Interactions between helminth parasites and allergy

Purpose of review To review the findings of recent human studies of the association between helminth parasite infections and allergy and discuss their potential relevance to public health. Recent findings Different helminth parasites may have different effects on allergy that may depend on the timing or intensity of the exposure or host genetic factors. Infections with Trichuris trichiura in early life are associated with a reduced prevalence of allergen skin test reactivity later in life and infants of helminth-infected mothers have been reported to have a reduced prevalence of eczema. Hookworm infection has been associated with a reduced prevalence of asthma in Ethiopia. Several studies have reported that anti-Ascaris IgE is an important risk factor for asthma, but this could be explained by an enhanced ability of atopics to produce IgE. Toxocara infections may be associated with an increased risk of wheeze in some populations that may be caused by the host response to the parasite or by parasite-enhanced Th2 responses to aeroallergens. Summary Although helminth infections can modulate the host inflammatory response directed against the parasite, a causal association between helminths and atopic diseases remains uncertain.