Experimental toxocariasis in BALB/c mice: relationship between parasite inoculum and the IgG immune response

BALB/c mice were inoculated with 5-500 Toxocara canis infective eggs, and bled at 15-120 days post infection (dpi) to evaluate the dynamics of IgG antibody response and larvae distribution. Positive results were observed in all occasions for every inoculum, and a direct proportional relationship between antibody detection and the parasitic load was observed. In samples collected at 60 dpi, detection of IgG was more intense, especially with the 50 and 500 egg doses; also, a correlation between antibody level and egg count was observed with these two inocula. At 120 dpi, a decrease in antibody titer was observed for all groups; and at the end of the experiment, larvae were recovered from carcass, liver and brain. In the liver, larvae were only found in mice inoculated with 500 T. canis eggs. In carcasses, these were recovered in all groups, and the group inoculated with 50 eggs showed the highest percentage of larvae in the brain.

Kinetics and avidity of anti-Toxocara antibodies (IgG) in rabbits experimentally infected with Toxocara canis / Cinética e avidez de anticorpos (IgG) anti-Toxocara em coelhos experimentalmente infectados com Toxocara canis

Abstract An evaluation was made of the kinetics and avidity of anti-Toxocara antibodies (IgG) in rabbits experimentally infected with embryonated Toxocara canis eggs. Seventeen four month old New Zealand White rabbits were distributed into two groups. In the experimental group, twelve rabbits were infected orally with 1,000 embryonated T. canis eggs. A second group (n = 5), uninfected, was used as a control. Serum samples were collected for analysis on days 7, 14, 21, 28 and 60 post-infection (DPI). An indirect ELISA test was performed to evaluate the reactivity index (RI) of IgG anti-T. canis antibodies and to calculate the avidity index (AI). The animals showed seroconversion from the 14th DPI, with high AI (over 50%) except for one animal, which presented an intermediate AI. At 60 DPI, all the animals were seropositive and maintained a high AI. The data indicated that specific IgG antibodies formed early (14 DPI) in rabbits infected with T. canis, with a high avidity index that persisted throughout the course of the infection.

Resumo O objetivo deste estudo foi o de avaliar a cinética e a avidez de anticorpos anti-Toxocara canis, em coelhas infectadas experimentalmente com ovos embrionados de Toxocara canis. Foram utilizados 17 coelhos New Zealand de linhagem branca, com quatro meses de idade, distribuídos em dois grupos. No grupo experimental, doze coelhas foram infectadas, oralmente, com 1.000 ovos larvados de T. canis. Um segundo grupo (n=5), não infectado, foi utilizado como controle. Nos dias 7, 14, 21, 28 e 60 pós-infecção (DPI), foram coletadas amostras de soro para análise. O teste de ELISA indireto foi realizado para avaliar o índice de reatividade (IR) de anticorpos IgG anti-T. canis e para cálculo do índice de avidez (IA). A soroconversão nos animais ocorreu a partir do140 DPI, com verificação de alto IA (superior a 50%), com exceção de um animal, que apresentou médio IA. Aos 60 DPI, todos os animais foram soropositivos e mantiveram alto IA. Os dados mostram que em coelhos infectados por T. canis, anticorpos IgG específicos formam-se precocemente (14 DPI), apresentando alto índice de avidez e que se mantém durante o curso da infecção.

Toxocara canis and the allergic process

The protective effect of infectious agents against allergic reactions has been thoroughly investigated. Current studies have demonstrated the ability of some helminths to modulate the immune response of infected hosts. The objective of the present study was to investigate the relationship between Toxocara canis infection and the development of an allergic response in mice immunised with ovalbumin (OVA). We determined the total and differential blood and bronchoalveolar lavage fluid cells using BALB/c mice as a model. To this end, the levels of interleukin (IL)-4, IL-5 and IL-10 and anti-OVA-IgE were measured using an ELISA. The inflammatory process in the lungs was observed using histology slides stained with haematoxylin and eosin. The results showed an increase in the total number of leukocytes and eosinophils in the blood of infected and immunised animals at 18 days after infection. We observed a slight lymphocytic inflammatory infiltrate in the portal space in all infected mice. Anti-OVA-IgE levels were detected in smaller proportions in the plasma of immunised and infected mice compared with mice that were only infected. Therefore, we concluded that T. canis potentiates inflammation in the lungs in response to OVA, although anti-OVA-IgE levels suggest a potential reduction of the inflammatory process through this mechanism.

