A protozoan parasite capable of causing sporadic or epidemic diarrheal illness.

1. Kapali Dibyak

2. C O N T E N T S
INTRODUCTION
MORPHOLOGY
LIFE CYCLE
PATHOGENESIS AND CLINICAL MANIFESTATION
LABORATORY DIAGNOSIS
TREATMENT
PREVENTION AND CONTROL
EPIDEMIOLOGY

3. I N T R O D U C T I O N
• A protozoan parasite capable of causing sporadic or epidemic diarrheal illness
• Also known as Giardia intestinalis or Giardia duodenalis
• Initially described by Antonie van Leeuwenhoek in 1681 while examining his own
diarrheal stools under the microscope
• Renamed by Stiles in 1915 in honor of Professor A. Giard of Paris and Dr. V. Lambl
of Prague as Giardia lamblia

4. M O R P H O L O G Y
• A typical eukaryotic organism
• Distinct nucleus and nuclear membrane,
cytoskeleton, and endomembrane system
• Still lacks nucleoli, peroxisomes and
mitochondria
• Two different forms:
1. Trophozoite
2. Cyst

5. Trophozoite
• Bilaterally symmetrical
• Pear-shaped Broad anterior; Attenuated
posterior
• Size: 12 to 15 μm long
5 to 9 μm wide
• Median bodies
• Two nuclei
• Four pairs of flagella
(Anterior, Posterior, Caudal and Ventral)
• A ventral disk

6. Cyst
• Egg-shaped
• Size: 7 - 10 μm in diameter
Covered by a wall 0.3 - 0.5 μm thick
• Mature cyst: Four nuclei
Immature cyst: Two nuclei
• Eight pairs of flagella

7. L I F E C Y C L E
1. Infection in a host is initiated when the
cyst is ingested with contaminated
water or food or through direct fecal-
oral contact
2. After exposure to the acidic environment
of the stomach, each cyst releases two
trophozoites in the proximal small
intestine
Excystation

8. 3. Trophozoites multiply by longitudinal
binary fission in the lumen of the proximal
small intestine where they can be free or
attached to the mucosa by a ventral
sucking disk
4. After exposure to biliary fluid, some of
the trophozoites transform back into
cyst in the jejunum and are passed in the
feces
Encystation

10. P A T H O G E N E S I S
A N D
C L I N I C A L M A N I F E S T A T I O N
• Cause Giardiasis
• Children are at much higher risk than adults
• Infection is initiated by ingestion of cyst
(as few as 10 cysts)
• Followed by excystation and colonization of
the small intestine by the trophozoites

11. • Majority of infected patients are asymptomatic
• Typical clinical symptoms usually begin 1 - 3 weeks after
ingestion of cysts
• Diarrhea
• Flatulence
• Foul-smelling, greasy stools that tend to float
• Stomach cramps or pain
• Nausea or Vomiting
• Dehydration

12. L A B O R A R T O R Y
D I A G N O S I S
• Choice of diagnostic techniques depends on
available equipment and reagents, experience,
and considerations of time and cost
• Can be done by one of the following methods:
1. Direct examination
2. Concentration
3. Antibody detection
4. Molecular

13. 1. Direct examination method
• The microscopic identification in fecal
samples is considered as the gold standard
method
• Detects both cysts and trophozoites
• Wet mount of fecal suspension is prepared
in:
i. Salt solution (0.85 NaCl)
ii. Fixation in Sodium acetate–acetic
acid Formalin (SAF)

14. • Wet mounts smear can be examined either
unstained or iodine stained
• Wet saline preparation of a fresh stool
allows motile trophozoites to be seen
• In stained and SAF preparation smears
the trophozoites will be non-motile

15. • Multiple stool samples should be tested
before a negative result is reported
• One stool sample will allow the diagnosis of
60 - 80% of infections
• Two stool samples will allow the diagnosis of
80 - 90%
• Three stool samples allows diagnosis over
90%
• In some cases, the examination of more than
three stool samples is necessary due to
intermittent or low levels of cyst shedding

16. 2. Concentration method
• To separate protozoan cysts and
helminthes eggs from excess fecal
debris
• For detection of lesser numbers
of cysts missed by using wet mounts
direct smear
• Two types of concentration method:
i. Floatation
ii. Sedimentation

17. Flotationmethod
• Separation through the use of a liquid with
high specific gravity such as NaCl, NaNO3,
ZnSO4
• Zinc sulfate has been recommended as the
best saturated solution for detection of cyst
• Cysts float and are visible on the surface and
the debris aggregate at the bottom of the
tube
• Walls of cysts often collapse
Final specific gravity of about 1.20

18. Sedimentationmethod
• Using centrifugation has led to the
recovery of cyst in fecal sediment
• Easiest but the preparation contains
more debris
• Formalin-ether or Formalin-ethyl acetate
sedimentation technique are best to
employ and generally applicable
• Lesser distortion of cysts compared to
flotation method

