Chapter 5: Part 2 Flashcards
Protozoa (member of the protist family)
- Eukaryotic cells; diverse group of 65000 species, vary in shape, lack a cell wall
- Chemoheterotophic; lack chloroplasts
- Unicellular; rarely colonial
- Most are harmless, free-living in a moist habitat (aquatic, damp soil)
- Some are animal parasites (human tissue habitat) and can be spread by insect vectors
- Cytoplasm divided into ectoplasm and endoplasm
- Feed by engulfing other microbes and organic matter
Cyst
protected structure; contains larval stage
Vegetative Form
active: Trophozoite
Definitive Host
final host; harbors the adult
Intermediate Host
secondary host; harbors a larval or intermediate form of parasite
Infective Form
egg, larva, cyst, trophozoite (how it gets to you)
Diagnostic Form
present in stool, migrates out of body
Mechanical Vector
Passive
- passed on outside; not in body;fly goes on poop–>poop then lands on sandwich (hitches a ride); does not spend time in life cycle
- non-specific
Biological Vector
Active
- spend life cycle in vector (host)
- specific
General Life Cycle Exhibited by Many Protozoa
- Cell rounds up, loses motility; drying, ;lack of nutrients
- Early cyst wall formation (encystment)
- Mature cyst (dormant, resting stage)
- Moisture, nutrients restored; cyst wall breaks open (excystment)
- Tropozoite is reactivated
- Trophozoite (active feeding stage)
Protozoan Identification
Classification is difficult because of diversity
- Simple grouping usually based on method of motility, reproduction, and life cycle
1. Mastigophora
2. Sarcodina
3. Ciliophora
4. Apicomplexa
Protozoan Identification: Mastigophora
primarily flagellar motility, some flagellar and amoeboid; sexual reproduction (flagellate)
Protozoan Identification: Sarcodina
primarily amoeba; asexual by fission; most are free-living; move by pseudopods
Protozoan Identification: Ciliophora
cilia; trophozoites and cysts; most are free-living, harmless
Protozoan Identification: Apicomplexa
motility is absent except male gametes; sexual and asexual reproduction; complex life cycle- all parasitic
Amoeboid Protozoa
Amoebiasis: Entamoeba histolytica
-reservoir/ source: Human/ water and food
Brain Infection: Naegleria, Acanthamoeba- free living in water
Infective Amoebas
Entamoeba histolytica- amoebic dysentery (bloody, pus diarrhea); worldwide
Ciliated Protozoa
(ciliophora)
Balantidiosis: Balantidium coli- zoonotic in pigs
Flagellated Protozoa
(mastigophora)
- Giardiasis: Giardia lamblia; reservoir/ source- zoonotic/water and food
- Trichomoniasis: T. hominis, T.vaginalis; reservoir/ source- humans
- Hemoflagellates
- Trypanosomiasis: Trypanosoma brucei, T. cruzi
- Leishmaniasis: Leishmania donovani, L. tropica, L. brasiliensis; reservoir/source- zoonotic/vector-borne
Apicomplexan Protozoa
- Malaria: Plasmodium vivax, P. falciparum, P. malariae; reservoir/ source- human/vector-borne
- Toxoplasmosis; Toxoplasma gondii; reservoir/ source- zoonotic/ vector-borne
- Cryptosporidiosis: Cryptosporidium; free-living/water and food
- Cyclosporiasis: Cyclospora cayetanensis; water/ fresh produce
Trypanosoma spp.: Trypanosoma brucei
- causes African Trypanosomiasis or African sleeping sickness
- vector: Glossina (Tsetse Fly)
- Central Nervous System Disease (coma)
Trypanosoma spp.: Trypanosoma cruzi
- causes American Trypanosomiasis or Chagas Disease
- Vector: Triatoma infestants (kissing bug)
- Cardiovascular Disease
Trypanosoma brucei Strains
- Trypanosoma brucei brucei: Equines, pigs, cattle, rodents
- Trypanosoma brucei gambiense: Humans, monkeys, dogs, pigs, antelopes: West and Central Africa
- Trypanosoma brucei rhodesiense: humans, wild game, pigs, rats(experiments); East and Central Africa
Trypanosoma brucei Strains: Trypanosoma brucei brucei
equines, pigs, cattle, rodents