Moniliformis moniliformis Infection in Two Florida Toddlers

Abstract

To the Editors: oniliformis moniliformis (thorny headed worm) is 1 of the 5 Acanthocephalan species widely distributed throughout the world. This helminth resides in the intestines of rodents, dogs, and cats, which serve as its definitive hosts. Infection with M. moniliformis is spread via intermediary hosts, primarily cockroaches, and beetles. Human infection with this organism is rare. The last reported case of human infection with M. moniliformis in the United States was in a boy from Pensacola, FL in 1989.1 We report 2 cases of M. moniliformis infection in central Florida. The first patient was a 23-month-old otherwise healthy girl with worms in her stool for 2 months. She was otherwise asymptomatic. She was treated for a presumed tapeworm infection with mebendazole, however, the worms persisted. The patient's stool sample contained a visible cream-colored worm which was approximately 20-cm long. The worm was segmented, with a beaded appearance, and did not have the typical flattened appearance of a tapeworm. Oval-shaped eggs measuring 60 × 83 μm were seen on microscopic examination. Based upon the morphology and measurement of the parasite and the ova, the worm was identified as M. moniliformis. Animal exposures included a dog and cat. She frequently put items, including insects, found on floor into her mouth. She was treated with three 11-mg/kg doses of pyrantel pamoate separated by 2-week intervals. No worms were seen after the third dose. She remains asymptomatic. The second patient was a 15-month-old girl from central Florida who also experienced asymptomatic passage of worms in the stool, identified as M. moniliformis (Figure). Animal exposures included a pet chinchilla as well as chickens, cows, dogs, cats, and young squirrels at her grandparent's farm. Her parents and grandparents had witnessed her putting cockroaches in her mouth on several occasions. The child was also was treated with mebendazole, followed by pyrantel pamoate after identification of the organism was made. No more worms were seen in the stool after treatment. The patient has continued to do well with no symptoms.FIGURE 1.: A, Macroscopic view of M. moniliformis from stool sample of patient 2. B, Microscopic view of M. moniliformis eggs from stool sample of patient 2.Human infection with any of the Acanthocephalan worms is rare, but is most commonly caused by infection with M. moniliformis and Macracanthorhyncus hirudinaeceus.2 Acanthocephalan worms possess unique physical characteristics helpful in identification. They lack a digestive tract, a coelom, and a circulatory system. They are also distinguished by their spinous retractile proboscis (“thorny head”), which enables attachment to the intestinal wall, and by their spindle shaped, pseudo-segmented body. Adult female worms measure 100 to 270 mm and males measure 40 to 130 mm. Their thick-walled, oval shaped eggs measure 85 to 118 × 40 to 52 μm.3 A wide range symptoms have been described, including diarrhea, weight loss, irritability, edema, weakness,4,5,6 and asymptomatic passage of worms.1,3,7 In many cases, there is a history of ingestion of a beetle, or a cockroach. Many cases are described in toddlers, who may be at particular risk because of their propensity to put nonfood objects into their mouths. ACKNOWLEDGMENT The authors thank Karen Kelly, MLS (ASCP) for specimen processing and images. Allison F. Messina, MD Division of Infectious Diseases Department of Pediatrics All Children's Hospital Frederick J. Wehle, Jr, MD Department of Pediatrics The Watson Clinic LLP Lakeland, FL Si Intravichit, MT, ASCP Kenneth Washington, MD Department of Pathology and Laboratory Medicine All Children's Hospital Saint Petersburg, FL