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Z Year3 Infectious Diseases > Malaria > Flashcards

Malaria Flashcards

1
Q

What is Malaria?

A

infection with Protozoan Plasmodium

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2
Q

Where is Malaria endemic?

A

in tropics – affects 250 million people worldwide yearly

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3
Q

What is the incubation period of malaria like?

A

usually 1-2 weeks but up to a year

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4
Q

How is Malaria transmitted?

A

Female Anopheles mosquito

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5
Q

What are the different plasmodium species?

A
  1. P.Falciparum (80% cases worldwide, highest mortalirt)
  2. P.vivax
  3. P.ovale
  4. P.malariae
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6
Q

When should you suspect Malaria?

A

Fever+recent travel + normocytic anaemia

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7
Q

What is the general patho of Malaria?

A
  1. Plasmodium spp. are transmitted by the bite of the female Anopheles mosquito
  2. protozoa infect red blood cells (RBCs) and grow intracellularly
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8
Q

What is injected into the bloodstream?

A

injection of sporozoites into the bloodstream by the bite of the female Anopheles
mosquito

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9
Q

What can other specieis of plasmodium do?

A
  1. invasion and replication in hepatocytes (exoerythrocytic schizogeny)
  2. P. vivax and P. ovale
  3. may develop into dormant hypnozoites and cause relapse within months or even years.
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10
Q

What happens to the parasites when they reinvade the blood?

A

called merozites

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11
Q

What happens inside the RBC?

A

parasites develop from ring forms (trophozoites) to multinucleated schizonts (erythrocytic
schizogeny)

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12
Q

What happens to the RBC?

A

RBCs rupture and release merozoites, which may reinfect new RBCs. Some differentiate
into male and female gametocytes

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13
Q

What happens to the gameocytes?

A

taken up by the Anopheles mosquitoes, develop into sporozoites in their
gut and migrate to the salivary gland of the mosquito to be transmitted in their bite.

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14
Q

Which populations have inate immunity to malaria?

A
  1. sickle cell trait
  2. G6PD deficiency
  3. pyruvate kinase deficiency
  4. thalassaemias
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15
Q

Why are trophozites important?

A

can be identified under a microscope to aid diagnosis of malaria

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16
Q

Why can there be jaundice in malaria?

A
  1. intravascular hemolysis
  2. disseminated intravascular coagulation
  3. rarely, ‘malarial hepatitis’. (I.e. jaundice not rly due to liver involvement, more to do with RBC destruction etc.)
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17
Q

What are the symptoms of malaria?

A
  1. Headache
  2. Weakness
  3. Myalgia/ Arthralgia
  4. Anorexia
  5. Cyclical fevers
18
Q

What are cyclical fevers?

A

characteristic paroxysms of severe cold / rigors followed by severing sweating

19
Q

What are the signs of malaria?

A
  1. Pyrexia
  2. Splenomegaly
  3. (Haemolytic) Anaemia
  4. Dark urine “Black water fever”
  5. DIC
20
Q

Why is there haemolytic anaemia in malaria?

A

due to destruction of parasitized RBC, uptake by spleen and marrow suppression

21
Q

What sort of disease is malaria?

A

notifiable disease and all cases of malaria should be notified to public health

22
Q

When do you suspect malaria?

A

patients with fever who have recently travelled to endemic regions, malaria must always be considered

23
Q

Why is there haemoglobinuria in Malaria?

A

P. falciparum can cause severe haemolysis with dark red urine (‘blackwater fever’)

24
Q

When is sever malaria more likely?

A
  1. children
  2. pregnant women
  3. older people
  4. immunocompromised people (for example those with splenectomy or HIV/AIDS)
25
Q

What are features of severe or complicated malaria in adults?

A
  1. Cerebral malaria — impaired conscious level (GCS < less than 11) or seizures.
  2. Renal impairment (may present with oliguria).
  3. Acidosis (may present with acidotic breathing).
  4. Hypoglycaemia (< 2.2 mmol/L) — common in pregnant women.
  5. Respiratory distress which may be due to pulmonary oedema or acute respiratory distress syndrome (ARDS) — common in pregnant women.
  6. Severe anaemia (may present with pallor).
  7. Spontaneous bleeding/disseminated intravascular coagulation.
  8. Shock (BP < 90/60 mmHg).
  9. Sepsis — more common in pregnant women.
  10. Haemoglobinuria — P. falciparum can cause severe haemolysis with dark red urine (‘blackwater fever’).
  11. Parasitaemia > 10%.
26
Q

What Ix is done for Malaria?

A

Giemsa-stained thick and thin blood smears

27
Q

What is the thick stain?

A

detects parasites present ((higher sensitivity) - to find out if have malaria

28
Q

What is thin stain?

A

identifies species (higher specificity)

29
Q

What else can you look for in Ix?

A
  1. Look for trophozoites and % RBC infected

2. High % (>30%) has high mortality

30
Q

Which smear is done first?

A

thick

31
Q

What does the Mx of Malaria depend on?

A
  • species of Plasmodium parasite
  • Severity of infection
  • Tolerability of specific drugs
  • Patterns of drug resistance
32
Q

How do you treat complicated/severe malaria?

A
  1. Artesunate

2. Quinine (2nd line)

33
Q

How do you treat uncomplicated malaria?

A
  1. Artemisinin combination therapy (ACT)

2. Atovaquone-proguanil (2nd line)

34
Q

What other drugs can be used in Malaria?

A
  1. chloroquine

2. Primaquine

35
Q

When is chrloriquine used?

A

treat uncomplicated P. malariae, P. ovale, P. knowlesi, and most cases of P. vivax malaria but use depends upon patterns of resistance and tolerance

36
Q

When is primaquine used?

A

the only currently effective drug for the eradication of hypnozoites (dormant parasites which persist in the liver after treatment of P. vivax and P. ovale)

37
Q

What do you need to screen for before starting Primaquine?

A

G6PD deficiency is essential before treatment with primaquine is started as it can cause haemolysis in G6PD deficient individuals, which can be fatal

38
Q

What is primaquine contraindicated in?

A
  1. Pregnancy

2. Breastfeeding

39
Q

What does sick cell trait protect against?

A

Sickle cell trait (HbS) is relatively protected against P. falciparum malaria (àbiologic advantage)

40
Q

What is resistant to infection by P.vivax?

A

duffy blood group negative red blood cells are resistant to infection by P. vivax

Z Year3 Infectious Diseases (5 decks)

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