Alive Strongyloides stercoralis in biliary fluid in patient: A case report

Abstract

BACKGROUND

Strongyloides stercoralis (S. stercoralis), is a prevalent parasitic worm that infects humans. It is found all over the world, particularly in tropical and subtropical areas. Strongyloidiasis is caused mostly by the parasitic nematode S. stercoralis. Filariform larvae typically infest humans by coming into contact with dirt, such as by walking barefoot or through exposure to human waste or sewage.

CASE SUMMARY

A 35-year-old male presented to our department with a 10-year history of abdominal pain and diarrhea, which had recently recurred for the past 3 months. A computed tomography (CT) scan revealed acute cholecystitis accompanied by a gallbladder stone. Additionally, a 5 mm stone was found obstructing the lower portion of the common bile duct, resulting in dilatation of both the intrahepatic and extrahepatic bile ducts to 8 mm, in contrast to a previous CT scan. Endoscopic ultrasonography revealed a prominent echogenicity in the lower portion of the common bile duct. Consequently, an endoscopic retrograde cholangiopancreatography was conducted via endoscopic sphincterotomy and balloon dilatation. The microscope revealed the presence of viable S. stercoralis rhabditiform larvae in the biliary fluid. We documented an uncommon instance of S. stercoralis infection in the biliary fluid of a patient suffering from gallstones and cholangitis.

CONCLUSION

The film we created provides a visual representation of the movement of the living S. stercoralis in biliary fluid.

Key Words: Strongyloides stercoralis; Biliary fluid; Cholangitis; Endoscopic retrograde cholangiopancreatography; Case report

Core Tip: We documented an uncommon occurrence of Strongyloides stercoralis (S. stercoralis) infection in the biliary fluid of a patient with gallstones and cholangitis. The film we recorded provides a visual representation of the movement of a living S. stercoralis in biliary fluid, a phenomenon that has not been previously documented. It is hypothesized that the presence of a living S. stercoralis could affect the process of bile extraction, leading to an increased likelihood of gallstone formation.

INTRODUCTION

Strongyloides stercoralis (S. stercoralis) is a prevalent nematode parasite that infects humans and is found globally, particularly in tropical and subtropical areas[1]. An estimated global population of approximately 600 million people may be affected by S. stercoralis infection[2]. Strongyloidiasis is caused mostly by the parasitic nematode S. stercoralis. Filariform larvae typically invade humans via contact with soil, such as by walking barefoot or through exposure to human waste or sewage[3]. The migration from the dermal entrance to the pulmonary and gastrointestinal systems might result in acute or chronic manifestations. Patients may experience irritation or itching, as well as recurring hives at the location where the larva entered the body[4]. Transpulmonary larval migration can cause temporary bronchitis, which is characterized by symptoms such as a dry cough, wheezing, and difficulty breathing[5]. Acute gastrointestinal strongyloidiasis can result in symptoms such as epigastric discomfort, abdominal distension, stomach pain, constipation, and diarrhea. Approximately half of individuals with persistent infection may exhibit no symptoms or experience only minor symptoms. Gastrointestinal symptoms such as anorexia, nausea, vomiting, abdominal discomfort, changes in bowel movements, and diarrhea are frequently observed in symptomatic patients[4,6].

Some people may experience recurring gastrointestinal symptoms. In endoscopy, an infection with S. stercoralis in the duodenum and/or colon can cause superficial ulceration, leakage, and redness of the mucosa. These symptoms can resemble inflammatory bowel disease[7]. Typically, the biliary system does not play a role in the life cycle of S. stercoralis. Several cases in which S. stercoralis was detected in the biliary fluid have been reported, leading to cholecystitis, obstructive jaundice, refractory pancreatitis, and even widespread portal vein thrombosis[8,9]. Additionally, certain findings have indicated that infection with S. stercoralis may increase the likelihood of developing biliary tract cancer[10]. There is still uncertainty regarding the connection between S. stercoralis infection and the biliary system. Instances of live S. stercoralis in biliary fluid are infrequently recorded and difficult to establish, primarily due to the challenge of accessing the bile duct. Confirmation typically requires procedures such as endoscopic retrograde cholangiopancreatography (ERCP), percutaneous transhepatic cholangial drainage (PTCD), or surgical intervention. We present a case where we discovered a living S. stercoralis in the biliary fluid of a patient with gallstones and cholangitis following ERCP. This research presents the first documented evidence of S. stercoralis activity in biliary fluid via video footage. It is hypothesized that S. stercoralis can travel from the duodenum to the biliary system via the duodenal papilla. This migration may trigger an immunological reaction, perhaps resulting in chronic infection or the development of cancer.

