Ascariasis is one of the most common helminthic diseases worldwide. One third of the world population has or have previously experienced an infestation by Ascaris lumbricoides, but the disease has a higher prevalence in developing countries, especially in communities with poor economic conditions. Parasitic infestations of the biliary tree are a common cause of biliary obstruction in tropical countries and can lead to complications such as recurrent pyogenic cholangitis, pancreatitis, hepatic abscesses, and septicemia. Ascaris lumbricoides organisms, which normally reside in the jejunum, are actively motile and can invade the papilla, thus migrating into the bile duct and causing biliary obstruction and secondary infection.
The diagnosis of biliary Ascariasis is usually made by ultrasound. The roundworms can be observed by ultrasound as tubular structures with echogenic walls and a hypoechogenic line inside, in the biliary ducts and the gallbladder. Sometimes movement can be seen in these images. It is less frequent to observe the parasites in the liver parenchyma, where they cause secondary abscesses. This condition is more commonly seen in children with malnutrition.