Análise epistemológica dos conhecimentos científicos sobre Toxocara sp. com ênfase na infecção humana / Epistemological analysis of the scientific knowledge about Toxocara sp. with the emphasis on human infection

Resumo Este artigo objetivou analisar a evolução do conhecimento sobre Toxocara sp. em seu aspecto zoonótico por meio de dados científicos entre os anos de 1996 a 2015 utilizando a epistemologia como ferramenta. A análise epistemológica da evolução do conhecimento sobre o aspecto zoonótico de Toxocara sp. no Brasil demonstrou que, de uma maneira geral, foram agregadas poucas novas informações as quais tiveram, ao longo do período estudado, absorção lenta, descontínua, e não foram inseridas na realidade social do ponto de vista de Saúde Pública.

Abstract The scope of this article was to analyze the evolution of knowledge about Toxocara sp. from a zoonotic point of view by means of scientific data published between the years 1996 and 2015 using epistemology as a tool. The epistemological analysis of the evolution of knowledge on the zoonotic aspect of Toxocara sp. in Brazil revealed that, in general, little new information was added which had, over the period studied, slow and discontinuous absorption, and was not incorporated in the social reality from the standpoint of public health.

Gastrointestinal parasites of cats in Brazil: frequency and zoonotic risk / Parasitas gastrointestinais em gatos no Brasil: frequência e risco zoonótico

Abstract Gastrointestinal helminths are considered to be the most common parasites affecting cats worldwide. Correct diagnosis of these parasites in animals living in urban areas is pivotal, especially considering the zoonotic potential of some species (e.g. Ancylostoma sp. and Toxocara sp.). In this study, a copromicroscopic survey was conducted using fecal samples (n = 173) from domestic cats living in the northeastern region of Brazil. Samples were examined through the FLOTAC technique and the overall results showed positivity of 65.31% (113/173) among the samples analyzed. Coinfections were observed in 46.01% (52/113) of the positive samples. The most common parasites detected were Ancylostoma sp., Toxocara cati, Strongyloides stercoralis, Trichuris sp., Dipylidium caninum and Cystoisospora sp. From an epidemiological point of view, these findings are important, especially considering that zoonotic parasites (e.g. Ancylostoma sp. and Toxocara sp.) were the nematodes most frequently diagnosed in this study. Therefore, the human population living in close contact with cats is at risk of infection caused by the zoonotic helminths of these animals. In addition, for the first time the FLOTAC has been used to diagnosing gastrointestinal parasites of cats in Brazil.

Resumo Helmintos gastrointestinais são considerados os mais frequentes parasitos que afetam gatos em todo o mundo. O correto diagnóstico desses parasitos, em animais que vivem em áreas urbanas, é crucial, especialmente quando considerado o potencial zoonótico de algumas espécies (ex. Ancylostoma sp. e Toxocara sp.). Neste estudo, uma pesquisa coproparasitológica foi realizada, utilizando-se amostras de fezes (n = 173) de gatos domésticos da região Nordeste do Brasil. As amostras foram examinadas através da técnica FLOTAC, e os resultados gerais mostraram uma positividade de 65,31% (113/173). Co-infecções foram observadas em 46,01% (52/113) das amostras positivas. Os parasitas mais comuns aqui detectados foram Ancylostoma sp., Toxocara cati, Strongyloides stercoralis, Trichuris sp., Dipylidium caninum e Cystoisospora sp. De um ponto de vista epidemiológico, esses resultados são importantes, especialmente considerando que os parasitos zoonóticos (ex. Ancylostoma sp. e Toxocara sp.) foram os mais frequentes nematódeos diagnosticados neste estudo. Portanto, a população humana, em estreito convívio com esses animais, apresenta risco de infecção por helmintos de caráter zoonótico. Além disso, pela primeira vez, a técnica de FLOTAC tem sido utilizada no diagnóstico de parasitos gastrointestinais em gatos no Brasil.

Toxocaríase experimental em hamster / Experimental toxocariasis in hamsters

INTRODUÇÃO: Toxocaríase é uma infecção parasitária de distribuição global, causada pela fase larval de Toxocara spp. Os hospedeiros naturais são cães e gatos, nos quais o parasita completa o ciclo chegando a fase adulta. Outros hospedeiros podem ser infectados pela fase larval do parasita, após ingestão de ovos embrionados do solo, mãos contaminadas, fomites, ou ingestão de carne ou vísceras de animais infectados. Em hospedeiros paratênicos o parasita não completa o ciclo, invadindo em estágio larval vísceras ou outros tecidos, onde podem sobreviver e induzir a patologia. O presente estudo teve como objetivo caracterizar o hamster (Mesocricetus auratus), como modelo experimental de toxocaríase, inicialmente através do estudo das lesões histopatológicas em fígado, pulmão e rim. A caracterização da resposta imunológica do modelo, foi feita através do estudo de citocinas envolvidas nas respostas Th1 e Th2, e foi sugerida uma correlação entre alterações glomerulares e depósitos de complexos antígenos-anticorpo pré-formados na circulação. MÉTODOS: Hamsters foram inoculados com ovos embrionados de Toxocara canis, e mantidos no biotério do Instituto de Medicina Tropical de São Paulo. O estudo histopatológico foi desenvolvido utilizando-se cortes parafinados corados por hematoxilina e eosina. Para detecção de antígenos nos tecidos foram realizadas reações imunohistoquímicas, utilizando-se anticorpo monoclonal e policlonal anti- Toxocara canis. Utilizando-se o soro dos animais infectados e animais controle, foi realizada pesquisa de antígeno e anticorpo por ELISA. Para pesquisa de imunoglobulinas IgG e IgM e complemento, foram utilizados cortes congelados de rins para realização de reação de Imunofluorescência. Fragmentos de rins foram incluídos para utilização em microscopia eletrônica, para detecção de antígenos de toxocara e de imune complexos. Para caracterização de resposta imunológica foram estudadas citocinas envolvidas na resposta Th1 e Th2 por técnica de...

