An Unpleasant Souvenir: Whipworm as an Incidental Finding During a Screening Colonoscopy

Abstract

Trichuriasis is a neglected tropical disease caused by Trichuris trichiura that spreads through the ingestion of embryonated eggs in contaminated soil, water, or food. In nonendemic areas, T trichiura infestation is very rare and sporadic and is often diagnosed in immigrants from endemic countries such as the Philippines. Whipworms feed on human blood and also erode the colonic mucosa, thereby evoking an inflammatory response. In milder forms, trichuriasis can be asymptomatic and often an incidental diagnosis on screening colonoscopy. Heavily infested patients usually present with abdominal pain, nausea, vomiting, tenesmus, chronic diarrhea, iron deficiency anemia, or stunted growth. T trichiura worms can be removed with biopsy forceps during a colonoscopy; however, most patients require a course of albendazole, mebendazole, or ivermectin. We describe a unique case of T trichiura as an incidental finding during a screening colonoscopy. The whipworms were retrieved using biopsy forceps and the patient was treated with albendazole. At the time of the colonoscopy, the patient did not exhibit any specific symptoms related to the worm infestation.

Introduction

Trichuris trichiura is a common soil-transmitted helminth that causes trichuriasis in human hosts.^1-3 It is one of more than 70 recognized species of Trichuris, with a long history of association with humans, as evidenced by the presence of its eggs in coprolites from archeological sites. ² Trichuris trichiura is transmitted via ingestion of embryonated eggs in contaminated soil or food and can cause a long-term infection.^2-4 Trichuriasis is endemic in tropical and subtropical countries as the causative agent thrives well in warm and humid climate.^2,5 This parasitic infection is more prevalent in areas with poor sanitation and limited access to clean water ² such as sub-Saharan Africa, India, China, and the Caribbean. ⁶ The severity of the symptoms has a positive correlation with the burden of the worms within the human gastrointestinal tract. ⁶ Signs and symptoms range from no symptoms to profuse diarrhea, abdominal pain, hematochezia, tenesmus, anemia, and rectal prolapse in severe cases.^1,3,4

Identification of T trichiura eggs in stool specimens is the primary diagnostic method especially in symptomatic patients. ³ Colonoscopy with biopsy has also been employed in cases where there is a high index of suspicion for trichuriasis despite a negative stool test. ³ Like in our case, T trichiura has also been found incidentally on screening colonoscopies. ³ Treatment involves the use of antihelminthic medications such as albendazole, mebendazole, and ivermectin, with the duration of treatment depending on the severity of the infection.^1,3 Endoscopic removal with biopsy forceps has also been reported in some cases. ⁷ Herein, we describe a unique case of a geriatric Asian female with a history of peptic ulcer disease who was found to have T trichiura worm during a screening colonoscopy. The parasite was treated with a 3-day course of oral albendazole, and posttreatment stool ova and parasite test results were negative.

Case Report

A 71-year-old female with a medical history of asthma, hypertension, and peptic ulcer disease presented to our ambulatory center for screening colonoscopy and an esophagogastroduodenoscopy (EGD) due to a dilated pancreatic duct and pancreatic cyst recently seen on imaging. The patient was in her usual state of health until 2 years ago when she experienced dull pain on the left side of her abdomen. The abdominal pain was intermittent, nonradiating, and associated with watery diarrhea, and a 30-pound weight loss over a few months. She denied experiencing nausea, vomiting, melena, hematochezia, or tenesmus. The patient stated that she attributed the pain to gastric ulcers and the weight loss to stress. Since it was at the start of the COVID-19 pandemic, the patient was unable to see a doctor due to fear of exposing herself to the virus. She stayed in the Philippines until international travel resumed.

When she returned to the United States 2 years later, the patient visited her doctor for evaluation of abdominal pain, and the blood work was significant for elevated pancreatic enzymes. Abdominal ultrasound showed a 1.5 × 1.9 × 1.7 cm hypoechoic focus in the pancreatic tail concerning for a pancreatic cyst versus cystic mass. An abdominal magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) without contrast showed distention of the pancreatic duct throughout the tail extending to a lesion in the body measuring 1.5 × 1.5 × 1.5 cm and worrisome for neoplasm. Also seen was the cystic lesion in the pancreatic tail of the pancreas measuring 1.2 × 1.4 × 1.1 cm concerning for a sequela of pancreatitis or an intraductal papillary mutinous neoplasm.

