This document provides an outline and overview of intestinal parasitic infections. It discusses the major helminth worms that can cause infection, including Enterobius vermicularis (pinworm), Ascaris lumbricoids (roundworm), and hookworms. It also discusses the main intestinal protozoa that can cause infection, such as Giardia intestinalis and Entamoeba histolytica. For each parasite, it provides details on transmission, symptoms, treatment approaches, and prevention strategies. The document serves as an educational guide on the characteristics and management of common intestinal parasitic infections.

1. F A T I M A M A H D I
6 T H Y E A R P H A R M A C Y
P H A R M - D O F F I C I N E
Intestinal Parasitic Infections

2. Outline
 Introduction
 Helminthes Worms
 Enterobious Vermicularis
 Ascaris Lumbricoids
 Hookworms
 Intestinal protozoa
 Giardia Intestinalis
 Entamoeba Histolytica
 Diarrhea
 References

3. Intestinal Parasites
 Intestinal parasitic infections are among the most
prevalent infections in humans in developing
countries.
 May lead to significant morbidity and mortality if
not recognized and treated appropriately.

4. Intestinal Parasites
 Caused by intestinal Helminths and Protozoan
parasites
 Helminthes worms: multicellular organisms that inhabit the
human gut
 Nematodes (roundworms)
 cestodes (tapeworms)
 trematodes (flatworms)
 Protozoan: unicellular, can multiply inside the human body
 Giardia intestinalis
 Entamoeba histolytica
 Cyclospora cayetanenensis
 Cryptosporidium spp.

5. HELMINTHES
WORMS

6. Nematodes
 Roundworms that include: ascariasis, hookworm,
enterobiasis, strongylodiasis..
 Helminthic parasites do not self-replicate, therefore
clinical disease requires the acquisition of a heavy
burden of adult worms through repeated exposure to
the parasite in its infectious stage.
 Humans do not develop significant protective
immunity to intestinal nematodes.

7. Nematodes
Enterobius Vermicularis

8. Enterobius Vermicularis
 Slender white worms, that are several millimeters
long.
 They cause pinworm infection
 Present in the cecum, appendix, and ascending
colon.
 Mostly a pediatric condition
 Transmission from person to person (children to
parents..)

9.  A small, white worms that can live in the intestines.
Enterobius Vermicularis

10. Enterobius Vermicularis
 Female pinworm migrates to the anal area, lays eggs
released to air, clothes, beddings, or hands swallowed
by the mouth causing infection.
 Symptoms:
 Itching and prickling in the anal area
 Restless sleep or difficulty sleeping
 In females, vaginal itching.
Most patients are asymptomatic
Diarrhea due to inflammation of the bowel wall can occur
during acute infection.

11. Enterobius Vermicularis
 Antihelmintics are effective (albendazole, mebendazole,
pyrantel pamoate)
 Reinfection immediately after the completion of therapy is
common; young pinworms may be resistant to drugs.
 Successful eradication requires at least 3 doses of
medication, separated by 3 weeks.
 Itching, irritation, and excoriation should be treated
symptomatically.

12. Enterobius Vermicularis
Albendazole
• Selectively,
irreversibly
blocks glucose
and other
nutrients
uptake.
• 400 mg PO
single dose;
repeat in 2-3
weeks if
needed.
• Can be mixed
with food
Mebendazole
• Decrease ATP
production in
the worm.
• 100 mg PO x1,
repeat in 2
weeks
• Take with food
Pyrantelpamoate
• A depolarizing
neuromuscular
blocking agent.
• 11 mg
(base)/kg PO
q2week x2
doses; not to
exceed 1 g/dose
• Treatment of
choice for
pregnant
women

13. Enterobius Vermicularis
 Follow-up is recommended if symptoms persist > 2
weeks or if signs of bacterial super-infection occur.
 If perianal itching or prickling pain persists perianal
swab
 Family members or classmates must be treated.
 Pregnancy
 Treatment should be reserved for patients with significant
symptoms.
 Pyrantel Pamoate > Mebendazole or Albendazole

14. Enterobius Vermicularis
 Advices for Prevention
 Personal and group hygiene
 Wash hands before eating
 Children must stop finger-sucking.
 Washing sheets, clothes, and towels in a washing machine,
regular laundry soap can eliminate pinworm eggs.