INTRODUCTION: Toxocariasis is a parasitic infection of global distribution, caused by the larval stage of Toxocara spp. The natural hosts are dogs and cats, in which the parasite completes the cycle reaching adulthood. Other hosts can be infected with the larval stage of the parasite, after ingestion of embryonated eggs from the soil, contaminated hands, fomites, or ingestion of meat or viscera of infected animals. In paratenics hosts the parasite not complete the cycle, encroaching on larval stage in viscera or other tissues where they can survive and induce pathology. The present study aimed to characterize the hamster, Mesocricetus auratus, as experimental model of toxocariasis, initially through the study of histopathological lesions in the liver, lung and kidney. The characterization of immune response model, was made through the study of cytokines Th1 and Th2 responses involved, and a correlation was suggested between glomerular changes and antibody-antigen complexes deposits preformed in the circulation. METHODS: Hamsters were inoculated with embryonated eggs of Toxocara canis, and kept in the bioterium of the Institute of Tropical Medicine of the São Paulo. The histopathologic study was developed using paraffin slides stained by hematoxylin and eosin. For detection of antigens in tissues immunohistochemistry reactions were performed using monoclonal and polyclonal anti-Toxocara canis sera. Using the serum of infected and control animals, search has been carried out of antigen and antibody by ELISA. For the search of immunoglobulins IgG, IgM and complement, were used slides prepared from frozen fragments of kidneys and a immunofluorescence reaction. Fragments of kidneys were included for electron microscopy to detect antigens of Toxocara and immune complexes. For characterization of Th1 and Th2 response cytokines involved were detected by RT-PCR technique. RESULTS: Histopathological findings demonstrated since the beginning of the...

EXPERIMENTAL INFECTION WITH Toxocara cati IN PIGS: MIGRATORY PATTERN AND PATHOLOGICAL RESPONSE IN EARLY PHASE / Infección experimental en cerdos con Toxocara cati: patrón migratorio y respuesta patológica en etapa temprana

Experimental inoculations of approximately 100,000 infective Toxocara cati larval eggs were done in twelve pigs. The T. cati eggs used for inoculation were collected from cat's feces. Another group of three pigs served as an uninfected control. Groups of infected pigs were euthanized at seven, 14, 21, and 28 days post-inoculation (dpi). Tissue samples were taken for digestion and histopathology changes in early phase. The number of larvae recovered from the lungs peaked at seven and 14 dpi and were also present at 21, and 28 dpi. Larvae of T. cati were present in the lymph nodes of the small and large intestine at seven, 14, and 28 dpi and at seven, 14, 21, and 28 dpi respectively. In other studied tissues, no larvae or less than one larva per gram was detected. The pathological response observed in the liver and lungs at seven and 14 dpi, showed white spots on the liver surface and areas of consolidation were observed in the lungs. The lungs showed an inflammatory reaction with larvae in center at 28 dpi. In the liver we observed periportal and perilobular hepatitis. The lymph nodes of the intestines displayed eosinophil lymphadenitis with reactive centers containing parasitic forms in some of them. The granulomatous reaction was not observed in any tissues. The role of the other examined tissues had less significance. The relevance of this parasite as an etiological agent that leads to disease in paratenic hosts is evident.

Se realizó la infección experimental de doce cerdos con aproximadamente 100.000 huevos infectivos de Toxocara cati. Los huevos de T. cati utilizados en la inoculación fueron recolectados de heces felinas. Otro grupo de tres cerdos no infectados se utilizó como control. Grupos de cerdos infectados se eutanaciaron a los 7,14,21 y 28 días posinoculación (pi). Se tomaron muestras de tejidos para digestión y evaluación de cambios histopatológicos en la etapa temprana de la infección. El número de larvas recuperadas de los pulmones se incrementó en los días 7 y 14 pi, recuperándose también los días 21 y 28 pi. Se encontraron larvas de T. cati en los linfonódulos del intestino delgado y grueso los días 7,14 y 28 pi y los días 7,14,21 y 28 pi respectivamente. En los restantes tejidos estudiados o no se recuperaron larvas o los valores fueron menores a una larva por gramo de tejido. La respuesta patológica observada en el hígado y los pulmones a los 7 y 14 días posinoculación, mostró en la superficie del hígado manchas blancas y en los pulmones áreas de consolidación. Los pulmones presentaron una reacción inflamatoria con presencia de larva en el centro en el día 28 pi. En el hígado se observó una hepatitis periportal y perilobular. Los linfonódulos del intestino presentaron una linfoadenitis eosinofílica con un centro reactivo conteniendo formas parasitarias en algunos de ello. En ninguno de los tejidos se observó la típica reacción granulomatosa. El rol de los restantes tejidos examinados fue de menor significancia. Queda evidenciada la importancia de éste parasito como un agente etiológico que desarrolla la enfermedad en hospederos paraténicos.

