Medication Summary
New fasciolicides are being used in small numbers of children with encouraging results and minimal toxicities. Triclabendazole is the drug of choice and was approved in the United States in 2019 after being available from the CDC for many years. [37] On the basis of limited data from the CDC, nitazoxanide might be effective therapy in some patients. Praziquantel, which is active against most trematodes (flukes), typically is not active against Fasciola parasites. Therefore, the CDC does not recommend praziquantel therapy for fascioliasis. [38]
Anthelmintics
Class Summary
Parasite biochemical pathways are different from the human host; thus, toxicity is directed to the parasite, egg, or larvae. The mechanism of action varies within the drug class. Antiparasitic actions may include the following:
- Inhibition of microtubules causes irreversible block of glucose uptake
- Tubulin polymerization inhibition
- Depolarizing neuromuscular blockade
- Cholinesterase inhibition
- Increased cell membrane permeability, resulting in intracellular calcium loss
- Vacuolization of the schistosome tegument
- Increased cell membrane permeability to chloride ions via chloride channels alteration
Triclabendazole (Egaten)
Triclabendazole is an anthelmintic agent. The mechanism by which triclabendazole exhibits its effect against Fasciola species is not fully elucidated. Studies in vitro and/or in infected animals suggest that triclabendazole and its active metabolites (sulfoxide and sulfone) are absorbed by the tegument of the immature and mature worms, leading to a decrease of the resting membrane potential, inhibition of tubulin function, and inhibition of protein and enzyme synthesis. It is indicated for treatment of fascioliasis in patients aged 6 years or older.
Nitazoxanide (Alinia)
Limited data suggest nitazoxanide might be effective therapy in some patients. It interferes with pyruvate:ferredoxin oxidoreductase (PFOR), essential to anaerobic energy metabolism.
Corticosteroids
Class Summary
Corticosteroids may ameliorate the treatment course in children with severe acute phase infection.
Prednisolone (Pediapred, Delta-Cortef, Econopred)
A short course that is given for 2 d preceding fasciolicidal therapy in children with severe acute phase infection is reported anecdotally to ameliorate the course of the illness and to decrease fever, pain, pruritus, and toxicity.
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Life cycle of Fasciola hepatica. Immature Fasciola eggs are discharged in the biliary ducts and in the stool (1). Eggs become embryonated in water (2), eggs release miracidia (3), which invade a suitable snail intermediate host (4), including the genera Galba, Fossaria and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts (4a), rediae (4b), and cercariae (4c)). The cercariae are released from the snail (5) and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress (6). After ingestion, the metacercariae excyst in the duodenum (7) and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adult flukes (8). Courtesy of the CDC's DPDx, Division of Parasitic Diseases and Malaria.
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Adult Fasciola hepatica fluke stained with carmine (30 mm by 13 mm). Courtesy of the CDC's DPDx, Division of Parasitic Diseases and Malaria.
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Fossaria bulamoides, a snail host for F hepatica in the western United States. Courtesy of the CDC's DPDx, Division of Parasitic Diseases and Malaria (Conchology, Inc, Mactan Island, Philippines).
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Fasciola hepatica egg in an unstained wet mount (400x magnification). F hepatica eggs are broadly ellipsoidal, operculated, and measure 130-150 μm by 60-90 μm. Courtesy of the CDC's DPDx, Division of Parasitic Diseases and Malaria.
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Adult of F hepatica observed with ERCP imaging in the common bile duct of a human patient. Courtesy of the CDC's DPDx, Division of Parasitic Diseases and Malaria (Dr. Subhash Agal, Kokilaben Dhirubhai Ambani Hospital, Mumbai, India).