15. Nematodes
Ascaris lumbricoids

16. Ascaris lumbricoids (Roundworm)
 Largest of the humans intestinal nematodes.
 Reach 15-35 cm in length in adulthood.
 Fertilized eggs cannot infect until they embryonate
outside the human body under proper conditions in
the soil.
 Infection by ingestion of embryonated eggs, reach the
small intestine and hatch.
 Larva released penetrates the intestinal wall, and
migrate to the lungs

18. Ascaris lumbricoids (Roundworm)

19. Ascaris lumbricoids
 Symptoms: usually asymptomatic
 Respiratory symptoms:
 Fever
 Nonproductive cough
 Dyspnea
 Wheezing
 Gastrointestinal (due to high parasite load)
 N, V
 Diffuse or epigastric abdominal pain, abdominal tenderness

20. Ascaris lumbricoids
 Complications
 Partial or complete bowel obstruction in large numbers
 Migrate into the appendix, hepatobiliary system, or
pancreatic ducts and rarely other organs such as kidneys or
brain.
 Appendectitis, pancreatitis.
 Malnutrition, iron deficiency anemia, and impairments of
growth and cognition.
 Urticaria early in disease due to allergic reaction to Ascaris
infection

21. Ascaris lumbricoids
 Treatment
 Benzimidazoles are effective (albendazole, mebendazole) are
first line treatment.
Benzimidazoles are not recommended in pregnant
women
 Ivermectin and pyrantel pamoate are alternatives.

22. Ascaris lumbricoids
Albendazole
ATP production in
worm energy
depletion
immobilization, and
death.
Adults and children
• 400 mg PO x1
day
Mebendazole
Selectively,
irreversibly blocks
glucose and other
nutrients uptake
Adults and children
• 100 mg PO q12hr
for 3 days
Pyrantel
Pamoate
Neuromuscular blocking
agent
Adults
• 11 mg (base)/kg PO x1
dose; not to exceed 1
g/dose.
• Children
• <2 years: Safety not
established
• >2 years : 11 mg/kg PO
x1 dose; not to exceed 1
g/dose.

23. Ascaris lumbricoids
Ivermectin
<15 kg: Safety and efficacy not established
15-24 kg: 3 mg PO; may repeat in 3 mo
25-35 kg: 6 mg PO; may repeat in 3 mo
36-50 kg: 9 mg PO; may repeat in 3 mo
51-65 kg: 12 mg PO; may repeat in 3 mo
66-79 kg: 15 mg PO; may repeat in 3 mo
>80 kg: 200 mcg/kg PO once
Take on empty stomach
Piperazine citrate
GI or biliary obstruction secondary to ascariasis; causes flaccid paralysis
of the helminth by blocking response to worm muscle to acetylcholine.

24.  Pregnant women
 Pyrantel Pamoate should be used
 Pyrantel pamoate (11 mg/kg up to a maximum of 1 g) is
administered as a single dose.
 Adverse effects include gastrointestinal disturbances,
headaches, rash, and fever.
Ascaris lumbricoids

25. Ascaris lumbricoids
 Prevention
 Implementing sanitation and education systems which
recommends
Discriminate defecation, educate aginst using human
feces as fertilizers
Hand-washing
Cleaning fruits and vegetables
Avoiding soil consumption.

26. Nematodes
Hookworms

27. Hookworms

28. Hookworms
 Two main types
 Necator americanus
 Ancylostoma duodenale
 Hookworm infection is acquired through skin
exposure to larvae in soil contaminated by human
feces.
 Larva migrates to lungs (mild reactive cough, sore
throat) coughed and swallowed to the small
intestine adult with teeth attach to mucosa
blood and serum protein ingestion.

29.  Most individuals with hookworm infection are
asymptomatic, diagnosis by stool examination.
 Symptoms:
 Erythematous, pruritic rash at site of entry.
 Cough, fever, wheezing, reactive bronchoconstriction
(pulmonary manifestations).
 Blood in stool.
 Late signs: iron deficiency anemia, hypoproteinemia, and
edema.
Hookworms

30.  Complications:
 Childhood syndrome (iron deficiency anemia, protein
malnutrition, growth and mental retardation, lethargy)
 Severe anemia affects cardiovascular performance in adults.
 Hypoproteinemia
 Weight-loss
 Anasarca (fluid retention in skin)
 edema
 Protein-losing enteropathy, with immunoglobulins among the
proteins lost, increased susceptibility to infections .
In patients with high enough iron intake, enteropathy may occur
independent of anemia.
Hookworms

31.  Treatment
 Antihelmintic treatment
 Iron supplement
 Appropriate diet
 Wheezing and cough are managed with inhaled beta agonists.
 In case of malnutrition, support is needed (folic acid)
 Severe anemia and patients with CV risks are
hospitalized.
 Blood transfusion in severe hemorrhage.
Hookworms

32. Albendazole
A single 400-mg dose
(most effective)
Mebendazole
100 mg twice daily for
3 days (more effective
than a single 500-mg
dose)
Pyrantel pamoate
11 mg/kg doses,
usually over 3 days
Hookworms
Drug of
choice in
pregnant
women

33. Hookworms
 Prevention
 Community-wide single-dose Albendazole at
intervals of 18 months.
 Improve sanitation and access to clean water.
 In endemic areas warn against wearing open
footwear or walking barefoot in such areas.

