Parasites: general concepts and ectoparasites Flashcards
Facultative parasite
organism that may become a parasite, but does not require a host for completion of its life cycle.
Example of facultative parasites
occur among many species of fungi:
- Blastomyces dermatitidis
- Blastomycosis
Opportunistic infection
infection caused by pathogens (bacteria, viruses, fungi or protozoa) that take advantage of an opportunity not normally available, such as:
- host with weakened immune system
- breached integumentary barriers
- altered microbiota
Parasitism
when an organism for all or part of its life, derives at least some, but not often all of its food from a living organism of another species (Host), usually living in or on the body or cells of the host, which is usually harmed to some extent by the association.
- ONE WHO EATS AT ANOTHER’S TABLE
Ectoparasite
live on the outside of the host
Endoparasite
live on the inside of the host
Epibiosis
any relationship between two organisms in which one grows on the other but is not parasitic on it
Phoresis
is a non-permanent, commensalistic interaction in which one organism attaches itself to another (the host) solely for the purpose of travel.
Epibiosis and phoresis
- The act of being carried
- In this case the organism or symbionts are nutritionally independent of each other and have a facultative association ( non-obligatory).
Commensalism
- Latin com mensa meaning “sharing a table”
- this occur when a smaller symbiont, the commensal, feeds on the food available in or on the surface of the host, for whom it is unusable or unwanted, while the host neither benefits nor is harmed.
Ht - x —> X
Parasitism
Ht+- 0 (- x)
Commensalism
Ht + Y
Mutualism
(symbiosis - long-term)
Ht
Host table complex (food available)
Helminths
- parasitic worms, large and multicellular
- includes a number a of phyla, many which are unrelated (phylogenetically) but they have superficial similarities:
- They are vermiform or “worm-like” in form
Phyla in Helminths
- Phylum Nematoda (roundworms)
- Phylum Platyhelminthes (flatworms)
- Phylum Acanthocephala (thorny-headed worms)
- Phylum Annelida (segmented worms) not parasites (leeches)