Contamination of fresh water sources by parasites poses an increased risk of infection to humans and animals. Researchers at Texas A&M University are working on improving methods of diagnosis and treatment of water-borne parasitic infections. The focus is on Heterobilharzia americana, a flatworm found in Texas and Louisiana that infects dogs and horses. A rising number of reported cases of canine infections prompted Dr. Karen Snowden, a professor in the Department of Veterinary Medicine and Biomedical sciences, to initiate this investigation.
Also known as the “blood fluke,” this parasite affects the intestinal system of dogs. Dr. Jessica Rodriguez, a graduate student, examined medical records of 238 dogs that were diagnosed in the last 22 years. The symptoms of infection are non-specific and include diarrhea, bloody stool, vomiting, and loss of appetite. Complications occur when the parasite enters the liver. Often, veterinarians have to resort to invasive methods like surgery before a diagnosis can be made. Dr. Rodriguez told the TAMU Times that, “We hope to increase veterinarians’ awareness of this parasite so that more dogs are diagnosed with non-invasive tests and before they become very ill.”
Apart from dogs, raccoons serve as a natural host for this parasite. Feces from infected animals contain parasite eggs, which hatch in fresh water and infect snails. Upon maturation, the larva leaves the snail and swims freely in the water until it infects a dog. The parasite migrates from the lung to the liver and finally to the intestine where they lay eggs. The eggs then get shed with the feces, allowing the cycle to repeat.