9. Malaria Flashcards

1
Q

What is the causative agent of malaria? What are the different species of this?

A

Protozoal parasite: Plasmodium

  • P. falciparum
  • P. vivax
  • P. ovale
  • P. malariae
  • P. knowlesii
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2
Q

Which Plasmodium species most commonly cause malaria and which is most lethal?

A
  • 75% cases = P. falciparum (90% cases Africa) - highest mortality (10-20%)
  • other cases mostly P. vivax or P. ovale (90% cases India)
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3
Q

How is Plasmodium transmitted?

A
  • Vector = pregnant female Anopheles mosquito

- (no person-to-person spread)

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4
Q

What is the incubation period in malaria?

A
  • minimum 6 days
  • P. falciparum: up to 6 mths
  • P. vivax/ovale: up to 1 yr+
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5
Q

What are the symptoms of malaria?

A

Often non-specific

  1. headache
  2. chills/sweating (cycle every 3rd/4th day)
  3. dry cough
  4. fatigue and muscular/back pain
  5. nausea and vomiting
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6
Q

What are the signs of malaria?

A

Often few signs

  1. fever
  2. +/- splenomegaly
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7
Q

What parasite load if required to cause severe falciparum malaria?

A

> 2%

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8
Q

What are the features of severe malaria in adults?

A
  1. impaired consciousness or seizures
  2. renal impairment: oligouria or high creatinine
  3. metabolic acidosis (pH <7.3), hypoglycaemia (<2.2mmol/l)
  4. pulmonary oedema or ARDS
  5. anaemia (haemoglobin <80g/L) and haemoglobinuria (withough G6PD deficiency)
  6. spontaneous bleeding/DIC
  7. shock (BP <90/60 mmHg)
  8. parasitaemia >10%
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9
Q

Which groups of people are more likely to develop severe malaria?

A

immunocompromised, e.g. pregnant, children, elderly

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10
Q

Which investigations are performed in suspected malaria cases?

A
  1. malaria parasite screen (thick and thin film +/- rapid antigen test) x3
  2. FBC and coagulation tests
  3. U and Es and LFTs
  4. glucose
  5. head CT if CNS symptoms
  6. CXR (for pulmonary oedema/ARDS)
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11
Q

How should P. falciparum malaria be treated?

A
  1. IV artesunate (7 days)

if not available:
2. IV quinine + PO doxycycline (monitor blood glucose)

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12
Q

How should P. vivax/ovale malaria be treated? Why?

A

chloroquine + primaquine

primaquine treats hypnozoite (dormant liver) stage of P. vivax - required to prevent recurrence of infection

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13
Q

What blood tests needs to be performed before primaquine treatment?

A

G6PD screen to ensure no G6PD deficiency - primaquine can cause acute haemolytic episodes in this condition

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14
Q

Does previous malaria infection confer immunity?

A

Regular infection (in endemic areas) allows development of protection against severe disease but this immunity is soon lost after leaving endemic area

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15
Q

How is malaria prevented?

A

Assess risk - knowledge of at risk areas

Bite prevention - repellent, nets, adequate clothing

Chemoprophylaxis - starts before and continues after return

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