EXAM 1 GI Parasites Flashcards
what is symbiosis?
- The intimate living together of two dissimilar organisms in a mutually beneficial relationship.
- An interaction between individuals of different species (symbionts).
- The term symbiosis is usually restricted to interactions in which both species benefit (see cooperation; mutualism), but it may be used for other close associations, such as commensalism, inquilinism, and parasitism.
what is a parasite?
An organism that lives and feeds on or in an organism of a different species and causes harm to its host; an organism that lives on or in a host organism and gets its food from or at the expense of its host; Organism that gains its nourishment from and lives in or on another organism.
what is a pathogen?
An agent that causes disease, especially a virus, bacterium, or fungus.
what is a host?
Species of animal or plant that harbors a parasite.
what are amoebas?
Not all closely related; Trophozoites move by pseudopodia; Multiply by binary fission; Found in nature; → Most are nonpathogenic
what is an infestation?
Parasitic infections are often referred to as infestations, especially for the macroscopic parasites.
what is eosinophilia?
an increase in the number of eosinophils in the blood, occurring in response to some allergens, drugs, and parasites, and in some types of leukemia.
what is hematology?
the study of the physiology of the blood
what are the 3 types of protozoa?
- Amoebas are not all closely related
- Flagellates are not all closely related
- Sporozoans are apicomplexans
Parasitic protozoa conduct respiration via what process?
facultative anaerobic processes
how do parasitic parasites reproduce?
Reproduce via binary fission (merogony), except sporozoans that include cycles of multiple fission (schizogony) alternating with sexual reproduction (sporogony)
describe platylhelminthes
flatworms (helminths)
– May not be a true phylum
– Class Trematoda (trematodes, flukes)
– Class Cestoda (cestodes, tapeworms)
what are the two types of helminths?
platyhelminths (flatworms) and nematoda (nematodes, roundworms)
what are the 3 general types of parasites?
protozoa, helminths, and arthropoda
describe arthropoda
– Class Hexapoda or Insecta (insects)
– Class Arachnida (including ticks and mites)
describe trophozites
- Motile
- Sensitive to environment (drying and gastric acid)
- Feeding
- Reproductive stage
- Find in diarrheal stools
- For most species, noninfectious
describe cysts
- Nonmotile
- Protected by cyst wall; Resistant to environment
- Nonfeeding
- Non-reproductive stage
- Find in more formed stools
- Infectious
they generally survive because they have a thick cell wall and are not particularly metabolically active
Infection by ___ occurs by ingestion of mature cysts (2) in fecally contaminated food, water, or hands.
Entamoeba histolytica
what is the primary known reservoir of Entamoeba histolytica?
humans
what is the reproductive mechanism of Entamoeba histolytica?
sexual
how can Entamoeba histolytica cysts be spread?
- they survive in the environment for weeks or months, especially under damp conditions
- domestic mammals, nonhuman primates, cockroaches, and flies may spread cysts
what disease is caused by Entamoeba histolytica?
dysentery
bloody diarrhea (trophs)
describe dysentery
disease caused by Entamoeba histolytica
o Lyses host tissue in colon → Ulcers in colon → Troph migrates to liver and brain, sometimes lungs
o If patient has pulmonary abscesses, it can be coughed up in sputum
o About 90% of people infected with E. histolytica are asymptomatically colonized
Entamoeba gingivalis is an ___ pathogen
opportunistic
Entamoeba gingivalis normally lives where?
in the gingival pockets near the base of the teeth in the human mouth
Entamoeba gingivalis may be coughed up in sputum specimens, thus it must be distinguished from ___
E. histolytica
infection by what parasite is characterized by stool that is watery early in illness, and then becomes foul smelling and can float?
Giardia lamblia
where is Giardia lamblia found?
streams, ponds, etc.
areas of poor sanitation or personal hygiene
untreated freshwater, especially in the wilderness
what is the route of transmission of Giardia lamblia?
oral/fecal
beavers appear to be a source of ___
Giardia lamblia