Giardiasis

GIARDIASIS
Prof. Dr. Saad S Al Ani
Senior Pediatric Consultant
Head of Pediatric Department
Khorfakkan Hospital
Sharjah, UAE
saadsalani@yahoo.com

Giardia intestinalis
https://www.cdc.gov/parasites/giardia/
10/06/2018GiardiasisProf.Dr.SaadSAlAni
2

FACTS
Giardia is a microscopic parasite that
causes the diarrheal illness known as
giardiasis.
Giardia is found on surfaces or in soil,
food, or water that has been contaminated
with feces from infected humans or
animals.
3

FACTS (CONT.)
 Giardia can be spread in different ways,
water (drinking water and recreational
water) is the most common mode of
transmission.
Giardiais protected by an outer shell
that allows it to survive outside the body
for long periods of time and makes it
tolerant to chlorine disinfection
4

FACTS (CONT.)
Giardia usually spreads when Giardia
lamblia cysts within feces contaminate food
or water which is then eaten or drunk
Giardia is one of the most common
parasitic human diseases globally
5
Minetti, C; Chalmers, RM; Beeching, NJ; Probert, C; Lamden, K (27 October 2016).
"Giardiasis". BMJ (Clinical research ed.). 355: i5369.
Esch KJ, Petersen CA (January 2013). "Transmission and epidemiology of zoonotic
protozoal diseases of companion animals" Clin Microbiol Rev. 26 (1): 58–85.

FACTS (CONT.)
 Infection is more common in children
than in adults
Infection with Giardia intestinalis most
often results from:
 Fecal-oral transmission
 Ingestion of contaminated water
6
Huston CD. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. Feldman M, Friedman LS, Brandt
LJ. Intestinal Protozoa. 8th ed. Philadelphia, PA: Saunders, An imprint of Elsevier Inc; 2006. 2: 2420-2423 / 106.

Contaminated food is a less common
etiology
G intestinalis is a particularly
significant pathogen for people with:
 Malnutrition
 Immunodeficiencies
 Cystic fibrosis.
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GiardiasisProf.Dr.SaadSAlAni
FACTS (CONT.)

Most infections are asymptomatic
Giardia is found in healthy people in
endemic areas
Asymptomatic carriage with
excretion of high numbers of cysts in
stools is common.
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FACTS (CONT.)

 Giardiasis does not have any race predilection
 Giardiasis is slightly more common in males
than in females
 Giardiasis affects people of all ages
 Infection is rare during the first 6 months of life
in breastfed infants
 infants and young children have an increased
susceptibility to giardiasis
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FACTS (CONT.)
1.Laupland KB, Church DL. Population-based laboratory surveillance for Giardia sp. and Cryptosporidium sp.
infections in a large Canadian health region. BMC Infect Dis. 2005 Sep 16. 5:72
2.John CC. Giardiasis and Balantidiasis. Kliegman RM, Behrman BE, Jenson HB, Stanton BF. Nelson Textbook
of Pediatrics. 279. Philadelphia, PA: Saunders, An imprint of Elsevier Inc; 2007. 18th ed: 1462-1464.

Cysts may survive for nearly
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Golden Age of Gaia
in cold water

RISK FACTORS
Include:
Travel in the developing world
Changing diapers
Eating food without cooking it
Owning a dog
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Minetti, C; Chalmers, RM; Beeching, NJ; Probert, C; Lamden, K (27 October
2016). "Giardiasis". BMJ (Clinical research ed.). 355: i5369

12
of raw water supplies from lakes,
streams, and ponds
Giardia has been found in as many as
Robertson LJ, Forberg T, Gjerde BK. Giardia cysts in sewage influent in Bergen, Norway 15-23
months after an extensive waterborne outbreak of giardiasis. J Appl Microbiol. 2008 Apr.
104(4):1147-52
Dreamstime.com

Giardia has been found in as many as
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Dreamstime.com
of filtered water samples
Robertson LJ, Forberg T, Gjerde BK. Giardia cysts in sewage influent in Bergen, Norway 15-23
months after an extensive waterborne outbreak of giardiasis. J Appl Microbiol. 2008 Apr.
104(4):1147-52

In 2013, there were about
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people worldwide with symptomatic
giardiasis
protozoal diseases of companion animals" Clin Microbiol Rev. 26 (1): 58–85.

