Toxocariasis ocular. A propósito de un caso / Ocular toxocariasis. Case report

RESUMEN Se presentó un caso clínico de un paciente de seis años de edad, con toxocariasis ocular. La manifestación clínica fue disminución de la agudeza visual monocular. El fondo de ojo izquierdo mostró un granuloma retiniano periférico, asociado a un desgarro retiniano perilesional. El examen oftalmológico confirmó el diagnóstico de Toxocara ocular. El paciente fue tratado posteriormente mediante corticoides sistémicos y fotocoagulación láser focal en el desgarro retiniano (AU).

ABSTRACT We present the clinical case of a male patient, aged 6 years, with ocular toxocariasis. The clinical manifestation was monocular visual acuity decrease. The left ocular fundus showed a peripheral retina granuloma, associated to a perilesional retinal tear. The ophthalmological examination confirmed the diagnosis of ocular Toxocara. After that the patient was treated using systemic corticoids and focal laser coagulation in the retinal tear (AU).

Frequency of anti-Toxocara antibodies in broiler chickens in southern Brazil / Frequência de anticorpos anti-Toxocara em frangos de corte no Sul do Brasil

Abstract The aim of this study was to evaluate the presence of anti-Toxocara antibodies in naturally infected broiler chickens (n = 189) from the state of Paraná, southern Brazil. The chickens were reared in a semi-intensive system by small family farmers (n = 7). An enzyme-linked immunosorbent assay (ELISA) was performed to detect the presence of anti- Toxocara spp. IgY after serum adsorption with Ascaridia galli antigens. An overall seroprevalence of 67.7% (128/189; 95% CI = 61.1-74.4) was observed. The frequency of positive animals by farm ranged from 29.6% to 100%. The optical density and reactivity index values observed in ELISA test indicated the possible chronicity of infection of the evaluated chickens. Associations between the presence of antibodies and the area where the chickens were reared (p = 0.382) or the population density of dogs on the farm (p = 0.785) were not observed. This study shows a high prevalence of Toxocara spp. antibodies in broiler chickens reared in semi-intensive systems and provides evidence that chickens are a good indicator of environmental contamination by larva migrans agents. Further studies are necessary to assess the risk factors associated with poultry infection and the likelihood of toxocariasis transmission to humans via the ingestion of free-range chicken meat.

Resumo A finalidade do presente estudo foi avaliar a presença de anticorpos anti- Toxocara, em frangos de corte naturalmente infectados (n = 189), no Norte do Paraná, Sul do Brasil. Os frangos foram criados em sistema semi-intensivo, em pequenas propriedades rurais (n = 7). Os testes sorológicos foram realizados pela técnica de ELISA, para detecção de anticorpos IgY (IgG), com pré-adsorção do soro com antígenos de Ascaridia galli. Foi observada uma prevalência de 67,7% (128/189; IC 95% = 61,1-74,4). A frequência de animais soropositivos por propriedade variou de 29,6% a 100%. Os valores da Densidade Ótica e do Índice de Reatividade observados no teste de ELISA indicaram uma possível cronicidade de infecção dos frangos avaliados. Não foi observada correlação entre a positividade dos animais, quando comparada a área (p = 0,382) e a densidade populacional de cães por propriedade (p = 0,785). O presente estudo verificou uma alta prevalência de anticorpos anti-Toxocara em frangos de corte criados em sistema semi-intensivo e oferece dados que apontam esses animais como bons indicadores de contaminação ambiental por agentes de larva migrans . Estudos futuros são necessários para avaliar os fatores de risco associados e a possibilidade da transmissão de toxocaríase ao ser humano pela ingestão de carne de frango.

