Abstract
SummaryThere 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.
Highlights
Over the past 20 years we have conducted a programme of research in Ecuador exploring how helminths may affect the development of allergy among children
There is an unresolved debate on whether soil-transmitted helminth (STH) parasites protect against allergy and allergic diseases including asthma, potentially of great importance in populations where improvements in hygiene and widespread use of anthelmintic drugs are expected to reduce the prevalence of STH prevalence dramatically over the coming years
We have reviewed a series of epidemiological and immunological studies done in Ecuador of the effects of endemic STH parasites on the development of allergic diseases and the allergic inflammatory response
Summary
Summary There is considerable interest as to potential protective effects of soil-transmitted helminths (STH) against allergy and allergic diseases. 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. A birth cohort suggested that early STH infections might reduce wheeze by 5 years. 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
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