii, bem como o isolamento e a caracterização genotípica das linhagens de T. gondii que infectam indivíduos de Erechim no Rio Grande do Sul. Para a caracterização fenotípica utilizamos duas cepas de T. gondii já bem estabelecidas, a cepa RH (tipo I) e a ME49 (tipo II), e uma cepa isolada a partir de gatos domésticos do Brasil, chamada TgCatBr71. Sendo assim, através da fenotipagem das células dendríticas de camundongos C57Bl/6 infectados com as cepas citadas, foi possível observar que essas cepas induzem expressão das moléculas de superfície CD40, CD80, CD86 e MHC classe II em DCs CD11c+, porém sem significativa diferença entre as cepas. Com relação as células CD4+ e células CD8+, observamos o aumento das células CD8+ no decorrer da infecção pelas cepas RH e ME49, indicando a importância deste tipo celular na resposta protetora contra T. gondii. Avaliamos também a produção de citocinas IL-12, IFN-g e IL-10 em células esplênicas de camundongos infectados pelas três cepas no decorrer da infecção e detectamos que camundongos infectados pela cepa tipo II (ME49) apresentam síntese maior dessas citocinas do que camundongos infectados pela cepa tipo I (RH) e pela cepa TgCatBr71. Assim, concluímos que esta cepa TgCatBr71 se assemelha bastante a cepa do tipo I (RH), tanto em relação a evolução da doença no camundongos como nos padrões da resposta imune do hospedeiro. E que apesar dessas duas cepas diferirem da cepa tipo II (ME49), resultando em graus diferentes de patologia em camundongos C57Bl/6, todas a três cepas parecem produzir semelhante resposta imune protetora do hospedeiro. / More than 2 billion people are infected with Toxoplasma gondii around the world. In the endemic region of Erechim, RS, Brazil, about 90% of the population is soropositive and about 18% of these individuals have ocular lesions with clinical manifestations. The genetic structure of strains of T. gondii has been investigated, despite the infection has spread throughout the world, the large number of intermediate hosts and the ability to reproduce sexually. Strains of T. gondii with atypical or new combination of alleles have been isolated from wild animals and other continents, such as South America and Africa, and also from patients with unusual clinical presentations. In murine models, the type I genetic lineage are highly virulent, in contrast to strains type II and type III.Our work proposes the phenotypic characterization of the host immune response against the infection by different strains of T. gondii, and the isolation and genetic strains characterization of T. gondii that infect individuals of Erechim in RS, Brazil. In the phenotypic characterization were used two strains of T. gondii already well established, the strain RH (type I) and ME49 (type II), and a strain isolated from domestic cats from Brazil, called TgCatBr71 (type BrI). Thus, by phenotyping dendritic cells of C57BL/ 6 mice infected with the strains mentioned, we observed that these strains upregulated the expression of surface molecules such as CD40, CD80, CD86 and MHC class II in DC CD11c+ although with no significant difference between the strains. With respect to the CD4+ and CD8+ cells, the observed increase in CD8+ T cells during the infection by strains RH and ME49, indicating the importance of this cell type in the protective response against T. gondii. We also evaluated the production of cytokines IL-12, IFN-g and IL-10 from spleen cells and found that mice infected by the strain type II (ME49) have increased synthesis of these cytokines than mice infected by the strain type I (RH) and the strain type BrI (TgCatBr71). Thus, we concluded that type BrI (TgCatBr71) strain is similar to type I (RH) strain, both for the evolution of the disease and also concerning the immunological parameters evaluated. Besides, despite these two strains differ from the strain type II (ME49), resulting in different degrees of pathology in mice C57BL / 6, all three strains seem to produce similar protective immune response of the host.