Producción y evaluación del antígeno recombinante TES-30 de Toxocara canis para el inmunodiagnóstico de toxocariasis / Production and evaluation of the recombinant antigen TES-30 of Toxocara canis for the immunodiagnosis of toxocariasis

Introducción. Toxocara canis es un nematodo patógeno de cánidos que accidentalmente puede ser transmitido a los humanos. A pesar de la importancia de la serología para el diagnóstico de esta zoonosis, los kits diagnósticos usan antígenos crudos de excreción-secreción, en su mayoría glucoproteínas que no son específicas de especie, por lo cual pueden presentarse reacciones cruzadas con anticuerpos generados contra otros parásitos. Objetivos. Producir el antígeno recombinante TES-30 de T. canis y evaluarlo para el inmunodiagnóstico de la toxocariasis. Materiales y métodos. Se clonó el gen que codifica TES-30 en el vector de expresión pET28a (+), usando oligonucleótidos de cadena sencilla unidos mediante reacción en cadena de la polimerasa (PCR). La proteína rTES-30 se purificó por cromotografia de afinidad (Ni 2+ ). La reacción serológica de rTES-30 se evaluó mediante immunoblot . Teniendo en cuenta que no existe una prueba de referencia , se observó el comportamiento del antigeno en comparación con la prueba de rutina para el inmunodiagnóstico de la toxocariasis, es decir, la técnica ELISA convencional con antígenos de excreción-secreción. Resultados. El rTES-30 se produjo a partir de un cultivo de Escherichia coli LB, con un rendimiento de 2,25 mg/l y 95 % de pureza. La concordancia de la reacción entre el immunoblot rTES-30 y la ELISA convencional, fue de 73 % (46/63) y de 100 % con los 21 sueros no reactivos. De los 21 sueros con diagnóstico de otras parasitosis, 19 fueron reactivos con ELISA, mientras que tan solo siete fueron positivos con el immunoblot rTES-30. La concordancia entre la ELISA y el immunoblot fue moderada (índice kappa de 0,575; IC 95% 0,41-0,74). Conclusiones. Los datos presentados respaldan la utilidad del immunoblot r TES-3 0 para la confirmación de los posibles positivos por ELISA, no solo en los estudios epidemiológicos, sino también, como candidato para el desarrollo de pruebas diagnósticas de la toxocariasis ocular en Colombia.

Introduction: Toxocara canis is a pathogenic nematode of canines which can be accidentally transmitted to humans. Although serology is the most important diagnostic tool for this zoonosis, diagnostic kits use crude excretion/secretion antigens, most of them being glycoproteins which are not species-specific and may cross-react with antibodies generated against other parasites. Objectives: To produce the rTES-30 recombinant antigen of Toxocara canis and evaluate it in the immunodiagnosis of toxocariasis. Materials and methods: The gene that codes for TES-30 was cloned in the expression vector pET28a (+) using single-stranded oligonucleotides united by PCR. The protein rTES-30 was purified by Ni 2+ affinity chromotography. Seroreactivity of rTES-30 was evaluated by immunoblot. Given that there is no gold standard test, the behaviour of the antigen was compared with the method that is routinely used to immunodiagnose toxocariasis, i.e., the conventional ELISA technique using excretion/secretion antigens. Results: The rTES-30 was produced from an Escherichia coli LB culture which yielded 2.25 mg/L of the antigen with a purity of 95%. The results obtained showed 73% (46/63) concordance of reactivity between the rTES-30 immunoblot and the conventional ELISA, and 100% concordance with the non-reactive sera (21). Nineteen of the 21 sera positive for other parasitoses reacted with ELISA, while only seven of these were positive with the rTES-30 immunoblot. Concordance between the ELISA and the immunoblot was moderate (kappa coefficient: 0.575; 95% CI: 0.41- 0.74). Conclusions: The data presented show the potential of the rTES-30 inmunoblot for confirmation of possible ELISA positives, not only in epidemiological studies, but also as a candidate for the development of diagnostic tests for ocular toxocariasis in Colombia.

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.

Determination of IgG avidity in BALB/c mice experimentally infected with Toxocara canis / Determinação da avidez de IgG em camundongos BALB/c experimentalmente infectados com Toxocara canis

Toxocariasis is a zoonotic disease in that IgM titers can remain high for long periods making difficult to determine the stage of the disease. The aim of this study is to investigate the applicability of indirect ELISA, associated with urea, to discriminate between the acute and chronic toxocariasis. IgG avidity was evaluated in 25 BALB/c mice experimentally infected with 1000 Toxocara canis eggs. Blood samples were collected, and sera treated with 6 M urea and assayed by ELISA every two weeks. The percent IgG avidity was determined using the mean absorbance of sera treated with urea, divided by the mean absorbance of untreated sera. In the first 15 days post-inoculation, was observed a low percentage, between 7.25 and 27.5%, IgG avidity, characteristic of an acute infection. After 60 days of infection, all the mice showed between 31.4 and 58% IgG avidity, indicating a chronic infection.

