Malaria

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Information amended from the BAEM "Malaria" broadsheet publication, knowledge from Dr Jon Dallimore

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Background
Symptoms
Notes / Hints
Complications
History
Signs
Investigations
Treatment

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Plasmodium vivax, ovale, malariae, and falciparum (P. falciparum most virulent)

Disease initiated by the bite of a female anophelene mosquito

Aneophelene mosquito originates from the tropical areas between 60° and 40°

• > 2 million deaths per year
• By far the most common tropical diagnosis in the UK - probably about 3,000 per annum
  Approx. 50% due to P. falciparum and virtually all cases develop within 3 months
• ~ 10 die per annum - usually because of delay in diagnosis
• Safest to assume malaria in all febrile travellers
• Delay in treatment may lead to severe consequences
• Patients may be unaware that they have been at risk

The diagnosis may be overlooked if a travel history is not In the Americas malaria ranges from Mexico in the north to southern Brazil. In Africa it is found throughout sub-Saharan Africa to the Transvaal and east Natal in South Africa. It is found in western Saudi Arabia, the Yemen, Iraq, Iran, and then eastwards throughout the Indian sub-continent, Indochina, Indonesia, and the Philippines.obtained. Relapse of malaria can occur many months or even years after arrival in Ireland.

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History

• A thorough travel history is mandatory history details to be recorded on all in Travellers' Fever
• High index of suspicion in any patient who has travelled to, or through, malaria prone areas, (Map above)

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Signs

Pyrexia is usual but may be intermittent, rigors, modest enlargement of the spleen and tender hepatomegaly are other features. In falciparum malaria there may be confusion, delirium, coma, convulsions, opisthotonus, pallor, jaundice, heart failure and shock.

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Notes

Malaria is :  Easy to include, difficult to exclude

A few tricks of the trade:

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Investigations

All travellers returning from the tropics with a fever should have 

• Thick and thin blood films (stained with Giemsa's stain) to ID species and % parasitised (98% sensitivity in expert lab.)
  • The thick smear is most useful when there is low parasitaemia
  • A single blood film may be falsely negative
  • Not important to take blood during fever
• Full blood counts
  • Repeated after treatment has been initiated to assess progress (anaemia)
• Platelet counts: may be low (If less than 50 x 109/L screen for FDPs and bleeding time to identify DIC)
• Blood glucose: exclude hypoglycaemia
• Blood cultures: septicaemia may be a complication of severe falciparum malaria.
• Chest X-ray: shadows may indicate pulmonary ooedema or adult respiratory distress syndrome
• Urine output, urea, creatinine: o assess dehydration and identify renal failure
• ABG (in severe cases): to assess pulmonary ooedema / respiratory distress syndrome.

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Complications

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Treatment

• If unclear which type of malaria parasite, then treat as for P falciparum
• If there any doubt in the diagnosis or treatment then call for more experienced help

Uncomplicated malaria due to P. vivax, ovale or malariae

• Hospital admission may not be required. (Seek expert advice if unsure)
• An initial dose of 600mgs of chloroquine (of base) (child 10mg/kg) then a single dose of 300mg (child 5mg/kg) after six to eight hours then a single dose of 300mg (child 5mg/kg) daily for two days
• Chloroquine resistant P. vivax has been reported from New Guinea
• Primaquine 15mg daily for 14 - 21 days is required in addition to chloroquine for P. vivax, and P. ovale after checking G-6-P-D status. Radical cure with primaquine should be delayed in pregnant women until the pregnancy is over. Instead chloroquine should be administered at a dose of 600mg each week during the pregnancy

Uncomplicated P. falciparum

• Hospital admission normally considered essential
• Quinine sulphate 600mg orally (child 10mg/kg) every 8 hours for 7 days, followed by either fansidar 3 tablets as a single dose or, if malaria is fansidar resistant, by doxycycline 200mg daily minimum for 7 days. (Refer to BNF for paediatric dose)
• Alternative therapy: Mefloquine 20-25mg/kg (of mefloquine base up to a maximum of 1.5g) as 2-3 divided doses 6-8 hours apart; or alternatively halofantrine 1.5g (refer to BNF for paediatric dose) divided into 500mg at intervals of 6 hours (on an empty stomach), and repeated after a week, however, halofantrine has significant cardio-toxicity and should only be administered by clinicians experienced with its use with monitoring facilities

Complicated P. falciparum

• ITU admission
• Quinine dihydrochloride salt 20mg/kg (up to 1400mg) IV infusion in saline over 4 hours, then after 8-10 hours maintenance dose of 10mg/kg (up to 700mg) over 4 hours for each dose every 8-12 hours.
  • Change to oral treatment as above) as soon as possible to complete the seven day course
• Followed by either fansidar 3 tablets as a single dose, or (if fansidar resistant) doxycycline 200mgs daily for at least seven days.
• N.B. The loading dose of quinine should not be used if the patient has received quinine (or quinidine) or mefloquine during the previous 24 hours. Instead give the maintenance dose of 10mg/kg (up to a maximum of 700mgs).
• Check with pharmacy as to the availability of parenteral quinine as some hospitals may not stock this.
• Quinine for IV infusion is a non-proprietary product available on special order or from specialist centres.

Poor Prognostic Signs

Pitfalls

• Malaria patients can deteriorate despite treatment
• Negative blood film does not exclude malaria
• Other infections may complicate malaria
• Hypoglycaemia may be a complication of malaria and its treatment
• Consider malaria, even in people who have not travelled abroad recently
• Temperature may be normal and signs absent when they present to the ED
• Prophylaxis does not exclude the diagnosis of malaria
• Be aware that all antimalarials have side effects

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Links

• British Airways
• Aerospace Medical Association
• UK Foreign Office Medical Travel Advice 
• Exodus Ireland - Travel Medicine
• CDC Travellers Health
• UK National Travel Health Network
• TRAVAX
• Health Protection on Malaria

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Content by Dr Jon Dallimore, Dr Íomhar O' Sullivan, 23/06/2000. Reviewed by Dr ÍOS 12/12/2002, 13/06/2005, 110/11/2007. 20/12/2007. Last review Dr IOS 18/01/12