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1. 1
Worm infections
of the large intestine
Rahajeng N. Tunjungputri, MD, MSc
Department of Parasitology
Faculty of Medicine Diponegoro University
2012

2. Outline
2
 Epidemiology
 Trichuris trichiura
 Enterobius vermicularis
 Gastrodiscoides hominis

3. Epidemiology – Trichuris trichiura
3
 800 million people infected worldwide
 Children living in poverty in the tropics and subtropics
 It is most common in poor rural communities and areas in
which sanitary facilities are lacking and hands, food, and drink
are easily contaminated
 Many people harbor infections with both Trichuris and
Ascaris
 In up to 10% of patients in endemic areas worm burden may
be high (up to 200 worms/pts) and suffering from disease
 Genetic studies: 25% of the variation in susceptibility to
infection with T. Trichiura is due to genetic factors

4. Worldwide distribution of T. trichiura
4

5. Epidemiology – Enterobius vermicularis
5
 Enterobius vermicularis, or pinworm, is highly prevalent
throughout the world
 infecting about 10% of population in developed countries,
the infection rate in children is even higher
 US: E. vermicularis is the most common of all helminthic
infections (42 million cases in 1980s); prevalence 15-50% in
children
 Pinworm infection is particularly common among:
 Children, institutionalized groups, and households
 not associated with socioeconomic level

6. Major intestinal nematodes
6

7. Trichuris trichiura
7
 The development to adult
worms is about 3 months
 there may be no
shedding of eggs in this
period
 Worms live approx. 3 years
 Adult worms inhabit the
caecum and colon
 May extend in severe
infection
 Transmission

8. 8
 Whip-like structure
 Adult: the anterior 3/5 is slender
and the posterior 2/5 is thick
 Thin anterior portion: has
capillary-like esophagus,
embedded in the mucosa
 The posterior end: lies free in the
intestinal lumen
 After mating, the female worm
produces 7000 to 20,000 eggs/day
 Eggs are barrel shaped, bile
stained with bipolar plugs

9. Adults of T. trichiura
9

10. 10

11. Eggs of T. trichiura
under the high power
11

12. 12

13. 13

14. 14

15. Trichuriasis
15
 Most people: asymptomatic, eosinophilia
 In heavy infections, the mucosa is inflamed, edematous, and
friable, and increased TNF-α
 growth retardation and impaired cognitive function
 Children with chronic Trichuris colitis:
 chronic abdominal pain and diarrhea
 iron deficiency anemia
 growth retardation
 dysentery syndrome: tenesmus and frequent passage of stools
containing large amounts of mucus and often blood
 Recurrent rectal prolapse is common

16. 16

17. 17

18. Barium enema, air contrast
18

19. Diagnosis
19
 Trichuriasis
 Finding eggs in stool (level of egg output is high)
 Identifying the adult worms on the mucosa of the
prolapsed rectum
 Findings of worms in colonoscopy
 Occasionally by air contrast barium enema in massive
infection

20. Treatment
20
 Single doses of albendazole, mebendazole, and
pyrantel pamoate cure less than 50% of patients
 Light and moderate infection:
 Three days of albendazole (400mg PO/day)
 Severe infection
 5-7 days of albendazole

21. Enterobius vermicularis
21
 E. vermicularis is a small
white worm measuring 1
cm in length
 inhabiting the cecum,
appendix, and adjacent gut
 Enterobius ova are ovoid
but flattened on one side
and measure
approximately 56 × 27 μm

22. 22

23. 23

24. E. vermicularis life cycle
24
 Hatch in the duodenum
 5 or 6 weeks  develop into
adult worms (max. 1 mo)
 Gravid female worms
 Contain 10,000 ova/each
 Migrate at night to the
perianal and perineal
regions to deposit egg 
itching
 Eggs mature in 6 hrs (due to
O2)
 Eggs are transferred and
attached to bedding, linnen
etc

25. Transmission of enterobiasis
25
 The modes of transmission are:
 viathe hands of the patient (underneath the fingernails)
through frequent scratching  autoinfection
 Transmission through eggs viable on
 Direct
exposure of eggs to clothes, bed linen, fabrics
 Contaminated dust on objects
 Walls of school hall, classroom, toilets
 Toys, furnitures
 Sexual partners engaging in oral-anal sex
 Larvae migrate into the sigmoid colon  retroinfection

26. Enterobiasis
26
 Most: asymptomatic
 Perianal and perineal pruritus and scratching  restlessness,
secondary infection
 Vulvovaginitis, vaginal discharge
 Migration of the parasite may lead to ectopic disease, such as
pelvic, cervical, vulvar, and peritoneal granulomas 
mimicking pelvic mass/ PID
 Studies: more normal than inflamed appendices removed at
surgery for suspected appendicitis contained pinworms 
symptoms resembling appendicitis without invasion of the
mucosa

27. Appendix
27

28. Case report
28
 A 13 year old girl presented to the emergency room with a
five day history of vomiting, diarrhoea, fever, and abdominal
pain. She was not sexually active
 In her spare time she earned money as a babysitter for 6–12
year old children
 Physical examination revealed signs of peritonitis;
leukocytosis and eosinophilia
 USG: fluid in the peritoneum
 Laparoscopy  pathology

29. 29
 The patient was treated with
two 400 mg doses of
albendazole administered
one week apart.
 The family contacts also
received a dose of
mebendazole.

30. Diagnosis
30
 Microscopic examination of an adhesive cellophane tape
pressed to the perianal area early in the morning before
bathing or defecation (eg. By parents)
 A single examination detects 50% of infections, three
examinations detect 90%, and five examinations detect 99%

31. Treatment
31
 Single doses of one of the followings:
 albendazole (400 mg)
 mebendazole (100 mg)
 ivermectin (200 μg/kg)
 pyrantel pamoate (11 mg/kg up to 1 g)
are highly effective. A second dose is given 2 weeks later
because of the frequency of reinfection and autoinfection
 Other infected patients should be treated

32. Gastrodisciasis
32
 Caused by Gastrodiscoides hominis reported from Assam state in India,
Bangladesh, Phillipines, SEA countries, Nigeria
 Morphology:
 a ventral sucker located in the posterior end
 the anterior region is narrow and ends with a rounded tip.
 the posterior region contains the reproductive organs including an
ovary in the shape of an oval located under the 2 lobed testes
 Eggs are similar to Fasciola spp. but larger

33. 33
 Definitive hosts:
 Human, pigs, rats
 Intermediate hosts:
 IH1: Snails
 IH2: Water plants
 India: water caltrops thrive in ponds
fertilized by “night soil” (human feces)
 Transmission: ingestion of
metacercaria in plants

34. Gastrodisciasis
34
 Clinical sign
 Usually asymptomatic
 Occasionally diarrhea, fever, abdominal pain, colic,
and an increase in mucous production
 Diagnostics
 Stool examination
 Treatment
 Praziquantel

35. Prevention
35
 Treatment of patients and infected people with frequent
contacts
 Other infected family members, classmates, or residents of
long-term care facilities should be treated at the same time
as the index case
 repeated treatment courses may be needed
 Maintenance of hygiene and sanitation (hand washing)
 Cleaning surface area, bed sheets, clothes, towels; preventing
the spread of eggs

36. Research application
36
 Trichuris has been shown to secrete molecules that induce
antiinflammatory cytokines
 It appears that infection with eggs of the porcine whipworm
Trichuris suis may lead to improvement of inflammatory
bowel disease
 characterization of the responsible immunomodulatory
molecules could lead to new therapeutic approaches

37. Discussion
37