You wake to the all-too familiar symptoms of an imperfect meal; or maybe it’s the stomach flu. This time, the belly pain and diarrhea are not from a bad tuna sandwich, rather an intestinal parasite has made itself at home in your gut. You're not alone as the tiny protozoan called Dientamoeba fragilis infects people worldwide, from all walks of life. And while you share a lot with your pooch, this little gift did not come from him.
Despite more than a century of research, scientists still do not fully understand the life cycle of Dientamoeba fragilis, nor how it infects humans. Some suggest that people become infected by ingesting material contaminated with the parasite, which is shed in the feces of its host. Another widely debated theory has D. fragilis catching a ride on the egg of a helminth -- a group of parasitic worms that includes pinworms -- and then ingested along with the egg. Despite these uncertainties, scientists agree that humans seem to be its preferred host, though D. fragilis has been found in lowland gorillas, some other monkeys, sheep and pigs; more specifically, pigs from Italy. Beginning in 1952 and as recently as 2008 and 2012, scientists have tried, and failed, to find Dientamoeba in dogs, or any household pet for that matter. So unless you're relatively close to a lowland gorilla, or frolic with pigs in Italy, you're not going to contract this little guy from your four-legged family members.
Listen to Your Mother
Your close relationship with Fido -- and his waste -- will not result in Dientamoeba infection, but it can put you at risk of contracting a parasite capable of jumping between humans and pets. The Companion Animal Parasite Council suggests that people who frequently have contact with contaminated soils -- gardeners, plumbers and sunbathers -- are at greater risk of acquiring organisms like hookworms or roundworms. To greatly minimize this risk, protect your pet with year-round, broad-spectrum parasite control. Remember to bring a sample of Fido's stool to his annual physical. Lastly, follow this age-old parental wisdom: Always wash your hands after you, or your dog, use the restroom.
- Parasitology: The Ambiguous Life of Dientamoeba Fragilis: the Need to Investigate Current Hypotheses on Transmission
- International Journal of Infectious Diseases: Clinical and Microbiological Features of Dientamoebiasis in Patients Suspected of Suffering from a Parasitic GastroIntestinal Illness: A Comparison of Dientamoeba Fragilis and Giardia Lamblia Infections
Barbara Cozzens has been writing for more than 20 years. Her work has appeared in publications of the Nature Conservancy, the World Bank Group, National Geographic Society, Duke University and others. Cozzens holds a Bachelor of Arts in biology from Colgate University and a Master of Environmental Management from Duke University's Nicholas School of the Environment.