Parasitic infections

Question 1

How does infection by Giardia occur?

Answer 1

Ingestion of cysts in contaminated water or food

Question 2

What are the characteristic symptoms of Giardia?

Answer 2

Acute onset of diarrhea
Abdominal cramps
Bloating
Flatulence 
Sulfuric belching

Stools–profuse and watery at first, but later greasy and foul smelling–Steatorrhea

Weight loss

Question 3

What is the tx for guard?

Answer 3

Metronidazole

Question 4

What individuals are mostly affected by Cryptosporidiosis?

Answer 4

Immunocompromised hosts–Chronic diarrhea

Question 5

What are sources of Cryptosporidium?

Answer 5

C. parvum–Dairy calves, young lambs and goats

Water supply and swimming pools–Oocytes have an extreme tolerance to chlorine

Question 6

Severity and duration of cryptosporidium is dependent on what?

Answer 6

Immune status of host

Immunocompetent–> cryptosporidia cause a self-limiting, usually watery, diarrhea lasting 10-14 days

Immunocompromised–> cryptosporidiosis is more severe–often chronic and incurable illness that can be life-threatening

Question 7

What is the tx for cryptosporidiosis?

Answer 7

Fluid and electrolyte support

Nitazoxanide in immunocompetent host shortens the duration of symptoms

Question 8

What is the pathogenic entamoeba species?

Answer 8

E. histolytica

Question 9

How does E. histolytica spread through the body?

Answer 9

Trophozoites penetrate the intestinal wall and get into the portal circulation

Question 10

What can result from hematogenous spread of E. histolytica?

Answer 10

Hepatic disease

-Abscess formation within liver—can rupture into the pleural space

Question 11

What is the presentation for E. histolytica that has caused hepatic disease?

Answer 11

Persisting fever

RUQ or epigastric pain and/or shoulder pain

Question 12

What are the 2 forms of E. histolytica?

Answer 12

Cyst stage–infective form

Trophozoite stage–form that causes invasive disease

Question 13

What is the tx for E. histolytica?

Answer 13

Metronidazole

Question 14

What are the 2 Taenia tapeworms and where do they come from?

Answer 14

T. saginata–beef tapeworm

T. solium–pork tapeworm

Question 15

What is released from the tania solium penetrating the intestinal wall and allows travel to the striated muscles, brain, liver, and other organs where they develop into cysticerci?

Answer 15

Oncospheres

Question 16

What is Cysticercosis?

Answer 16

Tissue infection with larval cysts of the cestode T. solium–pt serves as an intermediate host for the parasite

Question 17

What is a major complication of taenia solium infection?

Answer 17

Neurocysticercosis–CNS infection that causes intracerebral lesions–causing mass effects, seizures, or both

Question 18

What tapeworm can be caused by ingestion of freshwater fish?

Answer 18

Diphyllobothrium latum

Question 19

What are the symptoms seen with D. Latum infection

Answer 19

Normally asymptomatic but some pts can have weakness, dizziness, salt craving, diarrhea, and intermittent abdominal pain

Prolonged infection can lead to macrocytic anemia–megaloblastic anemia resulting from deficiencies of vitamin B12 and folate

Question 20

What are the symptoms seen with ascaris lumbricoids?

Answer 20

Nonproductive cough
Chest discomfort
Fever
Eosinophilia that disappear often by the time the worms reach maturity

Severe cases
-Dyspnea and an eosinophilic pneumonia–Loffler syndrome– with transient patchy infiltrates seen on X-ray

Question 21

What are complications seen with chronic ascariasis?

Answer 21

Intestinal obstruction
Obstruction of bile and pancreatic ducts
Appendicitis
Intestinal perforation

Question 22

What is the lifecycle of Ascaris?

Answer 22

Infective eggs swallowed–larvae hatch, invade intestinal mucosa and carried to portal circulation —to the lungs

Larvae mature in the lungs–penetrate the alveolar walls, ascend the bronchial tree to the throat–> then swallowed

Question 23

What are some complications seen with trichuris (whipworm) infection?

Answer 23

Frequent, painful passage of stool that contains a mixture of mucus, water, and blood

Rectal prolapse can occur

Children can become severely anemia and have growth retardation

Question 24

What are the 2 hookworms (ankylostomiasis)?

Answer 24

Ancylostoma duodenale

Necator americanus

Question 25

How do hookworms infect?

Answer 25

Larvae penetrate the skin and are carried through the veins to the heart and then to the lungs–ascend the bronchial tree tot he pharynx and then swallowed –reach the small intestine where they reside and mature into adults

Question 26

What are the major manifestations of hookworm disease?

Answer 26

Iron deficiency anemia and protein energy malnutrition resulting from blood loss

Question 27

Name the pinworm?

Answer 27

Enterobius vermicularis

Question 28

Where do most symptoms occur with a enterobius vermicularis infection?

Answer 28

Related largely to perianal and perineal pruritus and scratching

Question 29

What is the major complication of strongyloidiasis (strongyloides stercoralis)

Answer 29

Hyperinfection–seen in immunodeficient pts

Massive dissemination of filariform larvae to the lungs, liver, heart, CNS, and endocrine glands

–Induces inflammation that may result in symptomatic dysfunction of these organs and even septic shock