1_Protozoan 1

Question 1

parasites:

define

Answer 1

1. broad, diverse spectrum of agents
2. infects: single agent/ or multiple hosts
3. *SYMBIOTIC w/ host - chronic infxns allow the host to survive for a while
4. repro: sexual or asexual reproduction in complex life-cycles

Question 2

who is most at risk for parasitic diseases?

Answer 2

• impoverished, immunocompromised segments of world populations

As an aside, these are a major cause of human misery in health and death

Question 3

Taxonomy of Protozoa

Answer 3

• Kingdom: Parasite
• Subkingdom: Protozoa (unicellular eukaryotes)
• Genus:
  
  • Rhizopods (amebas)
  • Flagellates
  • Ciliates
  • Sporoza

Question 4

Metazoa:

define

Answer 4

• subkingdom of parasite kingdom
• multicellular eukaryotes

Question 5

categories and examples of Metazoa Helminthes (worms)

Answer 5

• FLATWORMS
  
  • trematodes (fluke) - schistosome
  • cestodes (tapeworms, segmented ribbon-like) - taenia solium
• ROUNDWORMS
  
  • nematodes

Question 6

Examples of nematodes that infect intestine and tissues?

Answer 6

Round worms:

• trichuris
• enterobius
• ancylostoma
• ascaris
• trincinella
• filiariasis
• onchocerca
• larva migrans

Question 7

possible methods of transmission for parasites?

Answer 7

• vectors
  
  • invertebrates, insects, snails
• oral-fecal route
  
  • contamination of water or food
  • undercooked food
• contact
  
  • skin penetration
  • sexual intercourse

Question 8

2 stages of Entamoeba histolytica:

life cycle

Answer 8

1. trophozoite - asexual reproduction
   
   • amoeboid; 15-30 micrometers
   • vesicular nucleus
   • inclusion bodies
   • small central karyosome; no mitochondria
   • may have ingested erythrocytes
2. cyst
   
   • spherical, w/ 1-4 nuclei (12-15 micrometers)
   • refractile wall
   • cytoplasm contains dark staining chromatoidal bodies
   • survive days to weeks in external environment

Question 9

Transmission and infection:

Entamoeba histolytica

Answer 9

1. cysts: in contaminated food and water, poor sanitary condition
   
   • ingestion of mature cysts
   • excystation in small intestine
2. trophozoites: multiply in large intestine
   
   • dehydration of feces in colon triggers cyst formation
   • passed in feces
   • contaminate food and water
   • transmission can occur thru fecal exposure during sexual contact
   • ulcerate and perforate the intestine
   • can lead to systemic invasion of liver, lung, and brain

Question 10

life cycle of :

Naegleria fowleri

Answer 10

1. cyst stage
2. trophozoite stage
3. flagellate forms

Question 11

Life cycle of:

Giardia lamblia

Answer 11

1. Cyst - dormant; found in contaminated food &water
   
   • ingestion of mature cysts
   • excystation in small intestine
   • trophozoites attached to the mucosa by a ventral sucking disk by multiply by binary fission
   • encystation w/ dehydration in the colon; cysts passed in the feces to contaminate food and water
2. Trophozoite - flagellate; asexual reproduction
   
   • half pear-shaped w/ 2 nuclei; 12-15 micrometer
   • 2 parabasal bodies
   • 8 flagella
   • 2 large suction discs located anteriorly
   • 2 axostyles arranged in bilat symmetry

Question 12

life cycle of:

trichomonas vaginalis

Answer 12

*only 1 life stage: trophozoite

• flagellate
• half pear shape w/ single nucleus;
  
  • 4 anterior flagella, and lateral flagella attached by an undulating membrane
  • 2 axostyles arranged asymmetrically
• *organism does NOT encyst
• 15-18 microns;

Question 13

Reservoir for trichomoniasis vaginalis?

Answer 13

ONLY HUMANS;

there is no non-human reservoir