Factors affecting disease manifestation of toxocarosis in humans: genetics and environment.

Toxocara canis is regarded as the main cause of human toxocarosis but the relative contribution of T. cati is probably underestimated; serological and other diagnostic methods used in most studies of this zoonotic disease do not distinguish between the two parasites. The definitive hosts for T. canis are caniidae. Pups generally have higher infection rates than adult animals and are a major source of eggs in the environment. Humans usually acquire T. canis infection by accidental ingestion of embryonated eggs or encapsulated larvae from the environment or contaminated food, such infections may lead to visceral larva migrans (VLM), ocular larva migrans (OLM) or covert toxocarosis (CT). Although a mixed Th1- and Th2-mediated immunological response, particularly with high levels of IgE and eosinophilia is observed, the underlying mechanisms of molecular and immunopathogenesis for the development of the symptomatic syndromes of VLM, OLM, or of asymptomatic CT are largely unclear. Studies have indicated that immunological defences against various infectious diseases may be highly influenced by complex interactions of environmental and host genetic factors e.g. MHC class I and II, also known as human leucocyte antigen (HLA). Toxocara spp. infections are associated with a polarized CD4(+) Th2 response with high IgE levels and eosinophilia, mediated mainly by HLA class II molecules. Associations have been made between HLA class II and pathological severity and host genetic effects on exposure to infection. Recent research suggests Foxp3(+) CD4(+)CD25(+)-expressing T regulatory (Treg) cells play a role in regulation of the immunopathology of granulomas in experimental toxocaral granulomatous hepatitis and in enhanced expression of TGF-ß1, which is an important factor for the local survival and function of Treg observed during T. canis invasion in the mouse small intestine, liver, muscle, and brain. Since the potential susceptibility loci HLA class II molecules, are considered involved in the regulation of a Th2-dominant immunity which is highly controlled by Foxp3(+) CD4(+)CD25(+) Treg cells by stimulation through TGF-ß1, which thus provides a beneficial environment to T. canis larvae but severe injuries to local organs. However, TGF-ß1 variant Leu10Pro known to be involved in disease severity warrants further elucidation as this too may have a role in the severity of human toxocarosis. Exploration of TGF-ß1 polymorphism, Foxp3(+) CD4(+)CD25(+) Treg cells, and MHC polymorphisms may allow insight into the contribution made by environmental and genetic factors in influencing disease syndrome type and severity in humans with toxocarosis.

Human toxocariasis: contribution by Brazilian researchers / Toxocaríase humana: contribuição dos pesquisadores brasileiros

In the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of São Paulo (IMT).

São abordados os principais aspectos da história natural da infecção humana por larvas de Toxocara que pode resultar na ocorrência da síndrome de larva migrans visceral e/ou ocular. Deu-se destaque, principalmente, à contribuição de pesquisadores brasileiros e, em especial, aos pertencentes ao quadro do Instituto de Medicina Tropical de São Paulo.

Prevalence of Toxocara-induced liver granulomas, detected by immunohistochemistry, in a series of autopsies at a Children's Reference Hospital in Vitoria, ES, Brazil.

The aim of this investigation was to study the frequency of visceral larva migrans (VLM) granulomas in autopsies at a Children's Reference Hospital in Vitoria, ES Brazil, where anti-Toxocara antibodies are frequently detected in the serum of children admitted at the hospital. Two liver fragments from 310 autopsies of children aged between 1 and 15 years were paraffin embedded, and sections were stained with hematoxylin and eosin and submitted to detection of Toxocara antigens using a rabbit anti-Toxocara serum. Among the 24 cases with granulomatous lesions, ten had eosinophil-rich granulomas positively stained with the anti-Toxocara serum. Some were typical epithelioid granulomas, with a positive reaction in multinucleated giant cells, epithelioid cells, or necrotic debris. The results showed that VLM granulomas are the most frequent granulomatous hepatitis in children in our county. This agrees with the high prevalence of anti-Toxocara antibodies in the serum of children admitted to the Children's Reference Hospital. The 3.2% frequency of liver VLM granulomas in autopsies is less than the 30-39% frequency of positive serology in these children, probably reflecting the low larval burden in infected children.

Contaminação por fezes caninas das praças públicas de Cuiabá, Mato Grosso / Contamination for faecal samples dogs of the public squares of Cuiabá, Mato Grosso

O presente trabalho teve o objetivo de avaliar a contaminação das praças públicas de Cuiabá, Estado de Mato Grosso, por fezes de cães. Foram pesquisadas 55 praças, de agosto a novembro de 2006. Destas, 14 localizavam-se no centro da cidade e 41 em diversos bairros periféricos do município. As amostras foram coletadas pela manhã, armazenadas em sacos plásticos sob refrigeração e processadas no Laboratório de Doenças Parasitárias do Hospital Veterinário da UFMT, através das técnicas de Willis-Mollay e Hoffmann, Pons e Janer, 1934. Das 55 praças, 40 possuíam amostras de fezes de cães. Ao todo foram coletadas 121 amostras e em 45 foram observados ovos de helmintos. Destas, 38 (84,4%) apresentaram ovos de Ancylostoma sp; 07 (15,5%) de Toxocara sp; 09 (20%) de Trichuris vulpis e 01 (2,2%) de Platynossomum sp e Cystoisospora sp. Vinte e duas das 121 amostras encontradas foram nas praças centrais e 99 nas de bairros periféricos, entretanto não houve diferença estatística significativa (p>0,05) entre as mesmas. Este estudo revelou alta contaminação de praças públicas da cidade de Cuiabá por ovos de helmintos, incluindo os de importância em saúde pública, o que indica risco de transmissão dessas zoonoses a população.