GLOBAL RATES OF GIARDIASIS
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Hotel Can Darder Caracas Chronicles
in the developed world in the developing world

16
of those infected have no symptoms.
Minetti, C; Chalmers, RM; Beeching, NJ; Probert, C; Lamden, K (27 October
2016). "Giardiasis". BMJ (Clinical research ed.). 355: i5369.

Person-to-person spread is common, with
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of family members with infected
children themselves becoming
infected
www.mychaos.co.uk

The rate of symptomatic infection
varies from
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in the natural setting

The incubation period
averages
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weeks
with a mean days

Duration of symptoms
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The average duration of symptoms in
all ages ranges from
weeks

The infective dose
The infective dose is low in humans
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Cysts
of
are capable of causing clinical disease in
Subjects

REMEMBER
Ingestion
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Cysts
results in a
infection rate

Predisposing factors to symptomatic
infection
Include :
 Hypochlorhydria
 Various immune system deficiencies
 Blood group A
 Malnutrition
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GIARDIASIS (BEAVER FEVER)
Is a parasitic disease caused by Giardia
lamblia
Giardiasis is a major diarrheal disease
found throughout the world
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protozoal diseases of companion animals". Clin Microbiol Rev. 26 (1): 58–85
Daly ER, Roy SJ, Blaney DD, et al. Outbreak of giardiasis associated with a
community drinking-water source. Epidemiol Infect. 2010 Apr. 138(4):491-500

Giardiasis usually represents a zoonosis
with cross-infectivity between animals
and humans. Giardia intestinalis has been
isolated from the stools of beavers, dogs,
cats, and primates
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ZONOSIS

Giardia life cycle
Giardia has one of the simplest life cycles
of all human parasites
The life cycle is composed of 2 stages:
(1) The trophozoite which exists freely
in the human small intestine
(2) The cyst, which is passed into the
environment.
No intermediate hosts are required.
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Giardia life cycle (Cont.)
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https://commons.wikimedia.org/wiki/File:Giardia_life_cycle_nl.svg

GIARDIA CYST
https://www.sciencesource.com/archive/Giardiasis-Cysts
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The trophozoite form of G lamblia
The trophozoite form of G lamblia
 Teardrop-shaped
 Measures 9-21 micrometers long by
5-15 micrometers wide.
29
https://www.flickr.com/photos

The trophozoite form of G lamblia(Cont.)
 Has a convex dorsal surface and a flat
ventral surface that contains the
ventral disk, a rigid cytoskeleton
composed of microtubules and
microribbons.
30

The trophozoite form of G lamblia (Cont.)
 Contains 4 pairs of flagella, directed
posteriorly, that aid the parasite in
moving.
 Two symmetric nuclei with
prominent karyosomes produce the
characteristic face like image that
appears on stained preparations
31

The cyst form of G lamblia
The cyst form of G lamblia
 Smooth-walled and oval in shape
 Measuring 8-12 micrometers long
by 7-10 micrometers wide.
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http://www.phsource.us

The cyst form of G lamblia (Cont.)
 As the cyst matures, nuclear division occurs
and readies the cyst to release 2 trophozoites
upon excystation
 Excystation occurs within 5 minutes of
exposure of the cysts to an environment with
a pH between 1.3 and 2.7
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http://www.phsource.us

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http://ninajuling.tripod.com/secondpage.htm

EPIDEMIOLOGY
United States statistics
 Most water-borne outbreaks in the United States
have occurred in western mountain regions (e.g.,
Rocky Mountains, Sierra Nevada, Cascades)
 The incidence of giardiasis is high among
individuals who camp and backpack in
mountainous Western states
 Other groups at increased risk for infection
include :
 Children
 Homosexual men
 Individuals with immunoglobulin deficiency states
(inherited or acquired).
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 Endemic infection occurs most commonly
from July through October among children
younger than 5 years and adults aged 25-39
years.
 Carrier rates as high as 30-60% have been
documented among:
 Children in day care centers
 Institutions
 On Native American reservations.
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EPIDEMIOLOGY (CONT.)

