Toxocariasis is the most common helminth infection in industrialized countries. Previous studies have suggested a relationship between Toxocara infection and the development of atopic diseases including asthma. The study aimed to investigate whether Toxocara infection is more prevalent among asthma patients and whether antihelmitic treatment in Toxocara infected asthmatics results in better asthma control.
Methods:
The study included 163 patients diagnosed with asthma and a control group consisting of 38 healthy subjects. All subjects were tested for Toxocara IgG (ELISA) and underwent skin prick testing with a panel of aeroallergens. Stool samples were examined for helminth ova. Asthma patients also underwent pulmonary function testing and validated asthma control questionnaires were administered. Asthmatic patients received guideline-directed treatment, those with positive IgG for Toxocara also received treatment with albendazole. All patients in the asthma group were reassessed after 6 months.
Results:
Toxocara seropositivity in patients with asthma was 39% and this was significantly more than Toxocara seropositivity among non-asthmatic subjects (P < 0.001). We found no statistically significant difference between the rates of allergic sensitization in Toxocara-positive asthmatic patients compared to those Toxocara-negative. At the first visit asthmatic patients infected with Toxocara displayed lower forced expiratory volume in 1s (FEV1) and poorer asthma control as indicated by questionnaire scores than Toxocara-negative patients, and the differences were found to be statistically significant. Reassessment at 6 months showed no difference in FEV1 and questionnaire scores between the two groups.
Conclusions:
Our results confirm previous observations of higher Toxocara seropositivity rates in asthmatic patients. Our data also suggest that Toxocara infected asthmatic patients have diminished lung function compared to those not infected and that they may benefit from antihelmintic treatment.