Efficacy of nitazoxanide against toxocara canis: larval recovery and humoral immune response in experimentally infected mice / Eficácia da nitazoxanida contra Toxocara canis: recuperação larvária e resposta imune humoral em camundongos experimentalmente infectados

SUMMARYThe efficacy of nitazoxanide (NTZ) against toxocariasis was investigated in an experimental murine model and results were compared to those obtained using mebendazole. Sixty male BALB/c mice, aged six to eight weeks-old, were divided into groups of 10 each; fifty were orally infected with 300 larvaed eggs of T. canisand grouped as follows, G I: infected untreated mice; G II: infected mice treated with MBZ (15 mg/kg/day) 10 days postinfection (dpi); G III: infected mice treated with NTZ (20 mg/kg/day) 10 dpi; G IV: infected mice treated with MBZ 60 dpi; G V: infected mice treated with NTZ 60 dpi; GVI: control group comprising uninfected mice. Mice were bled via retro-orbital plexus on four occasions between 30 and 120 dpi. Sera were processed using the ELISA technique to detect IgG anti- Toxocaraantibodies. At 120 dpi, mice were sacrificed for larval recovery in the CNS, liver, lungs, kidneys, eyes and carcass. Results showed similar levels of anti- ToxocaraIgG antibodies among mice infected but not submitted to treatment and groups treated with MBZ or NTZ, 10 and 60 dpi. Larval recovery showed similar values in groups treated with NTZ and MBZ 10 dpi. MBZ showed better efficacy 60 dpi, with a 72.6% reduction in the parasite load compared with NTZ, which showed only 46.5% reduction. We conclude that administration of these anthelmintics did not modify the humoral response in experimental infection by T. canis. No parasitological cure was observed with either drug; however, a greater reduction in parasite load was achieved following treatment with MBZ.

RESUMOFoi investigada a eficácia da nitazoxanida (NTZ) na toxocaríase murina experimental e os resultados comparados com os obtidos usando mebendazol (MBZ). Sessenta camundongos BALB/c machos, com idade entre seis e oito semanas foram divididos em grupos de 10 cada, 50 foram infectados oralmente com 300 ovos larvados de T. canise agrupados a seguir: GI: camundongos infectados não tratados; GII: camundongos infectados tratados com MBZ (15 mg/kg/dia) 10 dias pós-infecção (dpi); GIII: camundongos infectados tratados com NTZ (20 mg/kg/dia) 10 dpi, GIV: camundongos infectados tratados com MBZ 60 dpi; GV: camundongos infectados tratados com NTZ 60 dpi; GVI: controle não infectado. Os camundongos foram sangrados via plexo retro orbitário em quatro ocasiões entre o 30º e 120º dpi. Os soros foram processados pela técnica de ELISA para detecção de anticorpos IgG anti- Toxocara.Aos 120 dpi, os animais foram sacrificados para a recuperação larvária do SNC, fígado, pulmões, rins, olhos e carcaça. Os resultados mostraram níveis similares de anticorpos IgG anti- Toxocaraentre os camundongos infectados mas não submetidos a tratamento e os grupos infectados e tratados com MBZ ou NTZ, aos 10 e 60 dpi. Os valores da recuperação larval foram similares nos grupos tratados com NTZ e MBZ 10 dpi. MBZ mostrou melhor eficácia aos 60 dpi, com redução de 72,6% da carga parasitária comparada com NTZ, que mostrou redução somente de 46,5%. Concluímos que a administração destes anti-helmínticos não modificou a resposta humoral na infecção experimental por T. canis. Não foi observada cura parasitológica com nenhuma das drogas; porém maior redução na carga parasitária foi obtida após o tratamento com MBZ.

Seropositivity for ascariosis and toxocariosis nd cytokine expression among the indigenous people in the Venezuelan delta region / Seropositividad para ascariosis y toxocariosis y expresión de citocinas entre la población indígena de la región del delta Venezolano

The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.