 International statistics
 Giardia has a worldwide distribution,
occurring in both temperate and tropical
regions
 Prevalence rates vary from 4-42%
 In the developing world, G intestinalis infects
infants early in life and is a major cause of
epidemic childhood diarrhea.
 Prevalence rates of 15-20% in children younger
than 10 years are common
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Caccio SM, Ryan U. Molecular epidemiology of giardiasis. Mol Biochem Parasitol. 2008
Aug. 160(2):75-80

 Giardia has been identified as the causative
agent in a large percentage of cases among
travellers to the region of St. Petersburg, Russia,
where tap water is the primary source
 The highest prevalence of G intestinalis reached
73.4% in Western Nepal
 The Dhaka study performed within the urban
areas had identified G intestinalis in 11% of
diarrheal stool specimens
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Dib HH, Lu SQ, Wen SF. Prevalence of Giardia lamblia with or without diarrhea in South
East, South East Asia and the Far East. Parasitol Res. 2008 Jul. 103(2):239-51

CLINICAL PRESENTATION
Clinical signs and symptoms of giardiasis include
the following:
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Clinical signs and symptoms
 Diarrhea  Nausea  Low-grade fever
(infrequent)
 Malaise,
weakness
 Malodorou
s, greasy
stools
 Various neurologic
symptoms (e.g.,
irritability, sleep
disorder, mental
depression,
neurasthenia)
 Abdominal
distention
 Anorexia
 Flatulence  Weight loss
 Abdominal
cramps
 Vomiting  Urticaria

REMEMBER
Diarrhea is the most common symptom of
acute Giardia infection, occurring in
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of symptomatic subjects
Abdominal cramping, bloating, and
flatulence occur in
of symptomatic
patients

Gastrointestinal manifestations
Abrupt onset (rare)
 a small number of persons develop abrupt onset
of :
 these symptoms last 3-4 days
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• Explosive watery diarrhea • Vomiting
• Abdominal cramps • Fever
• Foul flatus • Malaise

Gastrointestinal manifestations (Cont.)
Subacute syndrome ( More common)
 After the symptoms of abrupt onset
 Most patients experience a more insidious onset
of symptoms, which are recurrent or resistant.
 Stools become malodorous, mushy, and greasy
 Watery diarrhea may alternate with soft stools or
even constipation
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 Upper GI symptoms:
 often exacerbated by eating
 accompany stool changes
 may be present in the absence of soft stools.
 These include:
 upper and midabdominal cramping
 nausea
 early satiety
 bloating
 substernal burning
 acid indigestion.
43
Gastrointestinal manifestations (Cont.)

Constitutional symptoms
Anorexia, fatigue, malaise, and weight
loss are common
Weight loss occurs in more than 50% of
patients
Chronic illness may occur
• Adults may present with long-standing
malabsorption syndrome
• children may present with failure to
thrive
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Extraintestinal manifestations
Are rare
Include allergic manifestations such as:
 Urticaria
 Erythema multiforme
 Bronchospasm
 Reactive arthritis
 Biliary tract disease
The etiology is likely a result of :
 Host immune system activation
 Cross-reactivity/molecular mimicry.
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Symptoms of chronic infection
46
Symptoms of chronic infection
• Malaise • Weight loss
(~66% of symptomatic patients)
• Nausea • Post infection lactase deficiency
(2-40% of cases)
• Anorexia • Chronic diarrhea

