Eosinophilic count and seropositivity for IgG antibodies to toxocara spp. in children assisted at the public health service

Abstracts

OBJETIVO: Verificar a associação entre a presença de eosinofilia e a soropositividade para anticorpos IgG anti-Toxocara spp. em crianças atendidas pelo Sistema Único de Saúde no Noroeste do Paraná, Brasil. MÉTODOS: Estudo retrospectivo com crianças de sete meses a 12 anos, atendidas pelo Sistema Único de Saúde do Noroeste do Paraná, com teste ELISA para a pesquisa de anticorpos IgG anti-Toxocara spp. e contagem de eosinófilos (eosinofilia >600 células/mm³). RESULTADOS: Entre as 1.199 crianças, 386 (32,2%) apresentaram anticorpos IgG anti-Toxocara spp. A soroprevalência e a eosinofilia foram mais frequentes em crianças de sete meses a cinco anos. A eosinofilia foi observada em 7,8% dos pacientes soro-reagentes ao Toxocara spp.. CONCLUSÕES: Foi observada elevada prevalência de anticorpos anti-Toxocara spp., principalmente nos menores de cinco anos. Com exceção de algumas crianças que apresentaram sintomas respiratórios e presença de eosinofilia, a maioria foi assintomática e não mostrava eosinofilia. A pesquisa de eosinófilos é ferramenta secundária para o diagnóstico de toxocaríase.

toxocaríase; criança; eosinofilia

OBJETIVO: Verificar la asociación entre la presencia de eosinofilia y una suero-positividad para anticuerpos IgG anti-Toxocara spp. en niños atendidos por el Sistema Único de Salud en el noroeste de Paraná, Brasil. MÉTODOS: Estudio retrospectivo en niños de siete meses a 12 años de edad, atendidos por el Sistema Único de Salud en el noroeste de Paraná, con prueba de ELISA para la investigación de anticuerpos IgG anti-Toxocara spp. y recuento de eosinófilos (eosinofilia > 600 células/mm³). RESULTADOS: Entre los 1.199 niños, 386 (32,2%) presentaron anticuerpos IgG anti-Toxocara spp. La suero-prevalencia y la eosinofilia fueron más frecuentes en niños de siete meses a cinco años. La eosinofilia fue observada en 7,8% de los pacientes suero-reactivos al Toxocara spp. CONCLUSIÓN: Se observó elevada prevalencia de anticuerpos anti-Toxocara spp., principalmente en niños menores de cinco años. Excepto por algunos niños que presentaron síntomas respiratorios y presencia de eosinofilia, la mayoría de ellas fue asintomática y mostraban eosinofilia. La investigación de eosinófilos es herramienta adicional a los casos con indicios clínicos de toxocariase.

toxocariase; niño; eosinofilia; Toxocara spp

ORIGINAL ARTICLE

Ariella Andrade Marchioro^I; Cristiane Maria Colli^II; Salete Mattia^III; Márcia Liz Paludo^IV; Gisely Cardoso de Melo^V; Carolina Moreira Adami^VI; Sandra Marisa Pelloso^VII; Ana Lúcia F. Guilherme^VIII

^IMestranda do Programa de Pós-graduação em Ciências da Saúde da UEM, Maringá, PR, Brasil

^IIDoutoranda do Programa de Pós-Graduação em Ciências da Saúde pela UEM, Maringá, PR, Brasil

^IIIMestre em Ciências da Saúde pela UEM; Coordenadora da Vigilância Sanitária de Paiçandu, PR, Brasil

^IVMestre em Ciências da Saúde pela UEM, Maringá, PR, Brasil

^VDocente do Centro Universitário Nilton Lins, Manaus, AM, Brasil

^VIBolsista e Acadêmica em Farmácia da UEM, Maringá, PR, Brasil

^VIIDoutora em Enfermagem pela Universidade de São Paulo (USP); Docente do Programa de Pós-Graduação em Ciências da Saúde da UEM, Maringá, PR, Brasil

^VIIIDoutora em Ciências Ambientais pela UEM; Professora Associada do Departamento de Ciências Básicas da Saúde, Disciplina de Parasitologia da UEM, Maringá, PR, Brasil

Endereço para correspondência

ABSTRACT

OBJECTIVE: To study the association between the presence of eosinophilia and IgG antibodies to Toxocara spp. in children assisted by the public health service, in the northwestern region of Parana State, in southern Brazil.

