In eastern Asia, human fasciolosis appears to be sporadic. Few cases were documented in Japan, Koreas, Vietnam, and Thailand. Australia and the Oceania
In Australia, human fasciolosis is very rare (only 12 cases documented). In New Zealand, F. hepatica has never been detected in humans. Other animals
A number of drugs have been used in control fasciolosis in animals. Drugs differ in their efficacy, mode of action, price, and viability. Fasciolicides (drugs against Fasciola spp.) fall into five main chemical groups:Halogenated phenols: bithionol (Bitin), hexachlorophene (Bilevon), nitroxynil (Trodax)
Salicylanilides: closantel (Flukiver, Supaverm), rafoxanide (Flukanide, Ranizole)
Benzimidazoles: triclabendazole (Fasinex), albendazole (Vermitan, Valbazen), mebendazol (Telmin), luxabendazole (Fluxacur)
Sulphonamides: clorsulon (Ivomec Plus)
Phenoxyalkanes: diamphenetide (Coriban)Triclabendazole (Fasinex) is considered as the most common drug due to its high efficacy against adult as well as juvenile flukes. Triclabendazole is used in control of fasciolosis of livestock in many countries. Nevertheless, long-term veterinary use of triclabendazole has caused appearance of resistance in F. hepatica. In animals, triclabendazole resistance was first described in Australia, later in Ireland and Scotland and more recently in the Netherlands. Considering this fact, scientists have started to work on the development of new drug. Recently, a new fasciolicide was successfully tested in naturally and experimentally infected cattle in Mexico. This new drug is called Compound Alpha and is chemically very similar to triclabendazole.
Signs and symptoms
Humans
The course of fasciolosis in humans has 4 main phases:Incubation phase: from the ingestion of metacercariae to the appearance of the first symptoms; time period: few days to 3 months; depends on number of ingested metacercariae and immune status of host
Invasive or acute phase: fluke migration up to the bile ducts. This phase is a result of mechanical destruction of the hepatic tissue and the peritoneum by migrating juvenile flukes causing localized and or generalized toxic and allergic reactions. The major symptoms of this phase are:
Fever: usually the first symptom of the disease; 40–42 °C (104–108 °F)
Abdominal pain
Gastrointestinal disturbances: loss of appetite, flatulence, nausea, diarrhea
Urticaria
Respiratory symptoms (very rare): cough, dyspnoea, chest pain, hemoptysis
Hepatomegaly and splenomegaly
Ascites
Anaemia
Jaundice
Latent phase: This phase can last for months or years. The proportion of asymptomatic subjects in this phase is unknown. They are often discovered during family screening after a patient is diagnosed. Chronic or obstructive phase:This phase may develop months or years after initial infection. Adult flukes in the bile ducts cause inflammation and hyperplasia of the epithelium. The resulting cholangitis and cholecystitis, combined with the large body of the flukes, are sufficient to cause mechanical obstruction of the biliary duct. In this phase, biliary colic, epigastric pain, fatty food intolerance, nausea, jaundice, pruritus, right upper-quadrant abdominal tenderness, etc., are clinical manifestations indistinguishable from cholangitis, cholecystitis and cholelithiasis of other origins. Hepatic enlargement may be associated with an enlarged spleen or ascites.