Orientador: Paulo Francisco Domingues / Banca: Hélio Langoni / Banca: Alexander Welker Biondo / Resumo: A toxoplasmose é uma das mais freqüentes zoonoses parasitárias, de distribuição mundial, cujo agente etiológico é o Toxoplasma gondii. A infecção em suínos tem sido descrita em diversos países, demonstrando seu caráter cosmopolita e a susceptibilidade desta espécie. O T.gondii pode ser transmitido sob várias formas, e com relação à espécie suína, a ingestão de carne crua ou mal cozida e seus derivados são importantes vias de transmissão para o homem. Estudou-se a prevalência de anticorpos anti-Toxoplasma gondii em 550 amostras de soros de suínos de criações de "fundo de quintal" na microrregião de Registro - SP, utilizando como prova sorológica o método de aglutinação direta (MAD). Este mostrou-se uma ferramenta diagnóstica de fácil realização, baixo custo, não necessitando de equipamentos especiais para a leitura e interpretação dos resultados. Das 550 amostras de soro, 111(20,18%) reagiram positivamente com os títulos 64 (15,32%), 256 (27,93%), 1024 (39,64%), 4096 (10,81%), 16384 (4,50%) e 65536 (1,80%). Concluí-se que os resultados obtidos indicam alta prevalência desta enfermidade nas condições e região de origem dos animais. À medida que foram obtidos títulos altos de anticorpos contra o agente, pode-se concluir também que há risco potencial de transmissão da toxoplasmose para o homem, sugerindo que muitos desses animais poderiam apresentar bradizoítos em sua musculatura / Abstract: Toxoplasmosis is one of the most frequent parasitic zoonosis with worldwide distribution whose etiological agent is Toxoplasma gondii. The infection in swine has been described in many countries, showing the cosmopolitan character and susceptibility of this specie. T.gondii can be transmitted by many ways. The ingestion of swine raw or badly cocked meat and derivatives are important pathways of transmission to man. The anti-T.gondii antibodies prevalence was studied in 550 serum samples of swine under rustic condition (animals with no breed, popular named as "backyard breeding") in Registro-SP, using the modified agglutination test (MAT). Such method is verified as an easy-appliance tool, with low costs and non necessity of special equipment in order to achieve interpretation of results. In 550 samples of serum, 111 (20.18%) were positive with titles of 64 (15.32%), 256 (27.93%), 1024 (39.64:%), 4096 (10.81%), 16384 (4.50%), 65536 (1.80%). These results achieved indicate a high prevalence of the disease on the region studied and under the specific conditions described. The high rate obtained as result also leads to the conclusion that there is potential risk of toxoplasmosis transmission to man due to the possibility of the animals to have bradyzoits in their musculature / Mestre

Resumo: A toxoplasmose é similar em humanos e em ratos, sendo estes, o modelo experimental, mais utilizado para o estudo da doença. Há poucos relatos da transmissão desta enfermidade pelo leite materno, e desta forma o objetivo do presente estudo foi pesquisar a presença de Toxoplasma gondii no leite de ratas experimentalmente infectadas e a transmissão galactogênica. Utilizaram-se ratas Wistar (Rattus norvegicus), divididas em três grupos: G1, G2 e G3, contendo seis fêmeas cada um. Foram inoculadas via oral com 104 bradizoítos da cepa BTU4, genótipo I, isolada de cão com cinomose. As ratas do G1 e G2 foram infectadas 60 dias antes do acasalamento e as do G3 logo após o parto. Os animais do G2 foram submetidos à imunossupressão pós-parição. Para a detecção do parasito no leite utilizou-se a reação em cadeia pela polimerase (PCR) e para verificar a transmissão para os filhotes pesquisou-se nestes anticorpos anti-T. gondii pela imunofluorescência indireta (RIFI) e método de aglutinação direta (MAD), e a bioprova pela inoculação de camundongos com pool de tecidos (cerebral, pulmonar, hepático, cardíaco, muscular esquelético, língua e diafragma) de cada ninhada, bem como pela PCR nestes tecidos individualmente. A PCR foi positiva em três amostras de leite, duas provenientes da rata 1 do G1, e uma da rata 3 do G3. Os filhotes de todas as ratas do G1 soroconverteram, mas foram negativos na bioprova. Filhotes das ratas 1 e 3 do G3 soroconverteram, e a bioprova foi positiva. Amostras de fígado, musculatura esquelética