Trichuris trichiura Infection

Continuing Education Activity

Trichuris trichiura, also known as the human whipworm, is a roundworm that causes trichuriasis in humans. Infections involving a high-worm burden typically include distal parts of the large intestine. This activity reviews the evaluation and management of trichuriasis and highlights the role of interprofessional team members in collaborating to provide well-coordinated care and enhance outcomes for affected patients.

Objectives:

• Describe the epidemiology of trichuriasis infections.
• Review the presentation of a patient with trichuriasis infection.
• Outline the treatment options for trichuriasis.
• Summarize the importance of improving care coordination among interprofessional team members to improve outcomes for patients affected by trichuriasis infection.

Introduction

Trichuris trichiura, also known as the human whipworm, is a roundworm that causes trichuriasis in humans. It is referred to as the whipworm because it looks like a whip with wide handles at the posterior end. The whipworm has a narrow anterior esophagus and a thick posterior anus. The worms are usually pink and attach to the host via the slender anterior end. The size of these worms varies from 3 to 5 cm. The female is usually larger than the male.[1]

The female worm can lay anywhere from 2,000 to 10,000 eggs per day. The eggs are deposited in soil from human feces. After 14 to 21 days, the eggs mature and enter an infective stage. If humans ingest the embryonated eggs, the eggs start to hatch in the human small intestine and utilize the intestinal microflora and nutrients to multiply and grow. The majority of larvae move to the cecum, penetrate the mucosa, and mature into adulthood. Infections involving a high-worm burden will typically involve distal parts of the large intestine.[1]

Trichuriasis is 1 of 3 well-documented soil-transmitted helminth (STH) infections; the other 2 are ascariasis and hookworm infection. It is considered a neglected tropical disease by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).

Children appear to be vulnerable to the parasite and poor sanitation is associated with a heavy disease burden. In parts of Asia and Africa where hygiene conditions are lacking, the prevalence of human whipworm is very high.

Etiology

The most common cause of trichuriasis is the ingestion of infected eggs that are found in soil. This is often due to poor sanitary conditions, including open defecation and using human feces as fertilizer. Some recent studies show that people with certain chromosome traits may be predisposed or have increased susceptibility to acquiring trichuriasis.[2]

Epidemiology

The egg of the whipworm is the infective stage, and favorable conditions for its maturation are a warm and humid climate. This is why most of the disease burden is seen in tropical climates, specifically in Asia and less often, in Africa and South America. It is also found in rural parts of the southeast United States. It is estimated that worldwide there are between 450 million to 1 billion active cases with most diagnosed in children. It is thought there is partial protective immunity that develops with age.[3][4] 

Worldwide, almost half of the 5 billion people that live in developing countries are infected with at least one soil-transmitted helminth species, and 10% with two or more helminth species.[4] Young boys tend to be most affected as they are more likely to play outside and exhibit pica behavior.

Pathophysiology

The worm is acquired through fecal-oral transmission. A human host consumes infected eggs, typically while eating and drinking contaminated food or water. Once the embryonated eggs are ingested, the larvae hatch in the small intestine. From there they migrate to the large intestine, where the anterior ends lodge within the mucosa. This leads to cell destruction and activation of the host immune system, recruiting eosinophils, lymphocytes, and plasma cells. This causes the typical symptoms of rectal bleeding and abdominal pain. The parasite usually takes up residence in the terminal ileum and cecum. In some patients, the entire colon and rectum may be infested with the worm. The worm may live anywhere from 1-4 years without treatment. Eggs are expelled in the host feces unembryonated. The eggs will become embryonated in 2–4 weeks and are then infective.[5]

History and Physical

Patients with trichuriasis will typically reside in or have visited areas that are endemic to the whipworm. The patient will usually complain of abdominal pain, painful passage of stools, abdominal discomfort, and mucus discharge. Diarrhea and constipation are also common presenting complaints. Nocturnal passage of stools is a common occurrence. Many patients are asymptomatic as the clinical disease is dependent on parasite burden.[5] Rectal prolapse is known to occur in a heavy infestation. Children may develop anemia, growth deficiency, and even impaired cognitive development. The latter 2 are thought to be due to iron deficiency and poor nutrition secondary to worm burden and are not a direct cause of the infestation.[4][6]

In general, the physical examination of these patients is normal. The exam may reveal signs of anemia, including pallor. Patients with a prolonged infection may have clubbing.

Evaluation

Laboratory diagnosis of trichuriasis is based on the microscopic examination of stool samples to determine the presence and, if possible, the number of eggs.[5] During a heavy infestation, the eggs may be seen on a stool saline smear, but this has a low sensitivity. The WHO recommends using the Kato-Katz method for counting eggs per unit weight of feces. They also recommend using 2 slides per sample.[5] One weakness of stool sample examination is that from the time the eggs are ingested to the development of the mature worm, there is a time lag of about three months. During this period, there may be no signs of an infestation and the stools may not show evidence of any eggs or shedding.