BEHAVIORAL AND MEMORY CHANGES IN Mus musculus COINFECTED BY Toxocara canis AND Toxoplasma gondii / Alterações comportamentais e na memória de Mus musculus coinfectado por Toxocara canis e Toxoplasma gondii

Several researchers have stated that parasites can alter the behavior of their hosts, in order to increase the transmission rate, principally when prey-predator relationships are a reliable way of infection transmission. The aim of this study was to verify the occurrence of changes in anxiety and short-term memory patterns in experimentally infected Mus musculus by Toxocara canis and/or Toxoplasma gondii. Forty male Mus musculus (Balb/c) eight-week-old were divided into four groups of 10 mice each. One group was infected with 300 eggs of Toxocara canis; a second group was submitted to infection with 10 cysts of Toxoplasma gondii; a third group was concomitantly infected with both parasites with the same inoculums and the last group was maintained without infection. The anxiety levels were evaluated using an elevated plus maze and an actometer; the short-term memory was determined by a two-way active avoidance equipment. The determination of anxiety levels were conducted 40 and 70 days after infection and the short-term memory was evaluated 140 days after infection. Mice chronically infected by Toxoplasma gondii showed impaired learning and short-term memory, but no significant differences were found in mice infected by Toxocara canis or concomitantly infected by Toxocara canis and Toxoplasma gondii when compared to non infected mice.

Pesquisadores afirmam que parasitos podem alterar o comportamento de seus hospedeiros a fim de aumentar a sua taxa de transmissão. O objetivo deste estudo foi verificar a ocorrência de alterações na ansiedade e padrões de memória de curta duração em Mus musculus experimentalmente infectados por Toxocara canis e/ou Toxoplasma gondii. Utilizaram-se 40 camundongos da espécie Mus musculus machos (Balb/c) com oito semanas de idade, divididos em quatro grupos de 10 ratos cada. Um grupo foi infectado com 300 ovos de Toxocara canis, um segundo grupo foi submetido à infecção com 10 cistos de T. gondii, um terceiro grupo foi infectado concomitantemente com ambos os parasitas e o último grupo foi mantido sem infecção. Os níveis de ansiedade foram avaliados por meio de labirinto em cruz elevado e actômetro, a memória de curta duração foi determinada por esquiva aversiva. A determinação dos níveis de ansiedade foi realizada 40 e 70 dias após infecção e a memória de curto prazo foi avaliada 140 dias após a infecção. Camundongos cronicamente infectados por Toxoplasma gondii mostraram deficiência de aprendizagem e memória de curto prazo, mas não foram encontradas diferenças significantes em camundongos infectados por Toxocara canis ou concomitantemente infectados por Toxocara canis e Toxoplasma gondii quando comparados com camundongos não infectados.

Parasitosis intestinales y tisulares y su relación con la eosinofilia en una comunidad indígena Yukpa de la Sierra de Perijá, estado Zulia / Intestinal and tissue parasites and their relation with eosinophilia in a Yukpa Amerindian community from the Mountains of Perijá, state of Zulia

Para determinar la prevalencia de parasitosis intestinales y tisulares y su relación con la eosinofilia en una comunidad indígena Yukpa, se analizaron 91 muestras fecales y sanguíneas. A las muestras fecales se les practicó examen coproscópico y concentrado. Se realizó hematología completa para determinar cuenta blanca y porcentaje de eosinófilos, y en suero se efectuó un test de ELISA para la detección de anticuerpos anti- Toxocara canis y anti- Toxoplasma gondii. Se observó una elevada prevalencia de parasitosis intestinales (90,10%). Se apreció predominio de protozoarios sobre helmintos, siendo para los primeros el más prevalente Blastocystis sp. (51,64%) y para los segundos Ascaris lumbricoides (38,46%). La seroprevalencia de anticuerpos anti-Toxocara canis fue de 24,17% y anti-Toxoplasma gondii de 43.95%. No se observó diferencias estadísticamente significativas entre los grupos de edad y sexo en las diferentes parasitosis intestinales y tisulares. No se encontró asociación entre la seroprevalencia para Toxocara canis y la eosinofilia. Se apreció una asociación estadística significativa entre la presencia de eosinofilia y las helmintiasis. Estos resultados sugieren que existe una alta prevalencia de infecciones parasitarias en estas comunidades debido probablemente a sus costumbres y las condiciones sanitarias en las que habitan.

To determine the prevalence of intestinal and tissue parasites and their relationship with eosinophilia in Yukpa Amerindians, 91 fecal and blood samples were analyzed. The fecal samples underwent microscopic and concentrated examinations. Complete hematology was performed to determine white count and percentage of eosinophils; and ELISA tests were performed on the serum to detect anti-Toxocara canis and anti-Toxoplasma gondii antibodies. A high prevalence of intestinal parasites (90.10%) was observed. The predominance of protozoa over helminths was noted; for the first, the most prevalent were Blastocystis hominis (51.64%), and for the second, Ascaris lumbricoides (38.46%). Seroprevalence of anti-Toxocara canis antibodies was 24.17% and for anti-Toxoplasma gondi, 43.95%. No statistically significant differences were observed between age and sex groups for the different intestinal and tissue parasites. No association between seroprevalence for Toxocara canis and eosinophilia was found. A statistically significant association between the presence of eosinophilia and helminthiasis was observed. These results suggest that there is a high prevalence of parasitic infections in these communities due probably to their customs and the sanitary conditions in which they live.

