protozoa Flashcards
Protozoa as a group? related by? where they live? parasitic?
- Diverse group of eukaryotic microbes
- Related only by their simple organization: unicellular or multicellular without specialized tissues
- Most are free-living in aquatic environments or on decaying organic matter
- Some are parasitic
Encystation (many protozoa are capable of this)
• formation of a cyst
– resting state with a wall and low metabolic
activity
– function of cysts
• protection from changes in environment
• sites for nuclear reorganization and cell division
• transfer from one host to another
Excystation
• escape of vegetative form from cyst
• usually triggered by return to favorable environment
• trophozoite
– vegetative form released by parasitic species
– excystation often triggered by entry into new host
Locomotory Organelles
• some protozoa are nonmotile • motile species use one of following: – cilia – flagella – pseudopodia (s., pseudopodium) • cytoplasmic extensions
Reproduction
• asexual – usually by binary fission • mitosis followed by cytokinesis • sexual – usually by conjugation • exchange of gametic nuclei between paired protozoa of opposite mating types
Zooflagellates, spp
Motile due to one or more flagella
Giardia lamblia
Trichomonas vaginalis
Trypanosomes
Giardia lamblia disease
giardiasis - gastrointestinal disorder
Trichomonas vaginalis disease
trichomoniasis - sexually
transmitted disease
Trypanosomes, class/ disease
hemoflagellates
important blood pathogens
e.g., African sleeping sickness
Giardiasis
affects?
most common cause of?
gastrointestinal disorder
Most common cause of epidemic waterborne diarrheal disease
Giardiasis caused by? forms? transmission? reservoir? carriers?
caused by Giardia lamblia– forms cysts and trophozoites
– trophozoites attach to intestinal epithelium and interfere with nutrient absorption
• transmission usually by cyst-contaminated water
– numerous animal reservoirs
– asymptomatic human carriers are common
Giardiasis clinical manifestations (acute and chronic)
– acute giardiasis - severe diarrhea, epigastric pain, cramps, voluminous flatulence,
and anorexia
– chronic gastritis - intermittent diarrhea with periodic appearance and remission of
symptom
giardasis tx, prevention
– antiprotozoal agents (metronidazole)
– avoiding contaminated water or purify it by boiling or filtering (cysts are resistant to chlorine treatment)
Trichomoniasis cause? transmission? form transmitted in?
Trichomonas vaginalis
• sexually transmitted
– One of the most common sexually transmitted diseases (found in 15% of women)
– No cyst stage (only trophozoites)
Trichomoniasis clinical manifestations
– accumulation of leukocytes at site of infection
– in females, results in yellow purulent vaginal discharge and itching
– in males, usually asymptomatic or burning urination
Trichomoniasis diagnosis and tx? (drug name)
observation of parasite in vaginal discharge, semen or urine
– antiparasite therapy (metrodiazole)
Trichomonas tenax
resides in mouth
Usually associated with poor oral hygiene
Aspiration associated with pneumonia
Hemoflagellate Diseases caused by? groups? transmitted how? what do these infect?
• caused by flagellated protozoa
– two major groups
• leishmanias
• trypanosomes
- transmitted by bites of infected arthropods
- infect blood and tissues of humans
Trypanosomes
flagellum?
pathogens of what?
hemoflagellates
important blood pathogens
african trypanosomiasis spp? common name? transmitted by? reservoirs? affected tissues?
Trypanosoma brucei
• African sleeping sickness
• transmitted by tsetse flies – reservoirs included domestic cattle and wild animals
- Chronic bloodstream infection with bouts of parasitemia
- CNS invasion after months to years
african trypanosomiasis clinical manifestations
– interstitial inflammation and necrosis within lymph nodes and small blood vessels of brain and heart, leading to lethargy and death within 1 to 3 years
african trypanosomiasis diagnosis
diagnosed by observation of motile parasites in blood
african trypanosomiasis tx/ vax
drug therapy during systemic stage, but not as effective when CNS involved.
Vaccine not useful due to antigenic variation.
Chagas disease additonal name? transmitted by? resivoirs? infection age in endemic regions? early disease? % with later complications?
American trypanosomiasis
transmitted by kissing bug (= reduviid bug); reservoirs included domestic cattle and other animals
– In endemic regions most people in population infected in childhood
– Early disease mild; small % develop complications 10-20 years later
•