CASE PRESENTATION

Chief complaints

Chronic abdominal pain and diarrhea persisting for 10 years, with recent recurrence over the past 3 months.

History of present illness

The patient had no prior history of visiting an epidemic area. Colonoscopy revealed the presence of scattered erosions and superficial ulcers on the mucosa of the colon. As a result, the individual was diagnosed with inflammatory bowel disease and S. stercoralis infection a decade earlier. The patient received treatment with albendazole and prednisone. He experienced notable improvement in his symptoms. He took prednisone sporadically. Five years ago, the individual experienced intensified abdominal pain and diarrhea, along with symptoms of nausea, vomiting, and the presence of mucus and pus in his stool. During that period, a laboratory analysis revealed an increased eosinophil count of 0.99 × 10⁹/L, which accounted for 14.3% of the total white blood cell count. He was diagnosed with incomplete ileus and an infection caused by S. stercoralis. Albendazole was administered once more to eliminate the S. stercoralis infection. He was discharged after receiving the treatment due to symptom relief. The patient suffered from abdominal pain in the area around the belly button, along with loose stools occurring 4-5 times a day for a period of 3 months. He was readmitted to our hospital. Laboratory investigations revealed a white blood cell count and eosinophil count within the normal range.

History of past illness

The patient had no special past illnesses.

Personal and family history

The patient had no special family history. The patient had no prior history of visiting epidemic areas. The patient had no prior history of eating raw fish or meat.

Physical examination

The patient had experienced abdominal pain in the area around the belly button for the past 10 years. During hospitalization, the patient experienced acute discomfort in the upper right abdomen accompanied by vomiting and fever. Murphy’s sign was positive.

Laboratory examinations

The human immunodeficiency virus antibody test was negative. The levels of cytomegalovirus-DNA and Epstein-Barr virus-DNA were within the normal ranges. The values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase, total bilirubin (TBIL), albumin, and amylase were within the normal ranges. Stool examination revealed the presence of viable rhabditiform larvae of S. stercoralis when observed under a microscope.

Imaging examinations

Endoscopy revealed diffuse erosions in the duodenum and inflammation with a rough surface in the colon and terminal ileum (Figure 1). Biopsy pathology revealed the presence of infiltrating neutrophil cells in both the glandular epithelium and stroma. Figure 2 shows the presence of eggs and immature forms of S. stercoralis in the glandular cavity, which is shown by their strong affinity for basophilic staining. He had palliative care and experienced amelioration of the symptoms. During hospitalized, he experienced acute discomfort in the upper right abdomen accompanied by vomiting and fever. Murphy’s sign was positive. Computed tomography (CT) scan revealed acute cholecystitis with a gallbladder stone and a 5 mm stone obstructing the lower portion of the common bile duct. Compared with a previous CT scan, this obstruction caused dilation of both the intrahepatic and extrahepatic bile ducts to 8 mm (refer to Figure 3). Endoscopic ultrasonography revealed a prominent echogenicity in the lower portion of the common bile duct. Consequently, ERCP was performed, involving the use of endoscopic sphincterotomy and balloon dilation. Two openings were detected in the duodenal papilla, showing the distinct connection of the pancreatic duct and biliary duct to the intestinal wall, without a shared channel (see Figure 4). Throughout the process, biliary fluid was gathered for laboratory analysis and culture. Two dark brown stones measuring 6 mm-7 mm in diameter were removed from the common bile duct (Figure 4). Endoscopic nasobiliary drainage was carried effectively. The biliary fluid was examined under the microscope, where alive S. stercoralis rhabditiform larvae were discovered (Figure 5 and Video 1).

Figure 1 Endoscopy revealed diffuse erosions in the duodenum.

Figure 2 Strong affinity for basophilic staining (arrow) in the glandular cavity indicating the presence of eggs and immature forms of Strongyloides stercoralis.

Figure 3 Computed tomography scan showing a gallstone obstructing the lower portion of the common bile duct and a gallbladder stone. A and B: Gallstone (arrow) in the common bile duct; C: Gallbladder stone (arrow).

Figure 4 Two openings were detected in the duodenal papilla, revealing the distinct connection of the pancreatic duct and biliary duct to the intestinal wall. A: Duodenal papilla; B: Black stone dragged into the duodenal cavity; C: Gallstones (arrow) in the common bile duct during endoscopic retrograde cholangiopancreatography; D: Bile fluid extracted during endoscopic retrograde cholangiopancreatography; E: Endoscopic nasobiliary drainage.

Figure 5 Alive Strongyloides stercoralis rhabditiform larvae discovered in bile fluid, as depicted under a microscope.

FINAL DIAGNOSIS

The final diagnosis included: (1) S. stercoralis infection; (2) Cholangitis; and (3) Choledocholithiasis.

