48 - Tropical parasitic infestations

Abstract

Parasitic infections of the hepatobiliary system are relatively common in developing countries. The biliary tract is commonly infested by Ascaris lumbricoides, Echinococcus granulosus, Clonorchis sinensis, and Fasciola hepatica. Biliary tract involvement usually occurs during migration of the parasites through the intestinal tract (A. lumbricoides, C. sinensis). In some parasitoses, the route of entry into the biliary tract is via the liver (E. granulosus, F. hepatica). The clinical manifestations of biliary parasitoses are protean and range from mild cholestasis to acute cholangitis and cholangiocarcinoma. Therefore a high index of suspicion is required, along with cognizance of the varied clinical presentation, diagnostic modalities, and treatment approaches for various parasites that infest the biliary tract. Characteristic findings in noninvasive imaging modalities such as endoscopic ultrasonography and magnetic resonance cholangiopancreatography allow early diagnosis of biliary parasitosis. Although endoscopic cholangiopancreatography (ERCP) is an excellent diagnostic modality, it is mainly performed with a therapeutic intent now. The predominant indication of ERCP in these patients is persistent biliary obstruction with or without cholangitis. Endotherapy usually consists of sphincterotomy and clearance of the bile duct with a balloon or basket. In addition, temporary biliary stent placement may be required in some cases with persistent biliary fistula after surgery for hydatid cyst. In the absence of complications arising as a result of biliary obstruction, conservative management alone is sufficient. Anthelminthic drugs remain an important component of treatment and in prevention of reinfestation in endemic regions.