Doctors noted that the problems began with a raised, itchy rash and mild diarrhea. The red, wavy skin lesions originated in his perianal region, then began to migrate under his skin, reaching all over his trunk and limbs. Doctors outlined individual red squiggles on his skin with pen and noted that 24 hours later, the squiggles had moved.

The shifting rash—and the identification of Strongyloides stercoralis larvae in a stool exam—clenched the diagnosis. Doctors prescribed the man the anti-parasitic ivermectin, and the rash and diarrhea improved.