34. INTESTINAL
PROTOZOA

35. Intestinal Protozoa
 Invisible, one-celled microorganisms.
 Reproduce rapidly takes over the intestine then
goes to other organs and tissues.
 Some feed on RBC.
 They can destroy tissues.

36. Intestinal
ProtozoaGiardia Intestinalis

37. Giardia Intestinalis
 Major causative agent of diarrhea
 Children>adults
 Can be asymptomatic, acute or chronic diarrhea
 High infection rate
 Transmission fecal-oral, and by ingestion of contaminated
water.
 Person-person and person-animal transmission

38. Giardia Intestinalis
 Symptoms
 Most common in acute phase:
 Diarrhea (90%)
 N,V, AP and distention, flatulance (70%)
 Malodorous, greasy stools
 Most common in chronic phase:
 Malaise, weakness
 Anorexia and weight loss
 Extraintestinal manifestations: rare
 Neurologic symptoms (irritability, sleep disorder)
 Urticaria

39. Giardia Intestinalis
 Complications
 Persistent gastrointestinal symptoms
 Chronic illness with weight loss
 Malabsorption syndrome in adults
 Failure to thrive in children
 Growth retardation
 Disaccharidase deficiency
 Zinc deficiency in schoolchildren
 Lactose intolerance

40. Giardia Intestinalis
 Treatment
 ATB therapy
 Fluid and electrolyte management
 Several month of lactose-free diet for acquired lactose
intolerance
Metronidazole is first line treatment

41. Giardia Intestinalis
Metronidazole
• Adults
• 250mg PO TID for 5-7 days
• 500 mg PO BID for 5-7 days
• Pediatrics 15 mg/kg/day IV/PO divided q8hr for 5 days
Tinidazole
• Adults: 2 g PO once
• Pediatrics:
• < 3 years, safety and efficacy not established
• >3 Years, 50 mg/kg PO once; 2 g maximum
Take with food.

42. Giardia Intestinalis
Paromomycin
• Poorly absorbed aminoglycoside, used in
pregnant women
• Mostly GI side effects
• 25-30 mg/kg/day divided TID PO x5-10 days
 When the disease is mild and hydration and nutrition can be
maintained, therapy can be delayed at least until after the first
trimester .
 Metronidazole or Tinidazole are alternative agents but should not
be used during the first trimester.

43.  Prevention:
 Personal hygiene and hand washing , especially in
daycare
 Travelers to endemic areas not to eat uncooked food
(grown, washed with contaminated water)
 Water purification
Giardia Intestinalis

44. Intestinal
ProtozoaEntamoeba histolytica

45. Entamoeba histolytica
 Causes the infection “Amebiasis”
 Intestinal disease (eg, colitis)
 Extraintestinal manifestations
 Liver abscess (most common)
 Pleuropulmonary, cardiac, and cerebral dissemination
 Severe infection for
 Children (neonates)
 Pregnant and postpartum women
 Those using corticosteroids
 Those with malignancies
 Malnourished individuals
 Transmitted via ingestion of cysts (feces infected soil,
water, food handlers..)

46.  Symptoms: can be asymptomatic
 Intestinal colitis (Amebic colitis)
 Gradual onset, over 1-2weeks (different from bacterial
dysentery)
 Cramping abdominal pain, watery or bloody diarrhea, and
weight loss or anorexia.
 Fever (less common)
 Rectal bleeding w/o diarrhea (children)
 Fulminant amebic colitis
 Rapid onset of severe bloody diarrhea
 Severe abdominal pain
 Fever
 Intestinal perforation is common
Entamoeba histolytica

47.  Extraintestinal symptoms
 Amebic liver abscesses, most common extra-intestinal
manifestation
 Pleuropulmonary disease
 Peritonitis
 Pericarditis
 Brain abscess
 Genitourinary disease
Entamoeba histolytica

48.  Treatment
 Symptomatic, invasive Amebiasis, and amebic colitis
 Metronidazole (can work on liver abscesses and can cross BBB)
Treatment with metronidazole is followed by a luminal agent
 Symptomatic non-invasive amebiasis
 luminal agents (ex: Paromomycin)
 Broad-spectrum ATB
 Bacterial superinfection in cases of fulminant amebic colitis and
suspected perforation.
 Bacterial co-infection of amebic liver abscess.
Entamoeba histolytica

