Malaria Flashcards

1
Q

Malaria aetiology

A

Infection with protozoan Plasmodium:
Plasmodium falciparum (most common)
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae

Transmitted by the bite of a female Anopheles mosquito. The protozoa infect RBCs and grow intracellularly

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2
Q

What are the risk factors for malaria

A

Travel to endemic area (Africa, South of the Sahara, Papua New Guinea (Oceania))
Lack of appropriate chemoprophylaxis
Absence of insecticide-treated bed net in an endemic area
Settled migrants returning from travel to an endemic area

Severe infection:
Low host immunity
Pregnancy
Age <5 years
Immunocompromise
Older age

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3
Q

Who has innate immunity to malaria

A

Sickle cell trait
GP6D deficiency
Pyruvate kinase deficiency
Thalassaemia

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4
Q

What are the symptoms of malaria

A

Fever (peak every 48h for falciparum)
Flu-like symptoms
Severe sweating
Shivering/rigors
Headache
Weakness
Myalgia
Arthralgia
Anorexia, diarrhoea, N&V, abdominal pain

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5
Q

What features of malaria are characteristic of falciparum

A

Cerebral involvement: headache, disorientation, seizure, coma
Severe anaemia
Renal failure - anuria/oliguria
Hypoglycaemia
Pulmonary oedema
DIC/bleeding (gums, nose, venepuncture sites, haematemesis, melaena)
Hypovolaemia
Acidosis
Hyper parasitaemia

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6
Q

What are the differentials for malaria

A

Dengue fever
Zika virus
Chikungunya virus
Yellow fever
Pneumonia
Influenza

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7
Q

What are the signs of malaria on exam

A

Obs: Pyrexia, Hypotension (falciparum), Tachypnoea (malaria with acidosis)

General:
- Anaemia: SOB, pallor
- Rigors
- Jaundice (falciparum)
- Altered level of consciousness, confusion (falciparum)

Abdominal
- Hepatosplenomegaly

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8
Q

What investigations should be done for malaria

A

Bedside: urinalysis (protein+, haem +), urinary bilirubin (raised)

Bloods:
- Thick/thin blood film x3 (Giemsa-stained): Intra-erythrocytic ring-formed parasites, Schizonts (falciparum), >2% parasite count = severe
- FBC: thrombocytopenia, anaemia, variable WCC
- U&Es: Usually normal or mildly impaired, renal failure if severe
- HIV serology
- ICT test: Detects histidine protein 2 found only in P. falciparum
- QBC: Orange stain on parasite nucleus
- Malaria antigen detection test: OptiMAL -IT (parasite LDH), Paracheck-Pf (plasmodial HRP-II)

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9
Q

What is the management for malaria (non-falciparum, uncomplicated falciparum, mild falciparum, severe falciparum, parasite count >10%), hypnozoites

A
  1. Immediate admission + notify Public Health England
  2. Treatment depends on the strain, severity, tolerability, resistance
    Non-falciparum: Chloroquine
    Uncomplicated falciparum: Chloroquine phosphate (oral)
    Mild falciparum: ACT (Artemisinin Combination therapy)
    Severe falciparum: IM/IV Artesunate (parenteral)
    Parasite count >10%: Exchange transfusion

+ Primaquine (not G6PDD) for eradication of hypnozoites (dormant parasites in liver in vivax and ovale)

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10
Q

What can be used for prevention/prophylaxis for malaria

A

Awareness of risk - geographical (high altitudes - different transmission), individualise e.g. pregnancy, season, accomodation
Bite prevention e.g. bite repellent, insecticide-treated nets (ITNs)
Chemoprophylaxis e.g. malarone, mefloquine, doxycycline (varies by region), Quinine (reduces but does not eliminate risk of infection)
Diagnose promptly and treat without delay

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11
Q

What are the complications of malaria

A

cerebral malaria: seizures, coma
acute renal failure: blackwater fever, secondary to intravascular haemolysis, mechanism unknown
acute respiratory distress syndrome (ARDS)
hypoglycaemia
disseminated intravascular coagulation (DIC)
Metabolic acidosis
Severe anaemia (Red cell lysis, autoimmune haemolysis)
Septicaemia

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12
Q

What is the prognosis for malaria

A

Children <5 are most vulnerable, with most deaths in the African region (95%)
Majority of deaths are from Plasmodium falciparum infection
Approximately 90% of travellers who acquire malaria will not become symptomatic until they return home
Malaria can progress from asymptomatic to death in 36-48 hours
Up to 80% of patients with cerebral malaria will recover with treatment, but mortality is still 15% to 20%

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13
Q

What characterises severe malaria

A

Parasitaemia:
Children >2%
Adult >10%
Presence of one schizoint (cell full of parasites)

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