Diagnosis: Dipylidium caninum infection. The sample tapeworm was M cm in length and was longer than it was wide (figure 1). On examination in the microbiology laboratory, it was determined that the segment was most consistent with D. caninum. Both the patient and his brother were treated with single doses of oral praziquantel (10 mg/kg). Shortly after receiving treatment, the patient passed what was described as a "ball of worms" by his father. These worms were collected by the father and submitted to the microbiology laboratory (figures 2 and 3). On examination, there were 3-4 tapeworms that were identified as D. caninum. The patient is currently doing well and has no evidence of residual infection. D. caninum is an intestinal tapeworm, typically found in dogs and cats, that occasionally infects humans. Dipylidium species are also known as the dog tapeworm, cat tapeworm, cucumber tapeworm, or double-pore tapeworm. Humans become accidental hosts on ingesting an infected flea. This zoonotic disease should be suspected on observation of motile proglottids the size of rice grains in a stool specimen. Onethird of recognized infections occur in children <6 months of age, but such infections may still be underrecognized in children [1, 2]. D. caninum infection is often suspected on the basis of the description of proglottids in the child's stool. The usual description is that they resemble grains of rice or cucumber seeds in size and shape [3, 4]. Because of their ability to migrate from the anus independent of defecation, proglottids are often noticed actively moving in the child's stool. Patients are classically asymptomatic, although diarrhea, abdominal pain, and anal pruritis have been described in association with this infection [5]. This case demonstrates the benign presentation of D. caninum infection in an infant. Figure 2. A close-up of a Dipylidium caninum proglottid demonstrating the bilateral uterine pores (arrows) (original magnification, x4).