While undergoing further workup, the patient continued to experience occasional dull pain in the left lower abdomen, but without diarrhea. She was referred to an interventional gastroenterologist for an EGD with endoscopic ultrasound-guided fine-needle aspiration, which revealed pancreatic abnormalities consistent with atrophy of the entire pancreas. The pancreatic duct had a dilated endosonographic appearance in the entire pancreas. The pancreatic duct measured up to 6 mm in diameter. A 1.9 cm cystic lesion was observed in the pancreatic tail.

Given the history of colonoscopy with polypectomy 5 years ago, the patient also underwent a screening colonoscopy, which showed nonbleeding internal hemorrhoids and a single nonbleeding colonic angioectasia that was treated with argon plasma coagulation to prevent bleeding (Figure 1). Worms were found in the ascending colon and in the cecum (Figure 1) and were removed using cold forceps for histology. The examined portion of the ileum was normal. Histopathological examination revealed a colonic mucosa with eosinophilia and active colitis consistent with the patient’s parasitic infestation. The morphology of the parasite was consistent with T trichiura (whipworm). The patient was treated with oral albendazole 400 mg daily, for 3 days. Stool ova and parasite tests after the treatment were negative.

Figure 1.

Endoscopic image showing worms in the ascending colon (panels A and B), a single medium-sized localized angioectasia in the sigmoid colon (panel C), and nonbleeding internal hemorrhoids on retroflexion (panel D).

Molecular testing showed AccuCEA: 648 ng/mL, amylase: 485 U/L with no KNAS or GNAS mutations. On routine follow-up, the patient continued to complain of lower abdominal pain and weight loss. Repeat imaging of the abdomen demonstrated 4.7 × 8.0 × 4.8 cm pancreatic body and tail mass with extensive invasion of the surrounding vasculature. Two weeks later, the patient underwent a laparoscopic peritoneal washing, laparoscopic biopsy of the pancreatic mass, subclavian chemo port placement, and diagnostic laparoscopy. Cytology was positive for malignant cells consistent with pancreatic adenocarcinoma. The patient is currently undergoing neoadjuvant chemotherapy with FOLFIRINOX (folinic acid, fluorouracil, irinotecan hydrochloride, and oxaliplatin) and is estimated to complete 6 to 8 cycles before repeat imaging for restaging. She continues to have the lower abdominal pain which improves with gabapentin and is most likely due to the pancreatic cancer.

Discussion

Trichuriasis is a neglected parasitic infection caused by the whipworm T trichiura and is endemic in tropical regions due to a warm and humid climate.^2,8 It is estimated that 500 million people are infected worldwide, with at least 1 billion people at risk of infection every year. ⁹ Trichuriasis cases in nonendemic countries are sporadic and related to international travel to endemic countries. ⁹ Our patient for example, had recently traveled to Asia where she spent at least 2 years. Trichuriasis is acquired through fecal-oral transmission when a human host consumes a water or food contaminated with T trichiura eggs.^3,4 These eggs eventually hatch in the small intestines and migrate to the large intestines. Their presence activates an immune response that is responsible for the recruitment of eosinophils, lymphocytes, and plasma cells. The parasite usually resides in the terminal ileum and cecum; however, it is not uncommon for the entire colon and rectum to be involved. The adult worm lays eggs, which will ultimately be shed in the feces. ²

T trichiura infestation is usually without symptoms, but a higher worm burden can lead to intestinal mucosal injury.^8,10 Symptoms include loss of appetite, weight loss, abdominal pain and distension, bloody diarrhea, and tenesmus.^2,7 Chen et al ¹¹ reported an interesting case of T trichiura as an endoscopic finding in a farmer with a 6-month history of abdominal pain and a positive fecal blood test. Complications of untreated or unresolved trichuriasis include iron deficiency anemia, severe dehydration, asthenia, rectal prolapse, and trichuris dysentery syndrome (TDS).^2,6,7,12 Zanwar et al ¹² described a unique case of TDS in a pediatric patient mimicking inflammatory bowel disease (IBD). The patient presented with bloody stools and generalized abdominal pain for 2 months, and blood work was significant for severe microcytic anemia and eosinophilia. Diagnostic colonoscopy revealed numerous worms in the entire colon, and the infection was resolved with oral albendazole. Our patient had a short course of watery diarrhea while in the Philippines but none was reported while in the United States. Abdominal pain, which persisted even after treatment was most likely due to the pancreatic cancer. At the time of the colonoscopy, the patient did not exhibit any specific symptoms related to the worm infestation.