19. 3. Antibody detection method
• The presence of IgM, IgG and secretary IgA
humeral response to acute giardiasis has been
noted
• In persons with acute giardiasis, level of IgM
antibody fall to levels of healthy persons
between 2 – 3 weeks after drug treatment
indicating
• Detection of IgM antibody may be a useful
indicator for diagnosis of current infection
• IgG antibody response may remain for up to
18 months after infection

20. • Secretary IgA (sIgA) antibody has been
detected in duodenal fluid and saliva samples of
infected people
• Detection and monitoring this antibody may be
a useful tool for serodiagnosis
• One of the best antigens that have ever been
used is Giardia stool antigen with a relative
molecular mass of 65 Kda (GSA65) which is
present in both trophozoites and cysts

21. 4. Molecular method
• Not used in routine medical laboratories
• Multiplex real-time PCR have been used for
the simultaneous detection of parasites in
environmental sources such as water and
sewage
• Real-time PCR has been reported to be more
sensitive and beneficial than ELISA and fecal
microscopy for diagnosis

22. Methods Sensitivity % Specificity %
1. Direct stool examination 34.7 – 55 96 - 100
2. Concentration method 65.2 – 83 85 – 97
3. Antigen detection method 44 – 100 68 – 100
4. Molecular method 58 – 92 56 – 100
Comparative table

23. T R E A T M E N T
Clinical scenario Drugs and Duration of treatment
1. Symptomatic adult and pediatric Metronidazole for 5 – 7 days
Alternative Furazolidone for 7 – 10 days
Quinacrine for 5 – 7 days
Albendazole for 5 – 7 days
Ornidazole - Single dose
Tinidazole – Single dose
2. Pregnancy
First trimester Paromomycin for 5–10 days
Second and third trimester Paromomycin for 5–10 days
Metronidazole for 5–7 days
3. Resistant infection or relapse Drug of different class or combination
Nitroimidazole + Quinacrine for 2 weeks or
more

24. Gardner, T. B., & Hill, D. R. (2001). Treatment of giardiasis. Clinical microbiology reviews, 14(1), 114–128.
https://doi.org/10.1128/CMR.14.1.114-128.2001

25. P R E V E N T I O N
A N D
C O N T R O L M E A S U R E S
1. Practice Good Hand Hygiene
Since found in soil, wash hands with soap
and water after field work, landscaping, or
gardening

26. 2. At childcare facilities
• Exclude children who are sick with diarrhea
from childcare settings until the diarrhea
has stopped
• Clean, sanitize, or disinfect toys and
surfaces
• Wash hands regularly with soap and water to
keep kids and caregivers healthy
• Encourage good diapering practices

27. 3. At the pool and lake
• Do not swallow the water
• Do not swim or let kids swim if sick with
diarrhea
• Shower before getting in the water
• Take young children on frequent bathroom
breaks or check diapers every hour
• Change diapers in a bathroom or diaper-
changing area not in waterside

28. 4. Avoid water that might be contaminated
• Do not drink untreated water or use ice
made with water from lakes, rivers, springs,
ponds, streams or shallow wells
• Drink bottled water
• Make water safe by boiling for 1 minute or
treating it
• Use a water filter that has been certified
for “cyst” and “oocyst” reduction

29. 5. Avoid food that might be contaminated
• Do not eat fruits and vegetables
washed in water that might be
contaminated
• Avoid eating uncooked foods when
traveling in countries where the food
supply might be unsafe

30. E P I D E M I O L O G Y
• Occurs in the aquatic environment
throughout the world
• 280 million cases estimated by WHO
• Prevalence is higher in areas of poor
sanitation particularly in developing
countries
• Included in the World Health
Organization’s Neglected Disease
Initiative in 2006

31. • https://www.uptodate.com/contents/giardiasis-epidemiology-clinical-manifestations-and-diagnosis
• https://www.amboss.com/us/knowledge/Giardiasis
• https://www.cdc.gov/dpdx/giardiasis/index.html
• https://www.cdc.gov/parasites/giardia/pathogen.html
• https://www.cdc.gov/parasites/giardia/index.html
• https://web.stanford.edu/group/parasites/ParaSites2006/Giardiasis/morphology.htm
• https://www.intechopen.com/books/current-topics-in-giardiasis/the-cytoskeleton-of-giardia-intestinalis
• https://www.healthline.com/health/giardiasis#symptoms
• https://www.healthknowledge.org.uk/public-health-textbook/disease-causation-diagnostic/2b-epidemiology-diseases-
phs/infectious-diseases/giardia-
lamblia#:~:text=Giardia%20lamblia%20is%20the%20most,sanitation%20particularly%20in%20developing%20countries
• https://www.intechopen.com/books/current-topics-in-giardiasis/giardiasis-epidemiology
• DOI: 10.1128/CMR.14.3.447-475.2001
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6441489/
• https://doi.org/10.3390/ijms22115943
• DOI: 10.1128/CMR.14.1.114–128.2001