Parasitology

Question 1

Protozoa
“animal-like”

Answer 1

-unicellular heterotrophic
-lack photosynthetic capability
-motile
-reproduce by asexual fission

Question 2

T/F Examples of protists are algae, slime molds, & water molds

Answer 2

True

Question 3

Subphylum Mastigophora

Answer 3

-include flagellated protozoa
-Giardia lamblia, Leishmania species, Trypanosoma brucei rhodesiense, & Trypanosoma brucei gambiense, Trypanosoma cruzi

Question 3

Subphylum Sarcodina

Answer 3

-Move by pseudopodia
-Entamoeba histolitica produces diseases in humans

Question 3

Phylum Apicomplexa (Sporozoa)

Answer 3

-Flagella
-Includes Plasmodium species (Malaria), Toxoplasma gondii (Toxoplasmosis), Cryptosporidium parvum (Cryptosporidiosis)

Question 3

Phylum Ciliophora

Answer 3

-Cilia
-Cilia completely covers organism; found near oral cavity & helps propel food into opening (cytosome)
-Includes Balantidium coli (causes ulcers in large intestines)

Question 4

Phylum Microspora

Answer 4

-Polar filament
-Microsporidium (Diarrhea): intracellular protozoan infection of immune compromised individuals

Question 5

Protozoa Environment

T/F Majority of protoza are free-living (found in marine, fresh water & terrestrial habitats) while some are parasitic (hosts ranging from algae to humans).

Answer 5

True

Question 6

T/F Protozoa are:
-Essential decomposers
-Require large amounts of moisture
-Important part of food chain by: eating bacteria, maintaining ecological balance in soil, & reduce sewage solids

Answer 6

True

Question 7

Structure of Protozoa

Answer 7

-Lack cell wall (shape determined by material beneath plasma membrane

-Have membrane bound nucleus & organelles

-lack photosynthetic chloroplasts

-Have Cilia, flagella (diff from prokaryotes), pseudopodia, or polar filaments

-Pull in food, water, H2O from outside (readily diffuse thru cell membrane)

-Pinocytosis or Phagocytosis

Question 8

Protozoa Reproduction

Answer 8

-require more than 1 habitat or host
-polymorphic: can be found in morphologically distinct forms @ diff stages of life
-can exist as trophozite (vegetative/feeding form) or as cyst (resting, infectious form when protozoa lacl nutrients, moisture, oxygen, etc.)

Question 9

Protozoa Reproduction

Asexual &/or Sexual reproduction common

Answer 9

Binary fission: DNA replication followed by division of 2 cells longitudinally (flagellates) or transversely (ciliates)

*if protozoa has both flagella & cilia the method of replication decides how they’re classified

Multiple fissions (Schizogony): Multiple DNA divisions resulting in a cell w/many single-celled infectious organisms

*Release of these parasites at regular intervals produce the characteristic cyclic symptoms of malaria

Question 10

Blood & Tissue Protozoa

Leishmaniasis

Answer 10

-zoonotic protozoa carried by rodents, dogs, & foxes; transmitted to humans by bite of sandfly

-Promastigote (flagellated motile form) invades macrophages & transforms into nonmotile amastigote. Amastigotes multiplies in phagocytic cells in the lymph node, spleen, liver, & bone marrow

Question 11

Cutaneous Leishmaniasis (L. tropica and L. mexicana)

Answer 11

-Skin ulcer develops at site of bite due to skin destruction following activation of intact Cell-Mediated Immunity (ulcer takes about a year to heal)

-Diffuse
*Nodular lesions diffuse across body due to inactive CMI response.
*Untreated infections can last for years

Question 12

Mucocutaneous Leishmaniasis (L. braziliensis)

Answer 12

-Initial dermal ulceration heals. However, ulcers appear in the mucous membranes of the nose and mouth that may erode the nasal septum, soft palate and lips if left untreated

Question 13

Visceral Leishmaniasis -Kala-azar (L. donovani)

Answer 13

-Common in young malnourished children

-Fever, anorexia, weight loss, & abdominal swelling (from enlargement of the liver (hepatomegaly) and spleen (splenomegaly) due to invasion of fixed reticuloendothelial cells (fixed phagocytic cells) of these organs

-Often fatal

Question 14

African Sleeping Sickness

Answer 14

-Following bite, the trypomastigote (flagellated motile form) spreads via the bloodstream to the lymph nodes and CNS

-Initial painful skin ulcer heals w/n two weeks followed by fever,headache, dizziness, and lymph node swelling that takes place due to systemic spread

-fevers are intermittent due to variable surface glycoproteins (VSG)

-CNS symptoms develop
-Daytime drowsiness (thus sleeping sickness), slurred speech, problems walking, coma, death

Question 15

How many forms of African Sleeping Sickness are there?

Answer 15

Two forms:

-West African Sleeping Sickness (Trypanosoma brucei gambiense)
**Notable for slowly progressing symptoms

-East African Sleeping Sickness (Trypanosoma brucei rhodesiense)
**More severe with death occurring w/n weeks

Question 16

Chagas’ Disease

Answer 16

-Trypanosoma cruzi

-Trypomastigotes tunnel into the human host, transform into amastigote which invades skin, macrophages, lymph nodes, and spread in the blood to distant organs

-A hard, red area develops at site of entry followed by systemic spread with fever, malaise, and swollen lymph nodes.

-infected include the heart and CNS.

Question 17

Chaga’s Disease can occur in these 3 phases:

Answer 17

-Acute phase – fever, malaise, swollen lymph nodes, meningoencephalitis, acute myocarditis (resolves in about a month)

-Intermediate phase – low levels of parasites in blood and positive antibody responses against T. cruzi but NO Symptoms (most people remain here for life)

-Chronic phase – organs primarily affected are the heart, colon, esophagus)
dementia, megacolon, megaesophagus, heart damage, heart failure

Question 18

Plamodium species (Malaria)

Answer 18

• ~200 million global cases of malaria leading to a mortality of more than one million people per year

-Periodic episodes of high fever and shaking chills (paroxysms), followed by periods of profuse sweating (occurs when the red blood cells burst and release merozoites)

-Tertian malaria - P. vivax and P. ovale – every 48 hrs

-Quartan malaria - P. malaria – every 72 hrs

-**P. falciparum – most common and deadly; irregular episodes