Dengue diagnosis was one of the topics discussed at "the adult
dengue" presentations. In this paper, a review is presented focusing on the main challenges of
dengue laboratory diagnosis. Accurate and efficient diagnosis of
dengue is important for clinical care, surveillance support, pathogenesis studies, and
vaccine research. Laboratory diagnosis is also important for case confirmation. Laboratory
dengue diagnosis can be performed through virus isolation, genome and
antigen detection and serological studies. For virus detection,
dengue viremia is short, usually observed two or three days before onset of
fever and lasts four to five days later. Therefore, samples for virus detection must be taken in the first four to five days of the disease during febrile phase. In recent years, PCR (polymerase chain reaction) has become an important tool as a quick method for diagnosis of
dengue, another is detection of NS1
antigen, using commercial ELISA kit. Serological studies, for primary
infection, the dominant
immunoglobulin isotype is
IgM,
anti-IgM may appear during febrile phase (50% of cases), the other half, it appears within 2-3 days of defervescence. Once detectable,
IgM levels rise quickly and appears to peak about 2 weeks after the onset of symptoms, then they decline to undetectable level over 2-3 months.
Anti-IgG appears shortly afterwards with very low level. The physiological definition of a primary
infection is therefore characterized by a high molar fraction of anti-
dengue IgM and low molar fraction of
IgG. Secondary
dengue infections are characterized by a rapid increase in
IgG antibodies, anti-
dengue IgM appears in most instances, the level are dramatically lower.