Intro to Eukaryotic Pathogens: Part 2 Helminths/Worms-Steinauer

Question 1

What are the basic facts about helminths/worms?

Answer 1

oDo not multiply within human host
oPathogenesis dependent on:
1. Number of worms
2. Host immune response
3. Genetics of parasite
oChronic infection
oImmunomodulation:
•May increase susceptibility to other pathogens.
•May also help in chrone’s disease and MS.

Question 2

What is the basic anatomy and life cycle of a Trematode: fluke?

Answer 2

Basic Anatomy
•Leaf shaped
•Incomplete digestive system
Life cycle
•Definitive host → first intermediate host → second intermediate host
•First intermediate host is almost always a snail and this is where it multiplies
•Second intermediate host is where parasite encysts in tissues

Question 3

•Get from eating water vegetables
•Acute
    o Mostly asymptomatic
    o Epigastric pain
    o Subcapsular hematoma of liver
•Chronic
    o Mimics gall bladder disease
    o Right upper quadrant pain and tenderness

Answer 3

Fasciola hepatica

Question 4

• Liver fluke
• Found in Eastern part of world
• Encyst in fish and infect people who consume fish
• Less inflammation
• Mostly asymptomatic
• Chronic liver disease

Answer 4

Clonorchis sinensis

Question 5

Live in mesenterial veins of intestines
Acute schistosomiasis
    •Only in travelers
    •65% of infections
    •

Answer 5

Schistosoma or bilharzia

Question 6

What is the basic anatomy of Cestodes: tapeworms?

Answer 6

Ribbons or repeated proglottid
No digestive system
Inhabit digestive tract
Polyzoic
    •Proglottids (“Scales”)
       oNot independent of each other
       oPackets of eggs
    •Strobila
       oCollection of proglottids

Question 7

What is the life cycle of Cestodes: tapeworms?

Answer 7

All adults infect digestive tract
Symptoms
    •Asymptomatic
    •Abdominal pain, nausea, vomiting
    •Vitamin deficiency
Immature stages
    •Very pathogenic
    •Ex: taenia solium

Question 8

Pork (solium) and beef (saginata) tapeworm
Solium
•Humans can be infected as secondary intermediate host
•Human cysticercosis
oNeurologic symptoms (neurocysticercosis)
oLeading cause of seizure disorders worldwide

Answer 8

Taenia solium and taenia saginata

Question 9

What is the basic anatomy of Nematoda: roundworms?

Answer 9

• Huge number of species
• Dioecious
• Complete digestive system

Question 10

Soil transmitted Helminths (STH) intestinal worm:
•Anemia and protein deficiency from blood loss
•Abdominal pain, nausea, vomiting, diarrhea

Answer 10

Hookworms

Question 11

Soil transmitted Helminths (STH) intestinal worm:
•Small intestine
•Abdominal pain, diarrhea, malaise, intestinal blockage, impaired development
•Respiratory symptoms due to lung migration

Answer 11

Ascaris lumbricoides

Question 12

Soil transmitted Helminths (STH) intestinal worm:
•Whipworm
•Large intestine
•Thing anterior end buried in mucosa
•Physical damage, diarrhea, rectal prolapse

Answer 12

Trichuris trichiura

Question 13

• Sharp, pointed tail
• More common in temperate regions than tropical regions
• Relatively non-pathogenic but cause discomfort
• Most common intestinal helminth
• Symptoms: pruritis
• Diagnostics: flashlight test, scotch tape test

Answer 13

Pinworms aka Enterobius vermicularis

Question 14

• Causes lymphatic filariasis
• Chronic manifestation: elephantiasis
• Inhabits lymphatic ducts usually near lymph glands in lower half of body

Answer 14

Wuchereria bancrofti

Question 15

• River blindness
• Passed through blackfly bite
• Ocular lesions that result in blindness
• Skin disease – disabling itching

Answer 15

Oncocerca volvulus

Question 16

What is the diagnostic technique: flotation?

Answer 16

• Zinc sulfate

* Most nematode or cestode eggs float to top

Question 17

What is the diagnostic technique: sedimentation?

Answer 17

• Formalin-ethyl acetate

* Most trematode eggs