clinical diagnosis, epidemiological survey, vaccine development), the type of laboratory facilities and technical expertise available, costs, and the time of sample collection. The choice of diagnostic method depends on the purpose for which the testing is done (e.g. To distinguish primary and secondary dengue infections, IgM/IgG antibody ratios are now more commonly used than the haemagglutination-inhibition test (HI) ( 6вЂ“ 8).ДЄ range of laboratory diagnostic methods has been developed to support patient management and disease control. Early convalescent stage IgM levels are significantly lower in secondary infections than in primary ones and may be undetectable in some cases, depending on the test used ( 5). The dominant immunoglobulin isotype is IgG which is detectable at high levels, even in the acute phase, and persists for periods lasting from 10 months to life. Anti-dengue serum IgG is generally detectable at low titres at the end of the first week of illness, increasing slowly thereafter, with serum IgG still detectable after several months, and probably even for life ( 2вЂ“ 4).ДЄpproximate time-line of primary and secondary dengue virus infections and the diagnostic methods that can be used to detect infection.Дuring a secondary dengue infection (a dengue infection in a host that has previously been infected by a dengue virus, or sometimes after non-dengue flavivirus vaccination or infection), antibody titres rise rapidly and react broadly against many flaviviruses. IgM levels peak about two weeks after the onset of symptoms and then decline generally to undetectable levels over 2вЂ“3 months. These antibodies are detectable in 50% of patients by days 3-5 after onset of illness, increasing to 80% by day 5 and 99% by day 10 ( Figure 4.1).

IgM antibodies are the first immunoglobulin isotype to appear.

for yellow fever, Japanese encephalitis, tick-borne encephalitis), the patients develop a primary antibody response characterized by a slow increase of specific antibodies. When dengue infection occurs in persons who have not previously been infected with a flavivirus or immunized with a flavivirus vaccine (e.g. At the end of the acute phase of infection, serology is the method of choice for diagnosis.ДЄntibody response to infection differs according to the immune status of the host ( 1).

During the early stages of the disease, virus isolation, nucleic acid or antigen detection can be used to diagnose the infection. After the onset of illness, the virus can be detected in serum, plasma, circulating blood cells and other tissues for 4вЂ“5 days. Laboratory diagnosis methods for confirming dengue virus infection may involve detection of the virus, viral nucleic acid, antigens or antibodies, or a combination of these techniques. early detection of severe cases, case confirmation and differential diagnosis with other infectious diseases), surveillance activities, outbreak control, pathogenesis, academic research, vaccine development, and clinical trials. Efficient and accurate diagnosis of dengue is of primary importance for clinical care (i.e.

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