(Opisthorchis viverrini, Clonorchis sinensis)
|Parasite: Opisthorchis viverrini, Clonorchis sinensis|
|Common name: Southeast Asian liver fluke, Chinese or Oriental liver fluke|
|Hosts: fish eating mammals such as dogs, cats, pigs, humans.|
|Pre-patent period: 3-4 weeks|
|Location of adults: bile duct, liver, gallbladder, pancreatic duct|
|Distribution: Southeast Asia and Far East Asia|
|Transmission route: eating raw or undercooked freshwater fish infected with metacercariae|
In most cases, liver fluke infection in dogs is asymptomatic. When clinical signs occur they include lethargy, diarrhoea and dehydration. Migration of immature flukes can cause acute hepatitis and pancreatitis.
The diagnosis of liver flukes infection in dogs is based on the detection of characteristic operculated eggs with a fully developed miracidium (Fig 1) by faecal sedimentation (SOP 4).
Off-label use of praziquantel 40 mg/kg given as a single oral dose is reported effective at killing adult liver flukes.
Owners should be advised not to feed their dog raw or undercooked freshwater fish. For further control options, refer to the General Considerations and Recommendations section.
Humans become infected through the ingestion of undercooked fish infected with metacercariae of liver flukes. Dogs may act as reservoirs for human infection by contaminating the environment with liver fluke eggs. Humans infected with liver fluke are mostly asymptomatic however chronic infection may lead to biliary and hepatic disease and cholangiocarcinoma.