Protozoal and Helminthic Infections of GIT

Question 1

Describe the morphology of giardia lambila

Answer 1

• bi-nucleated
• flagellated
• heart-shaped

Question 2

How is G. lambila diagnosed?

Answer 2

• 3 stool samples

- antigen detection assays

Question 3

Describe the pathogenesis of G. lambila

Answer 3

• attaches to wall of upper small intestine by a ventral sucker
• causes villous atrophy which causes malabsorption
• cysts can remain viable in the environment for 24-48 days
• can gain access to biliary system and reside in gallbladder

Question 4

What is the clinical presentation of G. lambila?

Answer 4

• self-limiting diarrhoea (can resolved without treatment)
• can be asymptomatic
• foul smelling, fatty stool

Question 5

Describe the life cycle of cryptospordium parvum

Answer 5

• sporulated resistant oocysts ingested from environment
• sporozoites released and attach to surface intestinal epithelium and enters cell (rather than attaching to it)
• merozoites develop
• after sexual phase, oocysts produced and released in faeces

Question 6

Describe the life cycle of entamoeba histolytica

Answer 6

• cysts are ingested and release sporozoites in terminal ileum
• they adhere to epithelial cells of large intestines
• enzymatic penetration into blood vessels
• in rare cases can spread to distal organs
• resistant cysts pass out in stool

Question 7

What is the clinical manifestation of E. histolytica?

Answer 7

Spectrum:

• small superficial ulcers with mild diarrhoea
• severe ulceration of colonic mucosa with amoebic dysentery
• trophozoites can spread to liver to cause abscesses

Question 8

What are the methods of transmission of nematode infection and examples of infections?

Answer 8

through soil

• swallowing infective eggs:
• ascaris
• trichiuris
• larval skin penetration/systemic migration through lung to intestine:
• strongyloides stercoralis

Question 9

How are nematode infections diagnosed?

Answer 9

stool microscopy

Question 10

Describe the life cycle of strongyloids stercoralis

Answer 10

• disrupt intestinal mucosa causing villous atrophy
• small intestine larvae will invade intestinal mucosa of the colon or skin of perianal region to enter circulation to the lungs and back to the small intestines in a cycle

Question 11

What is the clinical presentation of strongyloids stercoralis?

Answer 11

• diarrhoea
• malabsorption
• anal pruritis
• dehydration

Question 12

Describe the clinical manifestation of trichiuris trichiura

Answer 12

• asymptomatic if mild
• abdo pain
• nausea
• bloody diarrhoea
• rectal prolapse

Question 13

What is the clinical manifestation of ascaris lumbricoides?

Answer 13

• asymptomatic
• allergic reactions
• intestinal obstruction
• malnutrition
• can be expelled from mouth or nose
• Loffler’s syndrome

Question 14

Describe the clinical manifestation of enterobius vermicularis

Answer 14

• intense itching
• inflammation
• diarrhoea
• eosinophilia

Question 15

Describe the life cycle of ancyclostoma duodenale (hookworm)

Answer 15

• larvae penetrates skin and enters bloodstream where it migrates to gut by the lungs
• attaches to small intestine and females lay eggs

Question 16

What is the clinical presentation of hookworm?

Answer 16

iron-deficiency anaemia

Question 17

How does taenia solium (tapeworm) infect?

Answer 17

• has scolex which they use for attachment to the wall of the large intestines

Question 18

What is the clinical symptoms of taenia solium?

Answer 18

• vague GI symptoms

- abdo pain, nausea, weight loss, diarrhoea