Diagnostic tests for dengue
The epidemic arbor viral disease “DENGUE “is caused by an infection with 1 of the 4 stereotypes of virus called Flavivirus. This arthoropod borne illness is predominantly transmitted by mosquitoes of genus Aedes ( Aedes albopictus , Aedes aegypti). Historically this illness was documented in the Chinese encyclopedia of symptoms during chin dynasty (CE 265 – 420). First outbreak of dengue has been recorded in 1635 in west indies , as the time flew this illness became more epidemic gaining new names in accordance with its occurrence (1779 – 1780) as “Break bone fever” in Asia, North America, Africa and ” Dandy fever” in regions of East Africa ( 1820).
Incubation period of dengue is 3 – 14 days and the symptoms may begin after the 2 weeks of transmission. Progression of this illness can be categorized into initial dengue in which symptoms like”Dengue triad “(Fever, headache, rash) can be seen and the severe dengue stage shows dengue hemorrhagic syndrome, dengue shock syndrome. Both of these severe stages include maculopapular rash on the skin, myalgia, vomiting, arthralgia, altered taste sensation, dehydration. Early detection of this disease is less harmful and can be cured effectively where as if left untreated may even lead to fatal risk of life, death.
Various sophisticated techniques have been developed these days which are more efficient in diagnosing it. Serological diagnosis has been cardinal in early stages of dengue in which the amount of antibody titers including IgM and IgG are checked in paired serum samples. Viral genome sequences in autopsy, serum, cerebrospinal fluid can be diagnosed using RT-PCR (reverse transcriptase polymerase chain reaction). NS1 (Nonstructural protein) test along with Immunofluorescence essays like MAC –ELISA test are more popular in early detection of illness. In patients suspected with dengue significant low levels of WBC, neutrophils, and platelet counts are seen hence complete blood picture can rule this out. Hematocrit level are known to rise up to 20% hence for every 24 hours, these levels are to be monitored. Coagulation studies include testing prothrombin time, activated partial thromboplastin, fibrinogen levels. Ultrasonography is recommended to rule out the suspicion of pleural effusion and thickened urinary bladder in case of dengue hemorrhagic fever. In case of early coagulation guaiac testing is done followed by typing and cross matching of blood ( In dengue shock syndrome ) .Complete urine examination tests , CSF test , should be done in order to exclude or confirm patient condition of body fluids .Biopsy of skin lesions may reveal any abnormality in blood vessels. Head computed tomography is performed to check any intra cranial bleeding in case of dengue hemorrhagic fever. PRNT (plaque reduction neutralization test) is used to determining the type of stereotype of virus causing dengue in which the serum sample is diluted with viral suspension and the amount of plaque formation units are measured. This quantifies titer of neutralizing antibodies for a virus.