Fluke infections can affect the area of the body where they live, such as the intestines, biliary system, liver, or lungs. Many times light infections can be asymptomatic. Heavier infections can cause abdominal pain, fever, diarrhea, ascites, swelling, malaise, inflammation, eosinophilia, and other symptoms, depending on the species.
The genus Schistosoma may cause its own set of symptoms. For instance, S. mansoni will affect the liver, S. haematobium will affect the bladder, etc. However, it is not the worms themselves that cause the symptoms, but the inflammatory responses to the eggs that they produce in great numbers. The worms tend to be "invisible" to the immune response, but their eggs are highly immunogenic. Eggs can damage and cause scarring in the liver, intestine, bladder, and sometimes lung and central nervous system if the eggs enter the circulation.
Various anti-helminthic drugs are available to treat fluke infections. For instance, triclabendazole is used to treat Fasciola, and Praziquantel is used to treat Fasciolopsis. Praziquantel is the usual treatment for Schistosomiasis. Prevention involves avoiding contact with bodies of water.
Since worms are eukaryotic, multicellular animals like us, a drug must be used that targets structures that the parasite has that we do not. As an example, praziquantel can affect the worm's tegument (outer covering). The
CDC parasite site has more complete information on treatment.
