How is it Diagnosed?
Dengue is diagnosed based on clinical presentation, travel history, and specific
laboratory investigations. The diagnosis is particularly considered in individuals
presenting with acute febrile illness and a history of mosquito exposure in endemic
areas.
Clinically, dengue typically manifests as sudden-onset high fever, severe headache,
retro-orbital pain, myalgia, arthralgia, rash, and sometimes minor bleeding (gum
bleeding, petechiae). Severe cases may progress to dengue hemorrhagic fever or
dengue shock syndrome, marked by plasma leakage, bleeding, and organ impairment.
Early laboratory diagnosis involves detecting the dengue virus or its components.
During the first 5 days of illness, the NS1 antigen test (non-structural protein 1) is most
effective in identifying acute infection. It offers rapid results and is highly specific.
After the initial phase, serological tests such as IgM and IgG ELISA are used to detect
antibodies against the dengue virus. IgM appears after 4–5 days and indicates recent
infection, while IgG signifies past exposure. A fourfold increase in IgG titers in paired
samples also supports diagnosis.
Complete blood count (CBC) is useful for monitoring disease progression.
Thrombocytopenia (low platelet count) and hemoconcentration (increased hematocrit)
are common findings and help in recognizing severe dengue. Liver function tests may
reveal elevated transaminases.
RT-PCR testing is available in specialized centers to confirm the viral serotype. Accurate
diagnosis guides supportive management and helps prevent complications.