Patients experiencing the symptoms such as fever over 40 °C, headache, muscle pain, vomiting and etc, who reside or traveled to the dengue infected region may go through the diagnostic testing, (CDC, 2019, “Diagnosis”).
Since the symptoms of Dengue infection overlap with influenza, early stage diagnosis may be challenging. Around 75% of dengue infection is asymptomatic and a part of patients with symptoms may develop their illness into the second phase after a week.
The patients with severe dengue infection may experience nose bleed, vomiting blood, passing blood in the stool and difficulty breathing. This may result in falling blood pressure and dehydration, so the patients are recommended to be hospitalized, (Lab Tests Online, 2019, “Dengue Fever Testing”). There are a number of commercial tests available for detecting DENV infection.
Nucleic acid amplification tests (NAATs)
Reverse transcriptase-polymerase chain reaction (RT-PCR) detects the dengue RNA from the patient’s blood. If real-time RT-PCR is used, the specific serotype of dengue virus causing the infections can be determined, (WHO, 2009, “Dengue Diagnosis”). This testing is effective for the first week after the infection. Due to high costs, NAATs are not usually available for most clinics, despite the high accuracy, (WHO, 2009, “Dengue Diagnosis”).
Detection of antibodies that are produced due to dengue virus infection could also be used for the diagnosis. These tests are effective at the later stage of the illness. However, the result of serologic tests can be positive due to other viral diseases such as Zika. Serologic test is the least expensive method of testing Dengue, (WHO, 2009, “Dengue Diagnosis”) If the result of IgG test is positive while IgM is low or negative, this indicates the past dengue infection, (WHO, 2009, “Dengue Diagnosis”). The past dengue infection may cause severe development of the disease for the secondary infection.
Detection of antigen
The high concentration of NS1 (non-structural protein 1) and envelope/membrane antigen detected from ELISA (enzyme-linked immunosorbent assay) suggests the dengue infection at the later stage of the illness. NS1 is produced by all flaviviruses and causes strong responses, (WHO, 2009, “Dengue Diagnosis”). The commercial test kits involving the detection of NS1 are available. However, the result may not be as sensitive as NAATs, (WHO, 2009, “Dengue Diagnosis”).
Cross-reactive flaviviruses should also be performed to check the other viral infection that may cause cross-reactivity.
Current development in diagnostic methods
Biosensors based on screen-printed carbon electrodes (SPCEs) for dengue specific IgM antibodies are being developed. This method of detection demonstrated high specificity and sensitivity compared to commercial ELISA, and cost effective. This is also highly compatible with newly developed microelectronic tools, (Om Parkash et al., 2020). More details of the techniques can be read from https://www.mdpi.com/2075-4418/11/1/33/htm.