Physical Examination
Physical examination does not
contribute to the diagnosis of giardiasis
Weight loss may be evident
No known unique physical findings are
attributable to giardiasis.
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Physical Examination (Cont.)
On abdominal examination, patients may
have nonspecific tenderness without
evidence of peritoneal irritation
Rectal examination should reveal heme-
negative stools
In severe cases, evidence of dehydration
or wasting may be present.
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Complications of giardiasis
May include the following:
 Development of chronic illness with weight loss
 Malabsorption syndrome in adults
 Failure to thrive in children
 Disaccharidase deficiency
 Zinc deficiency in schoolchildren 1
 Growth retardation 2
 Persistent gastrointestinal symptoms 3
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1.Quihui L, Morales GG, Mendez RO, Leyva JG, Esparza J, Valencia ME. Could giardiasis be a risk factor for low zinc status in
schoolchildren from northwestern Mexico? A cross-sectional study with longitudinal follow-up. BMC Public Health. 2010 Feb 20.
10(1):85.
2.Pickering LK. Giardia lamblia (Giardiasis). Long SS. Principles and Practice of Pediatric Infectious Diseases. 3rd ed.
Philadelphia, PA: Churchill Livingstone An imprint of Elsevier Inc; 2008. 265: 1241-1245.
3.Ouattara M, N'guessan NA, Yapi A, N'goran EK. Prevalence and spatial distribution of Entamoeba histolytica/dispar and Giardia lamblia
among schoolchildren in Agboville area (Côte d'Ivoire). PLoS Negl Trop Dis. 2010 Jan 19. 4(1):e574.

The diagnosis
 Stool examination
• Ideally, 3 specimens from different days
should be examined because of potential
variations in fecal excretion of cysts.
• G intestinalis is identified in 50-70% of
patients after a single stool examination and
in more than 90% after 3 stool examinations.
 Stool ova and parasite (O&P) examination
aids in the diagnosis of giardiasis in 80-85% of
patients
Nagaty IM, Hegazi MM. Dot-ELISA copro-antigen and direct stool examination in diagnosis of giardiasis patients. J Egypt Soc Parasitol.
2007 Aug. 37(2):641-8.
50

The diagnosis (Cont.)
 Stool antigen enzyme-linked immunosorbent assays
 These tests are best used as a screening test in
high-incidence settings such as:
• Day-care centers
• For identification of subjects during an
epidemic,
 They should not take the place of stool
microscopy.
Nagaty IM, Hegazi MM. Dot-ELISA copro-antigen and direct stool examination in diagnosis of
giardiasis patients. J Egypt Soc Parasitol. 2007 Aug. 37(2):641-8.
51

The diagnosis (Cont.)
 Stool antigen enzyme-linked immunosorbent assay
(ELISA) may be helpful , If the results from 3 O&P
tests are negative and giardiasis is still suspected
 Upper endoscopy with biopsies and duodenal
aspirate is a reasonable alternative
Nagaty IM, Hegazi MM. Dot-ELISA copro-antigen and direct stool examination in diagnosis of
giardiasis patients. J Egypt Soc Parasitol. 2007 Aug. 37(2):641-8.
52

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Differential diagnoses of Giardiasis
• Amebiasis • Food poisoning • Sprue
• Crohn disease • Irritable bowel
syndrome
• Strongyloidiasis
• Cryptosporidiosis • Lactose
intolerance
• Viral
gastroenteritis

Treatment
 Generally, do not treat asymptomatic persons
who excrete the organism, except to :
 Prevent household transmission( e.g., from
toddlers to pregnant women or to patients
with hypogammaglobulinemia or cystic
fibrosis)
 Permit adequate treatment in individuals
with possible Giardia intestinalis –associated
antibiotic malabsorption who require oral
antibiotic treatment for other infections
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Kiser JD, Paulson CP, Brown C. Clinical inquiries. What's the most effective
treatment for giardiasis?. J Fam Pract. 2008 Apr. 57(4):270-2

Treatment
Metronidazole is the most commonly
prescribed antibiotic for this condition
Appropriate fluid and electrolyte
management is critical, particularly in
patients with large-volume diarrheal
losses
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Abdul-Wahid A, Faubert G. Characterization of the local immune response to cyst
antigens during the acute and elimination phases of primary murine giardiasis. Int J
Parasitol. 2008 May. 38(6):691-703.

Prognosis
The prognosis for patients with giardiasis is
generally excellent.
 Most patients are asymptomatic
 Most infections are self-limited.
Giardiasis is not associated with mortality
except in rare cases of extreme dehydration,
primarily in infants or malnourished
children.
56

Prevention
Careful hand washing
 Infected persons and persons at risk
should carefully wash their hands after
they have any contact with feces
 Careful hand washing is important,
especially for caregivers of diapered
infants in day-care centers
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Giardiasis

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