1. Allison Lake Microbiology 234
Giardia Lamblia
Allison Lake
Microbiology 234

2. A Brief History..
In 1681 a linen merchant by the name of Anton Van Leeuwenhoek discovered a moving “animalcule” believed to be Giardia in his own feces.
It’s common name
comes from scientists
Alfred Giard and Vilem
Lambl
Scientists thought it
was harmless until a
large diarrhea
incidence in the 70’s
“animalcules a-moving very prettily. . .Their bodies were somewhat longer than broad, and their belly, which was flatlike, furnisht with sundry little paws. . . and albeit they made a quick motion with their paws, yet for all that they made but slow progress” (Katz, Despommier, and Gwadz, p ).

3. In Rural America Failure to Thrive
A 20-month old boy came to his doctor with a history of failure to thrive. Although he was breast-fed and at normal weight when born, he was under 20 pounds and measured 2 feet, 8 inches. No history of vomiting or diahrrea
His doctor recommended PediaSure, which did little for growth
Testing of the blood, electrolytes, calcium, total protein, albumin, and many others came back normal
In Rural America

4. Failure to Thrive
It was revealed that the patient’s sibling had giardia a few years prior, and a stool giardia antigen test came back Positive!
It’s likely that he picked up a cyst of Giardia from contaminated water while camping
Treatment: after diagnosis the child took antibiotic metronidazole 15mg/kg/day for 7 days
3 months later he gained almost 3 lbs and continued to grow normally with negative results for Giardia Lamblia. None of his family members contracted Giardia from him.
(Mikla N. Derlet MD, James H. Brien DO, John Belko MD)

5. Anaerobic flagellated protozoan parasite
Etiology
Anaerobic flagellated protozoan parasite
Giardia lamblia contain 2 nuclei with 4 pairs of associated flagella for easy motility
They have a tear-drop shape and
measure micrometers
They contain no mitochondria, Golgi apparatus , endoplasmic reticulum or lysosomes

6. Staining
Giardia are easily stained in their trophozoite phase with methylene blue.
They show a striking characteristic of a smiling face when stained.

7. Virulence Factors
Giardia has two life stages: trophozoite (for motility) and cyst phase (for protection).
Giardia’s cytoskeleton is known as an important factor in attachment, motility, cell division, cell transport and encystation
After a cyst enters the host it readily produces 2-4 trophozoites by binary fission
The trophozoites have a large sucking disk on their anterior side for attaching to the villi of the small intestine
Trophozoites also have 8 flagella used mostly for movement
They also contain mitosomes and iron-sulfur proteins involved in catalysis and electron transport

8. Pathophysiology
Incubation period varies from 1-2 weeks with a mean of 9 days
Duration of symptoms usually lasts 3-10 weeks
Adhesion of trophozoites causes loss of intestinal brush border surface area, villus flattening and atrophy, malabsorption and overgrowth of enteric bacteria.
Can release cytopathic substances that damage the intestinal epithelium and can cause diarrhea
Villous atrophy also in the duodenum and jejunum

9. Symptoms
(Dogs can get it, too!)
Symptoms include: violent diarrhea, excess gas, stomach or abdominal cramps, upset stomach, loss of appetite, weight loss, malabsorption and nausea which can result in dehydration and nutritional deficiency

10. Contraction & Transmission
Giardia is contracted through contaminated water and food, and by fecal-oral route.
It’s also common to contract Giardia from another person
The parasite enters the body in cyst form and then goes through excystation
Giardia cysts can live 2 months outside the body and can tolerate low temperatures
These cysts are commonly found in lakes, creeks and rivers and are picked up from hikers and swimmers
They can also be found in child-care centers where children transmit Giardia via fecal-oral route
Both cysts and trophozoites can be expelled through defecation
cysts= infection

11. Diagnosis
An antigen test for giardial proteins can be performed from the stool that can identify roughly 90% of cases.
It can also be diagnosed by collecting stool samples and examining them under a microscope for Giardia parasites. It generally takes multiple samples for a successful diagnosis of about 90%.
Microscopic examination is helpful because it can also identify other intestinal parasites that can cause similar symptoms

12. Treatment
Standard treatment medications include: Metronidazole, {Tinidazole} , Furazonidole, Quinocrine hydrochloride and lastly, Nitazoxanide for children
Tinidazole is most widely used and has a 90% success rate
A few antibiotics may need to be used due to Giardia’s resistance to some drugs

13. Prevention Wash your hands Practice good hygiene with your kids
Vaccinate your dogs from Giardia
Don’t drink from freshwater sources-
if you’re desperate, boil it first!

14. statistics
The CDC estimates that there are approximately 1.2 million cases of Giardia in the U.S. every year
It is most frequently reported in children from ages 1-4
In 2009 Oregon had Giardiasis stats nearly twice that of the rest of the United States with 11.2 cases/100,000

15. Why does it matter?
Giardia & the world
In the United States, Giardiasis is the most common intestinal parasite
Estimated incidence worldwide is 2.8 million cases annually
Giardia affects those in all kinds of communities around the world, particularly children
Although it is usually a mild infection, it can prove deadly to those with compromised conditions
Millions of dollars are spent on treating those with Giardia every year!
It is important to treat because it can eventually cause malnutrition from malabsorption
The best way to prevent it is to encourage good hygiene and drinking filtered water only

16. References
Belko, J., Derlet, M., (2006) 20-month old boy with gailure to thrive, retrieved July 23th, 2015 from from
Cowan, Marjorie (2013) Microbiology fundamentals: a clinical approach, McGraw Hill, New York, NY, USA
Chandlee, D., Clark, J., Wisti, K., Zucker, M., Giardiasis, Clark College, retrieved on July 13th, 2015 from
Dawson, S., Dawson Lab, About Giardia, retrieved July 13th from
Painter, J., Gargano, J., Collier, S., Yoder, J., (2015) Giardiasis Surveillance- United States, , Centers for Disease Control and Prevention, retrieved July 13th from
Public Health Oregon, Giardiasis, Selected reportable communicable diseases , retrieved July 14th from