METHODS: A retrospective study of children aged seven months to 12 years old assisted by the Public Health Service in northwest state of Paraná, Brazil. ELISA test was performed in all children in order to detect IgG antibodies to Toxocara spp. and eosinophil amounts (eosinophilia > 600 cells/mm3).

RESULTS: Among 1,199 screened children, 386 (32.2%) had IgG antibodies to Toxocara spp. The seroprevalence of Toxocara spp. and the eosinophilia were more common among children of seven months to five years old. Eosinophilia was observed in 7.8% of seropositive patients to Toxocara spp.

CONCLUSIONS: There was a high prevalence of anti-Toxocara spp., mainly in children under five years old. With the exception of some children who had respiratory symptoms and eosinophilia, most of them were asymptomatic and did not present eosinophilia. Eosinophilic count is a secondary laboratory finding in the diagnosis of toxocariasis.

Key-words: toxocariasis/diagnosis; child; eosinophilia.

RESUMEN

OBJETIVO: Verificar la asociación entre la presencia de eosinofilia y una suero-positividad para anticuerpos IgG anti-Toxocara spp. en niños atendidos por el Sistema Único de Salud en el noroeste de Paraná, Brasil.

MÉTODOS: Estudio retrospectivo en niños de siete meses a 12 años de edad, atendidos por el Sistema Único de Salud en el noroeste de Paraná, con prueba de ELISA para la investigación de anticuerpos IgG anti-Toxocara spp. y recuento de eosinófilos (eosinofilia > 600 células/mm³).

RESULTADOS: Entre los 1.199 niños, 386 (32,2%) presentaron anticuerpos IgG anti-Toxocara spp. La suero-prevalencia y la eosinofilia fueron más frecuentes en niños de siete meses a cinco años. La eosinofilia fue observada en 7,8% de los pacientes suero-reactivos al Toxocara spp.

CONCLUSIÓN: Se observó elevada prevalencia de anticuerpos anti-Toxocara spp., principalmente en niños menores de cinco años. Excepto por algunos niños que presentaron síntomas respiratorios y presencia de eosinofilia, la mayoría de ellas fue asintomática y mostraban eosinofilia. La investigación de eosinófilos es herramienta adicional a los casos con indicios clínicos de toxocariase.

Palabras-clave: toxocariase/diagnóstico; niño; eosinofilia; Toxocara spp.

Introduction

With worldwide geographical distribution, toxocariasis is a zoonotic disease prevalent in tropical and developing countries, associated with socio-economic status of the population and affecting mainly children^(1-5).

The human infection takes place due to the accidental ingestion of embryonated eggs Toxocara canis or Toxocara cati, intestinal parasites of cats and dogs, respectively, found in soil and sand contaminated with feces of these species⁽⁶⁾. The ingested eggs hatch in the small intestine, larvae penetrate the mucosa and migrate to the liver, passing through the lungs and reach various tissues through the systemic circulation. Migration triggers the production of eosinophilic granuloma, with consequent inflammation⁽⁷⁾. The destruction of parasites by the eosinophils is caused by the toxic action of their cytoplasmatic granules^(8,9), which damage non-phagocytic organisms, such as helminths in tissue migration phase⁽¹⁰⁾. The production of eosinophils is influenced by the helminth species, number of parasites, location in the host and time since infection⁽¹¹⁾. Some authors state that helminthiasis that cause tissue invation lead to eosinophilia more often; once eosinophilia is more intense during larval development and migration^(12,13).

