Dengue fever - serological diagnosis

Patients with dengue fever can develop thrombocytopenia and subsequent intracerebral haematomas.

Dengue fever is caused by the dengue virus. There are four serotypes of the virus (DENV 1 to 4) that primarily cause dengue fever in humans (1). A fifth serotype (DENV 5) has been identified that is in wild animals but can cross species and affect humans (2), and its immunological response is significantly different from the DENV 1-4. (3)

The virus is transmitted through:

• female mosquito of species Aedes aegypti
• Aedes Albopictus

NS1

NS 1 (nonstructural protein 1) is a glycoprotein. It is synthesised by flavi virus (which includes the dengue virus). The NS1 is secreted by infected mammalian cells.

The test for NS1 should be within a week of onset of the symptoms. NS1 antigen is detectable until 9-days from the symptoms

Sensitivity of NS1 for primary disease is: > 90%
Sensitivity of NS1 for secondary disease is 60%-80%

Dengue IgM/IgG serological test

IgG and IgM are after the first 5 days of infection.

In primary infections after 5 days of the onset of symptoms, the IgM titre is greater than that of IgG. Later on in the disease, the IgG levels would increase

In secondary infection, the IgG is greater than IgM after 5 days of the infection.

Note: Primary infection is the first infection due to a dengue virus. The secondary disease is caused by a dengue virus with a different serology than which caused the dengue fever previously.

 

References

1. Chan HBY, How CH, Ng CW. Definitive tests for dengue fever: when and which should I use? Singapore Med J. 2017 Nov;58(11):632-635. doi: 10.11622/smedj.2017100. PMID: 29167907; PMCID: PMC5691225.

2. Mustafa MS, Rasotgi V, Jain S, Gupta V. Discovery of fifth serotype of dengue virus (DENV-5): A new public health dilemma in dengue control. Med J Armed Forces India. 2015 Jan;71(1):67-70. doi: 10.1016/j.mjafi.2014.09.011. Epub 2014 Nov 24. PMID: 25609867; PMCID: PMC4297835.

3. Mustafa MS, Rasotgi V, Jain S, Gupta V. Discovery of fifth serotype of dengue virus (DENV-5): A new public health dilemma in dengue control. Med J Armed Forces India. 2015 Jan;71(1):67-70. doi: 10.1016/j.mjafi.2014.09.011. Epub 2014 Nov 24. PMID: 25609867; PMCID: PMC4297835.