#Back2School: Dengue Fever- Step by Step diagnostic approach
Dengue is endemic in more than 120 countries, particularly the Southeast Asian and Western Pacific regions, the Caribbean, Latin America, and some regions in the US, Africa, and Middle East. Severe dengue fever is characterised by marked thrombocytopenia, severe haemorrhage, plasma leakage leading to shock or fluid accumulation with respiratory distress, and severe organ impairment.

Confirmatory tests include viral antigen or nucleic acid detection and serology. Difficult to distinguish clinically from Zika and chikungunya virus infections without diagnostic testing. No specific antiviral agent has been developed. Meticulous fluid therapy and the identification of the critical phase are the most important aspects of management. A tetravalent vaccine has been approved in some countries. Other vaccine candidates are currently in clinical development..

WHO case definition:
The 1997 dengue case definition is limited in terms of its complexity and applicability. This led to a new WHO classification where dengue severity is divided into dengue without warning signs, dengue with warning signs, and severe dengue. While WHO still supports both case definitions, there is a move towards using the 2009 case definition due to its ease of use.

The WHO classification separates patients into 1 of 3 groups (A, B, or C), depending on the clinical presentation.

Group A:
• No warning signs (particularly when fever subsides)
• Able to tolerate an adequate volume of oral fluids and pass urine at least once every 6 hours
• Near-normal blood counts and haematocrit.

Group B:
• Developing warning signs (i.e., abdominal pain or tenderness, persistent vomiting, clinical fluid accumulation such as ascites or pleural effusion, mucosal bleeding, lethargy, liver enlargement >2 cm, increase in haematocrit concurrent with rapid decrease in platelet count)
• Co-existing risk factors for serious infection (e.g., pregnancy, extremes of age, obesity, diabetes, renal impairment, haemolytic diseases)
• Poor family or social support
• Increasing haematocrit or a rapidly decreasing platelet count.

Group C:
• Established warning signs
• In the critical phase of infection, with severe plasma leakage (with or without shock), severe haemorrhage, or severe organ impairment (e.g., hepatic or renal impairment, cardiomyopathy, encephalopathy, or encephalitis).

Refer to the slideshow for Management approach.

Source: BMJ Best Practice
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