Soil-transmitted helminth parasites and allergy: Observations from Ecuador

Parasite Immunol. 2019 Jun;41(6):e12590. doi: 10.1111/pim.12590. Epub 2018 Oct 17.


There is considerable interest as to potential protective effects of soil-transmitted helminths (STH) against allergy and allergic diseases. Here, we discuss findings of studies done of the effects of STH parasites on atopy and allergic diseases in Ecuador. While cross-sectional studies have consistently shown a reduced prevalence of allergen skin prick test (SPT) reactivity among infected schoolchildren, the removal of these infections by repeated deworming did not affect SPT prevalence over the short-term (ie, 12 months) but may have increased SPT prevalence over the long-term (ie, 15-17 years). In the case of allergic symptoms, cross-sectional studies have generally not shown associations with STH and intervention studies showed no impact on prevalence. However, a birth cohort suggested that early STH infections might reduce wheeze by 5 years. Allergic sensitization to Ascaris, however, explained a significant proportion of wheezing among rural schoolchildren. Studies of the effects of STH on immune and inflammatory responses indicated a potential role of STH in contributing to more robust regulation. The effects of STH on allergy are likely to be determined by history of exposure over the life-course and by interactions with a wide variety of other infectious and non-infectious factors.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Ecuador
  • Helminthiasis / immunology*
  • Helminthiasis / parasitology
  • Helminths / immunology*
  • Humans
  • Hypersensitivity / immunology*
  • Hypersensitivity / parasitology
  • Observational Studies as Topic
  • Soil / parasitology*


  • Soil