Estudo de marcadores imunológicos para o diagnóstico e avaliação terapêutica da toxocaríase

In human toxocariasis, there are few approaches using immunological markers for diagnosis and therapeutic assessment. An immunoblot (IB) assay using excretory-secretory Toxocara canis antigen was standardized for monitoring IgG, IgE and IgA antibodies in 27 children with toxocariasis (23 visceral, three mixed visceral and ocular, and one ocular form) for 22-116 months after chemotherapy. IB sensitivity was 100% for IgG antibodies to bands of molecular weight 29-38, 48-54, 95-116, 121-162, >;205 kDa, 80.8% for IgE to 29-38, 48-54, 95-121, >; 205 kDa, and 65.4% for IgA to 29-38, 48-54, 81-93 kDa. Candidates for diagnostic markers should be IgG antibodies to bands of low molecular weight (29-38 and 48-54 kDa). One group of patients presented the same antibody reactivity to all bands throughout the follow-up study; in the other group, antibodies decayed partially or completely to some or all bands, but these changes were not correlated with time after chemotherapy. Candidates for monitoring patients after chemotherapy may be IgG antibodies to >; 205 kDa fractions, IgA to 29-38, 48-54, 81-93 kDa and IgE to 95-121 kDa. Further identification of antigen epitopes related to these markers will allow the development of sensitive and specific immunoassays for the diagnosis and therapeutic assessment of toxocariasis.Métodos imunológicos desempenham papel importante no diagnóstico da toxocaríase, entretanto há poucos estudos sobre marcadores diagnósticos e de acompanhamento terapêutico. Foi padronizado ensaio de immunoblot (IB) empregando antígeno de excreção-secreção de Toxocara canis para pesquisa de anticorpos IgG, IgE e IgA em 27 crianças com toxocaríase nas formas visceral (23), mista visceral e ocular (3) e ocular (1), por 22-116 meses após quimioterapia. Foram observados dois perfis de reatividade dos anticorpos: permanência contra todas as frações no decorrer do estudo; diminuição ou negativação contra algumas ou todas as frações, porém, essas mudanças não se correlacionaram com tempo de tratamento. A sensibilidade do IB foi 100,0% para anticorpos IgG específicos para frações de massa molecular de 29-38, 48-54, 95-116, 121-162, >; 205 kDa, 80,8% para IgE específicos para 29-38, 48-54, 95-121, >; 205 kDa e 65,4% para IgA específicos para 29-38, 48-54, 81-93 kDa. Anticorpos IgG específicos para frações de baixa MM (29-38 e 48-54 kDa) podem ser sugeridos como candidatos a marcadores diagnósticos. Por sua vez, anticorpos IgG para fração >; 205 kDa, IgA para 29-38, 48-54, 81-93 kDa e IgE para 95-121 kDa podem ser candidatos a marcadores terapêuticos. A identificação de epítopos antigênicos relacionados a estes marcadores poderá ser importante para o desenvolvimento de ensaios altamente sensíveis e específicos no diagnóstico e avaliação terapêutica da toxocaríase

Frequency of seropositivity to Toxocara canis in children of different socioeconomic strata

Para estudar a freqüência da infecção pelo Toxocara canis em crianças de classes sociais diferentes de Brasília, Brasil, foram testados soros de 602 crianças de ambos os sexos, de 1 a 12 anos, distribuídas em dois grupos representativos de condições socioeconômicas distintas. As amostras do primeiro grupo foram obtidas em laboratório público que atende bairros pobres. As do segundo grupo foram colhidas em laboratório privado, que serve à classe média. Os anticorpos anti-Toxocara foram detectados pelo método ELISA, com antígenos de Toxocara canis, e absorção com antígenos do Ascaris suum. A prevalência de soropositividade foi de 21,8% (66/302) no primeiro grupo e de 3% (9/300) no segundo (p<0,0001). Não houve diferença quanto ao gênero ou idade das crianças. Os resultados sugerem significativa prevalência de toxocaríase na população infantil de Brasília, com predomínio nas classes sociais menos favorecidas economicamente. __________________________________________________________________________________________ ABSTRACTFrequency of seropositivity for Toxocara in children from different socioeconomic strata in the city of Brasilia (Brazil) was measured. Six hundred and two children of both sexes, aged one to 12 years were distributed in two socioeconomically distinct groups. The samples of sera of the first group were obtained from blood drawn for routine tests in the laboratory of a public hospital attending children from low-income families. Samples from the second group were obtained from private laboratories attending children from middle-class families. Antitoxocara antibodies were detected by ELISA, using Toxocara canis excretory-secretory antigens previously absorbed with Ascaris suum extract. The prevalence of seropositivity was 21.8% (66/302) in the first group and 3% (9/300) in the second (p< 0.0001). No differences in frequency according to age or sex could be detected. Our results suggest a high prevalence of childhood toxocariasis in Brasilia, with children from lower income brackets being the most affected

