Affiliation: *National Institute of Health, Department of Medical Sciences
**Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
Source: Journal of Clinical Virology 2004; 31: 185-189
Dengue viruses are a serious cause of illness in tropical and subtropical areas of the world. Laboratory diagnosis is essential for confirmation of dengue virus infections. Detection of specific IgM by IgM-capture enzymed-linked immunoassay (ELISA) has been widely used as a main serological diagnostic technique. Objectives: The levels of specific IgM in secondary dengue virus infections were compared with those in primary infections. Study design: A total of 1780 samples collected from 924 confirmed dengue cases were tested for anti-dengue IgM by IgM-capture ELISA. Results and conclusions: Specific IgM was detected in all the cases with primary dengue virus infection on disease day 9 or later. However, specific IgM cannot be detected in 28% (204/716) of the cases in secondary infections. The average titers of IgM were higher in primary infections than in secondary infections. The results confirmed that IgM detection is a reliable serological diagnostic test in primary dengue virus infections. Although IgM detection is also a useful test, other serological diagnostic tests or tests for dengue virus detection are necessary for confirmation of all the secondary dengue virus infections.