The role of Toxocara larva migransin hypereosinophilia with unknown origin in patients referred to laboratories

Background: Toxocariasis is a parasitic infection in dogs and cats, and human gets infected with larva migrants when embryonated eggs are accidentally ingested. Migration of toxocara larvae to tissues causes inflammatory responses (visceral, ocular and cerebral) and eosinophilia increase in blood. This study was aimed to investigate the human toxocariasis, one of the possible causes of hypereosinophilia with an unknown origin.

Methods: This case-control study was performed on 100 hypereosinophilic patients (cases) and 100 people with normal eosinophil count (controls) that referred to hematology department of laboratories of Arak University of Medical Sciences in 2012. Epidemiological data were collected by a questionnaire and diagnosis was performed using excreted-secreted antigens of Toxocara (TES Ag - ELISA).

Results: Positive test for toxocariasis in hypereosinophilic patients was 16% and in patients with normal eosinophil count was zero (P=0.001). There was no statistically significant difference between groups in terms of gender, age, residential place, occupation and education level (P>0.05). However, there was a significantly higher history of contact with dogs and consumption of unclean fruits and vegetables in the infected patients (p<0.05). The mean of eosinophilia in patients with toxocariasis showed a significant difference compared with that of eosinophilia in patients not infected with toxocariasis (p=0.001).

Conclusion: The results confirmed the role of toxocariasis in hypereosinophilic patients with unknown origin, and eosinophilia can be considered to analyze and treat toxocariasis.