El objetivo del presente estudio fue determinar la seropositividad de infección por Ascaris suum y Toxocara canis, utilizando antígenos de excreción/secreción (E/S) de Ascaris suum (AES) y Toxocara canis (TES) en una población indígena. Adicionalmente, se cuantificó la expresión de citocinas a partir de células de sangre periférica. Un total de 50 indígenas Warao se incluyeron en el estudio; 43 fueron adultos y 7 niños. Entre los adultos, 44,1% fueron seropositivos para ambos parásitos; mientras que los niños sólo mostraron seropositividad a uno u otro de los helmintos. Para ascariosis, el porcentaje de seropositividad para los antígenos AES fue alto tanto en adultos como en niños; 23,3% y 57,1%, respectivamente. Para toxocariosis, el porcentaje de seropositividad para los antígenos TES fue bajo en adultos así como en niños; 9,3% y 14,3%, respectivamente. El porcentaje de seronegatividad fue similar tanto para los antígenos AES como para TES en adultos (27,9%) y niños (28,6%). Cuando la seropositividad fue analizada a través de la técnica de Western blotting utilizando los antígenos AES; 3 bandas de 97,2, 193,6 y 200,2 kDas fueron principalmente reconocidas. Para los antígenos TES, 9 bandas fueron mayormente identificadas; 47,4, 52,2, 84,9, 98,2, 119,1, 131,3, 175,6, 184,4 y 193,6 kDas. Los análisis coproparasitológicos mostraron que los parásitos Blastocystis hominis, Hymenolepis nana y Entamoeba coli fueron los parásitos intestinales más comúnmente observados. La cuantificación de la expresión de las citocinas IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 e IL-4 mostró que hubo un significante incremento de la expresión de IL-4 entre los indígenas con seropositividad para los antígenos TES (p < 0.002). La seropositividad para Ascaris y Toxocara fue prevalente entre los indígenas Warao.

Immunopathological Changes in the Brain of Immunosuppressed Mice Experimentally Infected with Toxocara canis

Toxocariasis is a soil-transmitted helminthozoonosis due to infection of humans by larvae of Toxocara canis. The disease could produce cognitive and behavioral disturbances especially in children. Meanwhile, in our modern era, the incidence of immunosuppression has been progressively increasing due to increased incidence of malignancy as well as increased use of immunosuppressive agents. The present study aimed at comparing some of the pathological and immunological alterations in the brain of normal and immunosuppressed mice experimentally infected with T. canis. Therefore, 180 Swiss albino mice were divided into 4 groups including normal (control) group, immunocompetent T. canis-infected group, immunosuppressed group (control), and immunosuppressed infected group. Infected mice were subjected to larval counts in the brain, and the brains from all mice were assessed for histopathological changes, astrogliosis, and IL-5 mRNA expression levels in brain tissues. The results showed that under immunosuppression, there were significant increase in brain larval counts, significant enhancement of reactive gliosis, and significant reduction in IL-5 mRNA expression. All these changes were maximal in the chronic stage of infection. In conclusion, the immunopathological alterations in the brains of infected animals were progressive over time, and were exaggerated under the effect of immunosuppression as did the intensity of cerebral infection.

Immunopathological Changes in the Brain of Immunosuppressed Mice Experimentally Infected with Toxocara canis

Toxocariasis is a soil-transmitted helminthozoonosis due to infection of humans by larvae of Toxocara canis. The disease could produce cognitive and behavioral disturbances especially in children. Meanwhile, in our modern era, the incidence of immunosuppression has been progressively increasing due to increased incidence of malignancy as well as increased use of immunosuppressive agents. The present study aimed at comparing some of the pathological and immunological alterations in the brain of normal and immunosuppressed mice experimentally infected with T. canis. Therefore, 180 Swiss albino mice were divided into 4 groups including normal (control) group, immunocompetent T. canis-infected group, immunosuppressed group (control), and immunosuppressed infected group. Infected mice were subjected to larval counts in the brain, and the brains from all mice were assessed for histopathological changes, astrogliosis, and IL-5 mRNA expression levels in brain tissues. The results showed that under immunosuppression, there were significant increase in brain larval counts, significant enhancement of reactive gliosis, and significant reduction in IL-5 mRNA expression. All these changes were maximal in the chronic stage of infection. In conclusion, the immunopathological alterations in the brains of infected animals were progressive over time, and were exaggerated under the effect of immunosuppression as did the intensity of cerebral infection.

