7/28/2019 case 2.ppt

1/20

Case report: I2

:

7/28/2019 case 2.ppt

2/20

History A 25-year-old woman had recently

returned from a trip to the RockyMountains. She had been traveling with

a group of campers, who had obtained

theirdrinking waterfrom a lake. A few

days after returning home, she presented

to her internist suffering from profuse(

) watery diarrhea, crampy epigastric

pain, and foul()-smelling flatulence ().She discovered that most of the other

campers had reported symptoms similar

to her own.

7/28/2019 case 2.ppt

3/20

History Three stool specimens were submitted

for laboratory analysis.All specimens

were negative forenteric bacterialpathogens, and two were also negative

forparasites. Since the specimens for

ova and parasites were received in vialscontaining the preservatives polyvinyl

alcohol and 10% formalin, no wet mounts

() were made to detect motility. Apermanent trichromestain revealed rare,

oval protozoan trophozoites, measuring 9

to 20 jjum in length and 5 to 15 jjim in

width.

7/28/2019 case 2.ppt

4/20

History The broad anterior end of each

trophozoite( )contained aconcave area which covered half the

ventral surface. The structure of this

parasite gave the overall appearance of a

"smiling face" . Rare cysts, having fournuclei, and characteristic median bodies

and longitudinal fibers were also seen.

Typical cysts are demonstrated.

7/28/2019 case 2.ppt

5/20

7/28/2019 case 2.ppt

6/20

Questions 1.

Which protozoan parasite is causing the

camper's infection?

Which form of this parasite is infectious?

A:

Giardia lamblia. (giardiasis) cyst

7/28/2019 case 2.ppt

7/20

7/28/2019 case 2.ppt

8/20

7/28/2019 case 2.ppt

9/20

Accidentally putting something into your mouthor swallowing something that has come intocontact with feces of a person or animal

infected with Giardia. Swallowing recreational watercontaminated

with Giardia. Recreational water includes waterin swimming pools, hot tubs, jacuzzis,fountains, lakes, rivers, springs, ponds, orstreams that can be contaminated with sewageor feces from humans or animals.

Eating uncooked food contaminated withGiardia.

Accidentally swallowingGiardia picked up fromsurfaces (such as bathroom fixtures, changingtables, diaper pails, or toys) contaminated withfeces from an infected person.

7/28/2019 case 2.ppt

10/20

3.

How can this infection be controlled and

prevented?

A:

Practice good hygiene.

Avoid water that might be contaminated.

Avoid food that might be contaminated. Avoid fecal exposure during sexual

activity.

7/28/2019 case 2.ppt

11/20

4.

How does this parasite attach itself to

the intestinal wall? A:

Giardia is a flagellated (having whip-like

appendages for locomotion) protozoanthat, in the trophozoite (active) form,

attaches itself with an adhesive disk

(ventral side) to the lining of the upperintestinal tract of the host

animal. There, it feeds and

reproduces.

7/28/2019 case 2.ppt

12/20

Which condition

might result as a consequence of this

attachment?

1.malabsorptive diarrhea

2.fatty, four-smelling stools after eating

3.milk allergy or lactose intolerance (

7/28/2019 case 2.ppt

13/20

5.

How is this infection treated?

The most common treatment for giardiasis ismetronidazole (Flagyl) for 5-10 days. Iteradicates the Giardia more than 85% of thetime, but it often causes gastrointestinal side

effects such as nausea and a metallic tasteas well as dizziness and headache.

The only drug approved for treating giardiasis

in the U.S. is furazolidone (Furoxone) for 7-10 days. It is approximately as effective asmetronidazole.

Ti id l i il bl t id th U S d i

http://www.medicinenet.com/script/main/art.asp?articlekey=751http://www.medicinenet.com/script/main/art.asp?articlekey=5489http://www.medicinenet.com/script/main/art.asp?articlekey=5489http://www.medicinenet.com/script/main/art.asp?articlekey=6114http://www.medicinenet.com/script/main/art.asp?articlekey=20628http://www.medicinenet.com/script/main/art.asp?articlekey=20628http://www.medicinenet.com/script/main/art.asp?articlekey=6114http://www.medicinenet.com/script/main/art.asp?articlekey=5489http://www.medicinenet.com/script/main/art.asp?articlekey=5489http://www.medicinenet.com/script/main/art.asp?articlekey=751

7/28/2019 case 2.ppt

14/20

Tinidazole is available outside the U.S. and ishighly effective at treating giardiasis(>90%). Italso can be given as a single dose and is welltolerated.

Quinacrine is very effective for treatinggiardiasis but is no longer available in the U.S.

Paromomycin and albendazole, thougheffective, are less effective than othertreatments.

Occasionally, treatment fails to eradicateGiardia. In such cases, the drug may bechanged or a longer duration orhigher dosemay be used. Combination therapy also maybe effective (e.g., quinacrine and

metronidazole).

http://www.medicinenet.com/script/main/art.asp?articlekey=5176http://www.medicinenet.com/script/main/art.asp?articlekey=5176

7/28/2019 case 2.ppt

15/20

6.

Describe the life cycle of this parasite.

At some time in its active life, the trophozoite

releases its hold on the bowel wall and floats

in the fecal stream. As it makes its journey, it

transforms into an egg-like structure called acyst, which is eventually passed in the

stool. Duration of cyst excretion, called

shedding, may persist for months. Once

outside the body, the cysts can be ingested

by another animal. Then, they hatch into

trophozoites due to stomach acid action and

digestive enzymes, and the cycle repeats.

7/28/2019 case 2.ppt

16/20

7.

Describe the pathogenesis of this infection.

A significant infestation can leave millions oftrophozoites stuck tight to the intestinallining. There, they cripple the guts ability to

secrete enzymes and absorb food, especiallyfats, thereby producing the diseasessymptoms. The symptoms typically appearone to two weeks after ingestion, with anaverage ofnine days, but four weeks is notuncommon. Symptoms can vanish suddenlyand then reappear. They may hide formonths. They may not appear at all.

7/28/2019 case 2.ppt

17/20

8.

How is the laboratory diagnosis of this infection made?

A:

Giardia lamblia is frequently diagnosed by visualizingthe organism, either the trophozoite or the cyst instained preparations orunstained wet mounts with

the aid of a microscope. A commercial fluorescent antibody kit is available to

stain the organism.

Organisms may be concentrated by sedimentation orflotation; however, these procedures reduce the

number of recognizable organisms in the sample. An enzyme linked immunosorbant assay(ELISA)

that detects excretory secretory products of theorganism is also available.

http://www.cfsan.fda.gov/cgi-bin/bbbglos?Enzyme-Linked=Immunosorbent=Assayhttp://www.cfsan.fda.gov/cgi-bin/bbbglos?Enzyme-Linked=Immunosorbent=Assay

7/28/2019 case 2.ppt

18/20

9.

Discuss the epidemiology of this infection.

A: Giardiasis is more prevalent inchildren than in adults,

possibly because many individuals seem to have alasting immunityafter infection. This organism isimplicated in 25% of the cases ofgastrointestinaldisease and may be present asymptomatically. Theoverall incidence of infection in the United States isestimated at 2% of the population. This disease afflictsmany homosexual men, both HIV-positive and HIV-negative individuals. This is presumed to be due tosexual transmission. The disease is also common inchild day care centers, especially those in whichdiapering is done.

7/28/2019 case 2.ppt

19/20

10.

How does the structure of these

trophozoites account for the "smiling-face"

appearance?

A:

http://www.yosemite.org/naturenotes/images/Giardia.jpg

7/28/2019 case 2.ppt

20/20

Thanks for your

attention !!!