Parasitology

Question 1

Rickettsia

Answer 1

Causes Rocky Mountain spotted fever, rickettsial pox, epidemic typhus, murine typhus, and scrub typhus
Doesn’t grow on artificial media
Lice, ticks, mites, and fleas act as vectors
Obligate intracellular parasite that is diagnosed through serology
BSL-3 biohazard

Question 2

Coxiella

Answer 2

Causes Q fever
Obligate intracellular parasite diagnosed through serology
Zoonotic disease found in cattle, sheep, and goats
Highly contagious, BSL-3 biohazard, reportable disease, and a potential bioterrorism agent

Question 3

Ehrlichia

Answer 3

Causes Ehrlichiosis
Diagnosed through the presence of morulae (clusters of organism) in WBC in a blood smear
Obligate intracellular parasite
Transmitted through ticks
Disease state is very similar to Rocky Mountain fever

Question 4

Entamoeba histolytica

Answer 4

Round nucleus with fine, even peripheral nuclear chromatin and a small, delicate central karyosome
Causes acute amebic dysentery and can cause extraintestinal amebiasis

Troph form has 1 nucleus and delicate, finely granular cytoplasm
Troph form typically is identifiable by the presence of ingested RBCs and seldom contains bacteria
Has a single, long, finger-like pseudopod with directional motility

Cyst form has 2-4 nuclei, 10% of cysts have a cigar-shaped chromatoid body, and can have glycogen vacuoles

Question 5

Entamoeba hartmanni

Answer 5

Nucleus and troph form are similar to E. histolytica, just much smaller and will contain ingested bacteria
Cyst form is similar to E. histolytica, just smaller
Nonpathogenic

Question 6

Entamoeba coli

Answer 6

Nucleus has coarse, irregular peripheral chromatin and an eccentric karyosome

Troph form has coarse cytoplasm with many vacuoles and ingested bacteria
Troph form is short and blunt with multiple pseudopods and sluggish, nondirectional motility

Cyst form is round with occasional chromatoid bodies with splintered end, and can have glycogen vacuoles

Nonpathogenic

Question 7

Endolimax nana

Answer 7

Nucleus has no peripheral chromatin and a large irregular karyosome

Troph form has a single nucleus and finely granular cytoplasm
Troph form has blunt pseudopods and a sluggish, nonprogressive motility

Cyst form is round to oval, usually with four nuclei
There are no chromatoid bodies and can have a poorly defined glycogen mass

Nonpathogenic and one of the smallest amoeba

Question 8

Iodamoeba butschlii

Answer 8

Nucleus has no peripheral chromatin and a large karyosome surrounded by a layer of small granules

Troph form has coarsely granular cytoplasm with vacuoles and bacteria
Troph form has blunt pseudopods and a sluggishly progressive motility

Cyst form is ovoid with one nucleus and a prominent glycogen vacuole

Nonpathogenic and only amoeba with just one nucleus in cyst