Toxocaríase em crianças atendidas em Unidade de Pneumologia do Serviço de Saúde Pública, Paraná, Brasil

O teste imunoenzimático (ELISA) constitui a ferramenta mais utilizada no diagnóstico individual da toxocaríase humana e/ou em inquéritos soroepidemiológicos para pesquisa de anticorpos IgG anti-Toxocara spp. Tendo em vista a elevada freqüência da toxocaríase (32,2% e 56,0%) observada em crianças atendidas em Unidades Básicas de Saúde de municípios do noroeste do Paraná, durante pesquisas realizadas ao longo dos últimos oito anos, o objetivo deste trabalho foi comparar estas frequências em crianças encaminhadas a uma unidade de Pneumologia do serviço de saúde pública da cidade de Maringá, noroeste do Estado do Paraná, Brasil e descrever os achados laboratoriais, clínicos e epidemiológicos das crianças soropositivas. A pesquisa foi realizada no Centro de Especialidades Regional - CISAMUSEP - entre julho de 2009 a julho de 2010, em crianças com idade entre um e 15 anos. De 167 crianças investigadas, sete (4,2%) apresentaram anticorpos IgG anti-Toxocara spp. Entre elas, duas (1,2%) crianças soropositivas apresentaram eosinofilia (baixos níveis), seis mostraram níveis elevados de IgE e cinco, teste alérgico positivo, principalmente para ácaros. Concluindo, no noroeste do estado do Paraná foram observados raros casos de crianças com toxocaríase envolvendo o trato respiratório e que foram atendidas por serviços públicos de Pneumologia ainda que na região estudada tenha sido observada elevada prevalência de toxocaríase em crianças assistidas pelas Unidades Básicas de Saúde (BHU).The enzyme-linked immunosorbent assay (ELISA) is the most widely used tool to detect anti-Toxocara IgG antibodies for both serodiagnostic and seroepidemiological surveys on human toxocariasis. In the last eight years a high prevalence of toxocariasis (32.2-56.0%) has been reported in children attending public health units from municipalities in the state of Paraná, Brazil. Therefore, the aim of this work was to compare the frequency found among the general child population with that of children attending a public pneumology service in Maringá, Paraná, Brazil and describe the laboratorial, clinical and epidemiological findings. The research was conducted at the Consórcio Público Intermunicipal de Saúde do Setentrião Paranaense (CISAMUSEP) from July 2009 to July 2010 among children aged between one and 15 years. From a total of 167 children studied, only 4.2% (7/167) tested positive for anti-Toxocara spp. IgG antibodies and presented mild eosinophilia (2/7), increased serum IgE levels (6/7) and a positive allergy test for mites (5/7). The presence of pets (dogs or cats) at home did not correlate with the seroprevalence. In conclusion, cases of toxocariasis involving the respiratory tract are rare in children attending a public health pneumology unit in the northwestern region of Paraná State, despite the high prevalence of this type of toxocariasis among the infantile population attending Basic Health Units in the same geographical area

Avaliação sorológica, clínica e epidemiológica da toxocaríase em áreas urbanas do sul do Brasil

