Protozoa Flashcards
Symbiosis
Close and prolonged interaction between organisms of different species. A long term relationship. Parasitism, commensalism or mutualism.
Symbiont
Induviduals involved in a symbiosis.
Parasitism
Symbiotic relationship between 2 different species where one member benefits and the other is harmed.
Parasite
Organism that live in or on a host and gains its nourishment at the expense of the host.
Obligatory Parasite
A parasite that cannot exist outside its host.
Facultative Parasite
A parasite that can exist independdent of its host
Endoparasite
Parasite that is established inside the host’s body.
Ectoparasite
Parasite that is established in or on the exterior surface of its host.
Host
Species of animal or plant that harbors a parasite
Definitive Host
Host in which the adult and/or sexual phase of the parasite occurs.
Intermediate Host
Host in which the larval and/or asexual phase of the parasite occurs
Accidental/Incidental Host
Host other than the normal host that harbors a parasite.
Reservoir Host
Host that harbors a parasite that is also parasitic for humans and from which humans can become infected.
Infective Stage
Stage in the parasitic life cycle that is capable of invading a definitive host.
Diagnostic Stage
Stage in the parasitic life cycle that can be identified by examining appropriate specimens from the host.
Infestation
Parasitic infection, especially for macroscopic parasites.
Amoebas
Class of parasites Move via Pseudopods Replicate via Binary Fission Found in nature Most are nonpathogenic
Trophozoite
Motile stage of most parasitic amoebas and flagellates
Feeding
Find in darrheal stools
Noninfectious
Cysts
Nonmotile stage of most parasitic amoebas and flagellates
Protected by cyst wall
Resistant to drying and gastric acid
Infectious
Life cycle of intestinal amoebas (Entamoeba histolytica)
- Host ingests infective cysts
- Cysts in GI tract excyst to form trophozoite
- Troph multiplies by binary fission
- Troph encysts
- Host excretes cysts in stool
How to identify trophozoites
Size
Arrangements of chromatin in nucleus
“Clean” vs. “dirty” cytoplasm
Presence or absence of inclusions in cytoplasm
How to identify cysts
Size
Shape
# of nuclei
Presence or absence of chromatid bodies or other inclusions in cytoplasm
Entamoeba hystolytica diseases and transmission
Dysentery - bloody diarrhea (trophs)
Ulcers - in liver, brain and colon
Transmitted in food, water, sexually
Cysts viable for 30 days
Dientamoeba fragilis diseases and transmission
Diarrhea, abdominal pain, anorexia, nausea, vomiting, fatigue and weight loss
No cyst stage
Transmitted in food and water
Ciliates
Ciliated trophozoites
Balantidium coli is only known ciliate parasite of humans
Balantidium coli diseases and transmission
Only known ciliate parasite in humans and largest protozoan in humans
Balantidiasis
Transmitted in food and water
Flagellates
Flagellated trophozoites
Giardia and Trichomonas
Giardia duodenalis/lamblia diseases and transmission
“Little old man with glasses” appearance
Giardiasis - 1-14 day incubation, lasts 1-3 weeks, acute or chronic diarrhea, nausea and vomiting, followed by foul smelling stool
Transmission by fecal/oral route in water
Trichomonas vaginalis diseases and transmission
Vaginosis - not a pathogen per se, but causes pH and other imbalance in the vagina
Transmitted sexually
No cyst stage
Zoonotic Diseases
A disease that can be transmitted from animals to people.
Usually exists only in animals but can be transmitted to humans
Cryptosporidium parvum diseases and transmission
Causes mild, self-limiting watery diarrhea (small bowel)
Remission ~ 10 days
Transmission in water, food, animals and people
Resists chlorine and ozone treatments
Characteristics of Protozoa
Eukaryotes
Membrane bound nucleus
Etc.
Sequelae
Diseases that can come as a result of and following another disease
