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Chapter 12

MALARIA AND DENGUE

PRACTICE POINTS

  • Malaria causes haemolysis which may be life-threatening, especially in young children and pregnant women.
  • For adults, consider transfusion if haemoglobin < 7 g/dL.
  • For children, always transfuse if haemoglobin < 4 g/dL.
  • Consider transfusion if haemoglobin 4–6 g/dL and clinical features of hypoxia; acidosis; impaired consciousness or hyperparasitaemia (> 20%).
  • Dengue Haemorrhagic Fever requires good medical supportive care. Clinical indications for red cell, platelet and plasma transfusion are the same as for other medical and surgical indications. 
  • Annual outbreaks of these mosquito borne diseases can affect both children and adults. Malaria may cause severe haemolysis. The dengue virus can cause severe diffuse haemorrhage and anaemia as part of Dengue Haemorrhagic Fever. Prevention and early diagnosis may reduce the need for transfusion.

Annual outbreaks of these mosquito borne diseases can affect both children and adults. Malaria may cause severe haemolysis. The Dengue virus can cause severe diffuse haemorrhage and anaemia as part of Dengue Haemorrhagic Fever. Prevention and early diagnosis may reduce the need for transfusion.

This chapter does not deal with all aspects of diagnosis and management of these infectious illnesses, rather the transfusion requirements as part of patient management.

12.1 MALARIA

The diagnosis and treatment of malaria and any associated complications are a matter of urgency as death can occur within 48 hours in non-immune individuals. Malaria presents as a non-specific acute febrile illness and cannot be reliably distinguished from other causes of fever on clinical grounds.

The differential diagnosis is therefore broad.

  • The clinical manifestations may be modified by partial immunity acquired by previous infection or sub-curative doses of antimalarial drugs.
  • Since fever is often irregular or intermittent, history of fever over the last 48 hours is important.
  • Malaria in pregnancy is more severe and is dangerous for mother and fetus; partially immune pregnant women, especially prima gravidae, are also susceptible to severe anaemia due to malaria.
  • Young children who have not yet developed some immunity to the parasite are at particular risk.

12.1.1 Management

Promptly treat infection and any associated complications, following local treatment protocols. Urgent treatment on basis of clinical assessment may be required if delays in laboratory investigations are likely. Correct dehydration and hypoglycaemia and avoid precipitating pulmonary oedema with fluid overload.

Specific treatments for serious complications:

  • Transfusion to correct life-threatening anaemia.
  • Haemofiltration or dialysis for renal failure.
  • Anticonvulsants for seizures.

In endemic malarial areas, there is a high risk of transmitting malaria by transfusion. Give the transfused patient malaria chemoprophylaxis.

12.1.2 Transfusion

Erythrocyte transfusion is preferable to whole blood in order to maximise oxygen-carrying capacity without extra volume.

Adults, including pregnant women:

  • Consider transfusion if haemoglobin < 7 g/dL.
Children:
  • Always transfuse if haemoglobin < 4 g/dL.
  • Transfuse if haemoglobin 4–6 g/dL and clinical features of hypoxia; acidosis; impaired consciousness or hyperparasitaemia (> 20%).

12.2 DENGUE FEVER AND DENGUE HAEMORRHAGIC FEVER

Dengue is transmitted by a mosquito (Aedes aegypti) and caused by any of the Dengue flaviviruses (DEN-1, DEN-2, DEN-3 and DEN-4). The Dengue virus can cause Dengue Fever (DF), or the more severe disease, Dengue Haemorrhagic Fever (DHF).

DHF clinical manifestations are:

  • sudden onset of fever, severe headache, myalgias and arthralgias, leukopenia, thrombocytopenia and mucocutaneous hemorrhagic manifestations,
  • complicated by shock and life-threatening haemorrhage.

12.2.1 Incidence

  • Variable, depending on epidemic activity.
  • Globally, there are an estimated 50 to 100 million cases of DF and several hundred thousand cases of DHF per year.
  • Average case fatality rate of DHF is about 5%.
  • With good medical management, mortality due to DHF can be less than 1%.

12.2.2 Risk groups

  • Residents of or visitors to tropical urban areas.
  • Increased severe and fatal disease in children under 15 years.
  • No cross-immunity from each serotype, therefore a person can theoretically experience four Dengue infections.

12.2.3 Prevention

The emphasis for Dengue prevention is on sustainable, community-based, integrated mosquito control with limited reliance on insecticides (chemical larvicides and adulticides).

Preventing epidemic disease:

  • requires a coordinated community effort to increase awareness about dengue/DHF,
  • how to recognise it, and
  • how to control the mosquito that transmits it. 

Residents are responsible for keeping their yards and patios free of sites where mosquitoes can be produced.

12.2.4 Treatment

There is no specific medication for treatment of a Dengue infection and the focus is on symptomatic relief and maintenance of oral fluids. Analgesia (pain control) is usually needed and acetaminophen (paracetamol) is preferable to aspirin or non-steroidal anti-inflammatories due to their anti-platelet effects. Hospitalisation for DHF is often required. 

12.2.5 Transfusion

When the haemorrhagic fever becomes life threatening due to blood loss and thrombocyto-penia, transfusion with red cells and/or platelet concentrate is indicated. Haemoglobin and platelet triggers (chapter 5) are appropriate. Fresh frozen plasma may have a role in haemostasis and its use should be guided by coagulation testing.

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