Dengue outbreak in Swat and Mansehra, Pakistan 2013: An epidemiological and diagnostic perspective

ObjectiveTo high light some epidemiological, clinical and diagnostic features of dengue fever during an outbreak and the role of different diagnostic techniques to achieve the highest level of accuracy in results.MethodsBlood samples (n = 323) were collected along with epidemiological and clinical data from suspected dengue patients who visited different hospitals in Swat and Mansehra district of Pakistan between May–November 2013 during a dengue outbreak. Samples were tested for the detection of viral nucleic acid by real-time PCR, non structural protein-1 (NS1) antigen and IgM antibodies by ELISA.ResultsOut of 323 cases with clinical dengue infection, 304 were positive by one or more diagnostic parameter; 201 samples were positive by real-time PCR, 209 were positive by NS1 ELISA and 190 were positive by IgM antibodies. Sensitivities of real-time PCR and NS1 ELISA were comparable for early diagnosis of dengue virus infection, IgM antibody detection assay was found useful for the diagnosis in the samples collected later than day 5 of onset.ConclusionsThe use of real-time PCR or detection of non structural protein NS1 by ELISA followed by IgM antibodies detection can be recommended for early diagnosis of dengue virus infection with a high level of accuracy.