e pulmão de filhotes do G1 foram positivas na PCR. Desta forma conclui-se que ocorreu a transmissão do T. gondii pelo leite, sugerindo-se novos estudos em lactentes, considerando-se a magnitude da doença em crianças e recém-nascidos. / Abstract: Toxoplasmosis is similar in humans and rats, and the latter constitute the most used experimental model to study this disease. Few reports on toxoplasmosis transmission through maternal milk are available in literature; thus, the aim of the present study was to investigate whether Toxoplasma gondii is present in and transmitted through the milk of experimentally infected rats. Wistar (Rattus norvegicus) female rats were divided into three groups: G1, G2 and G3, with six animals each. They were orally inoculated with 104 bradyzoites of BTU4 strain, genotype I, isolated from a dog with distemper. G1 and G2 rats were infected 60 days before mating and those of G3, soon after the parturition. G2 animals were subjected immunosuppression just after parturition. Polymerase chain reaction (PCR) was used to detect the parasite in the milk. To verify the parasite transmission to the offspring, these anti-T. gondii antibodies were investigated through indirect immunofluorescence assay (IFA) and direct agglutination test (DAT). Bioassay consisted of inoculating mice with a pool of tissues (brain, lungs, liver, heart, skeletal muscle, tongue and diaphragm) from each litter, as well as PCR in these tissues individually. PCR was positive in three milk samples, two from rat 1 (G1) and one from rat 3 (G3). The pups of all G1 rats seroconverted but were negative in the bioassay. The pups of rats 1 and 3 (G3) seroconverted and their bioassay was positive. Liver, skeletal muscle and lung samples were PCR-positive in G1 pups. Thus, we can conclude that T. gondii was transmitted through milk, suggesting the need of new studies in breast-feeding mothers as this disease is highly severe in children and newborns. / Orientador: Helio Langoni / Coorientador: Simone B. Lucheis / Banca: Italmar Teodorico Navarno / Banca: Katia Denise Saraiva Bresciani. / Mestre

El objetivo del presente trabajo fue determinar la frecuencia de anticuerpos contra Toxoplasma gondii en gatos de Lima Metropolitana. Además, estimar el grado de concordancia entre las técnicas de diagnóstico de inmunofluorescencia indirecta y hemaglutinación indirecta. Se analizaron las muestras de sueros de 178 gatos, obtenidas de diferentes clínicas veterinarias de Lima Metropolitana. Los resultados mostraron una frecuencia de reactores a Toxoplasma gondii de 17.9% con un intervalo de confianza de 95% entre 12.0 y 23.5% para la técnica IFI y 11.2% con un intervalo de confianza de 95% entre 6.6 y 15.8% para la técnica HAI. La evaluación de reactores según edad y sexo, no mostraron diferencia estadística significativa (p>0,05). Por otro lado, al evaluar el grado de concordancia entre ambas pruebas se halló un valor de Kappa (K) igual a 0.73 indicando que el grado de concordancia entre ambas pruebas fue del tipo sustancial; mientras que con la prueba de Mc Nemar se encontró significancia estadística (p menor 0.05), entendiendo que las pruebas no pueden ser reemplazadas mutuamente. / --- The aim of the present work was to estimate the frequency of Toxoplasmosis in cats in the city of Metropolitan Lima. Aside from determining the rate of concordance between the Indirect immunofluorescence (IFI) and Indirect haemaglutination (HAI) Assays, two of the very common diagnostic tests for Toxoplasmosis in our area, a number of 178 cat serum samples, collected in veterinary clinics of this city, were analyzed. The results determined a frequency of reactors to Toxoplasma gondii in 17.90% with a 95% confidence interval (CI) between 12.00% and 23.50% for IFI test and in 11.20% with a 95% confidence interval (CI) between 6.60% and 15.80% for HAI test. The evaluation of reactors, according to age and sex, did not provide statistically significant difference (p> 0, 05). On the other hand, when the rate of concordance among both assays was tested, there was a value of Kappa (K) similar to 0.73 indicating that the concordance is substantial between the two test; while in Mc Nemar’s test, there was statistically significant difference (p less 0.05), indicating that both tests cannot be replaced reciprocally. / Tesis