title: Effects of helminth co-infections on atopy, asthma and cytokine production in children living in a poor urban area in Latin America.
abstract: BACKGROUND
  Helminths are modulators of the host immune system, and infections with these parasites have been associated with protection against allergies and autoimmune diseases. The human host is often infected with multiple helminth parasites and most studies to date have investigated the effects of helminths in the context of infections with single parasite or types of parasites (e.g. geohelminths). In this study, we investigated how co-infections with three nematodes affect markers of allergic inflammation and asthma in children. We selected Ascaris lumbricoides and Trichuris trichiura, two parasites that inhabit the human intestine and Toxocara spp (Toxocara canis and/or T. cati), intestinal roundworms of dogs and cats that cause systemic larval infection in humans. These parasites were selected as the most prevalent helminth parasites in our study population.
  
  
  RESULTS
  36.4% of children were infected with one parasite; 12.7% with 2 and 5.2% with 3. Eosinophilia>4% and >10% was present in 74.3% and 25.5% of the children, respectively. Total IgE>200 IU/mL, sIgE≥0.70 kU/L and SPT positivity were present in 59.7%, 37.1% and 30% of the children, respectively. 22.7% had recent asthma (12.0% non-atopic and 10.7% atopic). Helminth infections were associated in a dose-dependent way to decrease in the prevalence of SPT and increase in eosinophilia, total IgE, and the production of the regulatory cytokine IL-10 by unstimulated peripheral blood leukocytes. No association with asthma was observed.
  
  
  CONCLUSIONS
  Helminth co-infections in this population were associated with increased markers of the Th2 immune response, and with a host immune regulatory phenotype that may suppress allergic effector responses such as immediate hypersensitivity reactions in the skin.
authors.affiliation: Departamento de Ciências da Biointeração, Instituto de Ciências da Saúde, Universidade Federal da Bahia, Salvador, Brazil. neuzalcantara@gmail.com.
authors.forename: Neuza Maria
authors.initials: NM
authors.lastname: Alcântara-Neves
authors.forename: Gabriela
authors.initials: G
authors.lastname: de S G Britto
authors.forename: Rafael Valente
authors.initials: RV
authors.lastname: Veiga
authors.forename: Camila A
authors.initials: CA
authors.lastname: Figueiredo
authors.forename: Rosimeire Leovigildo
authors.initials: RL
authors.lastname: Fiaccone
authors.forename: Jackson S
authors.initials: JS
authors.lastname: da Conceição
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 C
authors.initials: LC
authors.lastname: Pontes-de-Carvalho
authors.forename: Maurício Lima
authors.initials: ML
authors.lastname: Barreto
mesh_terms: D000818:Animals; D001249:Asthma / Q000097:blood / Q000150:complications* / Q000469:parasitology; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D002947:Cities; D060085:Coinfection / Q000097:blood / Q000150:complications* / Q000469:parasitology; D016207:Cytokines / Q000096:biosynthesis / Q000097:blood*; D003876:Dermatitis, Atopic / Q000097:blood / Q000150:complications* / Q000469:parasitology; D004802:Eosinophilia / Q000097:blood / Q000150:complications; D005260:Female; D006373:Helminthiasis / Q000097:blood / Q000150:complications; D006376:Helminths / Q000502:physiology*; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000150:complications / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D007843:Latin America; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D010271:Parasites / Q000502:physiology; D011203:Poverty; D012882:Skin Tests
chemical_list: D015415:Biomarkers; D016207:Cytokines; D007073:Immunoglobulin E