49. Metronidazole
• Invasive amebiasis
• Kills trophozoites from intestine
and tissues but doesn’t eradicate
from the intestine
• Can treat amebic liver abscess, if
not successful surgical
intervention needed
• Luminal agent should also follow
• Paromamycin not given at same
time with metronidazole
• Adults: 500-750 mg PO q8hr for
5-10 days
• Pediatrics: 35-50 mg/kg PO
divided q8hr for 10 day
• Pregnancy: B
• Lactation not recommended
Entamoeba histolytica

50. Tinidazole
Intestinal amebiasis
and amebic liver
abscess in adults and
children >=3 yrs
• Adults: 2g PO for 3 days
(intestinal) for 5 days
(liver)
• Pediatrics: >3yrs
30 mg/kg/day PO , 2 g
maximum, for 3 days
(intestinal), for 5 days
(liver)
Paromamycin
Intraluminal amebiasis.
Effective in acute and
chronic but not
extraintestinal
• Adult: 25-35
mg/kg/day divided
TID PO x5-10 days
• Pediatrics: 25-35
mg/kg/day divided
q8hr PO x7 days
Iodoquinol
Luminal amebicide,
poorly absorbed, best
tolerated when given
with meals
• Adults: 650 mg PO PC
TID for 20 days
• Pediatrics: 30-40
mg/kg/day divided PO PC
TID
PO for 20 days; not to
exceed 1.95 g/day
Entamoeba histolytica All 3 are
category C
for
pregnancyCan be used
in pregnant
women

51. Chloroquine
Extraintestinal amebiasis
1 g (600 mg base) PO qDay for 2 days, THEN
500 mg (300 mg base) qDay for 14-21 days
Entamoeba histolytica
 Prevention:
 Education for more sanitation and hygiene
 Eradicating fecal contamination of water and food
 Early ttt of carriers in non endemic areas
 Boiling water before use
 Vegetables washed and soaked with vinegar

52. Diarrhea
 Etiology: viral>bacterial>protozoan
 Viral: Watery diarrhea is the most common symptom; stools rarely
contain mucus or blood, low grade fever, vomiting. Shorter in
duration than bacterial
 Bacterial: Result in fever, and bloody diarrhea, severe abdominal
pain. (E.coli 1-2 days of watery diarrhea, then bloody). C. difficile
infection ranges from mild abdominal cramps and mucus-filled
diarrhea, can develop to hemorrhagic. Severe diarrhea (defined as
≥4 fluid stools per day for more than three days)
 Parasitic infections typically cause subacute or chronic diarrhea.
Most cause nonbloody diarrhea; an exception is E.
histolytica, which causes amebic dysentery. Fatigue and weight loss
are common when diarrhea is persistent.

53. Diarrhea
 Ask about:
 recent contact with someone with acute diarrhoea and/or
vomiting
 Exposure to a known source of enteric infection (possibly
contaminated water or food)
 Recent travel abroad.

54. Selected Oral Antibiotics for Infectious Gastroenteritis*
Organism Antibiotic Adult Dosage Pediatric Dosage
Vibrio cholerae Ciprofloxacin 1 g once NA
Doxycycline
†
300 mg single dose 6 mg/kg single dose
TMP/SMX 1 DS tablet bid for 3 days 4–6 mg‡/kg bid for 5 days
Clostridium difficile Metronidazole 250 mg qid or 500 mg tid for
10 days
7.5 mg/kg qid for 10–14 days
Vancomycin 125–250 mg qid for 10 days 10 mg/kg qid for 10–14 days
Fidaxomicin 200 mg bid for 10 days NA
Shigella Ciprofloxacin 500 mg bid for 5 days NA
TMP/SMX 1 DS tablet bid 4–6 mg‡/kg bid for 5 days
Giardia intestinalis
(lamblia)
Metronidazole 250 mg tid for 5 days 10 mg/kg tid for 7–10 days
(maximum 750 mg/day)
Nitazoxanide 500 mg bid for 3 days 1–3 yr: 100 mg bid for 3 days
4–11 yr: 200 mg bid for 3 days
≥ 12 yr: 500 mg bid for 3 days
Entamoeba histolytica Metronidazole
§
750 mg tid for 5–10 days 12–16 mg/kg tid for 10 days
(maximum 750 mg/day)
Campylobacter jejuni Azithromycin 500 mg once/day for 3 days 10 mg/kg once/day for 3 days
Ciprofloxacin 500 mg once/day for 5 days NA

55. References
 www.Medscape.com
 www.uptodate.com
 http://www.merckmanuals.com/professional/gastro
intestinal_disorders/gastroenteritis/overview_of_ga
stroenteritis.html
 http://www.ncbi.nlm.nih.gov/books/NBK63841/
 http://www.cdc.gov/parasites/
 Pharmacotherapy Principles & Practice 2007