Toxocariosis: seroprevalencia y contaminación ambiental en dos comunas periurbanas de la ciudad de Córdoba, Argentina / Toxocariosis: seroprevalence and enviroment contamination in two periurbana communities of Córdoba City, Argentina

La toxocariasis humana es una enfermedad parasitaria que se encuentra en todo el mundo.Los humanos están infectados por la ingestión de los huevos que contaminan el medio ambiente. El diagnóstico serológico se lleva a cabo mediante inmunoensayo enzimático y por lo general confirmado por Western blot. El objetivo de este estudio fue determinar la concentración de anticuerpos contra Toxocara canis y el total de los niveles de IgE en suero, el número de eosinófilos en sangre y grado de contaminación del suelo por la técnica de flotación en dos ciudades de la periferia de la ciudad de Córdoba, Argentina. De las 64 muestras de 29,7% (19/64) fueron reactivos y 70% (45/64) no fueron reactivos por ELISA. Sólo una muestra fue positiva por Western blot (1/64). Enterobius vermicularis, Giardia lamblia, Blastocystis sp. y Entamoeba coli fueron las especies parasitarias más frecuentes que se encuentran en las heces. La concentración total de IgE mostró diferencias significativas entre los grupos. Los niveles de eosinófilos mostraron un aumento significativo en la muestra positiva confirmado por Western blot en comparación con los otros dos grupos. De las 70 muestras de suelo, 77% (54/70) estaban contaminadas con huevos de Toxocara sp. Estos resultados revelan la presencia de reacciones cruzadas en la prueba de ELISA. Por esta razón, se propone el Western blot como técnica confirmatoria. Podemos concluir que la toxocariosis humana es un problema de salud grave que al día de hoy recibió poca atención de la comunidad médica. Los programas educativos deben ser desarrolladas para promover el concepto social de la tenencia responsable de mascotas. Otros estudios serán necesarios para determinar la contribución de esta enfermedad parasitaria a la morbilidad general de la población.(AU)

Comparison of Functional Gene Annotation of Toxascaris leonina and Toxocara canis using CLC Genomics Workbench

The ascarids, Toxocara canis and Toxascaris leonina, are probably the most common gastrointestinal helminths encountered in dogs. In order to understand biological differences of 2 ascarids, we analyzed gene expression profiles of female adults of T. canis and T. leonina using CLC Genomics Workbench, and the results were compared with those of free-living nematode Caenorhabditis elegans. A total of 2,880 and 7,949 ESTs were collected from T. leonina and T. canis, respectively. The length of ESTs ranged from 106 to 4,637 bp with an average insert size of 820 bp. Overall, our results showed that most functional gene annotations of 2 ascarids were quite similar to each other in 3 major categories, i.e., cellular component, biological process, and molecular function. Although some different transcript expression categories were found, the distance was short and it was not enough to explain their different lifestyles. However, we found distinguished transcript differences between ascarid parasites and free-living nematodes. Understanding evolutionary genetic changes might be helpful for studies of the lifestyle and evolution of parasites.

Prevalencia de helmintos intestinales en gatos domésticos del departamento del Quindío, Colombia / Prevalence of intestinal helminths in cats in Quindío, Colombia

Introducción. Las enfermedades producidas por helmintos están ampliamente distribuidas en el mundo y muchas de ellas se consideran zoonosis. Los animales de compañía cumplen un papel trascendental en la transmisión a los humanos. Objetivo. Determinar la prevalencia de helmintos intestinales en gatos del departamento del Quindío. Materiales y métodos. Se estudiaron 121 gatos domésticos del departamento del Quindío, de los cuales se registraron los datos de sexo, edad y condición corporal. Se recolectaron heces y se procesaron mediante las técnicas de Ritchie modificada y de Kato-Katz. Resultados. De los 121 gatos, 42,14 % (IC95%: 33,35-50,94) y 45,45 % (IC95%: 36,58-54,32) resultaron parasitados con alguna especie de helminto adulto según la presencia de huevos en sus heces, mediante las técnicas de Ritchie y de Kato-Katz, respectivamente. Toxocara cati fue el parásito más prevalente(Ritchie: 37,2 %; Kato-Katz: 43 %), seguido por Ancylostoma spp. (Ritchie: 7,43 %; Kato-Katz: 5,78 %) y Aelurostrongylus abstrusus (Ritchie: 0,82 %). Sesenta y cinco (53,71 %) gatos eran hembras y 56 (46,28 %) eran machos; la prevalencia de infección fue similar en ambos sexos. Los felinos mayores de 4 años de edad presentaron mayor prevalencia de parásitos (81,8 %), seguidos por los de 1 a 4 años (48,8 %) y, por último, por los menores de un año (28,6 %). Se encontró una buena condición corporal en 77,68 % y este grupo presentó menor frecuencia de helmintos intestinales. Conclusión. La prevalencia de helmintos intestinales en gatos domésticos del departamento del Quindío fue de 43,8 %, lo que hace necesario establecer programas de vigilancia y prevención en la población humana y felina.