The diagnosis of toxariasis is based on clinical manifestations and laboratory tests, especially the ELISA IgG antibodies to Toxocara spp. test and blood test^(14,15), and eosinophilia can be established, in children, as an absolute number of eosinophils >600/mm^3(16,17). Thus, the objective of this work was to verify the association between the presence of eosinophilia and seropositivity for IgG antibodies to Toxocara spp., in children assisted by pelo Unified Health System (SUS).

Methods

From February 2004 to November 2007, children aged seven months to 12 years old, assisted by SUS and residing in urban areas within the northwest of the state of Paraná⁽¹⁸⁾, Brazil, within the coverage are of the 15^th Regional Health System of the state of Paraná, Brazil. This random research was prompted by the shortage of data in the literature about the prevalence of toxocariasis in the state of Paraná, as well as by the large number of dogs, and by the frequent epidemiologic factors that contribute to the dissemination of a zoonotic disease that is highly neglected at public health care services. Thus, after spontaneously signing the informed consent form of the guardian (when there was indication of a blood test), serological investigation to detect the presence of IgG antibodies to Toxocara spp. was conducted randomly, and eosinophilia data was collected in the blood test.

Approximately 85% of the population in investigated municipalities (Astorga, Colorado, Mandaguaçu, Mandaguari, Marialva, Maringá, Nova Esperança, Paiçandu and Sarandi) reside in an urban area⁽¹⁸⁾. Based on the annual statistical survey, the size of the sample was calculated with an expected prevalence of 25% and 5%¹⁹ accuracy for IgG antibodies to Toxocara spp. For each listed municipality, a sample of children was calculated, with a 95% confidence interval, using the Statistica 7.1 software application. A total of 1,199 children were included in the research.

The municipalities of Astorga, Colorado, Mandaguaçu and Nova Esperança have populations ranging from 17,000 to 30,000 people, with 4,000 to 6,000 children aged seven months to 12 years old⁽¹⁸⁾. The municipalities of Marialva, Mandaguari and Paiçandu have a population ranging from 31,000 to 45,000 people, with 6,000 to 8,000 children in this age group⁽¹⁸⁾. The city of Sarandi, with 79,686 people, has 16,824 children in the seven months to 12 years old age group⁽¹⁸⁾. In the city of Maringá, with 325,968 people, we chose to investigate children assisted at Hospital Municipal de Maringá, which serves SUS patients exclusively; an average of 13,000 children are attended annually.

The results of the serology were then associated with the hematologic values obtained in the leukogram (absolute count of eosinophils). The adopted criterion to establish eosinophilia was a value equal or greater than 600 eosinophils/mm³ (0.60 x 10⁹ /L), the reference limit for age and sex^(16,17). The degree of eosinophilia was classified according to Naveira⁽¹¹⁾: non-eosinophilic (>1% and <4%), Degree I eosinophilia (>4% and <10%), Degree II (>10% and <20%), Degree III (>20% to <50%) and Degree IV (over 50%).

The IgG antibodies for Toxocara spp. were detected by the immunoenzymatic test ELISA (Enzyme Linked Immunosorbent Assay), using T. canis excretion-secretion antigen (TES)^(19,20). The sera were previously absorbed with Ascaris suum antigens, and all tests used positive (reagent) serum, negative (non-reagent) serum, and Reactivity Threshold Serum (RTS). The results were expressed in Reactivity Index (RI), relative to the optical density of the sample/optical density of the RTS. Reagent samples were considered to be those that presented RI >1. All samples were tested twice.

The data were compared by descriptive statistic and chi-squared test, using the BioEstat 3.0 software application. The test of proportions was carried out with the Statistica 7.1 software application. The research was approved by the Research Ethics Committee (COPEP/UEM), according to report nº 305/2004, as well as by the municipal departments of education and health at the investigated municipalities.

Results

From a total of 1,199 patients whose serologies were carried out during the period of the proposed study, 92 were from Astorga, 82 from Colorado, 59 from Mandaguaçu, 92 from Mandaguari, 123 from Marialva, 260 from Maringá, 98 from Nova Esperança, 82 from Paiçandu and 311 from Sarandi.