A comprehensive history and physical examination can lead to a timely diagnosis of trichuriasis or related parasitic infections. This investigation is augmented with blood work, an infectious stool workup, and in some cases, a colonoscopy. Eosinophilia on a complete blood count, albeit unspecific, typically raises a suspicion of a parasitic infection. ³ Microcytic anemia may be seen in long-term infections as the parasite damages the intestinal mucosa and feeds on blood. T trichiura eggs can be observed on stool microscopic examinations as barrel-shaped ova.^10-12 In endemic regions, the World Health Organization (WHO) recommends the use of the KATO-KATZ technique to quantify the burden of T trichiura eggs per gram of stool samples for a quicker and lower-cost diagnsosis.^8,13 Stool ova and parasite test has a very low sensitivity (2.7%-6.4%), thus, symptomatic patients with negative stool analysis warrant a colonoscopy or sigmoidoscopy to confirm a diagnosis.^1,3,11 On colonoscopy, the white worms can be seen attached to the mucosa in the ascending colon or cecum.^1,2 Dangling worms with their anterior portions threaded into the colonic mucosa give the classic “coconut cake rectum” look. ⁸ Tokmak et al ¹⁰ reported a unique case of trichuriasis that was first seen on a computed tomography (CT) scan as an irregular and nodular marked thickening of the cecum and ascending colon. The diagnosis was confirmed on colonoscopy and histopathology. A repeat CT scan 6 months after treatment revealed a colonic wall with normal thickness.

Once a diagnosis of trichuriasis is confirmed, treatment modalities may range from endoscopic removal to medications, or both. In nonendemic areas, colonoscopy serves as an important diagnostic and therapeutic tool, allowing direct visualization and retrieval of worms attached to the mucosa at their anterior ends.^1,14,15 Ona et al ¹⁴ described a case series of 2 unrelated Bangladeshi women who were found to have whipworm infection on a diagnostic colonoscopy. The 2 patients presented with abdominal pain, anorexia, and iron deficiency anemia, and the worms were removed using biopsy forceps. The patients’ symptoms resolved with albendazole. Kim et al ¹⁵ also described a case of long-term TDS in a young North Korean defector that was managed with endoscopic worm retrieval and albendazole. Similarly in our case, the whipworms were removed with biopsy forceps, and the patient was treated with albendazole to ensure complete eradication of the parasite.

In endemic regions, trichuriasis is treated with a 3-day course of albendazole 400 mg or mebendazole 500 mg, or mebendazole 100 mg twice daily. ¹⁶ Mebendazole, given at 100 mg twice daily for 3 days, shows a 70% success rate, with a second course recommended if no cure is achieved within 3 to 4 weeks. ⁶ Albendazole, though slightly less effective, offers better adherence as a single-dose regimen, potentially achieving cure rates of up to 80% when extended to 3 days. ⁶ For severe infections resistant to standard treatment, therapeutic colonoscopy with pincers is effective, ensuring successful outcomes. ⁵ Combination therapies, such as albendazole with ivermectin, have promising potential particularly in pediatric patients. ⁶ Monitoring treatment effectiveness is very important due to the partial efficacy of anthelmintic drugs against T trichiura, necessitating close follow-up for appropriate intervention. ¹⁶ In cases of severe anemia secondary to T trichiura infection, iron supplementation is recommended as a supportive measure. ¹⁶ Ensuring patient compliance is essential, with home visits by health care professionals if needed, especially in challenging follow-up scenarios. ⁶ Proper patient education on hygiene practices is critical to prevent reinfection, especially in endemic regions.^3,16

Conclusion

Trichuriasis is a neglected parasitic infection caused by T trichiura worms and is endemic to tropical and subtropical regions. Trichuris trichiura infection spreads via the fecal-oral route as the embryonated eggs are ingested in a contaminated medium. Although, trichuriasis is largely asymptomatic, some patients may present with gastrointestinal symptoms and iron deficiency anemia. Trichuris trichiura infestation in the United States is extremely rare and sporadic, thus it is often an incidental finding on screening colonoscopy. Trichuriasis is treated endoscopically and with antihelminthic medications such as albendazole, mebendazole, or ivermectin.