parasitology exam 2 QOTD

Why might a parasite species that has a paratenic host as part of its life cycle have an advantage over one that does not?

they increase the total population of parasite in environment and aid in the chance of one of its needed hosts becoming infected

List 4 general modes of transmission parasites utilize to infect their hosts.

any 4 of the following:

fecal-oral

trophic

vertical

direct penetration

sexual

vector

List 2 reasons why parasites have evolved to have site-specific adaptations.

any 2 of the following:

a single host has many varying environments

parasites are competing against the host's immune system

competition with other parasites

How do Trypanosoma brucei parasites regulate a change between slender blood forms and stumpy blood forms (and back again)?

Slender forms secrete SIF

As slender forms replicate, increased concentration of SIF

Concentration threshold reached (like quorum sensing) and triggers formation of stumpy forms.

At same time, host immune system leads to decreased parasite numbers.

SIF concentration lower, stop stop stumpy formation, slender forms begin growing again.