TREATMENT

The patient received a daily dose of 200 μg/kg, considering his weight of 77 kg. Consequently, a two-day course of ivermectin was prescribed at a rate of 15 mg per day.

OUTCOME AND FOLLOW-UP

At the one-month follow-up, no S. stercoralis was detected on fecal examination.

DISCUSSION

Infection of the biliary system by S. stercoralis is infrequent because accessing the bile duct is difficult. Direct evidence of S. stercoralis infection in biliary fluid is rarely recorded, unless the bile juice is extracted via ERCP or PTCD. We searched for case reports on S. stercoralis infection in biliary fluid that were published in PubMed. Only three case reports were found, as indicated in Table 1 and referenced in[8,11,12]. Two individuals experienced cholecystitis accompanied by biliary blockage, while another patient received a diagnosis of acute pancreatitis. All of the patients underwent ERCP; however, biliary fluid was successfully removed via ERCP in only one patient. Rhabditiform larvae were detected in the bile samples obtained from the two subjects who underwent PTCD, and in one case, S. stercoralis infection was confirmed by examining the biliary fluid taken during ERCP. Our case represents the first documentation of the presence of live rhabditiform larvae in biliary fluid obtained from ERCP via video technology. The current case experienced symptoms of acute pain in the upper right abdomen, accompanied by fever and abnormal liver function characterized by increased levels of AST, ALT, and TBIL. These symptoms were the result of gallstones obstructing the common bile duct, leading to cholangitis. The biliary fluid test revealed the presence of live S. stercoralis rhabditiform larvae, indicating that the larvae had migrated from the gut to the biliary tract through the duodenal papilla. Importantly, the biliary system is not normally involved in the life cycle of S. stercoralis. The living S. stercoralis exhibited erratic movement and “swimming” within the bile juice present in the biliary duct and gallbladder. This caused a disruption in the normal flow of biliary fluid, leading to the formation of biliary sludge. The presence of living S. stercoralis could affect the process of bile extraction, hence facilitating the development of gallstones. In this particular example, no occurrence of pancreatitis was noted before or after ERCP due to the separation of the biliary system and pancreatic duct. Ikeuchi et al[9] reported a case in which S. stercoralis infection led to obstructive jaundice and pancreatitis that did not respond to treatment. S. stercoralis was not detected in the bile juice but was detected in the biopsy of the duodenal papilla[9]. The author hypothesized that infection with S. stercoralis could cause papillitis, which in turn could lead to the development of acute cholangitis and recurrent episodes of acute pancreatitis. Additionally, other occurrences of S. stercoralis infection impacting the papilla, bile duct, and pancreas have been reported, resulting in symptoms such as jaundice, cholecystitis, or pancreatitis. However, the evidence was not convincing because there were no direct observations of biliary drainage. S. stercoralis infection can be detected in certain cases through the examination of a duodenal papilla biopsy or stool sample[10,13-15]. However, in our study, both the duodenum and biliary fluid contained S. stercoralis larvae, which served as conclusive evidence that S. stercoralis infection impacted the biliary tract, leading to cholangitis. Unfortunately, we were unable to obtain the gallstone for additional studies to confirm the presence of S. stercoralis larvae in the stones.

Table 1 Case reports on Strongyloides stercoralis infection in biliary fluid.

Ref.	Year	Diagnosis	Biliary sample	Form of S. stercoralis	Stool	Gallstone	Dilation of bile duct	Dilation of pancreatic duct	ERCP
Delarocque et al[12]	1994	Biliary obstruction	PTCD	Rhabditiform larvae	Yes	No	Yes	No	Unsuccessful
Perez-Jorge and Burdette[11]	2008	Acute pancreatitis	ERCP	S. stercoralis	Not mention	No	No	No	Yes
Filkins et al[8]	2017	Cholecystitis and extensive portal vein thrombosis	PTCD	Rhabditiform larvae	Not Mention	No	Yes	No	Normal
Our case	2024	Gallstones and cholangitis	ERCP	Rhabditiform larvae	Yes	Yes	No	No	Yes

S. stercoralis: Strongyloides stercoralis; PTCD: Percutaneous transhepatic cholangial drainage; ERCP: Endoscopic retrograde cholangiopancreatography.

CONCLUSION

We documented an uncommon occurrence of S. stercoralis infection in the biliary fluid of a patient suffering from gallstones and cholangitis. The film we created provides a visual representation of the movement of living S. stercoralis in biliary fluid, a phenomenon that had not been previously documented. Acquiring additional information on the life habits of S. stercoralis may prove beneficial. Additional evidence concerning the life cycle and pathogenesis of S. stercoralis is needed.