EXAM #2: MALARIA Flashcards Preview

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Flashcards in EXAM #2: MALARIA Deck (46)
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1
Q

What species of mosquito transmits malaraia?

A

Anopheles

2
Q

What is the genus that causes malaria? What type of microorganism is this?

A

Plasmodium

This is a protozoa.

3
Q

What are the five species of Plasmodium that cause malaria? Which are the two most common

A

1) P. falciparum*
2) P. vivax*
3) P. malariae
4) P. ovale
5) P. knowlesi

4
Q

Where are P. falciparum and P. vivax most endemic?

A

P. falciparum= Africa

P. vivax= Asia

5
Q

Describe the lifecycle of Plasmodium.

A

1) Mosquito bite introduces SPOROZITES into the blood
2) SPOROTITEZ travel to the liver
3) In the liver, SPOROTIZES divide into MEROZITES
4) MEROZITES are released from hepatocytes and:
- Transform into TROPHOZITES that make RBCs less flexible and cause extravascular hemolysis/ splenomegaly
- SCHIZONTS that cause RBC membrane rupture and intravascular hemolysis
- GAMETOCYTES that are taken up by new female anopheles mosquitoes to continue the lifecycle

6
Q

What is the hallmark clinical feature of malaria?

A

MALARIAL PAROXYSM that is due to the synchronous release of merozoites and the lysis of RBCs

7
Q

What is malarial paroxysm?

A

Alternating flu-like sx.

  • Fever
  • Chills
  • Headache
  • Muscle ache
8
Q

What are the three stages of malarial paroxysm?

A

1) Cold stage
2) Hot stage
3) Sweat stage

9
Q

Describe the pattern of paroxysm for the five Plasmodium species.

A
  • P. vivax and ovale= Q48 hours
  • P. malariae= Q72 hours
  • P. falciparum= roughly Q36-48
  • P. knowlesi= Q 24 hours
10
Q

What forms of Plasmodium can take on a dormant form and cause symptoms months or years after the initial infection?

A

P. vivax and ovale

11
Q

What is the most severe form of Malaria?

A

P. falciparum

12
Q

What is the severe complication of P. falciparum infection?

A

Cerebral malaria

**Leads to coma, seizures, and death (in 15-20% of patients)

13
Q

What is the severe complication of P. vivax and ovale infection?

A

Splenic rupture

14
Q

What is unique about P. malariea?

A

The parasitic load is so low that it may not be picked up on PBS, which leads to SYMPTOMATIC RECRUDESCENCE (onset of symptoms years after initial infection)

15
Q

Why is anemia a common complication of malaria?

A

Asexual stage of parasite destroys RBCs in the process of replication

16
Q

List the three mechanisms in the pathogenesis of anemia in Malaria.

A

1) RBC lysis
2) Clearing of uninfected RBCs that get coated with antigen
3) Suppression of erythropoiesis by cytokines
- TNF-a
- IL-1

17
Q

What stage of RBCs are favored by the different species of Plasmodium?

A
  • Falciparum and knowlesi favor both mature and young RBCs
  • Vivax and ovale favor RCs
  • Malariae prefers old RBCs
18
Q

Why is P. falciparum the most severe infection causing Malaria?

A

It infects the greatest number of RBCs

19
Q

P. falciparum infection can be associated with splenomegaly, hypoglycemia, and microvascular sequestration, why?

A

Splenomegaly= clearance of infected RBCs

Hypoglycemia= consumption of blood glucose by the organism

Microvascular sequestration?

20
Q

In addition to the parasite consumption of glucose, why else can plasmodium cause hypoglycemia?

A

1) Decreased oral intake
2) Depleted liver glycogen
3) Inhibition of gluconeogenesis

21
Q

How is Malaria diagnosed?

A
  • Recognize clinical syndrome
  • Be weary of travel history (africa/ asia)
  • PBS is the gold standard of diagnosis in suspected cases

Malaria should always be on the differential of a febrile patient that has traveled to a malarious area

22
Q

What are the characteristics of P. falciparum on PBS?

A
  • Red cells with multiple ring forms

- PURPLE BANANAS

23
Q

What are the characteristics of P. vivax on PBS?

A
  • Large distended RBC

- “Schuffner dots”

24
Q

What are the characteristics of P. ovale on PBS?

A
  • Large distended “oval” RBCs

- Schuffner dots

25
Q

What are the characteristics of P. malariae on PBS?

A

Band forms in RBCs

26
Q

Describe how Malaria can be diagnosed with immunodiagnosis.

A

A dipstick detects circulating antigen

27
Q

List the diseases that confer protection against malaria.

A

1) Sickle Cell Anemia
2) Thalassemia
3) G6PD
4) SE Asian Ovalocytosis
5) Absence of Duffy blood group antigen

28
Q

How is Malaria prevented?

A
  • Eradicate mosquito vector
  • Prophylaxis for travelers

Note that vaccine trials have been disappointing, and drug resistance is a major concern.

29
Q

What is Babesiosis?

A

US “Malaria” that is transmitted by ticks BUT without cyclic fever

30
Q

What are the reservoirs for Babesiosis?

A
Rodents= B. microti 
Cattle= B. divergens
31
Q

What groups of patients are most susceptible to Babesiosis?

A

1) Elderly
2) Asplenic
3) Immunosuppression

32
Q

What is the hallmark of Babesia species on PBS?

A

“Maltese Cross”

33
Q

How is Babesia treated?

A
  • Quinine

- Clindamycin

34
Q

Generally, what do anti-malarial drugs target?

A

Asexual form in the blood

35
Q

What is the difference between clinical cure and radical cure?

A

Clinical= symptoms resolved

Radical= symptoms resolved and parasites completely eliminated

36
Q

What drugs are used to treat Malaria?

A
Chloroquine
Quinine 
Meloquine
Doxycycline 
Primaquine
Malarone
37
Q

What are the drawbacks about Chloroquine?

A

High resistance with few strains that are actually susceptible

38
Q

Where is it responsible to prescribe Chloroquine?

A

“West of the Panama Canal”

39
Q

What are the adverse effects of quinine?

A

Cinchonism
Hypoglycemia

Poor TI*

40
Q

What is Cinchonism?

A
Tinnitus 
Hearing loss 
Headace 
Nasuea 
Vomiting 
Visual disturbance
41
Q

What are the advantages of Meloquine?

A
  • Higher TI than quinine
  • Well tolerated
  • Effective against all species
42
Q

Which drug kills the liver form of malaria? What are the clinical implications in regards to cure?

A

Primaquine

This is the only drug available for RADICAL cure*

43
Q

What species of malaria require Primaquine?

A

P. vivax

P. ovale

44
Q

What do you need to check before administering Primaquine?

A

G6PD

45
Q

What are the prophylaxis recommendations for traveling patients?

A

Review travel itinerary for likely species and drug susceptibility

46
Q

How long should it take for a patient to improve with malaria drug therapy?

A

48-72 hours

Thus, if no improvement, you may need to switch your therapy.