A middle-aged man (in his fifties) presented with recurrent right upper quadrant abdominal pain for 5 weeks, associated with nausea, night sweats and low-grade fever. His work involved frequent travel to Indonesia, China and parts of Latin America, although mainly confined to the big cities rather than to rural parts of these countries. He had gone to each of these countries (Brazil in Latin America) in the 2 months prior to the onset of his illness. Blood tests performed at a neighbouring medical facility showed marked eosinophila (39% of a WBC count of 13.1K), with mildly elevated alkaline phosphatase (183 U/L) and low albumin (30 g/L). Blood cultures were negative but a CT scan of the liver showed 3 hypodense lesions – the largest being approximately 3 cm x 3.5 cm – and gallbladder stones. One hypodense lesion had been subjected to radiologically-guided drainage, with negative cultures but eosinophils seen on cytology. A course of metronidazole (flagyl) had not helped.
- What is the likely diagnosis?
- How would you confirm the diagnosis?
- What would be the treatment of choice?
[Updated 8 August 2015]
This man, who is well traveled, presented with eosinophilic liver abscesses and hyper-eosinophilia. This is almost always due to a parasitic infection, in this context, either Clonorchis sinensis or Fasciola hepatica. Both are liver flukes acquired through the ingestion of contaminated food. The life cycle of Clonorchis sinensis is shown here at the CDC website, whereas that of Fasciola hepatica is shown here. C. sinensis infection occurs after consumption of undercooked (or salted/pickled) infected freshwater fish, whereas F. hepatica infection occurs after consumption of infected water plants – most commonly watercress. Among the Chinese in Singapore, watercress is commonly cooked as a soup with pork ribs (西洋菜汤). Prolonged cooking will kill the metacercariae of F. hepatica and thereby prevent human infection. However, if the watercress is only blanched (sometimes done and added in to the boiled soup because it looks nicer with a fresh green colour) or eaten raw in salad, infection can occur.
Diagnosis is confirmed in two ways – firstly, if the parasite (or sections of the flukes) are seen on histology of the liver abscess. This is extremely unlikely if only radiological drainage is performed (the adult flukes are about the size of the tip of the thumb – 13mm to 30mm in length). Or else serological testing can be performed. These tests are not done in Singapore, unfortunately, although the local labs can and do send the serum to accredited overseas laboratories for testing, with a turnaround time of up to 3 weeks. Sending off stool for detection of eggs has low yield.
The World Health Organisation only recommends praziquantel for the treatment of C. sinensis. However, albendazole has been tried in China, and is also listed on the CDC website for the treatment of C. sinensis. It is far easier to obtain albendazole in Singapore compared to praziquantel.
Unfortunately, only triclabendazole appears to be effective for the treatment of F. hepatica infection. It is not routinely available in Singapore, and has to be imported.
The patient in this vignette was found to be serologically positive for F. hepatica, and flew to a neighbouring country to purchase the drug triclabendazole, following which he had an uneventful recovery.