Stool samples may also demonstrate red blood cells (RBCs), and white blood cells (WBCs), specifically eosinophils. A complete blood count may show anemia.

There have been case reports of patients reporting symptoms in areas that have adequate resources where the diagnosis has been made with sigmoidoscopy or colonoscopy. The classic finding is the “coconut cake rectum” from white bodies of adult worms dangling from inflamed mucosa.

There have recently been studies that show a "whipworm dance" on ultrasound which is when the lumen of the appendix wriggles continuously. This is a modality that can easily be used in resource-poor settings.[7]

Polymerase chain reaction (PCR) assays are currently being developed and used in research settings. This has improved the specificity and sensitivity of detecting the whipworm.[5][8]

Treatment / Management

The treatment of trichuriasis is with mebendazole or albendazole. The suggested dose of mebendazole is 100 mg twice a day for 3 days or albendazole is 200 to 400 mg twice a day for 3 days. Mebendazole has been shown to be more effective and is considered first-line treatment. Albendazole and mebendazole have an inhibitory effect on tubulin polymerization which results in the loss of cytoplasmic microtubules. Ivermectin 200 mcg/kg daily can be used; however, it is not as effective as mebendazole and albendazole. Ivermectin binds with high affinity to the glutamate-gated chloride channel which occurs in invertebrate nerve and muscle cells, causing an increase in permeability of cell membrane to chloride ions with hyperpolarization of the nerve and muscle cells. The hyperpolarization leads to paralysis and death of the parasite.

It is important to keep in mind that there are often co-infections with other helminths so treatments with multiple medications may be required. The household members of an infected patient are at low risk but if the home has no sanitation, then the clinician should consider the possibility of transmission to others.

Differential Diagnosis

Given that a whipworm infection can cause abdominal pain, there includes a large differential of abdominal processes. These include but are not limited to appendicitis, colitis, cholecystitis, and perforated intestine. Bloody diarrhea can be caused by inflammatory bowel disease (IBD), bacterial pathogens, or other soil-transmitted helminths. The constellation of cognitive disruption, constipation, and abdominal pain can also be seen with lead toxicity and is an important consideration for children. Other parasitic helminth infections should also be included in the differential including hookworms and ascariasis as these are frequently present as a co-infection.

Prognosis

The whipworm tends to be more resistant to treatment than other helminths, with some studies listing cure rates as low as 28% to 36%. Whipworms can still be present after treatment, however, it is thought that a low worm count leads to no significant disease burden. While trichuriasis is not fatal, it can cause anemia and nocturnal stooling. Many patients develop colitis and malabsorption. Deficiencies of fat-soluble vitamins are not uncommon. Children may have poor growth and rectal prolapse.

Complications

Trichuris dysentery syndrome can be found in children (with no adult cases noted) and is seen when there is a very high worm burden. This often leads to diarrhea, tenesmus, iron deficiency anemia, and poor growth. The poor growth is typically secondary to poor nutrition and consequently causes cognitive delay.

Postoperative and Rehabilitation Care

Adults and children should be treated appropriately for the anemia they experience. Many global organizations stress the importance of increased education for children who have been treated for whipworm infection. Not doing so keeps them behind in school when compared to peers of their same age group who were not infected.

Deterrence and Patient Education

The best way to prevent trichuriasis is to improve personal hygiene, wash all fruit and vegetables, and educate patients and families about the importance of handwashing. Global initiatives have been started which focus on improved sanitation, poverty reduction, and periodic preventative chemotherapy. Preventative chemotherapy for STH infections is recommended by the WHO and is frequently provided as a mass drug administration (MDA) to school children. Albendazole and mebendazole are most commonly used as a single dose.[5] The development of a vaccine has been studied, but no vaccines against or T. trichiura are currently being evaluated in clinical trials.[5][9]

Pearls and Other Issues

Ongoing studies are being performed with regards to the hygiene hypothesis which has shown improved symptoms of diseases such as Crohn’s or ulcerative colitis with the use of the Trichuris suis (pig whipworm) ova.[10][11][12]

Enhancing Healthcare Team Outcomes

The diagnosis of whipworm is not easy as the infection is not often encountered in the US. The disorder is best managed by an interprofessional team that includes an infectious disease expert, internist, gastroenterologist, and a primary care clinician. Following treatment, the education of the patient is vital to prevent a recurrence. The infectious disease nurse should emphasize the need to improve personal hygiene, wash all fruit and vegetables, and teach everyone about the importance of handwashing. Global initiatives have been started which focus on improved sanitation, poverty reduction, and periodic preventative chemotherapy.[13]

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References

1.

