Dengue and other arboviral infections: SAQ

This boy has dengue with warning signs progressing into the plasma-leak critical phase. His travel to Bali without mosquito precautions, the defervescence of his fever with clinical deterioration, his abdominal pain, persistent vomiting and lethargy, his rising haematocrit with a falling platelet count, and the positive NS1 antigen together meet WHO 2009 criteria for dengue with warning signs, and his borderline perfusion places him at risk of severe dengue. He needs immediate admission for group B management with titrated isotonic crystalloid and serial monitoring. [2]

Question 1 (10 marks)

Outline the WHO 2009 classification of dengue, classify this child, and justify your disposition. (6 marks for the classification and its application; 4 marks for the disposition and the immediate plan.) [2]

The 2009 WHO scheme divides dengue into three categories: dengue without warning signs, dengue with warning signs, and severe dengue. Dengue without warning signs is a probable acute febrile illness with two or more supportive criteria (nausea or vomiting, rash, aches, leucopenia, positive tourniquet test) and no warning signs. Dengue with warning signs requires any one of the seven warning signs: abdominal pain, persistent vomiting, clinical fluid accumulation, mucosal bleeding, lethargy or restlessness, hepatomegaly greater than two centimetres, and a rising haematocrit with a falling platelet count. Severe dengue is defined by plasma leakage causing shock or respiratory distress, by severe bleeding, or by organ impairment. [2]

This child meets dengue with warning signs: he has abdominal pain, persistent vomiting, lethargy, and the characteristic rising haematocrit with a falling platelet count. He is not yet in severe dengue because he has no shock, respiratory distress, severe bleeding or organ impairment, but his pulse pressure has narrowed to 22 mmHg and his capillary refill is prolonged, so he is at the boundary of compensated shock. A systematic review confirmed that combinations of these warning signs each roughly double the odds of progression to severe disease. [3]

The disposition is WHO group B: admission for close monitoring and titrated isotonic crystalloid. The immediate plan is to establish intravenous access, send a baseline full blood count, haematocrit, platelets, electrolytes, liver function, albumin, coagulation, lactate and glucose, repeat the haematocrit every six to twelve hours, monitor perfusion hourly, and titrate fluid (0.9 per cent saline or Hartmann's) at 5 to 7 mL/kg per hour initially, reducing as the haematocrit stabilises. Aspirin and non-steroidal anti-inflammatories are avoided and paracetamol alone is used for fever. [2]

Question 2 (10 marks)

Describe the monitoring and fluid strategy for the next 48 hours, including the signs that would escalate management, and the safety-netting advice to the family. (5 marks for monitoring and fluid strategy; 3 marks for escalation triggers; 2 marks for safety-netting.) [2]

The monitoring strategy is built around the haematocrit trend and clinical perfusion. The haematocrit is checked every six to twelve hours through the critical phase and compared to the child's baseline; a rise of more than 20 per cent indicates significant leak, while a fall signals recovery and the need to taper intravenous fluid. The pulse pressure, capillary refill, peripheral warmth, urine output and conscious level are assessed hourly. The platelet count is followed as a supportive marker but does not alone drive fluid decisions. [2]

Fluid is given as titrated isotonic crystalloid (0.9 per cent saline or Hartmann's solution). For group B with warning signs the WHO handbook recommends 5 to 7 mL/kg per hour for the first hours, titrated down as the haematocrit stabilises and perfusion improves. The defining principle is that boluses are harmful in a stable child: a prophylactic bolus to prevent shock risks fluid overload. If the child develops compensated shock (pulse pressure below 20 mmHg), 10 to 20 mL/kg of isotonic crystalloid is given over one hour and the child reassessed before further fluid; only for hypotensive shock is a faster 20 mL/kg bolus appropriate. [2]

The escalation triggers are the red flags of severe dengue: a further fall in pulse pressure below 20 mmHg or cold shock, altered mental state, severe or persistent bleeding, a rising haematocrit despite fluid indicating active leak, and respiratory distress from a pleural effusion. Any of these moves the child to WHO group C, with transfer to a high-dependency or intensive-care setting and paediatric retrieval organised early. [3]

The safety-net advice to the family is specific and written. The parents are told that the dangerous part of dengue is the leak that comes as the fever settles, that the next 24 to 48 hours carry the highest risk, and that they must call for help or return immediately if the child becomes drowsy, vomits repeatedly, bleeds from the gums or nose, complains of severe abdominal pain, or develops cold hands and feet. This concrete, behaviour-based safety-net is the communication skill the exam rewards. [2]