title: Atopy is inversely related to schistosome infection intensity: a comparative study in Zimbabwean villages with distinct levels of Schistosoma haematobium infection.
abstract: BACKGROUND
  The hygiene hypothesis suggests that parasitic infections protect against allergic diseases by modulating the host's immune responses. Experimental studies indicate that this protection depends on the intensity of parasitic infection, but this observation has not been tested in human populations. The aim of this study is to investigate whether the intensity of Schistosoma haematobium infection is related to atopic responses and whether this relationship differs between populations with distinct parasite transmission dynamics.
  
  
  METHODS
  The study was conducted in two villages with different Schistosoma haematobium transmission dynamics, i.e. high (n = 365) and low (n = 307) transmission. Allergic reactivity to the common house dust mite (Dermatophagoides pteronyssinus) was measured by skin prick tests and allergen-specific IgE and IgG4 quantified by enzyme-linked immunosorbent assay. Atopic responses were related to current infection intensity and schistosome transmission levels.
  
  
  RESULTS
  Schistosome infection intensity was negatively associated with the skin prick reactivity, mite-specific IgE and the ratio IgE/IgG4 in the high-transmission village. However, when only low levels of infection were analyzed in the 2 villages, there was no correlation between mite-specific responses and infection intensity.
  
  
  CONCLUSIONS
  The relationship between schistosome infection and atopic responses is dependent on the intensity of current schistosome infection. Thus, consistent with results from animal models, with an increasing parasite burden, the immunoregulation of immune responses to allergens appears to become more pronounced.
authors.affiliation: Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, Edinburgh, UK. N.Rujeni@sms.ed.ac.uk
authors.forename: Nadine
authors.initials: N
authors.lastname: Rujeni
authors.forename: Norman
authors.initials: N
authors.lastname: Nausch
authors.forename: Claire D
authors.initials: CD
authors.lastname: Bourke
authors.forename: Nicholas
authors.initials: N
authors.lastname: Midzi
authors.forename: Takafira
authors.initials: T
authors.lastname: Mduluza
authors.forename: David W
authors.initials: DW
authors.lastname: Taylor
authors.forename: Francisca
authors.initials: F
authors.lastname: Mutapi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000485:Allergens / Q000276:immunology; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D040002:Dermatophagoides pteronyssinus / Q000276:immunology*; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008297:Male; D008875:Middle Aged; D012548:Schistosoma haematobium / Q000276:immunology*; D012553:Schistosomiasis haematobia / Q000276:immunology* / Q000469:parasitology / Q000635:transmission*; D012882:Skin Tests; D055815:Young Adult; D015030:Zimbabwe
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D007074:Immunoglobulin G; D007073:Immunoglobulin E