intro

Question 1

Symbiotic lifestyles

Answer 1

Symbiosis: the living together of two or more species in a prolonged and intimate relationship
Mutualism: good for both
Commensalism:good for one neutral for other
Parasitic: bad for one (host), good for other (parasite)

Question 2

Parasite types

Answer 2

Ectoparasites: infestation on or within the skin (arthropods)
Endoparasites: infection inside body (protozoans(unicellular) and helminths(multicellular worms))

Bacteria, fungi, and viruses are not historically parasites

Question 3

Host types

Answer 3

• Definitive host: contains the sexual stage of a parasites life
• Intermediate host: supports asexual repro or development of parasite
• Incidental/accidental/dead end host: contains the parasite in a non-obligatory part of its life
• Reservoir host: animals that maintain parasite in the wild
• Vector: host species that transmits the infectious form of a parasite to another host

Question 4

Worldwide occurrence of parasites

Answer 4

prevalence: number of cases/time (Sporadic

Question 5

Neglected parasitic infections in the US

Answer 5

• Chagas caused by Trypanosoma cruzi (swollen eye)
• Cysticercosis caused by Taenia solium (neuro)
• Toxocariasis caused by Toxocara canis or Toxocara cati (blind)
• Toxoplasmosis caused by Toxoplasma gondii (pregnancy)
• Trichomoniasis caused by Trichomonas vaginalis (STI)

Question 6

Immune response to parasites

Answer 6

no consistent host immune response to parasites:
Worm infections involve eosinophilia and elicit a Th2 response
Protozoans elicit a Th1 response

Question 7

Definition game:

• Egg
• Larva
• Cyst
• Cysticerci
• Hydatid cyst

Answer 7

• Egg: product of sexual reproduction that contains an embryonated pre larval form
• Larva: Immature post ovum (pre adult) form
• Cyst: dormant stage encapsulated in host tissues
• Cysticerci: encysted cestode larvae in tissues of intermediate host
• Hydatid cyst: specialized cystercercal form of eichinococcus granulosus in intermediate host