ILA 2 Parasitology Basics

Question 1

What is a parasitic infxn?

Answer 1

infection with the absence of disease - asymptomatic

Question 2

What is a parasitic disease?

Answer 2

Infxn that leads to tissue pathology or death

Question 3

What are the types of parasites?

Answer 3

• Protozoa - unicellular eukaryotes
• Helminths - round and flat worms
• Fungi - microspora

Question 4

What are the morphological characteristics of protozoa?

Answer 4

• cell membrane
• numerous organelles
• organs of motility - pseudopods, cilia, flagella
• Speciallized organelles and biochemical features - Apical organelle in apicomplexans, kinteoplasts in kinetoplastids, glycosomes in trypanosomes

Question 5

What are some examples of protozoa?

Answer 5

• Plasmodium
• Leishmania
• Trypanosoma
• Babesia
• Giardia
• Cryptosporidium
• Toxoplasma
• Naegleria
• Trichomonas
• Entamoeba
• Cyclospora

Question 6

How do protozoa cause disease?

Answer 6

Disease is a result of replication to large numbers in the host

Replication can occur intracellularly or extracellularly

Question 6

What kind of respiration do protozoa do?

Answer 6

Facultative anaerobic processes

Question 7

How do protozoa accomplish transmission to new hosts?

Answer 7

• Some form cysts to prevent desiccation in the external environment in order to promote transmission
• Others require vectors for transmission

Question 8

How do protozoa reproduce?

Answer 8

Binary Fission

some alternate with a period of sexual reproduction

Question 9

What are the morphological features of Helminths?

Answer 9

• Multicellular worms - round or flat
• Bilaterally symetric
• Macroscopic
• External surface coated with a cuticle - tegument in flatworms
• attachment structures: hooks, suckers, chitinase teeth or plates
• disease based on inoculum size

Question 10

What are nemathelminths?

Answer 10

• roundworms
• separate sexes
• complete digestive tract/system
• most are intestinal parasites

Question 11

What are platyhelminths?

Answer 11

• flatworms
• flat bodies, can be leaf-like (trematodes) or ribbon-like (cestodes) in shape

Question 12

What do you know about Trematodes?

Answer 12

• flukes, schistosomes
• incomplete digestive system - require an intermediate host
• most are hermaphrodites

Question 13

What do you know about Cestodes?

Answer 13

• Tapeworms
• All are hermaphrodites
• Lack digestive systems - nutrients absorbed through cell wall

Question 14

How do helminths store their nutrients?

Answer 14

as glycogen

Question 15

What do helminths use most of their energy for?

Answer 15

Reproduction (egg-laying)

Question 16

What are larvae?

Answer 16

Larvae are morphologically distinct from adult worms and must progress through several developmental stages (molts) to reach adulthood

May require oxygen in larval stages

Question 17

How are helminths transmitted?

Answer 17

• Ingestion (fecal or oral) - undercooked meat, contaminated vegetation; soil or water-borne contamination by feces
• Direct penetration of skin - contact, sting, or bite of an arthropod vector
• Sexual intercourse (trich)

Question 18

What is a definitive host?

Answer 18

the species in which the parasite undergoes sexual reproduction

Question 19

What is an intermediate host?

Answer 19

the species in which a part or whole of asexual reproduction occurs

Question 20

What is an incidental host?

Answer 20

an unnatural host to which the parasite may not be adapted for replication; unusual pathology

Question 21

What is meant by a reservoir?

Answer 21

Serve as the source of infection and potential reinfection of humans and as a means of sustaining a parasite when it is not infecting a human

Question 22

What are vectors?

Answer 22

An arthropod that transmits a disease