Malaria - the disease

Signs and symptoms of malaria

Uncomplicated malaria

Malaria is usually diagnosed by the characteristic signs and symptoms of the disease. Care should be taken to rule out influenza, the most common misdiagnosis.

• Fever is virtually always present.
• Common complaints include mild to moderate malaise, fatigue, muscle aches, back pain, headache, dizziness, loss of appetite, nausea, vomiting, abdominal pain, and diarrhoea. Some patients report a dry cough and shortness of breath.
• Gastrointestinal complaints can be considerable, suggesting a diagnosis of gastroenteritis.
• Young children and partly immune individuals may complain of fever and headache as their only symptoms.
• Physical examination usually demonstrates tachycardia, and warm flushed skin.
• The spleen is often palpable in initial infection, but this is more likely in subsequent attacks. It is usually soft, and may be tender.
• The liver is often enlarged and may be tender; jaundice is not unusual.
• Orthostatic hypotension often occurs during initial infections.
• Mental confusion and cyanosis are sometimes encountered.

See also: Diagnosing malaria

Severe malaria

Definition of severe falciparum malaria¹³

A patient with severe falciparum malaria may present with confusion, or drowsiness with extreme weakness (prostration). In addition, the following may develop:

• cerebral malaria, defined as unrousable coma not attributable to any other cause in a patient with falciparum malaria
• generalized convulsions
• severe normocytic anaemia
• hypoglycaemia
• metabolic acidosis with respiratory distress
• fluid and electrolyte disturbances
• acute renal failure
• acute pulmonary oedema and adult respiratory distress syndrome (ARDS)
• circulatory collapse, shock, septicaemia (‘algid malaria’)
• abnormal bleeding
• jaundice
• haemoglobinuria
• high fever
• hyperparasitaemia.

Important: These severe manifestations can occur singly or, more commonly, in combination in the same patient.

Cerebral malaria is the most serious manifestation of severe falciparum malaria and is caused by the adherence of parasitised red blood cells to the walls of small blood vessels. In non-immune patients, cerebral malaria can develop rapidly from uncomplicated disease, and is associated with high parasitaemia. Cerebral malaria is characterised by bleeding, acute neurological symptoms, disturbance of consciousness, coma, and rapid death.

Severe anaemia seems to involve haemolysis caused directly by the parasite, and disruption of the formation of red blood cells. In children in highly endemic areas, repeated infections (new or relapsing) may lead to anaemia, which is a major cause of death.