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.

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.

Identification of candidate antigens from adult stages of Toxocara canis for the serodiagnosis of human toxocariasis

In the present work, we identified adult Toxocara canis antigens through sodium dodecyl sulfate-polyacrylamide gel electrophoresis for potential use in human toxocariasis immunodiagnosis. The sensitivity and specificity of several semi-purified antigens, as well as their cross-reactivity with other parasitic infections, were assessed by IgM and IgG-enzime linked immunosorbent assay. Whilst we found that the crude extract of the parasite presented limited sensitivity, specificity and high cross-reactivity against other parasites, we identified 42, 58, 68 and 97-kDa semi-purified antigens as the most promising candidates for immunodiagnosis. Moreover, the 58 and 68-kDa antigens presented the lowest IgM cross-reactivity. When tested as a combination, a mixture of the 58 and 68-kDa antigens presented 100 percent sensitivity and specificity, as well as minor cross-reactivity. Although the combination of the 42, 58, 68 and 97-kDa antigens presented 100 percent sensitivity at a dilution of 1:40, the low specificity and high cross-reactivity observed suggested a limited use for diagnostic purposes. Our data suggested that the 58 and 68-kDa antigens might be most suitable for the immunodiagnosis of human toxocariasis.

Toxocara canis y asma bronquial / Toxocara canis and bronchial asthma

A fin de evaluar la relación entre la infección por Toxocara canis y los síntomas del asma bronquial en niños de una región subtropical con alta prevalencia de toxocariosis, se estudiaron 47 niños con asma y 53 sin asma como grupo control. Se efectuó el examen físico completo, registrándose datos clínicos y epidemiológicos. En los niños con asma se categorizó el patrón de presentación, frecuencia y gravedad de los síntomas con una escala de I a IV. Se investigó la presencia de anticuerpos anti-Toxocara canis en ambos grupos mediante el método de ELISA en fase sólida, empleando antígeno de excreción/secreción y se efectuó dosaje de Ig E total. Los resultados muestran una seropositividad del 55% en el total de los niños, del 57.4% en los niños con asma y del 52.8% en los controles. En los niños con sintomatología más grave (grado II, III y IV) hubo un 67.7% de seropositivos, mientras que en los niños con síntomas de grado I la seropositividad fue de 37.5% (p = 0.0470). La infección por T. canis actuaría como un co-factor agravante de los síntomas del asma bronquial.

In order to evaluate the association between the infection by Toxocara canis and the symptoms of asthma in children from a subtropical region with high prevalence of toxocariasis, 47 asthmatic children and 53 non-asthmatics as a control group were studied. A complete physical examination was performed and clinical and epidemiological data were registered. In asthmatic children the frequency and severity of symptoms were classified in grades I to IV. The presence of anti-Toxocara canis antibodies in both groups was evaluated employing a solid phase ELISA method with excretion/secretion antigens, and total Ig E was also measured. Results showed a total seropositivity of 55%, 57.4% in children with asthma and 52.8% in the control group. Among asthmatics with severe symptoms (grade II, III and IV), there was a 67.7% of seropositivity while in children with symptoms of grade I there was a 37.5% (p = 0.0470). The infection with T. canis could act as a co-factor increasing the severity of the symptoms of bronchial asthma.

Seroepidemiological investigation of toxocariasis in the Isparta Region of Turkey

Toxocariasis is a common disease around the world. Our objective was to determine Toxocara seroprevalence in humans in the city of Isparta, Southwest Turkey, in respect of some determinants such as age, socio-economic level, residence in city center or rural area etc. Five hundred and thirty four individual participants from Isparta center and 85 from Asagi Gokdere village were included in the study. T. cati specific antibodies were analyzed using excretory-secretory [ES]-enzyme-linked immunosorbent assay [ELISA] method. T. cati antibodies were detected as positive in 73 [13.6%] of 534 samples which were collected from subjects living in the city center and 24 [28.2%] of 85 samples from Asagi Gokdere village. Toxocara seropositivity was detected among 15.6% of whole study group. The seroprevalence of toxocariasis was significantly higher among subjects from village than in subjects from city center [P=0.001]. While gender, high school education, source of the water which is used, family income and geophagia/eating nail behaviors were the features which were detected as being associated with toxocariasis seropositivity [odds ratios=0.5; 6.52; 3.61; 0.43; 0.13 respectively], owning dogs or cats and hand washing were detected as being not associated with toxocariasis seropositivity [P>0.05]. Furthermore, Toxocara seropositivity was significantly higher among subjects in 0-10 than>40 year-old group [P=0.02]. It can be suggested that untreated lost pet population, environmental contamination, and way of life have influence on the epidemiology of toxocariasis