A toxocaríase é uma zoonose na qual os títulos de IgM podem permanecer elevados por longos períodos, tornando difícil a determinação do estágio em que a doença se encontra. O objetivo deste estudo foi investigar a aplicabilidade de um teste indireto de ELISA, associado com ureia, para fazer a discriminação entre as fases aguda e crônica da toxocaríase. A avidez de IgG foi avaliada em 25 camundongos BALB/c experimentalmente infectados com 1000 ovos embrionados de Toxocara canis. A cada duas semanas, amostras de sangue foram coletadas, o soro tratado com ureia 6M e realizado o ensaio pela técnica de ELISA. O percentual de avidez de IgG foi determinado, usando-se a média das absorbâncias dos soros tratados com ureia dividida pela média das absorbâncias dos soros não tratados. Nos primeiros 15 dias pós-inoculação, foi observado um baixo percentual de avidez de IgG, entre 7,25 e 27,5%, característico da fase aguda da infecção. Após 60 dias de infecção, todos apresentaram avidez de IgG entre 31,4 e 58%, indicando a fase crônica da infecção.

Evaluación de un antígeno purificado para el diagnóstico de toxocariosis / Evaluation of a purified antigen for the diagnosis of toxocariosis

La toxocariosis es una zoonosis causada por la ingestión de huevos infectivos de Toxocara spp. El diagnóstico de la enfermedad se basa en la detección de anticuerpos en el suero u otros fluidos biológicos. La técnica serológica más utilizada es el ELISA, que usa como antígeno los productos de excreción-secreción de larvas de tercer estadio (ES/L3). Estos productos antigénicos son glicoproteínas que se originan en los órganos secretorios del parásito y no son específicos de especie. Para evaluar la especificidad de la técnica de ELISA con el antígeno ES/L3, se emplearon sueros de personas con otras helmintiasis y con patologías no parasitarias. Se observó que estos sueros presentaron reactividad entre el 11 y el 70 % de los casos. El Western blot con suero de los mismos pacientes reveló que la glicoproteína que corresponde al triplete de 120 kDa fue la más inespecífica. Teniendo en cuenta estos resultados y con el propósito de purificar el antígeno se realizó una cromatografía de intercambio iónico. Cuando se analizaron los sueros de los pacientes con diferentes enfermedades parasitarias y no parasitarias con el antígeno ES/L3 purificado, solo fueron reactivos entre un 10 y un 20 % de ellos. La sensibilidad del test de ELISA determinada por el programa Epidat 3. 0 para los dos antígenos fue del 100 %, pero se observaron diferencias en la especificidad: para el antígeno ES/L3 total esta fue del 84 % y para el ES/L3 purificado del 99 %. Empleando el antígeno ES/L3 purificado se puede considerar que los sueros que son reactivos, en presencia de una sintomatología compatible, corresponden a pacientes que fueron o están parasitados con Toxocara canis.

Toxocarosis is a zoonotic disease caused by the ingestion of infective eggs of Toxocara spp. The diagnosis is based on the detection of antibodies in serum or other biological fluids. One of the current serological techniques for the diagnosis of toxocariasis is ELISA using excretory - secretory antigens of third stage larvae (ES/L3). These antigens are glycoproteins, which originate in the secretory organs of the parasite and are non species-specific. Sera from patients with other helminthiases and non- parasitic diseases were used to evaluate the specificity of ELISA using the excretory - secretory antigen (ES/L3). The reactivity of these sera was between 11 and 70%. Western blot using patients' sera revealed that the glycoprotein triplet having a molecular weight of 120 kDa was responsible for cross-reactivity. With these results, and for the purpose of purifying the antigen, ion exchange chromatography was performed. When the sera from patients with various parasitic and non-parasitic diseases were analyzed with the purified antigen ES/ L3, they were only reactive between 10 to 20%. The sensitivity of the ELISA test determined by program Epidat 3. 0 for the two antigens was 100%, but the following differences in specificity were observed: 84% for the total antigen ES/L3 and 99% for purified ES/L3. Using the ES/L3 purified antigen, it can be considered that the reactive sera, with compatible symptoms correspond to patients who are or were parasitized with Toxocara canis.