The present work had the objective to evaluate the contamination of the public squares of Cuiabá, State of Mato Grosso, for faecal samples of dogs. Fifty five squares had been searched, of August the November of 2006. Of these, 14 beed situated in the center of city and 41 in diverse outlying areas of the city. The samples were collected per the morning, stored in processed plastic bags under refrigeration and in the Laboratory of Parasitic Illnesses of the Hospital Veterinarian of the UFMT, through the techniques of Willis-Mollay and Hoffmann, Pons and Janer, 1934. Of the 55 squares, 40 had faecal samples of dogs. To 121 samples had been all collected and in 45 eggs of helminths had been observed. Of these, 38 (84,4%) had presented eggs of Ancylostoma sp; 07 (15,5%) of Toxocara sp; 09 (20%) of Trichuris vulpis ones and 01 (2,2%) of Platynossomum sp and Cystoisospora sp. Twenty and two of the 121 joined samples had been in the squares central offices and 99 in the ones of outlying areas, however did not have difference significant statistics (p>0,05) between the same ones. This study it disclosed high contamination of public squares of the city of Cuiabá for eggs of helminths, including of importance in public health, what it indicates risk of transmission of these zoonosis the population.

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.

Frequência de ovos de Toxocara spp. em três parques públicos da cidade de Porto Alegre, Rio Grande do Sul, Brasil / Frequency of Toxocara spp in three public parks of Porto Alegre city-Brazil

Com o objetivo de realizar um monitoramento mensal para verificar a presença e a frequência de ovos de Toxacara spp, foram coletadas, entre fevereiro de 2002 e janeiro de 2003, 216 amostras de areia em 18 caixas, de praças de recreação localizadas em três parques públicos da cidade de Porto Alegre, Rio Grande do Sul, Brasil. As amostras foram processadas em laboratório pela técnica de Faust modificada, sendo que os resultados mostraram ema frequência de ovos de Toxocara spp em 77,7 por cento das caixas examinadas. Esses dados indicam a necessidade da implantação de medidas sanitárias e educativas visando à prevenção do risco de contaminação da população, especialmente a infantil, por parasitos causadores da larva migrans visceral.

A seroepidemiological survey for toxocariasis in apparently healthy residents in Gangwon-do, Korea.

We investigated the sero-prevalence of toxocariasis among healthy Korean adults in 1999. A total of 314 sera from normal inhabitants in Whachon-gun, Gangwondo, Korea was examined for specific antibody levels against excretory-secretory products of second stage larvae of Toxocara (TES). The presence of cross-reactions with other helminthiases such as cysticercosis, paragonimiasis, sparganosis or clonorchiasis was also checked by specific IgG ELISA. Sera showing positive reaction against TES were also tested by IgG immunoblot and by IgE ELISA. Out of 314 subjects, 16 was found to be positive by TES IgG ELISA and immunoblot, among whom 12 were also positive by TES IgE ELISA. Among the 16 seropositive samples, two sera showed positive reaction against Paragonimus and sparganum antigen, respectively. These results inferred that cross-reactions were negligible between toxocariasis and other helminthiases. Toxocariasis seroprevalence among Korean rural adults was detected to be approximately 5%.

Visceral larva migrans due to Ascaris suum which presented with eosinophilic pneumonia and multiple intra-hepatic lesions with severe eosinophil infiltration--outbreak in a Japanese area other than Kyushu.

A 32-year-old man presented with the chief complaint of severe cough. Examination of peripheral blood showed a marked increase in eosinophils. Chest CT demonstrated multiple ground glass opacities in both lungs. Bronchoalveolar lavage showed abundant eosinophils. Abdominal CT demonstrated multiple low attenuation areas in the liver. Liver biopsy with ultrasonography revealed severe eosinophil infiltrations around the portal veins. Serologically, a multi-dot enzyme linked immunosorbent assay (DOT-ELISA) and ELISA inhibition test using microtiter plates were positive for Ascaris suum. Thus, visceral larva migrans due to Ascaris suum was diagnosed. Outbreaks of this disease in Japan have previously been confined to the Kyushu area. The present case which occurred outside that area, illustrates the importance of constant attention to the epidemiology of this disease.

[The association between human toxocariasis and pyogenic abscesses]. / A associação entre a toxocaríase humana e os abscessos piogênicos.

