Comparison of serology, virus isolation and RT-PCR in the diagnosis of dengue viral infections in Sri Lanka

Currently, the methods for the diagnosis of dengue infections include: antibody detection, virus isolation and antigen detection methods such as RT-PCR. To compare the usefulness of each of these methods in the diagnosis of dengue infections at various time points of illness, 226 patients with suspected dengue virus infections were enrolled and serum-tested by all the three methods during 1999 to 2001. Serological methods were most useful in the diagnosis of dengue infections at all time points of clinical disease and the percentage of detection of dengue virus-specific antibodies increased with the duration of illness. However, virus isolation and molecular detection methods were also sensitive in the detection of the dengue virus and its serotypes, especially during days 3 to 5 of illness. The dengue virus was detected in 26 (18.2%) of our patients and DENV-2 was the predominant virus serotype that was isolated. Virus isolation was not possible in patients with dengue-specific antibodies. In a majority of the patients (64%), dengue-specific IgM was only seen in their serum indicative of a primary dengue infection. Although serological methods appear to be most useful in the diagnosis of dengue infections, virus detection methods are vital in gathering epidemiological data regarding the evolution of dengue epidemics in Sri Lanka.