Introduction. Diseases caused by helminths are widely distributed in the world and many of them are considered zoonoses in which pets play a major role in transmission to humans. Objective. The prevalence of intestinal helminths was determined in cats in Quindío Province. Materials and methods. One hundred twenty-one cats were characterized --data recorded included sex, age and body condition. Fecal samples were collected and processed using the modified Ritchie and modified Kato-Katz techniques to determine the presence of intestinal helminths. Results. Of the 121 cats, 42.1%, (95% CI: 33.4-50.9) and 45.5% (95% CI: 36.6-54.3) were parasitized with at least one adult helminth species as evidenced by the presence of eggs in their fecal samples. Toxocara cati was the most prevalent parasite (Ritchie: 37.2%, Kato-Katz: 43%), followed by Ancylostoma spp. (Ritchie: 7.4%, Kato-Katz: 5.8%) and Aelurostrongylus abstrusus (Ritchie: 0.82%). Sixty-five cats (53.7%) were females and 56 (46.3%) males; the prevalence of infection was similar in both sexes. Cats older than 4 years had the highest prevalence (81.8%) followed by those aged 1 to 4 years (48.8%) and by those under 1 year (28.6%). The majority of cats, 77.7%, were found to be in good body condition and this group had the lowest frequency of intestinal helminths with both techniques. Conclusion. The prevalence of intestinal helminths in domestic cats in Quindío was 43.8%; it is necessary to establish surveillance and prevention programs in the human and feline populations.

Estandarización de la técnica de ELISA para el diagnóstico inmunológico de toxocariasis humana / Standardization of ELISA technique for the immunological diagnosis of human toxocariasis

La toxocariasis o síndrome de larva migrans visceral es causada por un nemátode del género Toxocara, parásito de animales domésticos (perros y gatos). El hombre es un hospedador accidental, al contaminarse con huevos embrionados del parásito. Las larvas invaden la pared intestinal y son transportadas a vísceras, musculatura o globo ocular, donde son atacadas por una reacción granulomatosa del hospedador. El diagnóstico de la enfermedad es complicado debido a la sintomatología inespecífica y que las larvas solo pueden ser evidenciadas por biopsias, que es un método invasivo. Los métodos inmunológicos son una alternativa, en tal sentido en esta investigación se planteó como objetivo estandarizar una técnica inmunológica para la determinación de anticuerpos anti-T.canis para el diagnóstico de toxocariasis humana. Los parásitos adultos expulsados por cachorros infectados se identificaron por microscopia óptica y electrónica, se obtuvieron los huevos, los cuales se hicieron embrionar para la liberación de las larvas, y éstas se mantuvieron en cultivo, para luego obtener y purificar los antígenos de excreción/secreción. Se estandarizaron las condiciones de reacción de la ELISA, obteniéndose como concentraciones óptimas 2 μg/mL de antígeno, dilución de suero y conjugado fueron de 1/400 y 1/20000 respectivamente. Los índices diagnósticos fueron: sensibilidad 100%, especificidad 98,9%, valor predictivo positivo 94,4% y valor predictivo negativo 100%. Con la técnica estandarizada se pudieron diferenciar los sueros de pacientes con Toxocariasis, con respecto a los de pacientes con otras helmintiasis y muestras de suero de individuos sanos, logrando el diagnóstico de Toxocariasis humana.

The toxocariasis or visceral larva migrans syndrome is caused by a nematode of the genus Toxocara, a parasite of domestic animals (dogs and cats). Man is an accidental host, by oral contamination with embryonated eggs of the parasite. The larvae invade the intestinal wall and are transported to the viscera, muscle or eyeball, where they are attacked by a granulomatous reaction of the host. The diagnosis of the disease is complicated by nonspecific symptoms and the larvae can only be demonstrated by biopsy which is an invasive method. Immunological methods are an alternative. The objective of this study was standardizing an immunological technique for the determination of anti-T. canis antibodies for diagnosis of human Toxocariasis. We identified by optical and electron microscopy, adult worms expelled by infected pups and we obtained eggs, which became embryos that released the larvae. These were maintained in culture. Excretion/secretion antigens (E/S) were purified from the culture. Subsequently, we standardized reaction conditions of the ELISA technique, obtaining as optimal concentrations 2 mg/mL of antigen, serum dilution and conjugate 1/400 and 1/20000 respectively. With the standard technique we evaluated 17 serum samples from patients with confirmed Toxocariasis, 50 patients with other helminth infections and 40 healthy individuals. The diagnostic indexes were sensitivity 100%, specificity 99%, 94% positive predictive value and negative predictive value 100%. The diagnostic indexes obtained show that the ELISA using excretion/secretion antigen of the parasite is suitable for immunodiagnosis of human Toxocariasis.

