title: Toxocara seropositivity, atopy and wheezing in children living in poor neighbourhoods in urban Latin American.
abstract: BACKGROUND
  Toxocara canis and T. cati are parasites of dogs and cats, respectively, that infect humans and cause human toxocariasis. Infection may cause asthma-like symptoms but is often asymptomatic and is associated with a marked eosinophilia. Previous epidemiological studies indicate that T. canis infection may be associated with the development of atopy and asthma.
  
  
  OBJECTIVE
  To investigate possible associations between Toxocara spp. seropositivity and atopy and childhood wheezing in a population of children living in non-affluent areas of a large Latin American city.
  
  
  METHODS
  The study was conducted in the city of Salvador, Brazil. Data on wheezing symptoms were collected by questionnaire, and atopy was measured by the presence of aeroallergen-specific IgE (sIgE). Skin prick test (SPT), total IgE and peripheral eosinophilia were measured. Toxocara seropositivity was determined by the presence of anti-Toxocara IgG antibodies, and intestinal helminth infections were determined by stool microscopy.
  
  
  RESULTS
  Children aged 4 to 11 years were studied, of whom 47% were seropositive for anti-Toxocara IgG; eosinophilia >4% occurred in 74.2% and >10% in 25.4%; 59.6% had elevated levels of total IgE; 36.8% had sIgE≥0.70 kU/L and 30.4% had SPT for at least one aeroallergen; 22.4% had current wheezing symptoms. Anti-Toxocara IgG was positively associated with elevated eosinophils counts, total IgE and the presence of specific IgE to aeroallergens but was inversely associated with skin prick test reactivity.
  
  
  CONCLUSIONS
  The prevalence of Toxocara seropositivity was high in the studied population of children living in conditions of poverty in urban Brazil. Toxocara infection, although associated with total IgE, sIgE and eosinophilia, may prevent the development of skin hypersensitivity to aeroallergens, possibly through increased polyclonal IgE and the induction of a modified Th2 immune reaction.
authors.affiliation: Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Bahia, Brazil.
authors.forename: Lívia Ribeiro
authors.initials: LR
authors.lastname: Mendonça
authors.forename: Rafael Valente
authors.initials: RV
authors.lastname: Veiga
authors.forename: Vitor Camilo Cavalcante
authors.initials: VC
authors.lastname: Dattoli
authors.forename: Camila Alexandrina
authors.initials: CA
authors.lastname: Figueiredo
authors.forename: Rosemeire
authors.initials: R
authors.lastname: Fiaccone
authors.forename: Jackson
authors.initials: J
authors.lastname: Santos
authors.forename: Álvaro Augusto
authors.initials: ÁA
authors.lastname: Cruz
authors.forename: Laura Cunha
authors.initials: LC
authors.lastname: Rodrigues
authors.forename: Philip John
authors.initials: PJ
authors.lastname: Cooper
authors.forename: Lain Carlos
authors.initials: LC
authors.lastname: Pontes-de-Carvalho
authors.forename: Maurício Lima
authors.initials: ML
authors.lastname: Barreto
authors.forename: Neuza Maria
authors.initials: NM
authors.lastname: Alcantara-Neves
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D001938:Brazil / Q000453:epidemiology; D002415:Cats; D002648:Child; D002675:Child, Preschool; D004285:Dogs; D004802:Eosinophilia / Q000453:epidemiology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology*; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D011204:Poverty Areas; D015995:Prevalence; D012135:Respiratory Sounds / Q000209:etiology*; D012882:Skin Tests; D011795:Surveys and Questionnaires; D014119:Toxocara / Q000276:immunology / Q000472:pathogenicity*; D014120:Toxocariasis / Q000150:complications* / Q000453:epidemiology*; D014505:Urban Population
chemical_list: D000909:Antibodies, Helminth; D007074:Immunoglobulin G; D007073:Immunoglobulin E