Case Report: Toxocariasis Manifesting as Eosinophilic Pleural Effusion

Toxocariasis is a prevalent zoonosis caused by infection with the larvae of Toxocara canis or Toxocara cati. It ranges in severity from mundane to life-threatening, depending on organ involvement. The lungs are often affected, manifesting as coughing, wheezing, and chest pain. However, pleural effusions rarely occur in patients with pulmonary toxocariasis. We report the case of a 74-year-old man with highly suspected toxocariasis who presented with an eosinophilic pleural effusion and eosinophilia. He developed dyspnea and a right-sided pleural effusion. Thoracentesis revealed an exudative effusion containing numerous eosinophils. The pleural effusion continued to increase, and the eosinophilia rapidly progressed. Although the patient had not recently had contact with animals or known exposure to contaminated food, water, or soil, toxocariasis was confirmed by positive serological test results for anti-Toxocara antibodies in the serum and pleural effusion. The patient was cured with albendazole treatment for 28 days. The pleural effusion and eosinophilia resolved and did not recur. Clinicians should consider toxocariasis in the differential diagnosis of patients presenting with eosinophilic pleural effusions.