IgG Antibody responses in mice coinfected with Toxocara canis and other helminths or protozoan parasites / Anticorpos IgG em camundongos coinfectados por Toxocara canis e outros helmintos e por protozoários parasitos

The immune response expressed by IgG antibodies in BALB/c mice experimentally infected with Toxocara canis, was studied with the aim of verifying the possible in vivo cross-reactivity between antigens of T. canis and other parasites (Ascaris suum, Taenia crassiceps, Schistosoma mansoni, Strongyloides venezuelensis and Toxoplasma gondii). Experiments included three groups of mice: one infected only by T. canis, another with one of the other species of parasites and a third concomitantly infected with T. canis and the other species in question. Animals were bled by orbital plexus at 23, 38 and 70 days post infection (p.i.). Sera were analyzed for anti-Toxocara antibodies by ELISA and Immunoblotting, using excretion-secretion antigens (ES), obtained from culture of third-stage larvae of T. canis. For all experiments a control group comprised by ten non-infected mice was used. Only in the case of A. suum infection, in these experimental conditions, the occurrence of cross-reactivity with T. canis was observed. However, in the case of co-infection of T. canis - S. mansoni, T. canis - S. venezuelensis and T. canis - T. crassiceps the production of anti-Toxocara antibodies was found at levels significantly lower than those found in mice infected with T. canis only. Co-infection with S. mansoni or S. venezuelensis showed lower mortality rates compared to what occurred in the animals with single infections. Results obtained in mice infected with T. canis and T. gondii showed significant differences between the mean levels of the optical densities of animals infected with T. canis and concomitantly infected with the protozoan only in the 23rd day p.i.

Estudou-se a resposta imune humoral expressa por anticorpos da classe IgG em camundongos BALB/c experimentalmente infectados com Toxocara canis em duas situações distintas. Na primeira, com o objetivo de verificar in vivo a possível reatividade cruzada entre Toxocara canis e outros parasitos (Ascaris suum, Taenia crassiceps, Schistosoma mansoni, Strongyloides venezuelensis e Toxoplasma gondii), foram realizados experimentos constituídos por três grupos de camundongos: um infectado apenas por Toxocara canis, outro com uma das demais espécies de parasitos estudados e um terceiro concomitantemente infectado por Toxocara canis e a espécie em questão. Todos os animais foram sangrados, através do plexo orbitário, 23, 38 e 70 dias após infecção. Os soros foram analisados para a presença de anticorpos anti-Toxocara por meio de teste imunoenzimático (ELISA) e por Immunoblotting, empregando-se antígeno de excreção-secreção (ES), obtido a partir da cultura de larvas de terceiro estádio de Toxocara canis. Para todos os experimentos utilizou-se grupo controle negativo constituído por 10 camundongos não infectados. Apenas no caso da infecção por Ascaris suum, nas condições experimentais observadas, logrou-se demonstrar ocorrência de reatividade cruzada com antígenos de Toxocara canis. Verificou-se, entretanto, no caso das coinfecções entre Toxocara canis-Schistosoma mansoni, Toxocara canis-Strongyloides venezuelensis e Toxocara canis-Taenia crassiceps produção de anticorpos anti-Toxocara em níveis significativamente inferiores do que os encontrados nos camundongos infectados somente por Toxocara canis. Nas coinfecções com Schistosoma mansoni ou Strongyloides venezuelensis observou-se, também, menor taxa de letalidade quando comparada à ocorrida nos animais com as respectivas infecções simples.

Transmission of Toxocara canis via Ingestion of Raw Cow Liver: A Cross-Sectional Study in Healthy Adults

The aim of this study is to ascertain the relationship between ingestion of raw cow liver and Toxocara canis infection. A total of 150 apparently healthy adults were divided into 2 groups; 1 group consisted of 86 adults with positive results of Toxocara ELISA, and the other group of 64 adults with negative results. One researcher collected the history of ingestion of raw cow liver within 1 year and recent history of keeping dogs. Among 86 seropositive adults for T. canis, 68 (79.1%) had a recent history of ingestion of raw cow liver. Multivariate statistical analysis showed that a recent ingestion of raw cow liver and keeping dogs were related to an increased risk of toxocariasis (odds ratios, 4.4 and 3.7; and 95% confidence intervals, 1.9-10.2 and 1.2-11.6, respectively). A recent history of ingestion of raw cow liver and keeping dogs was significantly associated with toxocariasis.

Prueba de avidez de los anticuerpos IgG en la infección por Toxocara canis / IgG antibodies avidity test in Toxocara canis infection / O teste de avidez dos anticorpos IgG na infecção por Toxocara canis

A fin de evaluar la utilidad de la prueba de avidez de los anticuerpos IgG para el reconocimiento de la fase de infección de la toxocariosis en individuos con alto nivel de exposición al parásito, se estudiaron 142 niños asintomáticos de ambos sexos, de 1-6 años de edad, residentes en la ciudad de Resistencia (NE de Argentina), con eosinofilia > 10% y con exámenes coproparasitológicos negativos para helmintos. Se realizó la prueba de ELISA-IgG en todos los casos y en aquellos con títulos > 1/80 se determinó el índice de avidez de IgG. De los 142 niños estudiados, 82 (57,7%) resultaron positivos a la prueba de ELISA-IgG pero sólo 6 (7.3%) tuvieron Índice de avidez menor al 50%, cinco tenían entre 1 y 2 años de edad y el restante 5 años (mediana: 1,5 años). Cuatro tuvieron títulos moderados de IgG (entre 1/80 y 1/640) y 2 títulos altos (entre 1/1280 y 1/10240). Los otros 76 niños con índice de avidez mayor al 50% tenían entre 18 meses y 5,5 años de edad (mediana: 4 años), 44 tuvieron títulos serológicos moderados y 32, títulos altos. Los resultados hallados en este trabajo reafirman que la población de la ciudad de Resistencia presenta altos niveles de exposición a T. canis y que la determinación del índice de avidez de IgG resulta útil para el diagnóstico diferencial entre toxocariosis reciente o tardía, aunque es más efectiva para descartar una infección reciente que para confirmarla.