Ultrastructural Localization of Toxocara canis Larval Antigen Reacted with a Seropositive Human Serum

Excretory-secretory products of Toxocara canis larvae have been considered as a major functional antigen in immune responses against toxocariasis. We studied ultrastructural localization of T. canis second-stage larval antigen using a seropositive human serum under immunogold electron microscopy. High-density gold particles were observed in the secretory cells, excretory duct, intestinal epithelium, and cuticle of the larval worm sections. The distribution of the positive reactions in the larval worms suggests that the nature of the antigen is excretory-secretory antigen including waste metabolites and secretory enzymes.

Freqüência de anticorpo anti-Toxocara canis em comunidade do Rio Uatumã, no Estado do Amazonas / Frequency of the antibody anti-Toxocara canis in a community along the Uatumã river, State of Amazonas

Um estudo seccional foi realizado nas Vilas Waimiri e Atroari em Balbina, entre julho e outubro de 2006, com o objetivo de estimar a freqüência de anticorpo antiToxocara canis da classe IgG e avaliar as variáveis epidemiológicas e socioculturais. Foram estudadas 34 famílias e incluídos 100 indivíduos, o que correspondeu a 5 por cento (100/2.000) da população das vilas. A idade variou de zero a 76 anos (M=22,9 Dp=18). Quanto ao gênero, 53 por cento eram femininos e 47 por cento masculino; 52 por cento das amostras foram positivas para Toxocara canis, 44,5 por cento negativas e 3,2 por cento inconclusivas. Observou-se menor número de indivíduos com sorologia negativa na Vila Atroari 29,5 por cento (13/44) em comparação com a Waimiri 46,4 por cento (26/56). Com relação ao contato com cães, dos 55 indivíduos com contato domiciliar 60 por cento (33/55) foram positivos para anticorpo antiToxocara canis Apresentaram sorologia positiva 66,6 por cento (10/15) dos indivíduos que tinham contato domiciliar com filhotes de cão (chi²22,149 p=0,008). A existência de contato domiciliar com cães e filhotes mostrou associação com a presença de anticorpo anti-Toxocara canis na população estudada.

A cross-sectional study was carried out in the Waimiri and Atroari settlements in Balbina, between July and October 2006, with the aims of estimating the frequency of the antibody anti-Toxocara canis of the IgG class and studying the epidemiological and sociocultural variables. Thirty-four families were studied and 100 individuals were included, corresponding to 5 percent (100/2000) of the population of the settlements. The age range was 0-76 years (mean = 22.9; standard deviation = 18). The gender distribution was 53 percent female and 47 percent male. The samples were 52 percent positive for Toxocara canis, 44.5 percent negative and 3.2 percent inconclusive. The number of individuals who tested serologically negative in Atroari (29.5 percent; 13/44) was lower than in Waimiri (46.4 percent; 26/56). In relation to contact with dogs, among the 55 individuals with contact in their homes, 60 percent (33/55) were positive for Ac anti-Toxocara canis and 40 percent (22/55) were negative (chi2= 14.317; p = 0.026). Among the individuals who had contact in their homes with puppies, 66.6 percent (10/15) were serologically positive (chi2= 22.149; p=0.008). The existence of home contact with dogs and puppies showed an association with the presence of Ac anti-Toxocara canis in the study population.