The research showed that 386/1,199 (32.2%) of children had the presence IgG antibodies to Toxocara spp. (Table 1). Most of the children in the study did not present eosinophilia (Table 1). Eosinophilia was observed in 126/1,199 (19.6%) of patients investigated. From the 386 patients serum-reagent to Toxocara spp., 30 (7.8%) showed concomintant eosinophilia. There was no association between eosinophilia and the presence of antibodies to Toxocara spp.; on the contrary, children who were not carriers of antibodies to Toxocara spp. presented, with greater frequency, an eosinophilic count over 600/mm³ (p=0.0332).

The seroprevalence of antibodies to Toxocara spp. and eosinophilia were more frequent in children aged seven months to five years old than in children aged six to eight years old and nine to 12 years old (p=0.011and p= 0.005, respectively).

Among the 30 individuals who were reagent to Toxocara spp. and with the increase of eosinophils (Table 2), most presented with degree I eosinophilia (p=0.0001). The distribution of eosinophilia degrees among the three age groups (Table 2) did not show statistica difference (p=0.51). From the 30 children, ten (33.3%) reported respiratory symptoms and, from these, seven presented degree I eosinophilia, with one child showing each of the remaining degrees of eosinophilia (II, III, and IV). Most reported contact with dogs and/or cats and with sand/dirt or lawn. The distribution of the eosinophilia degrees among the three age groups for children non-reagent to Toxocara spp. was not significant either (Table 2) (p=0.98).

Discussion

Most of the children in the study presented a normal eosinophil count, including those who were serum-reagent to Toxocara spp. It is known that the eosinophils commonly increase with allergic and parasitic processes^(21,22) and, mainly, in helminthiasis with tissue invasion, more intense during the larval migratory process^(12,13). Some factors are relevant for the development of symptoms, such as the number of migrating larvae, the hypersensitivity and immunological state of individuals.

Although toxocariasis is characterized by the presence of larvae in human tissues, the present study found no association between eosinophilia and seropositivity to Toxocara spp. These results are in agreement with the findings of Radman⁽²³⁾, Anaruma⁽²⁴⁾ and Paludo⁽⁵⁾. Other authors, however, have found an association, but using the relative count of eosinophiles^(25,26) or values under 600 eosinophiles/mm^3(3,27) as criteria for eosinophilia. If the relative count of these leukocytes was considered, there would be an increase from 30 (7.8%) to 133 (34.5%) eosinophilic children among the 328 serum reagent children. It is crucial, however, that the clinical aspects are considered, because from 30 seropositive children, only 33% presented toxocariasis symptomatology suggesting toxocariasis, all with eosinophilia. Due to the fact that most individuals remain asymptomatic, eosinophilia is an additional tool for the diagnostic conclusion. However useful for the diagnosis of toxocariasis^(1,3,5), the dosage of IgG antibodies does not work as a marker of cure for the disease, because their titles could remain high for years after treatment^(4,28). It should be undescored, however, that in the ten cases that were seropositive, eosinophilic and with a picture of asthma or bronchitis, treatments with tiabendazol 25mg/kg/day for seven days^(20,15) reduced the pulmonary symptoms and normalized the number of eosinophils. The clinical signs of toxocariasis, including the pulmonary clinical picture, are variable and depend on the number of ingested eggs, tissue involved and allergic response induced by the host^(29,30) .

Seropositivity was most frequent in younger children, which is in agreement with the results of Paludo⁽⁵⁾ and Karadam⁽²⁷⁾ . These findings are explained by the fact that children in this age group, due to their behavioral habits, are more exposed to contaminated sand and soil^(4,5).