Toxocara Seroprevalence in Schizophrenic Patients in Turkey

PURPOSE: To investigate the seroprevalence of toxocariasis in patients diagnosed as schizophrenia. PATIENTS AND METHODS: Ninety-eight schizophrenic patients hospitalized at The Elazig Psychiatric Hospital were included in the study. Anti-Toxocara IgG and/or IgM antibodies were determined by using commercial Toxocara canis IgG and/or IgM ELISA kit. RESULTS: Seropositivity for T. canis was detected in 45 (45.9%) of 98 patients and 2 (2.0%) of 100 control subjects the difference was statistically significant (p 0.05). CONCLUSION: In conclusion, the schizophrenic state seems to present a high risk for Toxocara infection in Turkey.

Seroprevalence of Toxocariasis among Healthy People with Eosinophilia

The aim of this study is to determine the Toxocara seropositive rate among healthy people with eosinophilia. A total of 97 people residing in Seoul who were healthy and whose blood eosinophilia was over 10%, as shown by regular health check-ups in 2004, were subjected to this study. Their sera were tested by immunoblotting and ELISA with the antigen of larval Toxocara canis excretory-secretory (ES) protein. Sixty-five sera were band-positive (67.0%). The seropositve control sera were positive to band sizes of 66 kDa, 56 kDa, 32 kDa, and 13 kDa. In ELISA, 63 sera (65.0%) were positive to T. canis ES protein. There was no significant correlation between the IgG ELISA titer and the level of eosinophilia (r = 0.156, P = 0.156). As there were insufficient data to determine whether there were cross-reactions with other helminthic infections, or whether atopy occurred, further studies are required to verify the cause of the seropositive reactions against T. canis ES antigen. Toxocariasis seropositivity is suggested to be the major cause of eosinophilia, since the Toxocara seroprevalence among Korean rural adults was shown to be approximately 5%.

Seroprevalence of Toxocariasis among Healthy People with Eosinophilia

The aim of this study is to determine the Toxocara seropositive rate among healthy people with eosinophilia. A total of 97 people residing in Seoul who were healthy and whose blood eosinophilia was over 10%, as shown by regular health check-ups in 2004, were subjected to this study. Their sera were tested by immunoblotting and ELISA with the antigen of larval Toxocara canis excretory-secretory (ES) protein. Sixty-five sera were band-positive (67.0%). The seropositve control sera were positive to band sizes of 66 kDa, 56 kDa, 32 kDa, and 13 kDa. In ELISA, 63 sera (65.0%) were positive to T. canis ES protein. There was no significant correlation between the IgG ELISA titer and the level of eosinophilia (r = 0.156, P = 0.156). As there were insufficient data to determine whether there were cross-reactions with other helminthic infections, or whether atopy occurred, further studies are required to verify the cause of the seropositive reactions against T. canis ES antigen. Toxocariasis seropositivity is suggested to be the major cause of eosinophilia, since the Toxocara seroprevalence among Korean rural adults was shown to be approximately 5%.

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

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.

Estudo clínico-epidemiológico da toxocaríase em população infantil / Clinical-epidemiological study of toxocariasis in a pediatric population