Toxocariasis is a worldwide public-health problem that poses major risks to children who may accidentally ingest embryonated eggs of Toxocara. The objectives of this study were to investigate the occurrence of anti-Toxocara spp. antibodies in children and adolescents and the variables that may be involved, as well as environmental contamination by Toxocara spp. eggs, in urban recreation areas of north central mesoregion, Paraná State, Brazil. From June 2005 to March 2007. a total of 376 blood samples were collected by the Public Health Service from children and adolescents one to 12 years old, of both genders. Samples were analyzed by the indirect ELISA method for detection of anti-Toxocara antibodies. Serum samples were previously absorbed with Ascaris suum antigens, and considered positive with a reagent reactivity index >;1. Soil samples from all of the public squares and schools located in the four evaluated municipalities that had sand surfaces (n = 19) or lawns (n = 15) were analyzed. Of the 376 serum samples, 194 (51.6%) were positive. The seroprevalence rate was substantially higher among children aging one to five years (p = 0.001) and six to eight years (p = 0.022). The clinical signs and symptoms investigated did not show a statistical difference between seropositive and seronegative individuals (p >; 0.05). In 76.5% of the investigated recreation places, eggs of Toxocara were detected in at least one of the five collected samples. Recreation areas from public schools were 2.8 times more contaminated than from public squares. It is important to institute educational programs to inform families and educators, as well as to improve sanitary control of animals and cleaning of the areas intended for recreation in order to prevent toxocariasis.A toxocaríase é um problema de saúde pública mundial, com maior risco para crianças que podem, acidentalmente, ingerir ovos embrionados de Toxocara spp.. Os objetivos deste estudo foram avaliar a ocorrência de anticorpos anti-Toxocara spp. em crianças e adolecentes e as variáveis que podem estar envolvidas, bem como a contaminação ambiental por ovos de Toxocara spp., em locais de recreação, em áreas urbanas da mesorregião norte central, Paraná, Brasil. De junho de 2005 a março de 2007 foram coletadas 376 amostras de sangue de crianças e adolescentes de um a doze anos, de ambos os sexos, atendidas pelo Sistema Único de Saúde. As amostras foram analisadas pelo método de ELISA indireto para detecção de IgG anti-Toxocara e previamente absorvidas com antígeno de Ascaris suum. Foram consideradas reagentes as amostras com índice de reatividade >; 1. A análise das amostras de areias (n = 19) e gramados (n = 15) de cada município foi realizada em todas as praças e escolas públicas. Das 376 amostras de soro, 194 (51,6%) foram positivas. A taxa de soroprevalência foi substancialmente mais elevada entre as crianças na faixa etária de até um a cinco (p = 0.001) e de seis a oito anos de idade (p = 0,022). Os sinais e sintomas clínicos investigados não mostraram diferenças estatísticas entre soropositivos e soronegativos (p >; 0,05). Em 76,5% dos locais de recreação investigados, ovos de Toxocara foram detectados em pelo menos uma das cinco amostras. Os locais de recreação das escolas públicas estavam 2,8 vezes mais contaminados do que as praças. É importante a realização de programas educativos junto às famílias e educadores, o controle sanitário de animais e a higienização dos locais destinados à recreação para prevenção da toxocaríase

Detecção de larvas de Toxocara canis em leite: um estudo experimental em coelhas.

Toxocariasis, caused most commonly by Toxocara canis, is an important cosmopolitan zoonosis. Paratenic hosts have been employed to provide knowledge regard to the transmission of toxocariasis. Transmammary transmission in murine experimentally infected was observed based on the recovery of larvae from the tissue. The aim of this study was to evaluate the possibility of transmammary transmission of Toxocara canis in rabbits by detecting larvae directly in milk. Seventeen sexually mature virgin white New Zealand female rabbits were divided into two groups. Twelve animals were orally inoculated with 1,000 T. canis embryonated eggs (infected group), and five animals remained uninfected (control group). One month following the infection, the females were mated. Manual collection of 500 ?L of milk from each rabbit was performed on days +7, +14 and +21 of lactation for three consecutive lactations. The recovery of larvae was determined via a centrifuge-sedimentation technique using ether and formalin solutions. ELISA test was run to confirm the production of anti-T. canis antibodies (IgG) by infected rabbits. The presence of larvae was observed in milk samples from 5 (41.7%) of the 12 infected rabbits. The total number of recovered larvae was 20, ranging from 1 to 4 larvae per lactation/rabbit. Larvae were recovered exclusively on days 7 and 14 of lactation. Recovery was verified in different lactations. No significant difference was observed with respect to the number of larvae either in the same lactation period or in different lactation periods. Anti-T. canis antibodies were detected in all infected rabbits. In conclusion, the presence of larvae in rabbit milk samples suggests the possibility of galactogenic transmission of T. canis in paratenic hosts. Moreover, the technique employed in this study allows for the recovery of larvae directly from milk

Anti-Toxocara spp. antibodies in an adult healthy population: serosurvey and risk factors in Southeast Brazil.

Objective: To evaluate the frequency of anti-Toxocara spp. antibodies in an adult healthy population. Methods: The study was performed by interviewing 253 blood donors, from 19 to 65 years of age, in a hematological centre in Presidente Prudente, São Paulo, southeast Brazil. A survey was applied to blood donors in order to evaluate the possible factors associated to the presence of antibodies, including individual (gender and age), socioeconomic (scholarship, familial income and sanitary facilities) and habit information (contact with soil, geophagy, onycophagy and intake of raw/undercooked meat) as well as the presence of dogs or cats in the household. ELISA test was run for detection of the anti-Toxocara spp. IgG antibodies. Bivariate analysis followed by logistic regression was performed to evaluate the potential risk factors associated to seropositivity. Results: The overall prevalence observed in this study was 8.7% (22/253). Contact with soil was the unique risk factor associated with the presence of antibodies (P=0.0178 ; OR=3.52; 95% CI=1.244-9.995) Conclusions. The results of this study reinforce the necessity in promoting preventive public health measures, even for healthy adult individual, particularly those related to the deworming of pets to avoid the soil contamination, and hygiene education of the population