Toxocara canis is a parasitic roundworm of particular public health concern. Eggs of Toxocara canis may be present in dog and cat faeces, which become infectious after being deposited for some weeks in the local environment.  Humans become infected after ingesting the eggs, by accident. In the human body, larvae do not become adult worms but rather can migrate to various tissues and organs, remaining either in a latent state or causing various clinical manifestations.

The clinical case here reported suggests how Toxocara canis may cause chronic symptoms, often considered allergic symptoms, the resolution of which requires corresponding anthelmintic therapy. Our allergologic evaluation therefore focused attention on those cases in which common allergologic treatments do not present a resolution, raising therefore the suspect of a possible under–lying parasitosis.

We examined a patient referred for dry cough and dyspena. The patient showed hypereosinophilia, but asthma symptoms improved after previously prescribed treatment with nasal steroid and formoterole/budesonide. Thus, tests for IGG antibodies Toxocara canis using ELISA and Western blot were recommended.   

The patient was positive for Toxocara canis and, therefore, anthelmintic therapy was prescribed. After treatment, the patient showed full remission of symptoms.  After treatment, we prescribed the same tests again, which were negative for Toxocara canis.

These findings suggest the possible role of Toxocara canis in inducing chronic symptoms, which may raise the suspect of a possible under–lying parasitosis, and which show remission after anthelmintic therapy.