Pathogenic Protozoa II

Question 1

In the mitotic cycle, trophozoites grow and undergo multiple nuclear division cycles without cytokinesis to produce large multinucleate forms called

Answer 1

Schizonts

Question 2

These then cleave (schizogeny) to produce multiple uninucleate infective progeny cells, released by

Answer 2

Host cell lysis

Question 3

In apicomplexa, what are

1. ) Rapidly-multiplying trophozoites
2. ) Slow-multiplying trophozoites
3. ) Semi-dormant trophozoites

Answer 3

1. ) Tachyzoites
2. ) Bradyzoites
3. ) Hypnozoites

Question 4

Kills more people than any infectious disease

Answer 4

Malaria

Question 5

Malaria plasmodia are transferred to humans by which three mechanisms?

Answer 5

1. ) Bite of female anopheles mosquito
2. ) Blood transfusion
3. ) Maternal-fetal route

Question 6

What are the 4 species of plasmodium that infect humans with malaria?

Answer 6

1. ) Falciparum
2. ) Malariae
3. ) Ovale
4. ) Vivax

Question 7

Monkey parasite recently shown to infect humans

Answer 7

Plasmodium knowlesi

Question 8

Found in all subtropical and tropical areas of the world except deserts, usually found below 1800m elevation

Answer 8

Malaria

Question 9

Was once endemic in the eastern and central United States, but extensive mosquito control efforts have eradicated it as an epidemic disease

Answer 9

Malaria

Question 10

What are the three diseases that give heterozygotes immunity to malaria

Answer 10

1. ) G-6-P deficiency
2. )Thalassemia
3. ) Sickle-cell anemia

Question 11

In mammals plasmodia first replicate in the liver. This is followed by multiplication and then gamete formation in

Answer 11

Red cells

Question 12

After transmission to humans, plasmodia first infect and multiply in

Answer 12

Liver cells

Question 13

The form of plasmodium most infectious to humans is the

Answer 13

Sporozoite

Question 14

Each infected liver cell releases thousands of merozoites into the bloodstream and these infect and multiply in

Answer 14

Erythrocytes

Question 15

Are not infectious for hepatocytes so there is no re-infection of the liver

Answer 15

Merozoites

Question 16

Merozoites are infectious for

Answer 16

Erythrocytes

Question 17

The only part of plasmodium that is infection to mosquitos is the

Answer 17

Gametocytes

Question 18

Microgametocytes produce flagella (exflagellation) and produce

Answer 18

Motile gametes

Question 19

In the gut these fertilize the larger macrogametocytes to form motile zygotes (ookinetes) which invade the gut wall and

Answer 19

Encyst (Oocysts)

Question 20

Oocysts then undergo sporogeny: they first grow and then divide to produce multiple sporozoites (the infectious form for mammals), which move to the mosquitos

Answer 20

Salivary glands

Question 21

Undergo only a single cycle of replication in the liver

Answer 21

P. falciparum and P. malariae

Question 22

Remain in liver as dormant hypnozoites which can persist long after erythrocytic forms have disappeared

Answer 22

P. vivax and P. ovale

Question 23

Can produce recrudescent infection of the liver and bloodstream for several years after the initial infection has lapsed

Answer 23

P. vivax and P. ovale

Question 24

By the time symptoms appear, P. falciparum and P. malariae have no liver stage, and therapy can be targeted to the bloodstream forms alone. This is called

Answer 24

Suppressive cure

Question 25

The other species require therapy sufficient not only to remove bloodstream infection but to eradicate slow-replicating hypnozoites from the liver and prevent relapse. This is called

Answer 25

Radical Cure

Question 26

In the erythrocytic cycle, a merozoite infects an erythrocyte and becomes a

Answer 26

Vacuolated ring form

Question 27

This enlarges [trophozoite], undergoes nuclear division [developing schizont] and finally cleaves [schizont] to produce numerous new

Answer 27

Merozoites

Question 28

Plasmodia degrade and catabolize hemoglobin. The released hematin precipitates to form granules of

Answer 28

Malaria pigment

Question 29

In P. vivax/ovale infections the granules are coarse and known as

Answer 29

Shuffner’s dots

Question 30

After erythrocyte lysis this pigment is phagocytosed by reticuloendothelial cells and produces

Answer 30

Gray/black tissue discoloration

Question 31

Malaria transmission is followed by an incubation or prepatent period, before the onset of symptoms. This period lasts

Answer 31

1-4 weeks

Question 32

Cycles of erythrocyte infection and release of merozoites may become highly synchronized. Waves of erythrocyte destruction produce waves of

Answer 32

Chills and fever

-Then sweats as fever relapses

Question 33

Malaria diagnosis is by

Answer 33

Blood smear

Question 34

Bouts of fever are often accompanied by headache, nausea/vomiting, and malaise. As disease continues, we see anemia, cachexia, and

Answer 34

Enlargement of liver and spleen

Question 35

In severe cases, especially of falciparum malaria, there may be extensive hemolysis with hemoglobin in the urine. This is called

Answer 35

Blackwater fever

Question 36

In falciparum malaria infected red cells at post-ring stages adhere to

Answer 36

Endothelium

Question 37

Are both involved in recovery from anemia

Answer 37

Humoral and cell-mediated immunity

Question 38

Produces some degree of immunosuppression, as measured by decreased response to vaccine antigens

Answer 38

Malaria

Question 39

There is also polyclonal B cell activation. These can interact with latent infection with Epstein-Barr virus to promote development of the B-cell tumor known as

Answer 39

Burkitt’s lymphoma

Question 40

Bloodstream infection with a given strain of Plasmodium produces a state of low level immunity to

Answer 40

Antigenically similar strains (premunition)

Question 41

Requires the continued presence of plasmodia; once bloodstream infection lapses, immunity wanes and re-infection can occur

Answer 41

Premunition

Question 42

The origin of the gin and tonic because the drink was used to mask the taste of

-Could cure malaria

Answer 42

Quinine

Question 43

Act by inhibiting the enzyme heme polymerase

-Still used in the treatment of CNS malaria

Answer 43

Quinine

Question 44

Contain a non-photosynthetic plastid with a genome like that of chloroplasts

Answer 44

Plasmodia

Question 45

What are the three genera of Microsporidia that infect humans?

Answer 45

Encephalitozoon, Enterocytozoon, and Nosemia

Question 46

Transmission is via contaminated food or water. Life cycle is similar to that of Apicomplexa

Answer 46

Microsporidia

Question 47

Microsporidia multiply intracellularly. The infectious form is the

Answer 47

Spore

Question 48

When a spore contacts a host cell the filament everts and pierces the host-cell plasma membrane. Osmotic flow of water into the spore forces the cytoplasm of the parasite through the polar filament and into the

Answer 48

Cytosol of host cell

Question 49

Have the smallest genomes of any eukaryotes, about 2 mb, smaller than many bacteria

Answer 49

Microsporidia

Question 50

Mostly intestinal, eye, or systemic infections, although any tissue can become infected

Answer 50

Microsporidia Infection