Bansal R, Huang T, Chun S. Trichuriasis. Am J Med Sci. 2018 Feb;355(2):e3. [PubMed: 29406051]

2.

Williams-Blangero S, Vandeberg JL, Subedi J, Jha B, Dyer TD, Blangero J. Two quantitative trait loci influence whipworm (Trichuris trichiura) infection in a Nepalese population. J Infect Dis. 2008 Apr 15;197(8):1198-203. [PMC free article: PMC4122289] [PubMed: 18462166]

3.

Truscott JE, Turner HC, Anderson RM. What impact will the achievement of the current World Health Organisation targets for anthelmintic treatment coverage in children have on the intensity of soil transmitted helminth infections? Parasit Vectors. 2015 Oct 22;8:551. [PMC free article: PMC4618937] [PubMed: 26490544]

4.

Ranjan S, Passi SJ, Singh SN. Prevalence and risk factors associated with the presence of Soil-Transmitted Helminths in children studying in Municipal Corporation of Delhi Schools of Delhi, India. J Parasit Dis. 2015 Sep;39(3):377-84. [PMC free article: PMC4554591] [PubMed: 26345038]

5.

Else KJ, Keiser J, Holland CV, Grencis RK, Sattelle DB, Fujiwara RT, Bueno LL, Asaolu SO, Sowemimo OA, Cooper PJ. Whipworm and roundworm infections. Nat Rev Dis Primers. 2020 May 28;6(1):44. [PubMed: 32467581]

6.

Brooker SJ, Mwandawiro CS, Halliday KE, Njenga SM, Mcharo C, Gichuki PM, Wasunna B, Kihara JH, Njomo D, Alusala D, Chiguzo A, Turner HC, Teti C, Gwayi-Chore C, Nikolay B, Truscott JE, Hollingsworth TD, Balabanova D, Griffiths UK, Freeman MC, Allen E, Pullan RL, Anderson RM. Interrupting transmission of soil-transmitted helminths: a study protocol for cluster randomised trials evaluating alternative treatment strategies and delivery systems in Kenya. BMJ Open. 2015 Oct 19;5(10):e008950. [PMC free article: PMC4611208] [PubMed: 26482774]

7.

Vijayaraghavan SB. Sonographic whipworm dance in trichuriasis. J Ultrasound Med. 2009 Apr;28(4):555-6. [PubMed: 19321687]

8.

Pilotte N, Papaiakovou M, Grant JR, Bierwert LA, Llewellyn S, McCarthy JS, Williams SA. Improved PCR-Based Detection of Soil Transmitted Helminth Infections Using a Next-Generation Sequencing Approach to Assay Design. PLoS Negl Trop Dis. 2016 Mar;10(3):e0004578. [PMC free article: PMC4814118] [PubMed: 27027771]

9.

Zawawi A, Else KJ. Soil-Transmitted Helminth Vaccines: Are We Getting Closer? Front Immunol. 2020;11:576748. [PMC free article: PMC7565266] [PubMed: 33133094]

10.

Shears RK, Bancroft AJ, Sharpe C, Grencis RK, Thornton DJ. Vaccination Against Whipworm: Identification of Potential Immunogenic Proteins in Trichuris muris Excretory/Secretory Material. Sci Rep. 2018 Mar 14;8(1):4508. [PMC free article: PMC5851985] [PubMed: 29540816]

11.

Schölmerich J, Fellermann K, Seibold FW, Rogler G, Langhorst J, Howaldt S, Novacek G, Petersen AM, Bachmann O, Matthes H, Hesselbarth N, Teich N, Wehkamp J, Klaus J, Ott C, Dilger K, Greinwald R, Mueller R., International TRUST-2 Study Group. A Randomised, Double-blind, Placebo-controlled Trial of Trichuris suis ova in Active Crohn's Disease. J Crohns Colitis. 2017 Apr 01;11(4):390-399. [PMC free article: PMC5881737] [PubMed: 27707789]

12.

Garg SK, Croft AM, Bager P. Helminth therapy (worms) for induction of remission in inflammatory bowel disease. Cochrane Database Syst Rev. 2014 Jan 20;2014(1):CD009400. [PMC free article: PMC10767620] [PubMed: 24442917]

13.

Maldonade IR, Ginani VC, Riquette RFR, Gurgel-Gonçalves R, Mendes VS, Machado ER. Good manufacturing practices of minimally processed vegetables reduce contamination with pathogenic microorganisms. Rev Inst Med Trop Sao Paulo. 2019 Feb 14;61:e14. [PMC free article: PMC6376928] [PubMed: 30785568]

Disclosure: Avinash Viswanath declares no relevant financial relationships with ineligible companies.

Disclosure: Siva Naga Yarrarapu declares no relevant financial relationships with ineligible companies.

Disclosure: Mollie Williams declares no relevant financial relationships with ineligible companies.