Abstract. A commercial IgM immunoblot kit was evaluated for dengue diagnosis with a panel of serum specimens collected from patients in a dengue endemic area. The kit is not recommended for use in its present form because of its undesirable rate of false-positive results. However, by substituting internal controls with the reference positive and negative controls that are more representative of those seen in endemic areas and by modifying the positive and negative scoring criteria, sensitivity and specificity of 80.3% and 94.5%, respectively, were obtained. These results are comparable with those obtained with the IgM ELISA on specimens, most of which were obtained from outpatient health care facilities. With further technical modifications, inclusion of a visual guide to ensure scoring standardization, and a more complete elaboration of the limitations of the test, wide application of the kit in diagnostic laboratories should be possible.Dengue fever is the most important arboviral disease in the world in terms of morbidity and mortality. 1 Incidence of the severe forms of dengue, dengue hemorrhagic fever and dengue shock syndrome (DSS), which emerged in Southeast Asia in the 1950s and 1960s, has increased dramatically in the Americas. Since the first major DHF outbreak in Cuba in 1981, 23 countries have reported confirmed cases of DHF, and outbreaks have occurred in Venezuela, Brazil, Colombia, and French Guiana. 2,3 Although many diagnostic techniques are available, the major problems of dengue diagnosis in many countries in the tropics are high cost and lack of reagents and equipment. Since reagents for most arboviral diseases, including dengue, have not been commercially available until recently, diagnostic services have been limited to a very small number of well-established and equipped laboratories. This is one of the major reasons for poor surveillance, under-reporting of cases, and the long time intervals between the onset of epidemic transmission and the mobilization of mosquito control. For physicians administering medical care, a major problem is the long period between submission of specimens and receipt of results. The recent proliferation of commercial dengue diagnostic kits is highly encouraging in this regard. 4 In particular, the kits that are simple to use are important for field applications in smaller clinics, hospitals, and other health care facilities. Recently, an immunoblot kit that satisfies some of those requirements was evaluated and judged to have excellent qualities in a multicenter study. 5 We have evaluated the same kit but obtained different results. Here, we report those data, discuss the problems of kit evaluation for dengue IgM detection, and present thoughts on how diagnostic kits should be evaluated. .
MATERIALS AND METHODSClinical specimens. A panel of 233 serum specimens (96 paired specimens and 137 single specimens) were collected from dengue patients in Puerto Rico. Confirmation of infection was by virus isolation, by the standard hemagglutination inhibition (HI) test o...