Serodiagnosis of toxocara antibodies among infants and pregnant women suspected of ocular or visceral toxocariasis using two types ELISA antigens [TEE and TEX]

The diagnosis of toxocariasis depends heavily on immunological tests because parasites may be few in the tissue of those infected and, unless situated in an organ such as the eye, may be difficult or impossible to locate. In general, patients with ocular toxocariasis have serum anti-T canis antibody titres that are significantly lower than those with visceral toxocariasis. An enzyme linked immunosorbent assay [ELISA] using T canis embryonated egg antigen [TEE] and [TEX] were used for diagnosis of toxocariasis. This assay showed a high degree of sensitivity and specificity. Aim of work, diagnosis of asymptomatic toxocariasis in infants before two years old and suspected infection in pregnant women by ELISA with comparison between two antigens TEE and capture TEX. This work was done between 8/2005 and 4/2006. Specimens of serum collected from 79 infants [apparent healthy] aged between 4 weeks to 30 moths [51 females and 28 males] Also, 28 specimens of serum collected from asymptomatic pregnant women aged between 18-32 years old and their infants [28] [17 females and 11 males] at the same age of infants above. The baseline laboratory studies that were done included WBCs, differential count and circulating eosinophil count. Examination of faeces for ova and any parasites. Serodiagnosis by ELISA using two of antigens, Toxocara canis embryonated egg antigen [TEE] and Toxocara canis antigen capture ELISA. Results, Toxocara antibodies found in 7 and 12 pregnant women serum when tested by TEE and capture TEX ELISA respectively. The serum samples of infants [28] which taken from infant's pregnant mothers given positive for Toxocara antibodies 3/28 and 7/28 when tested by TEE ELISA and capture TEX ELISA respectively. Active ocular toxocariasis diagnosed in one mother only in left eye. All inactive ocular toxocariasis diagnosed by capture TEX ELISA except one baby's serum only diagnosed by TEE ELISA. In conclusion, the capture TEX ELISA was better able to discriminate between positive and negative samples than TEE ELISA. In addition, testing samples by both capture TEX ELISA and TEE ELESA. Toxocariasis should be given more attention and that the ophthalmologists should be more aware of this disease-especially in children and young adults-and should more often include toxocariasis in the differential diagnosis of the ocular diseases

Seroprevalence of toxocariasis in children aged 1-9 years in western Islamic Republic of Iran, 2003

We determined the seroprevalence of Toxocara canis infection in 544 children under 10 years randomly selected from urban and rural areas of Hamadan. An enzyme-linked immunosorbent assay was used for detection of antibodies to T. canis excretion-secretion antigens. Using a questionnaire, epidemiological factors associated with infection were examined, including age, sex, residence. Antibodies to T. canis were detected in 29 children [5.3%] and 19 children [3.5%] were categorized as borderline positive; thus together this gave a prevalence of toxocariasis of 8.8%. No significant differences were found in terms of sex, age and residence.

Immunoblotting para diagnóstico de toxocarosis humana en un área subtropical / Immunoblotting for the diagnosis of human toxocarosis in a subtropical area

The diagnosis of toxocarosis is based upon the demonstration of antibodies by ELISA methods, although cross-reaction with other ascarids may occur in populations from tropical areas. For this reason, some authors proposed western blotting as a confirmatory test. The aim of this work was to develop an immunoblotting in simpler technical conditions and to compare results with the ELISA test. With this purpose sera from adults and children with sign and/or symptoms of toxocarosis and living in the metropolitan area of Resistencia city (Northeast of Argentina) were studied. ELISA test was performed and 120 positives and 60 negatives sera were selected and analyzed again by immunoblotting. Positive samples and controls showed a WB pattern with six bands of 67.6 kDa, 55.6 kDa, 43.9 kDa, 32.4 kDa, 26.6 kDa and 23.4 kDa, while negative controls from endemic and non-endemic areas of toxocarosis showed no bands. Out of the 180 samples studied, in 172 coincident results for both methods were obtained (95.6%), 6 ELISA negative samples were positive for WB (3.3%) and 2 ELISA positive samples resulted negative in the WB (1.1%). The immunoblotting technique described in this work may constitute an adequate method for the diagnosis of toxocarosis in subtropical areas, particularly useful in cases with negative or low-titers ELISA test results and with signs or symptoms of the infection.