In order to evaluate the usefulness of the IgG avidity test to recognize the phase of T. canis human infection in individuals highly exposed to the parasite, 142 asymptomatic children of both sexes, 1-6 years old, living in Resistencia (Northeastern Argentina), with eosinophilia > 10% and without helminthic intestinal infestation were studied. ELISA-IgG test was performed in all cases, and in those with serological titers > 1/80 IgG avidity was also measured. Out of 142 children studied, 82 (57.7%) were positive to ELISA test, but only 6 (7.3%) had an IgG avidity index < 50%. Five of them were aged between 1 to 2 years and the other was 5 years old (median 1.5 years). Four had moderate serological titers (between 1/80 and 1/640) and two had high titers (between 1/1280 and 1/10240). The other 76 children with IgG avidity indexes > 50% were between 18 months and 5.5 years old (median 4 years), 44 had moderate serological titers and 32 had high titers. The results found in this study reaffirm that the population in Resistencia city is highly exposed to T. canis infection and that the IgG avidity test may be helpful in differential diagnosis of recent and past toxocariosis, though it would be more effective to rule out a recently acquired infection than to confirm it.

Com o fim de avaliar a utilidade da prova de avidez dos Acs IgG para o reconhecimento da fase de infecção de toxocaríase em indivíduos com alto nível de exposição ao parasita, foram estudadas 142 crianças assintomáticas de ambos os sexos de 1 a 6 anos de idade, residentes na cidade de Resistencia (noreste argentino) com eosinofilia > 10% e com exames coproparasitológicos negativos para helmintos. Foi realizada a prova Elisa-IgG em todos os casos e naqueles com títulos > 1/80 foi determinado o índice de avidez de IgG. Das 142 crianças estudadas, 82 (57,7%) resultaram positivas à prova de Elisa-IgG porém só 6 (7,3%) tiveram índice de avidez < a 50%, 5 tinham entre 1 e 2 anos de idade e as outras 5 anos (média: 1,5 anos). Quatro tiveram títulos moderados de IgG (entre 1/80 e 1/640) e 2 títulos altos (entre 1/1280 e 1/10240). As outras 76 crianças com índice de avidez maior a 50% tinham entre 18 meses e 5,5 anos de idade (média: 4 anos), 44 tiveram títulos sorológicos moderados e 32 títulos altos. Os resultados encontrados neste trabalho reafirmam que a população da cidade de Resistencia apresenta altos níveis de exposição à T. canis e que a determinação do índice de avidez de IgG resulta útil para o diagnostico diferencial entre toxocaríase recente ou tardia, embora seja mais efetiva para descartar uma infecção recente que para confirmá-la.

Evidence for eosinophil recruitment, leukotriene B4 production and mast cell hyperplasia following Toxocara canis infection in rats

It is well known that eosinophilia is a key pathogenetic component of toxocariasis. The objective of the present study was to determine if there is an association between peritoneal and blood eosinophil influx, mast cell hyperplasia and leukotriene B4 (LTB4) production after Toxocara canis infection. Oral inoculation of 56-day-old Wistar rats (N = 5-7 per group) with 1000 embryonated eggs containing third-stage (L3) T. canis larvae led to a robust accumulation of total leukocytes in blood beginning on day 3 and peaking on day 18, mainly characterized by eosinophils and accompanied by higher serum LTB4 levels. At that time, we also noted increased eosinophil numbers in the peritoneal cavity. In addition, we observed increased peritoneal mast cell number in the peritoneal cavity, which correlated with the time course of eosinophilia during toxocariasis. We also demonstrated that mast cell hyperplasia in the intestines and lungs began soon after the T. canis larvae migrated to these compartments, reaching maximal levels on day 24, which correlated with the complete elimination of the parasite. Therefore, mast cells appear to be involved in peritoneal and blood eosinophil infiltration through an LTB4-dependent mechanism following T. canis infection in rats. Our data also demonstrate a tight association between larval migratory stages and intestinal and pulmonary mast cell hyperplasia in the toxocariasis model.

Prevalence of Toxocara canis in Dogs, North West Bank of Palestine

This study was performed to investigate the prevalence of Toxocara canis in local districts in North West Bank of Palestine. Fecal samples from 132 dogs were collected in Nablus, Tulkarm, and Jenin cities from September 2008 to April 2009 and examined for T. canis eggs with the floating technique. The overall infection rate of toxocariasis in dogs was 36.4%. The dogs less than 6 months old showed higher infection rates than those older than 12 months (P=0.04). Vigorous interventions are necessary, such as routine coprological examinations of dogs and prescription of anthelmintics to infected dogs.

Experimental Toxocara cati Infection in Gerbils and Rats

Mongolian gerbils and Wistar rats were inoculated orally with 240 and 2,500 Toxocara cati embryonated eggs, respectively, to evaluate the larval recovery in different tissues and organs, such as the liver, lungs, heart, kidney, and skeletal muscles after 5, 30, 49, 70, and 92 days post-infection (PI). Larval recovery rates were 1.7-30.0% in Mongolian gerbils on days 5-92 PI and 0.2-3.8% in rats on the same days. These results indicate that Mongolian gerbils and Wistar rats are suitable experimental paratenic hosts for the study of neurological toxocariasis as well as visceral toxocariasis.

