ILA 2 Parasitology Basics Flashcards
What is a parasitic infxn?
infection with the absence of disease - asymptomatic
What is a parasitic disease?
Infxn that leads to tissue pathology or death
What are the types of parasites?
- Protozoa - unicellular eukaryotes
- Helminths - round and flat worms
- Fungi - microspora
What are the morphological characteristics of protozoa?
- 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
What are some examples of protozoa?
- Plasmodium
- Leishmania
- Trypanosoma
- Babesia
- Giardia
- Cryptosporidium
- Toxoplasma
- Naegleria
- Trichomonas
- Entamoeba
- Cyclospora
How do protozoa cause disease?
Disease is a result of replication to large numbers in the host
Replication can occur intracellularly or extracellularly
What kind of respiration do protozoa do?
Facultative anaerobic processes
How do protozoa accomplish transmission to new hosts?
- Some form cysts to prevent desiccation in the external environment in order to promote transmission
- Others require vectors for transmission
How do protozoa reproduce?
Binary Fission
some alternate with a period of sexual reproduction
What are the morphological features of Helminths?
- 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
What are nemathelminths?
- roundworms
- separate sexes
- complete digestive tract/system
- most are intestinal parasites
What are platyhelminths?
- flatworms
- flat bodies, can be leaf-like (trematodes) or ribbon-like (cestodes) in shape
What do you know about Trematodes?
- flukes, schistosomes
- incomplete digestive system - require an intermediate host
- most are hermaphrodites
What do you know about Cestodes?
- Tapeworms
- All are hermaphrodites
- Lack digestive systems - nutrients absorbed through cell wall
How do helminths store their nutrients?
as glycogen
What do helminths use most of their energy for?
Reproduction (egg-laying)
What are larvae?
Larvae are morphologically distinct from adult worms and must progress through several developmental stages (molts) to reach adulthood
May require oxygen in larval stages
How are helminths transmitted?
- 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)
What is a definitive host?
the species in which the parasite undergoes sexual reproduction
What is an intermediate host?
the species in which a part or whole of asexual reproduction occurs
What is an incidental host?
an unnatural host to which the parasite may not be adapted for replication; unusual pathology
What is meant by a reservoir?
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
What are vectors?
An arthropod that transmits a disease
