What is Dengue Antigen?
Dengue viruses belong to the family Flaviviridae. It is transmitted by mosquitoes, namely Aedes aegypti and Aedes albopictus which are widely distributed in Tropical and Subtropical areas of the world. Dengue viruses have 4 subtypes, Dengue 1, 2, 3, and 4. Clinically, the disease may be subclinical, self-limiting, febrile (showing symptoms), or may progress to a severe form of Dengue hemorrhagic fever or Dengue shock syndrome.
Why is Dengue Antigen done?
- For the diagnosis of dengue virus infection. It is used to diagnose early detection of dengue virus infection and initial treatment procedures
- The dengue-antigen-NS1 test can be used along with the current antibody test. It helps in differential diagnostics of flaviviruses
- In the differential diagnosis of fever cases during the mosquito breeding season
What does Dengue Antigen Measure?
Dengue virus is a flavivirus with four distinct serotypes (Dengue virus 1, 2, 3, and 4). It is primarily transmitted by the Aedes aegypti mosquito, found in the tropical and subtropical regions.
Dengue nonstructural protein 1 (NS1) is an antigen produced by the replicating dengue virus. These antigens can be detected as early as the first day of symptoms and as late as day 18 of symptoms.
Clinically, in the beginning, there is sudden onset of fever combined with headache, muscle and joint pains (severe pain that gives it the nickname break-bone fever or bone crusher disease), distinctive pain from behind the eyes (retro-orbital pain) and rash (a generalized maculopapular rash with islands of sparing). After that, a hemorrhagic rash of characteristically bright red pinpoint spots (known as petechiae) can occur during the illness which is associated with thrombocytopenia. It usually appears first on the lower limbs and the chest, however, in some patients, it spreads to most of the body. Along with that, there can also be gastritis (inflammation in the stomach lining) with associated stomach pain, nausea (feeling sick), vomiting coffee-grounds-like congealed blood or diarrhea.
Dengue Hemorrhagic fever (DHF):
In DHF, the fever can go to a higher grade, it might also include variable bleeding manifestations like bleeding from the eyes, nose, mouth, ear and oozing blood from skin pores. Other bleeding manifestations include thrombocytopenia, and hemoconcentration (thickening of the blood).
Dengue hemorrhagic fever is a leading cause of serious illness and death among children. There is no specific treatment for dengue, but appropriate medical care can save the lives of patients with the more serious dengue hemorrhagic fever.
Interpreting Dengue Antigen results
Result in index
No detectable dengue NS1 antigen. The result does not rule out dengue infection. An additional sample should be tested for IgG & IgM serology in 7-14 days.
Repeat sample after 1 week
Presence of detectable dengue NS1 antigen. Dengue IgG & IgM serology assays should be performed on follow up samples after 5-7 days of onset of fever, to confirm dengue infection.
Note: Recommended to do NS1 Antigen by ELISA in the first 5 days of fever. After 7-10 days of continuous fever, the recommended test is Dengue fever antibodies IgG & IgM by ELISA.