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Flashcards in Parasitology 4 Deck (34):
1

Babesia microti infects _______ whereas Plasmodium infects ______

Babesia: RBCs only, not hepatocytes
Plasmodium: RBCs and hepatocytes

2

What are intermediate hosts of Babesia?

mice, small mammals, humans are accidental hosts

3

What geographic regions have high incidence of Babesia?

NE US, Midwest, same range as Lyme because also transmitted by nymph stage of Ixodes scapularis

4

Describe the lifecycle of Babesia

During a blood meal, a Babesia-infected tick introduces sporozoites into the mouse host. Sporozoites enter erythrocytes and undergo asexual reproduction (budding) In the blood, parasites differentiate into male and female gametes
A second tick must bite the mouse to ingest the gametes. Within the tick, gametes unite and undergo a sporogonic cycle resulting in sporozoites
Humans become infected if bitten by an infected tick

5

To diagnose Babesiosis, microscopy can be used to visualize Babesia inside ________

red blood cells

6

Patients who are acutely ill with Babesia will have _________ and _________

hemolytic anemia, thrombocytopenia

7

Describe pathology of Babesia

usually nothing, but some have hemolytic anemia and
nonspecific flu-like symptoms (fever, chills, body aches, weakness, fatigue)
weeks or months after exposure or if immunosuppressed
Some patients have splenomegaly, hepatomegaly, or jaundice

8

What drugs can be used to treat Babesiosis

combination therapies:
Atovaquone and azithromycin;
Clindamycin and quinine (severely ill patients)

+ supportive care

9

On microscopy, babesia can be distinguished from plasmodium based on the ________ appearance

Maltese cross

10

List the plasmodium species that cause malaria in humans

falciparum
vivax
ovale
knowlesi
ovale
malariae

11

Malaria infects ______ and ______ cells within the human

hepatocytes and erythrocytes

12

Most fatalities from malaria are in _____ and _______

children, prima gravada females

13

Plasmodium has an obligate ____ stage, sporozites hone in within 10 minutes

Liver
Target for vaccine development

14

Falciparum malaria shows ________ lysing of RBCs

synchronous

15

Vivax and ovale malaria can develop a __________ stage that is not seen in falciparum malaria

chronic liver stage

16

Malarial _______ form in human host but must be transmitted to mosquito to fuse

gametes

17

Which species of malaria can cause relapse from liver forms?

vivax and ovale

18

Which species of malaria can cause severe malaria?

falciparum, vivax, knowlesi

19

What is unique about knowlesi malaria?

- monkey reservoir
- shorter erythrocyte phase (more rapid fever spikes)

20

Describe symptoms of malaria

Chills, fever, splenomegaly, myalgia, headache

21

The malaria parasite has evolved "knob proteins" which function to:

exported to RBC surface, make RBCs sticky so they adhere to vascular endothelium, helps parasite avoid the RBCs being removed from circulation

22

What is the underlying pathophysiology of cerebral malaria?

Immune response causes leaky vasculature, breakdown of blood-brain barrier

23

The parasatemia of malaria demonstrates _________, another mechanism the parasite uses to evade immune response and complicates vaccine development

antigenic waves- antigenic variation over the course of a single infection
*** variable parasatemia within a given infection, even if blood sample shows low parasite level, could have serious infection

24

Are corticosteroids useful in treating cerebral malaria?

Unclear, probably limited effectiveness

25

Cerebral malaria is most commonly seen in _______ and _________

travelers and children >2 (able to mount robust immune response which leads to breakdown of BBB)

26

How does malarial infection lead to anemia?

- destruction of parasatized RBCs when parasites develop
- increased rate of removal of uninfected RBCs from circulation
- suppression of erythropoiesis
- immune destruction of RBCs coated with parasite derived molecules

27

Anemia from malaria usually occurs in _________

children <2 yrs, insufficient immune response to control parasites, so greater parasatemia

28

What is the standard method of diagnosing malaria?

Geimsa stain of thick and thin smears

now developing rapid immunoassay, PCR

29

If multiple parasitic rings are noted on a blood smear, the likely cause of the malaria is:

falciparum (or knowelsi)

30

Immunity to malaria can develop in people living in endemic areas, but it is ______ to develop, requires _____ infection, and is _____ lived

slow, multiple, short

31

How is malaria treated?

chloroquine, mefloquine, quinine
multidrug resistance common, especially chloroquine
newer drugs: malarone (atovaquone & proquanil), doxycycline, clindamycin, artesunates

IV quinidine still used for cerebral malaria

P. ovale/vivax must use primaquine for liver stages

32

What is the source of the RTS, S experimental malaria vaccine?

Circumsporozoite protein

33

________ women often lose resistance to infection

pregnant- especially first pregnancy

34

List some host mutations that confer some resistance to plasmodium infection

Sickle cell
G6PD deficiency
Thalassemia
Duffy group negative (receptor for vivax and knowlesi)