Systematic review and meta-analysis of the association of infection with Toxocara canis with atopy and asthma

Abstract

The human toxocariasis is the most important cosmopolite helminth infection in the world. The infection can modulate the immune response of the infected paratenic host, and it is suggested that it is an important risk factor for the development of asthma and be associated with increased levels of different markers of atopy. The aim of this study was to conduct a systematic review and meta-analysis of the association between human toxocariasis with asthma and atopic diseases. The literature search identified 1705 papers on the association of Toxocara spp with asthma, Then, 24 papers were selected based on the inclusion and exclusion criteria, following the PRISMA protocols. These papers served to analyze association data as a risk factor for increased asthma and investigate the association of this infection with the appearance of atopy markers (specific IgE). The results did not indicate association between asthma and Toxocara spp seropositivity, although there was a positive trend (OR 1.47; 95% CI 0.92-2.33). However, when studies were classified by type a positive association in the case-control type studies was found (OR 1.69; 95% CI 1.06-2.70). Furthermore, there was a positive association with this atopic marker in the analysis of the association of toxocariasis with specific IgE (OR 1.77; 95% CI 1.19-2.64). The evidence found was not entirely conclusive regarding the possibility of having T. canis infection as a risk factor for the development of asthma, although there is a positive statistical trend. On the other hand, the association with specific IgE results supports previous findings in the literature, where helminth infections can stimulate the production of this type of antibody, leading to a positive association with atopy.