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CDHB

Malaria

Epidemiology

• P. vivax predominates: India, Bangladesh, Pakistan, Sri Lanka and Central America.
• P. falciparum predominates: Africa, Papua-New Guinea, Haiti.
• P. falciparum and P. vivax both prevalent: South East Asia, South America, and Oceania.
• P. knowlesi is an emerging pathogen in South East Asia, especially Borneo and Malaysia: Morphologically resembles P. malariae, but may be associated with hyperparasitaemia and more severe disease.
• Chloroquine resistant P. falciparum common: South East Asia, South America, Papua-New Guinea and Sub Saharan Africa.
• Chloroquine resistance in P. vivax has recently been reported from Papua-New Guinea and the Solomon Islands and is becoming more widespread. Consult Infectious Diseases Service early. It is important to assume chloroquine resistance in all cases of P. falciparum until proven otherwise.

Presentation

• Prophylaxis should be continued for up to four weeks depending on the drug used after return from endemic areas. If this is not done clinical illness may occur.
• Incubation period - P. falciparum, 7-14 days, P. vivax 12-17 days, but may be longer if prophylaxis has been taken.
• Prodrome of 1-7 days may resemble a viral illness - malaise, headache, fatigue and myalgias. May also have chest pains, abdominal pain, arthralgias.
• Paroxysms lasting 8-12 hours:
  • Cold phase 1-2 hours, chills, rigors, headache, pallor and cyanosis.
  • Hot phase 1-4 hours, fever up to 41°C, warm dry skin, headache, nausea, vomiting, backache, abdominal pain, delirium, orthostatic hypotension.
• Sweating, flushing and vomiting often followed by euphoria and fatigue.
• Findings that may be associated - jaundice, petechial rash, retinal haemorrhage, pulmonary oedema.
• Complications:
  • P. falciparum:
    • Cerebral malaria, focal signs uncommon, mortality 20%.
    • Renal failure and haemoglobinuria.
    • Pulmonary oedema.
    • Hypoglycaemia especially during pregnancy, in children and quinine therapy.
  • P. vivax: rupture of spleen, be careful on palpation (rare).

    Note: The fever pattern may be suggestive of malaria but often does not follow the classical pattern. Lymphadenopathy, muscle tenderness, joint effusions and hepatitis DO NOT occur in malaria. Look for another cause.

Investigations

• Thick and thin blood films. If negative repeat examination daily. Antigen tests are very accurate for P. falciparum and less so P. vivax, but the gold standard remains thick and thin blood films.
• CBC + diff and film.
• Na, K, creatinine, AST, ALT, GGT, ALP, bili, glucose.
• CXR.
• Blood culture.
• Urinalysis.

Management

• P. vivax, P. ovale, P. malariae and P. knowlesi. These can usually be managed as an outpatient but you must be sure it is not P. falciparum.

  Note: All pregnant women with malaria should be admitted.

  Note: If the patient has acquired P. vivax in Papua New Guinea then admission and close observation may be needed. These patients should be treated with atovoquane / proguanil (see below).

  Otherwise, treatment is:

  • Chloroquine: 1000 mg stat PO, 500 mg 6 hours later then 500 mg daily for 3 days or hydrochloroquine 800 mg stat, then 400 mg 6 hours later then 400 mg daily for 3 days.
    • If neither are available, use atovaquone/proguanil 1000 mg/400 mg (i.e., 4 tablets) once daily with food for 3 days.
  • Primaquine: check for G6PD deficiency. Quick screening tests are available. If normal, then primaquine is safe. If G6PD deficient, check with Infectious Diseases.
    • P. vivax: give primaquine 30 mg PO daily for 14 days in addition to chloroquine.
    • P. ovale: give primaquine 15 mg PO daily for 14-21 days in addition to chloroquine.
    • P. malariae or P. knowlesi: Primaquine treatment is not needed. Give chloroquine only.
• P. falciparum. All patients should be admitted.
  • Oral therapy:
    • The Artemisinin derivatives are now considered the most effective treatment and should be used if available. Artemether/Lumefantrine 20 mg/120 mg per tab. Give 4 tabs stat and another 4 tabs 8 hours later on day 1, then 4 tabs BD on days 2 and 3. Discuss with the Infectious Disease Service if the patient is not already under their care.

      OR, quinine 600 mg q8h PO for 7 days plus doxycycline 100 mg BD PO for 7 days.

    • Oral atovaquone/proguanil may be appropriate in some patients with mild/moderate disease. Give atovaquone/proguanil 1000 mg/400 mg (i.e., 4 tablets) once daily with food for 3 days.
  • IV therapy: Quinine dihydrochloride 20 mg/kg (maximum dose 1400 mg) in 5% glucose by infusion over 4 hours. Monitor ECG during infusion. Do not give as a bolus. Loading dose not required if antimalarials have been given in the previous 24 hours. Hypoglycaemia may occur. Check blood glucose levels 6 hourly while on parenteral quinine. 8 hours from the start of the loading dose give quinine 10 mg/kg over 4 hrs by IV infusion then q8h until the patient can swallow (maximum dose 2100 mg/24 hours).
  • Treat seizures with diazepam.

    Note: Dose of quinine should be reduced in severe liver and renal disease.

Monitoring

• Blood films - contact laboratory, parasitaemia may not change for 24-48 hours but should be clear by day 5. Gametocytes persist for longer and do not necessarily indicate treatment failure.
• Blood glucose BD.
• CBC + diff, Na, K, creatinine, and bili daily.

Topic Code: 2723