Larval recovery of Toxocara cati in experimentally infected Rattus norvegicus and analysis of the rat as potential reservoir for this ascarid

Toxocara cati is a common feline parasite transmitted by the ingestion of embryonated eggs, by the transmammary route or by predation of paratenic hosts harbouring third-stage larvae in their bodies. In the present study, the larval distribution of T. cati in tissues and organs of Rattus norvegicus experimentally infected with 300 embryonated eggs was analysed. Third-stage larvae were recovered from livers, lungs, kidneys, eyes, brains and carcasses of infected rats, following tissue digestion with HCl 0.5 percent for 24 h at 37°C. Some differences from the known larval distribution of Toxocara canisin the same rodent species were found.

Ocular lesions in gerbils (Meriones unguiculatus) infected with low larval burden of Toxocara canis: observations using indirect binocular ophthalmoscopy / Lesões oculares em gerbils (Meriones unguiculatus) infectados com baixo número de larvas do Toxocara canis: observações com oftalmoscopia binocular indireta

To study the frequency of ocular lesions in 30 gerbils infected with 100 embryonated eggs of Toxocara canis, indirect binocular ophthalmoscopy was performed 3, 10, 17, 24, 31 and 38 days after infection. All the animals presented larvae in the tissues and 80 percent presented ocular lesions. Hemorrhagic foci in the choroid and retina were present in 92 percent of the animals with ocular lesions. Retinal exudative lesions, vitreous lesions, vasculitis and retinal detachment were less frequent. Mobile larvae or larval tracks were observed in four (13.3 percent) animals. Histological examination confirmed the ophthalmoscopic observations, showing that the lesions were focal and sparse. In one animal, there was a larva in the retina, without inflammatory reaction around it. The results demonstrated that gerbils presented frequent ocular lesions after infection with Toxocara canis, even when infected with a small number of embryonated eggs. The lesions observed were focal, consisting mainly of hemorrhages with signs of reabsorption or inflammation in different segments of eye, and differing from the granulomatous lesions described in ocular larva migrans in humans.

Para verificar a freqüência de lesões oculares em 30 gerbils infectados com 100 ovos larvados de Toxocara canis foi realizada a oftalmoscopia binocular indireta nos dias 3, 10, 17, 24, 31 e 38 após a infecção.Todos os animais apresentavam larvas nos tecidos e 80 por cento apresentavam lesões oculares, dos quais 92 por cento tinham lesões hemorrágicas focais na coróide e na retina. Lesões exudativas da retina, lesões do vítreo, vasculite e descolamento da retina foram menos freqüentes. Larva móvel ou traços de larva em quatro (13,3 por cento) animais. O estudo histológico confirmou as observações da oftalmoscopia, mostrando que as lesões eram focais e esparsas. Em um animal havia uma larva na retina, sem reação inflamatória em torno dela. Os resultados demonstraram que os gerbils apresentam freqüentes lesões oculares após infecção com o Toxocara canis mesmo quando infectados com pequeno número de ovos larvados. As lesões observadas eram focais, principalmente focos de hemorragia com sinais de reabsorção ou focos de inflamação nos diferentes segmentos do olho, diferentes das lesões granulomatosas descritas na larva migrans ocular humana.

Urban contamination with zoonotic parasites in the central region of Argentina / Contaminación urbana con parásitos zoonóticos en la región central de la Argentina

Adult worms develop in dogs and their eggs are shed in the feces. Non-embryonated eggs of Toxocara canis become infectious after about 2-6 weeks in the soil and the likelihood of their transmission to humans is through ingestion. In 2004 studies were carried out in the areas of urban recreation in the central region of Argentina. A total of 393 dog excrement samples were collected in eight different cities: 59.3 per cent were positive for parasites. These areas of urban recreation are contaminated with zoonotic parasites in the cities of Paraná (19 of 24 areas), Santa Fe (20 of 26), and Santo Tomé (14 of 18). Eggs of T. canis were present in 101 of 393 (25.7%) of the excrement samples, and eggs could be found in 53 of the 68 (77.9%) areas of urban recreation studied in these cities. This contamination is greater in areas of lower socio-economic conditions. The object of this paper is to discuss markers of parasitic contamination with the aim of triggering the necessary control measures.

Uno de los parásitos de cánidos de riesgo para la salud de los niños es el Toxocara canis. Las formas adultas y sus huevos no embrionados son liberados con las heces al medio ambiente. Después de aproximadamente dos semanas en el suelo, los huevos se transforman en infectivos y su ingestión por el ser humano puede provocar una infección parasitaria. En primavera y otoño de 2004, se llevaron a cabo estudios en áreas urbanas de recreación en una amplia zona geográfica de la Región Centro de la Argentina. Un total de 393 muestras de heces de canes fueron colectadas y analizadas en ocho ciudades; 59.3% de esas muestras fueron positivas para otros parásitos, además del T. canis. Las áreas de recreación pública de las ciudades demográficamente más importantes mostraron resultados positivos para parásitos zoonóticos en 19 de 24 áreas en Paraná, 20 de 26 en Santa Fe y 14 de 18 en Santo Tomé, es decir 53 de 68 (77.9%). Se encontraron huevos de T. canis en 101 de las 393 (25.7%) muestras fecales, y en el 60% de los parques públicos investigados en todas las ciudades. Esta contaminación fue mayor en barrios con condiciones socioeconómicas más bajas. En este trabajo se proponen medidas sanitarias de control y prevención.