Fortunately there are no square worms for their sharp edges would be most painful. It is the tiny filariform larvae that live in sandy soil, especially in the southeastern U.S., that infect sunbaters, children and outdoor workers. Eggs, found in animal feces, develop in the soil to the larval stage. At the point of entry, reddish papules develop. As the larvae migrate through the skin very pruritic, serpiginous tracts develop that advance several millimeters or centimeters each day.
Symptoms persist several weeks or months and are self limiting.
Intestinal infection may also occur with enteritis. Diagnosis is primarily clinical. Biopsy shows eosinophilic inflammation, usually without the parasite. Larvae can occur in sputum or gastric washings with pneumonia. Visceral larval migrans is due to the dog roundworm Toxacara canis.