Sero-epidemiology of toxocariasis in a rural settlement in Sa ˜ o Paulo state, Brazil L. E. PRESTES-CARNEIRO*, V. SANTARE ´ M*, S. C. S. ZAGO*, N. A. MIGUEL*, S. DE F. ZAMBELLI*, R. VILLAS*, A. J. VAZ { and G. RUBINSKY-ELEFANT { * Departamento de Imunologia, Universidade do Oeste Paulista, Rua Jose ´ Bongiovani 700, Cidade Universita ´ria, Presidente Prudente, 19050-680, Sa ˜o Paulo, SP, Brazil { Departamento de Ana ´lises Clı ´nicas e Toxicolo ´gicas, Faculdade de Cie ˆncias Farmace ˆuticas, Universidade de Sa ˜o Paulo, Avenida Lineu Prestes 580, 05508-900, Sa ˜o Paulo, Brazil { Instituto de Medicina Tropical de Sa ˜o Paulo — Pre ´dio II, Laborato ´rio de Soroepidemiologia e Imunobiologia, Avenida Dr Ene ´as de Carvalho Aguiar, 470 4u andar, Cerqueira Ce ´sar, 05403- 000, Sa ˜o Paulo, SP, Brazil Received 1 June 2007, Revised 13 September 2007, Accepted 17 September 2007 The seroprevalence of Toxocara canis and risk factors for infection with this parasite were explored in a rural settlement in Sa ˜o Paulo state, Brazil. Total IgA and IgE levels in 79 subjects were determined by turbidimetry and chemiluminescence, respectively. Total counts of leucocytes and erythrocytes and differential counts of leucocytes were made by flow cytometry. ELISA for the detection of anti-Toxocara IgG, IgA and IgE were standardized using Toxocara excretory–secretory antigens (TES) obtained from the cultured second-stage larvae of T. canis. Seventeen (21.5%) of the subjects were found positive for anti-Toxocara IgG, with no significant differences in such seropositivity with age or gender. Thirty (38%) of the subjects showed eosinophilia and 70 (89%) had elevated levels of total IgE. Among the 17 subjects found seropositive for anti-Toxocara IgG, the percentage of leucocytes represented by eosinophils (P50.0069) and total levels of IgE (P50.0452) were positively correlated with the levels of anti-TES IgE. Although anti-TES IgA was detected in 10 (59%) of the subjects, there was no significant correlation between the levels of total IgA and those of Toxocara-specific IgA. Only one of the 17 subjects found positive for anti-Toxocara IgG had attended a secondary school and all but two belonged to households with monthly incomes of ,U.S.$100. In the study community at least, seropositivity may be related to poor living standards and lack of basic sanitary conditions. The presence of anti-Toxocara IgE and IgA may facilitate the diagnosis of toxocariasis and may well be useful for monitoring the success of treatment. Human toxocariasis is one of the most wide- spread and prevalent helminthiases in devel- oping and industrialized countries, thanks to a large and increasing number of final hosts. The disease is caused by saprozoonotic parasites of dogs (Toxocara canis) and cats (T. cati). Human infection, predominantly with T. canis, occurs when embryonated eggs are ingested following their hand-to- mouth transfer. The mammal-infective second-stage larvae (L 2 ) in the eggs hatch and penetrate the intestinal wall, migrat- ing through the soft tissues of the body and causing either ocular or visceral larva migrans (Magnaval et al., 2001; Despommier, 2003). The diagnosis of toxocariasis and sero- epidemiological surveys are largely based on clinical examinations and immunology, since the isolation of the larvae, from liver and eye tissue, for example, is often difficult. The serological test most commonly used is an ELISA for detecting IgG that reacts with Toxocara excretory–secretory antigens (TES; Magnaval et al., 2001; Despommier, Reprint requests to: L. E. Prestes-Carneiro. E-mail: luiz@unoeste.br; fax: z55 18 2291013. Annals of Tropical Medicine & Parasitology, Vol. 102, No. 4, 347–356 (2008) # 2008 The Liverpool School of Tropical Medicine DOI: 10.1179/136485908X278801