OBJETIVO: A diversidade de manifestações clínicas da toxocaríase e sua relação com asma motivaram este estudo, cujo objetivo foi estudar a soropositividade de T. canis nas crianças atendidas no serviço público de saúde e sua associação com variáveis clínicas, epidemiológicas e laboratoriais. MÉTODOS: Este estudo é de corte transversal e controlado. Foram realizadas sorologias em 208 crianças de 1 a 14 anos de idade, atendidas nos ambulatórios de Pediatria, Imunologia e Pneumologia Pediátrica da Universidade de Santo Amaro, no período de janeiro de 2000 a janeiro de 2001. Os anticorpos foram detectados por ELISA usando-se antígeno de excreção e secreção do T. canis.. Foi utilizado teste qui-quadrado para associações da soropositividade para T. canis (título > 1:320) com cães filhotes domiciliares, contato com terra, geofagia, onicofagia, escolaridade materna, asma, tosse crônica, pneumonias de repetição, manifestações cutâneas, rinite, hepatomegalia, esplenomegalia, dor abdominal, anemia, eosinofilia, imunoglobulinas, parasitoses e desnutrição, e método de análise de variância por postos de Kruskal-Wallis para comparação média dos soropositivos e soronegativos, sendo significante p < 0,05. RESULTADOS: A soroprevalência foi 54,8 por cento, com média etária de 6,5 anos; nos soronegativos, 5,8 anos (não significante), também não houve diferença quanto ao sexo. A soropositividade foi significante com: cães filhotes domiciliares, contato com terra, hepatomegalia, asma, eosinofilia, IgE aumentada e desnutrição pregressa. CONCLUSAO: A soroprevalência encontrada foi alta. A infecção pelo T. canis deve ser investigada em crianças com fatores de risco como presença de cães filhotes domiciliares e contato com terra, em portadores de hepatomegalia e/ou asma, com eosinofilia ou aumento de IgE.

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.

A seroepidemiological study of toxocariasis and risk factors for infection in children in Sri Lanka.

A seroepidemiology study using TES-ELISA was carried out in 1,020 children aged 1-12 years in the Hindagala Community Health Project, Sri Lanka. Toxocariasis seroprevalence was 43% with 16.6% showing high antibody levels. Unconditional logistic regression analysis showed 7-9 year olds to be at the highest risk (OR 3.0820; CI = 1.95-4.87). Dog ownership, especially puppies (OR 29.28; CI = 7.40-116.0), and geophagia-pica (OR 6.3732; CI = 3.87-10.50), were significant risk factors. Family clustering of toxocariasis was significant (chi2 = 88.000; p = 0.0001). Abdominal pain (45%), cough (30%), limb pain (23%) and skin rashes (20%) were significantly associated with seropositivity indicating that toxocariasis causes covert morbidity. These findings are, overall, applicable to other areas in Sri Lanka. However, in the dry zone, survival of infective eggs in the soil could be affected by the climate while more importantly, in agricultural areas with a high buffalo population, Toxocara vitulorum could account for human toxocariasis. Using a species specific double sandwich ELISA based on 57 kDa protein of T. canis ES antigen, it is demonstrated that 91% of the seropositives were due to T. canis. Thus along with rabies and dirofilariasis, toxocariasis is an important zoonotic health hazard from dogs in Sri Lanka and prevention is indicated.

Human toxocariasis and ascariasis: concomitant parasitism in Srinagar, Kashmir, India.

Human toxocariasis caused by Toxocara canis is common in both developing and developed countries and leads to visceral larva migrans with high morbidity and mortality. Ascariasis caused by Ascaris lumbricoides, too has global distribution and in India, high prevalence rate has been reported in Kashmir (J & K State). Both nematode parasites, Toxocara canis and A. lumbricoides require similar biological and environmental conditions for the development of eggs in soil. Therefore, the present study was attempted to detect the antibody response to T. Canis excretory-secretory (ES) antigen by enzyme linked immunosorbent assay in patients attending Sher-I-Kashmir Institute of Medical Sciences, Soura, Srinagar, Kashmir to assess the magnitude of human toxocariasis in Kashmir, the highly endemic area of ascariasis. Interestingly, it was observed that 38 (82.60%) out of 46 patients harbouring Ascaris Iumbricoides had positive antibody response to T. Canis ES antigen while none of the 15 normal healthy subjects from the same endemic zone, 25 from low endemic zone Chandigarh and 15 from other parasitic infections (hookworm, hydatidosis, cysticercosis) indicated detectable positive response. Majority of the ascariasis positive patients studied were in the age group of 21-40 years. However, one ascariasis patient studied in the age group of 1-10 years (4 years old) had also positive antibody response to T. Canis antigen. This study is the first report of human toxocariasis in Kashmir, India, an endemic zone for ascariasis and emphasizes the need for detailed epidemiological study for the ultimate prevention and control of this disease

Ecchymoses: an unusual manifestation of toxocariasis in children.

