Going against the grain here, I think this is Toxocariasis (organism: Toxocara canis)
Reasoning: (from UTD): Toxocariasis (also called visceral larva migrans [VLM]) refers to human infection caused by helminths that are not natural human parasites. Toxocariasis occurs as a result of human infection with the larvae of the dog ascarid, Toxocara canis, or, less commonly, the cat ascarid, Toxocara cati. VLM is principally a disease of young children, especially those with exposure to playgrounds and sandboxes contaminated by dog or cat feces.
Transpulmonary migration of Strongyloides larvae can produce dry cough, throat irritation, dyspnea, wheezing, and hemoptysis. Similarly, pulmonary involvement of toxocariasis may cause dyspnea, wheezing, and a chronic, nonproductive cough. Strongyloides larvae may be detected in stool, sputum, bronchoalveolar lavage fluid, or pleural fluid
Considering that it's a 3-year-old boy and that ingestion is the primary mode of transmission, I think Toxocariasis is the better diagnosis here
submitted by โcassdawg(1780)
I think this is Strongyloides stercoralis (threadworm) is a roundworm whose larvae live in soil and who can cause pulmonary disease. It has the ability to penetrate skin from the soil but can also be obtained by ingesting feces contaminates soil (FA2020 p159) https://www.cdc.gov/parasites/strongyloides/gen_info/faqs.html
Most intestinal roundworms are fecal-oral route except strongyloides which can also penetrate skin, hookworm (necator americanus) which only penetrates skin, and trichinella which can come from undercooked meats (especially pork) but whose symptoms do not match that of the patient. Trichinella larvae enter the blood stream and infect muscle and can also cause trichinosis with fever, nausea, vomiting, periorbital edema, and myalgia.