The association between hepatic abscesses and schistosomiasis mansoni was confirmed by clinical and experimental studies. Other parasites may cause systemic immunologic changes and local structural alterations in the affected organs that can facilitate the seeding of these areas by bacteria. Tropical pyomyositis, pyogenic liver and renal abscesses are frequent diseases in tropical areas. The visceral larva migrans syndrome is caused by the presence, in the human body, of larvae of worms that have other animals as their definitive host, most commonly being caused by Toxocara canis. The larvae migrate to various body organs leading to many inflammatory reactions in the form of granuloma and tissue necrosis. In this review we discuss the possible host-parasite-bacteria interactions that would favour the formation of abscesses in the organs involved by the larva of T. canis and present preliminary results of a clinical and experimental study undertaken during the last four years to define the role of this parasite in the pathogenesis of the abscesses.

Visceral larva migrans in an adult.

Visceral larva migrans is rare in adults. An adult male in whom the diagnosis was made by suggestive clinical features and muscle biopsy and who responded to thiabendazole is described.

Larva migrans visceral. Primer reporte en el Perú / Visceral larva migrans in Peru. Report of the first three cases

El presente trabajo tiene como propósito presentar 3 casos clínicos pediátricos, diagnosticados de toxocariasis, vistos en Lima-Perú, entre los años 1987 y 1989. Los tres pacientes son menores de 5 años de edad, con antecedentes de comer tierra, que presentaron leucocitosis leve o severa con hipereosinofilia (1500 eosinofilos por mm3). el primer paciente tuvo además hipergammaglobulinemia y gran compromiso del estado general, requiriendo el uso de tiabendazol. El segundo paciente presentó dolor abdominal crónico y la biopsia hepática reveló granulomas con abundantes eosinófilos. el tercer paciente tuvo dolor articular crónico de rodilla derecha con sinovitis en los dedos de la manos y pies. Los tres pacientes tuvieron títulos en sangre para toxocariasis en la prueba de ELISA a 1/4096, (CDC de Atlanta). Se trata del primer reporte clínico de larva migrans visceral en el Perú.

Visceral larva migrans: a seroepidemiological survey in five municipalities of Säo Paulo State, Brazil

Realzou-se inquérito soroepidemiológico, para detecçäo de anticorpos anti-Toxocara, em 2.025 soros de indivíduos residentes em cinco municípios do Estado de Säo Paulo (Säo Paulo, Campinas, Santos, Marília e Presidente Prudente), através de técnica imunoenzimática (ELISA) e emprego de antígenos obtidos a partir de larvas de 2§ - 3§ estádio de Toxocara canis. Após absroçäo com extratos de Ascaris lumbricoides, revelou-se a presença de anticorpos anti-Toxocara, em níveis significativos, em 3,60% dos soros examinados, com predominância de indivíduos com idade inferior a 15 anos (6,41%). Observou-se, ainda, tendência a ocorrerem índices mais elevados de infecçäo por larvas de Toxocara entre indivíduos residentes em municípios com maior densidade demográfica (Säo Paulo, Campinas e Santos), especialmente no grupo com menos de 15 anos de idade

Human and dogs Toxocara canis infection in a poor neighborhood in Bogota

Prevalence of Toxocara canis antibodies was studied in a poor community of Bogotá, Colombia. Two-hundred-sevem patients, from both sexes and all age groups, were studied. Positive Elisa titers were found in 47.5% of the population, a high prevalence compared with reports from developed countries. T. canis ova were positive in 43.6% of fecal samples from dog puppies. An endemic pattern of the disease is described: socioeconomic status, weathers, pollution, poor hygiene and a significant population of infected dogs. Neither the physical examination nor Elisa titers could detect any case of T. canis disease

Toxocara canis infestation. Clinical and epidemiological associations with seropositivity in kindergarten children.

We studied a cohort of 333 children in kindergarten to determine the prevalence of seropositivity to Toxocara canis, and to detect and measure chronic health effects that might be attributable to past infection. We found that 23.1% of the children had serologic evidence of infection (antibody titer greater than or equal to 1:32), assayed by means of an enzyme-linked immunosorbent assay. Black children were more frequently infested than white children, as were children of parents who did not graduate from high school. In a subsample of seropositive and seronegative children, we found associations between seropositivity and both pica and puppy ownership; we did not find differences in the symptoms and signs that occur in toxocaral visceral larva migrans nor differences in measures of growth and nutrition. No child had ocular toxocariasis although 31.8% (106) of the children had antibody titers greater than or equal to 1:16. In a population in which approximately 20 to 30% of the children show serologic evidence of Toxocara infestation, care must be taken in differentiating toxocariasis-like ophthalmic lesions, due to the potential for the coincidental occurrence of retinoblastoma in a child who is seropositive for the Toxocara parasite.

Toxocaral infection in hydatid control officers: diagnosis by enzyme immunoassay.

An enzyme-linked immunosorbent assay for Toxocara canis larva excretory/secretory antigen has been set up in Christchurch. Employing this test, elevated specific antibody levels for toxocara larvae were found in 3.3% (3/90) of urban adult blood donors and 4.4% (4/90) of secondary school students. In comparison, elevated levels were present in 25.6% (23/90) of New Zealand hydatid control officers. It can be concluded from the present study that the higher risk of toxocariasis experienced by hydatid officers is reflected in elevated specific antibody titres in a significant proportion of individuals when compared with controls.