El diagnóstico de toxocariosis se basa en la demostración de anticuerpos mediante enzimo-inmunoensayos, aunque en poblaciones de área tropicales suelen ocurrir reacciones cruzadas con otros ascáridos. Por ello algunos autores han propuesto el Western Blot como test confirmatorio. El objetivo de este trabajo fue desarrollar un método de immunoblotting con condiciones técnicas sencillas y comparar su comportamiento con la reacción de enzimoinmunoensayo. Se estudiaron 180 muestras de suero de adultos y niños con signo-sintomatología compatible con toxocariosis. Se efectuó test de ELISA con Antígenos TES, seleccionándose 120 sueros positivos y 60 negativos, los que fueron analizados nuevamente por immunobloting y se compararon los resultados de ambos métodos. Las muestras y controles positivos mostraron en el WB un patrón de seis bandas con PMs de 67,6 kDa, 55,6 kDa, 43,9 kDa, 32,4 kDa, 26,6 kDa y 23,4 kDa. Los sueros de control negativo de área endémica y no endémica de toxocarosis no mostraron banda alguna. De 180 muestras estudiadas, en 172 se obtuvieron resultados coincidentes por ambos métodos (95,6%), 6 muestras negativas por ELISA resultaron positivas por Western Blot (3,3%) y dos muestras positivas por ELISA fueron negativas por Western Blot (1,1%). El ensayo de immunoblotting acá descrito constituiría un método adecuado para el diagnóstico de toxocariosis en áreas sub-tropicales, particularmente útil en los casos en los que el test de ELISA resulte negativo o positivo con títulos bajos y en presencia de signos y/o síntomas de la infección.

Toxocariosis en niños de una region subtropical / Toxocariasis in children from a subtropical region

La toxocariosis está presente en todo el mundo, pero se considera en mayor riesgo a los habitantes de zonas com deficiencias sanitarias y particularmente a los niños. El objetivo de este trabajo fue conocer aspectos inmunológicos y clínicos de la infección infantil en un área subtropical de Argentina, para lo cual se estudiaron 182 niños de ambos sexos de la ciudad de Resistencia (Noreste de Argentina), de 0 a 16 años, con eosinofilia mayor al 10%. Se realizaron exámenes clínicos, encuestas epidemiológicas, exámenes copropa-rasitológicos y dosajes de IgG e IgM anti Toxocara canis por EIE; los sueros positivos fueron confirmados por Western Blot. De los 182 niños estudiados, 122 resultaron seropositivos (67%), 28.8% no contaban con agua potable en su domicilio, 58.8% no tenían cloacas, 91.1% habían tenido contacto con perros y/o gatos, 30.0% tenían antecedentes de geofagia y 86.7% vivían sobre calles sin pavimento. La infección se presentó en forma asintomática en el 77.8% de los casos, como larva migrans ocular en el 6.7% y como larva migrans visceral en el 15.5 % de los casos. En 22 niños el seguimiento serológico post-tratamiento hasta los 18 meses mostró que la IgG se mantuvo estable en 10 casos, en 11 disminuyó pero manteniendo valores elevados y em uno aumentó. Hubo 19 casos con IgM positiva; 8 disminuyeron sus títulos, uno se mantuvo estable y 10 se negativizaron. Hubo un caso de reinfección. Estos resultados reafirman la importancia que las autoridades sanitárias deben asignar a esta infección, particularmente en las regiones carenciadas, en las que habitualmente no se reconoce a la toxocariosis como un problema relevante de salud pública.

Isotype specific immune responses in murine experimental toxocariasis

In this work, a murine experimental model of toxocariasis has been developed in BALB/c, C57BL/10 and C3H murine strains orally inoculated with 4,000 Toxocara canis embryonated eggs, in order to investigate the isotype-specific immune responses against excretory-secretory antigens from larvae. T. canis specific IgG+M, IgM, IgG, IgA, IgG1, IgG2a and IgG3 were tested by ELISA. The dynamics of the specific immunoglobulins (IgG+IgM) production showed a contrasting profile regarding the murine strain. Conversely to the results obtained with the IgM isotype, the IgG antibody class showed similar patterns to those obtained with IgG+IgM antibodies, only in the case of the BALB/c strain, being different and much higher than the obtained with IgG+IgM antibodies, when the C3H murine strain was used. The antibodies IgG+IgM tested in BALB/c and C57BL/10 were both of the IgM and IgG isotypes. Conversely, in the C3H strain only IgG specific antibody levels were detected. The IgG1 subclass responses showed a similar profile in the three murine strains studied, with high values in BALB/c, as in the case of the IgG responses