Cysts are resistant forms and are responsible for transmission of giardiasis. Both cysts and trophozoites can be found in the feces (diagnostic stages) . The cysts are hardy and can survive several months in cold water. Infection occurs by the ingestion of cysts in contaminated water, food, or by the fecal-oral route (hands or fomites) . In the small intestine, excystation releases trophozoites (each cyst produces two trophozoites) . Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk . Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in nondiarrheal feces . Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. While animals are infected with Giardia, their importance as a reservoir is unclear.
PRESENTED TO :
DR SHAKIRA SADIQ GILL
PRESENTED BY :
department epidemiology and public health
Introduction and etiology
Who is at Risk?
Signs & symptoms
Introduction and etiology
Giardiasis is a diarrheal illness caused by Giardia intestinalis (also known as
The parasite is passed in the stool of an infected person or animal (both
cysts & trophozoites)
The motile ,vegetative tropozpite is 10-20µm long and 8-15µm wide.
The parasite is protected by an outer shell that allows it to survive outside
the body and in the environment for long periods of time
During the past 2 decades, one of the most common causes of
waterborne disease (drinking and recreational) in humans in the United
Giardiasis is a global disease.
It infects nearly 2% of adults and 6% to 8% of children in developed
Nearly 33% of people in developing countries have had giardiasis.
In the United States, Giardia infection is the most common
intestinal parasitic disease affecting humans
G. intestinalis has high prevalence rates particularly among young
children in third world countries.
In tropical areas , about 50-80% of people are carriers.
The variable occurrence in distinct groups of the
population is apparently related to certain nutritional
Latin america is about 200 million, with some 500,000
new infections per year.
In humans,giardiasis is one of the the most common
intestinal parasitoses in western industrialized countries.
Geographical distribution of Giardia
More prevalent in warmer climates and in
young age animals and humans.
Infection occurs mostly in areas of low
sanitation standards and all the day care
Who is at risk?
Persons at increased risk include:
child care workers
children who attend day care centers
hikers, campers, swimmers
people drinking or accidentally swallowing untreated
loose or watery stool
Some may be asymptomatic
Manifest in 7-10 days
Lasts 2- 6 weeks
May lead to
• More severe condition
• Lasts 2 months - years
– Increased gas
– Loose stools
– Slowed growth
Incubation Period & Duration
Symptoms generally begin 1-2 weeks after being infected
Healthy persons, symptoms may last 2-6 weeks
Giardiasis is passed via the face- oral route.
Primary routes are personal contact and contaminated water and
people who have contact with individuals already infected.
It is a particular danger to people hiking or backpacking in
wilderness areas worldwide, especially if they have no immediate
access to medical supplies.
Cysts are resistant forms and are responsible for transmission
of giardiasis. Both cysts and trophozoites can be found in the
feaces (diagnostic stages) .
The cysts are hardy and can survive several months in cold
water. Infection occurs by the ingestion of cysts
in contaminated water, food, or by the fecal-oral route
(hands or fomites) .
In the small intestine, excystation releases trophozoites
(each cyst produces two trophozoites) .
o Trophozoites multiply by longitudinal binary fission, remaining
in the lumen of the proximal small bowel where they can be
free or attached to the mucosa by a ventral sucking disk
o Encystation occurs as the parasites transit toward the colon.
The cyst is the stage found most commonly in no diarrheal
o Because the cysts are infectious when passed in the stool or
shortly afterward, person-to-person transmission is possible.
While animals are infected with Giardia, their importance as a
reservoir is unclear.
Zoonotic Aspects of Giardia
Giardia lamblia which parasitize humans belong to either of
two genotypes, A or B,
These two genotypes also were found in cysts from fecal
samples of animal origin such as dogs, cats, some farm
animals and wild animals.
In addition, trophozoites recovered from cysts obtained
from environmental samples belonged to these two
genotypes as well, suggesting that the G. lamblia genotypes
A and B are widespread and possibly zoonotic.
Fecal immunoassays that are more sensitive and specific should be
Rapid immune-chromatographic cartridge assays also are available
but should not take the place of routine ova and parasite
PCR (e.g.,polymerase chain reaction) can be used to identify the
subtypes of Giardia.
• Giardia should be identified 50 to 70% of the time after
one stool, and 90% identification after three stools
• Biopsy tissue/duodenal aspirate stained by trichrome
or Giemsa stain.
• Enzyme immunoassay and fluorescent-anitbody
monoclonal antigen detection systems
Giardia is also suspected to be zoonotic communicable
between humans and other animals.
Major reservoir hosts include
cattle and birds
Giardiasis must be differentiated from:
Several prescription drugs are available
Alternatives to these medications include
paromomycin, quinacrine, and furazolidone.
Young children & pregnant women may be more
Drink plenty of fluids while ill
Practice good hygiene
Wash hands properly with soap and water
after using the toilet
before handling or eating food
after every diaper change
Protect others by not swimming if experiencing diarrhea
Avoid food that might be contaminated
Wash and/or peel all raw vegetables and fruits before eating
Use uncontaminated water to wash all food that is to be eaten
Avoid eating uncooked foods when traveling in countries with
minimal water treatment and sanitation systems