In the present study, we observed a high prevalence of antibodies to Toxocara spp., especially in children under five years old. Various works in other Brazilian regions have also observed a similar prevalence(1,3-5,31,32) . In the present research, with the exception of some children who presented respiratory symptoms and the presence of eosinophilia, most children were asymptomatic, and it was not possible to establish an association of the zoonotic disease and their symptomatollgy with eosinophilia. It should be underscored that the parasitosis evolves in an asymptomatic way(15,33,34) and the titles of IgG antibodies to Toxocara spp. may remain high for years after treatment(4,28). Thus the research of eosinophils becomes an additional, but secondary, tool to diagnose patients with clinical signs of toxocariasis.

References

• 1. Campos Júnior D, Elefant GR, Silva EO, Ganolfi L, Jacob CM, Tofeti A et al. Freqüência de soropositividade para antígenos de Toxocara canis em crianças de classes sociais diferentes. Rev Soc Bras Med Trop 2003;36:509-13.
• 2. Despommier D. Toxocariasis: clinical aspects, epidemiology, medical ecology, and molecular aspects. Clin Microbiol Rev 2003;16:265-72.
• 3. Figueiredo SD, Taddei JA, Menezes JJ, Novo NF, Silva EO, Cristóvão HLG et al Estudo clínico-epidemiológico da toxocaríase em população infantil. J Ped 2005;81:126-32.
• 4. Lopez MdeLA, Martin G, Chamorro M del C, Alonso JM. Toxocariosis em Niños de Una Region Subtropical. Medicina (Buenos Aires) 2005;65:226-30.
• 5. Paludo LM, Falavigna DL, Elefant GR, Gomes LM, Baggio ML, Amadei LB et al Frequency of Toxocara infection in children attended by the health public service of Maringá, South Brazil. Rev Inst Med Trop 2007;49:6-12.
• 6. Beaver PC. Parasitological Reviews - Larva Migrans. Exp Parasit 1956;5:587-621.
• 7. Barcat JA. Larva migrans: perros, parasitos y hombres. Medicina (Buenos Aires) 2000;60:270-2.
• 8. Gleich GJ. The eosinophil and bronchial astma: Current understanding. J Allergy Clin Immunol 1990;85:422-33.
• 9. Moqbel R, Lacy P. Exocytotic events in eosinophils and mast cells. Clin Exp Allergy 1999;29:1017-22.
• 10. Jacob CM. Doença Pulmonar secundária a migração de parasitas. In: Rozov T. Doenças Pulmonares em Pediatria. São Paulo: Atheneu; 1999. p. 317-25.
• 11. Naveira JB. Aspectos da biologia dos eosinófilos. Rev Bras Maraliolog Doenças Trop 1960;12:103.
• 12. Moqbel P, Pritchard DI. Parasites and allergy: evidence for a "cause and effect" relationship. Clin Exp Allergy 1990;20:611-8.
• 13. Mawhorter SD. Eosinophilia: caused by parasites. Pediatr Ann 1994;23:405-13.
• 14. Jacob CM. Síndrome da larva migrans visceral por Toxocara canis (Toxocaríase). In: Tonelli E, Freire LMS, editores. Doenças infecciosas na infância e adolescência. 2Ş ed. Rio de Janeiro: Medsi; 2000. p. 1421-31.
• 15. Pawlowski, Z. Toxocariasis in humans: clinical expression and treatment dilemma. J Helminthol 2001;75:299-305.
• 16. Bain BJ. Células Sanguíneas: consulta rápida. Porto Alegre: Artmed; 1998.
• 17. Henry JB. Diagnóstico clínico e tratamento por métodos laboratoriais. 20Ş ed. Barueri: Manole; 2008. p. 593.
• ¹⁸
  IPARDES [homepage on the internet]. IPARDES: Instituto Paranaense de Desenvolvimento Econômico e ial. [cited 2007 Oct 15]. Available from: http://www.ipardes.gov.br/modules/conteudo/conteudo.php?conteudo=6