OBJECTIVE: To investigate the aetiology of multiple ecchymoses associated with eosinophilia. SETTING: Professorial Paediatric Unit (PPU) at Lady Ridgeway Hospital (LRH) for children, Colombo. DESIGN: Prospective study from July 1998 to April 2000. MATERIALS AND METHODS: Patients admitted to the PPU with multiple ecchymoses associated with an absolute eosinophilia (> 1 x 10(9)/1) were investigated further to determine the possible aetiology; bleeding time, clotting time, platelet count, platelet function tests, stools examination and toxocara antibody tests were performed. Patients who were positive for toxocara were treated either with thiabendazole or albendazole. Patients who had geohelminth infestations were treated with mebendazole. RESULTS: 14 children (11 boys) were studied. 7 were between 1 and 5 years, and 7 were above 5 years of age. The mean eosinophil count was 4.3 x 10(9)/1. All patients had a prolonged bleeding time, but clotting time and platelet counts (mean value 220 x 10(9)/1) were normal. Platelet function tests were done in 5 patients. Twelve patients were positive for toxocariasis and the other 2 were positive for ascariasis. All children who were positive for toxocariasis had contact with pet cats or dogs. Six patients were treated with thiabendazole and 6 with albendazole. The two patients who had ascariasis were treated with mebendazole. Post-treatment mean eosinophil count was 0.63 x 10(9)/1, and the bleeding time was 4 minutes. CONCLUSION: Toxocariasis could present with ecchymoses due to an acquired bleeding disorder. Awareness of this would help to investigate, diagnose and treat early, and lessen parental anxiety.

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

Toxocara seroprevalence in children from a subtropical city in Argentina

Most studies from Argentina have focused on toxocariasis as an environmental problem of big cities, and there are no available data about children infection from small or middle-sized cities. In order to assess the prevalence of anti-Toxocara antibodies in infantile population, 206 children from Resistencia, of both sexes, aged 1-14 years old were studied by Elisa testing with E/S T. canis L2 antigens. Hematological parameters and immunoglobulin levels were determined; five days' stool samples were studied and epidemiological data were obtained by means of a questionnaire to parents. Results showed that 73 per cent of the children had one or more dogs living at home, 57 per cent reported geophagia and 37.9 per cent were positive for Toxocara serology, but there was no significant difference in prevalence neither for boys and girls, nor concerning age. An increased risk of infection was observed in age groups 5-6 and 7-8 for boys, and in age groups 3-4 and 5-6 for girls.

Frequency of human toxocariasis in Jos, Plateau State, Nigeria

The enzyme-linked immunosorbent assay (Elisa) was used to examine sera of 104 children and adults in Jos, Plateau State, Nigeria for anti-toxocaral antibodies, out of which 31 (29.8) were reactive. The seropositive rates were 30.4 for adults, 29.6 for children, 34 for females and 25.9 for males. However, the differences were not significant by age and sex. A highly significant association (p < 0.001) was observed between seropositivity and geography but none between seropositivity and dog ownership (p > 0.05).

Human toxocarosis: its seroprevalence in the City of La Plata

Toxocara canis is very common in dogs throughout the world. It is the primary cause of visceral larva migrans (VLM) in humans. Soil contaminated with T. canis embryonated eggs is the main source of infection of man. Our objective was to describe Toxocara seroprevalence in humans in the city of La Plata associated with some determinants such asage, presence or absence of clinical manifestations and risk factors. Blood samples were collected at random from 156 patients of different sex and age, with and without clinical symptoms compatible with the disease. The diagnostic technique ELISA test was performed with the Bordier Affinity Products Commercial Kit, using excretory-secretory Toxocara antigen with a sensitivity higher than 90 percent. The values were positive in 39 percent of the studied population. In the analysis according to age, the younger group presented significant differences with respect to the older one (Chi-square p<0.05). Positive patients presented clinical symptoms compatible with the disease (84 percent), and 41 percent presented some risk factor. The level of positivity obtained indicates a certain risk of being infectes mainly in patients younger than 15 years old. The authors agree that an early identification and treatment of VLM may save a life.