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Y3M - Infectious Disease > Malaria > Flashcards

Malaria Flashcards

1
Q

Give examples of malaria parasites.

A

Plasmodium falciparum

Plasmodium vivax

Plasmodium ovale

Plasmodium knowlesii

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2
Q

Where is malaria most common?

A

In Sub-saharan africa and south east asia.

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3
Q

Most common malaria species in Sub-saharan africa.

A

Plasmodium falciparum

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4
Q

Most common malaria species outside of sub-saharan africa.

A

Plasmodium vivax

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5
Q
A
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6
Q

Explain the malaria lifecycle.

A

Depends on the human and the mosquito.

Sporozoites are transferred to a person via a mosquito. The sporozoites then travel to the liver via the blood and mature in the liver.
In the liver schizonts are formed containing 30000 merozoite offspring.

If the species is able to be dormant in the liver such as vivax and ovale the merozoites can be released from the liver weeks, months or years after initial infection leading to recurrent disease.

The rupture of schizonts releases merozoites which will then enter the RBCs. In the RBCs the merozoites form larger trophozoites and erthrocytic schizonts.

The rupture of a erthrocytic schizont produces the clinical manifestations of malaria.

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7
Q

Clinical presentation of malaria. (Mainly falciparum)

A

Presentation most commonly occur within 3 months of return from an endemic area.

Non-specific symptoms such as;

Abrupt onset of rigors

Fever

Headache

Malaise

Myalgia

Diarrhoea

N+V

Cough

Fever pattern

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8
Q

Explain fever pattern in malaria.

A

Only occur if rupture of infected RBCs is synchronised.

Alternate day for falciparum, vivax and ovale.

Every 3rd day for malariae.

However most patients have no specific fever pattern.

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9
Q

Examination findings of malaria.

A

Fever

Jaundice, confusion, hepatosplenomegaly and seizures if severe disease.

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10
Q

Diagnosis of malaria.

A

Immediate blood testing is mandatory in the UK.

  • Microscopy of thick and thin blood film/smear.
  • Rapid diagnostic test (RDT) to detect parasite antigen. This is used for initial screen if expert microscopy is unavailable such as out of hours. It is used in addition to, not instead of blood film.

If malaria is suspected but blood film is negative then repeat at 12-24h and after further 24h.

Malaria is unlikely if three expert serial blood films are negative.

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11
Q

Differentials of malaria.

A

Dengue

Typhoid

Hepatitis

Meningitis/Encephalitis

HIV

VHF

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12
Q

Why do you need to be cautious of ruling out malaria in pregnant women?

A

Thick films can be negative despite parasites in the placenta.

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13
Q

What is additional information regarding RBCs should be given if the malaria is falciparum?

A

The estimated % of parasitised RBCs.

This is because the percentage is an estimation of the severity of disease and can give a prognosis of outcome and complications.

2% = chance of severe disease

10% = severe disease

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14
Q

Other investigations to be done in malaria.

A

FBC (anaemia and thrombocytopenia)

Crea

Urine output (AKI)

Clotting (DIC)

Glucose (hypo)

ABG/Lactate (acidosis)

Urinalysis (haemoglobinuria)

LFTs

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15
Q

Features of severe falciparum malaria.

A

Impaired consciousness/seizures

AKI

Shock

Hypoglycaemia

Pulmonary oedema/ARDS

Hb <80 g/L

Spontaneous bleeding or DIC

Acidosis

Haemoglobinuria

Parasitaemia > 10%

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16
Q

Treatment of uncomplicated falciparum malaria.

A

Artemisinin combination therapies (ACT) acvhieve rapid clearance of parasites by combined action at different stages of the parasite cycle.

1 - Artemether-lumefantrine 4 tables at 0, 4, 8, 24, 36, 48 and 60h

2 - Dihydroartemisinin (DHA) - piperaquine 4 tablets OD for 3d

This should be taken 3h before food to prevent excessive peaks levels.

17
Q

Possible adverse effects of ACT.

A

Long QT syndrome

Avoid in arrhythmia

18
Q

Options of treatment of uncomplicated falciparum malaria if ACT is unavailable.

A

Atovaquone-proguanil

Oral quinine sulphate + doxycycline

Remember that chloroquine is not used in the treatment of falciparum malaria

19
Q

Treatment of severe falciparum malaria.

A

Artesunate

if artesunate isn’t available then Quinine regimen can be done.

20
Q

Explain the artesunate regimen in severe falciparum malaria.

A

2.4 mg/kg IV at 0h, 12h, 24h and then daily for up to 5 days.

The patient should be converted to a full course of ACT when able to tolerate oral medication.

21
Q

Side effects of the artesunate regimen.

A

Delayed haemolysis 7-21d post treatment.

This is usually self-limiting but Hb should be check 14days post treatment.

22
Q

Explain the Quinine regimen in severe falciparum malaria.

A

This is given when artesunate is not available immediately. However it is safe to overlap or combine artesunate when available.

Loading dose 20mg/kg over 4h. Then 10mg/kg every 8h for next 48h or until the patient can swallow.

Convert to 600mg PO TDS to toal quinine course 5-7d.

Give with 7d oral doxycycline.

23
Q

What else should be monitored in severe falciparum malaria.

A

The capillary permeability is increased so pulmonary oedema might occur.

Monitor:

Blood glucose every 4h or 2h if quinine infusion.
Hb
Clotting
Electrolytes
Creatinine

Daily parasite counts

24
Q

Treatment of non-falciparum malaria.

A

If there is mixed infection with falciparum, treat as falciparum.
If severe/complicated non-falciparum disease - treat as falciparum
If uncomplicated disease treat with ACT as uncomplicated falciparum.

Chloroquine can be used for non-falciparum disease. However it should not be used if falciparum infection cannot be excluded.
ACT is usually more effective.
Chloroquine resistance exist.

25
Q

What additional treatment do vivax and ovale require?

A

They require eradication of liver hypnozoites with primaquine.

26
Q

Side effects of primaquine.

A

There is a risk of haemolysis in G6PD deficiency so this should be screened for prior to use.

27
Q

Explain malaria prevention.

A

Vector control

Chemoprophylaxis

Malaria eradication

28
Q

Explain vector control in malaria prevention.

A

Source reduction by destruction of mosquito breeding sites.

Long-lasting insecticidal nets

Indoor residual spraying

Genetic modification to develop mosquitoes that are not susceptible to malaria parasites.

29
Q

Explain chemoprophylaxis in malaria prevention for UK travellers going to an endemic malaria area.

A

1 - Bite prevention advice where insect repellents with 20-50% DEET. This should be applied after sunscreen with SPF >30 since DEET may decrease sunscreen efficacy.

2 - Chemoprophylaxis according to area of travel.

Y3M - Infectious Disease (21 decks)

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