• 19. De Savigny DH, Voller A, Woodruff AW. Toxocariasis: serological diagnosis by enzyme immunoassay. J Clin Pathology 1979;32:284-8.
• 20. Elefant GR, Jacob CM, Kanashiro EH, Peres BA. Toxocaríase. In: Ferreira AW, Ávila SLM, editores. Diagnóstico laboratorial das principais doenças infecciosas e auto-imunes. 2Ş ed. Rio de Janeiro: Guanabara Koogan; 2001. p. 323-32.
• 21. Wardlaw AJ. Eosinophilis in the 1990s: new perspective on their role in health and disease. Postgrad Med J 1994;70:536-52.
• 22. Mendes DM, Camargo de MF, Aun VV, Fernandes MM, Aun WT, Mello de JF. Eosinofilia. Rev Bras Alerg Imunopatol 2000;23:84-91.
• 23. Radman NE, Archelli SM, Fonrouge RD, Guardis M del V, Linzitto OR. Human Toxocarosis. It's Seroprevalence in the City of La Plata. Mem Inst Oswaldo Cruz 2000;95:281-5.
• 24. Anaruma FF, Chieffi PP, Correa CRS, Camargo ED, Silveira EPR, Aranha JJB et al. Human toxocariasis: a seroepidemiological survey in the municipality of Campinas, Brazil. Rev Inst Med Trop 2002;44:303-7.
• 25. Chiodo P, Basualdo J, Ciarmela L, Pezzani B, Apezteguía M, Minvielle M. Related factors to human toxocariasis in a rural community of Argentina. Mem Inst Oswaldo Cruz 2006;101:397-400.
• 26. Roldán WH, Espinoza YA, Huapaya PE, Huiza AF, Sevilla CR, Jiménez S. Frequency of human toxocariasis in a rural population from Cajamarca, Peru determined by dot-elisa test. Rev Inst Med Trop São Paulo 2009;51:67-71.
• 27. Karadam SY, Ertug S, Ertabaklar H, Okyay P. The comparision of IgG antibodies specific to Toxocara spp. among eosinophilic and non-eosinophilic groups. New Microbiol 2008;31:113-6.
• 28. Rubinsky-Elefant G, Shimizu SH, Sanches MC, Jacob CM, Ferreira AW. A serological follow-up of toxocariasis patients after chemotherapy based on the detection of IgG, IgA and IgE antibodies by enzyme-linked immunosorbent assay. J Clin Lab Anal 2006;20:164-72.
• 29. Glickman LT, Shofer FS. Zoonotic visceral and ocular larva migrans. Rev Clin North Am 1987;17:39-53.
• 30. Muradian V, Gennari SM, Glickman LT, Pinheiro SR. Epidemiological aspects of Visceral Larva Migrans in children living at São Remo Community, São Paulo (SP), Brazil. Vet Parasitol 2005;134:93-7.
• 31. Damian MM, Martins M, Sardinha JF, Souza LO, Chaves A, Tavares A M. Freqüência de anticorpo anti-Toxocara canis em comunidade do Rio Uatumã, no Estado do Amazonas. Rev da Soc Bras de Med Trop 2007;40:661-4.
• 32. Colli CM, Rubinsky-Elefant G, Paludo ML, Falavigna DL, Guilherme EV, Mattia S et al Serological, clinical and epidemiological evaluation of toxocariasis in urban areas of south Brazil. Revista do Instituto de Medicina Tropical de São Paulo 2010;52:69-74.
• 33. Di Bartolomeo S, Alonso L, Doblores A, San Miguel S, Rojkes E, Monachesi L et al. Eosinofilia: principal parámetro para la detección de toxocarosis. Acta Bioq Clín Latinoam 2001;4:527-30.
• 34. Magnaval JF, Glickman LT, Dorchies P, Morassin B. Highlights of human toxocariasis. Korean J Parasitol 2001;39:1-11.

Eosinophilic count and seropositivity for IgG antibodies to toxocara spp. in children assisted at the public health service

Evaluación eosinófila y suero-positividad para anticuerpos igG anti-toxocara en niños atendidos por el Sistema Único de Saludç

Publication Dates

• Publication in this collection
  14 Apr 2011
• Date of issue
  Mar 2011

History

• Accepted
  11 June 2010
• Received
  16 Oct 2009