Efficacy of the RT-PCR test for dengue fever after day five in pediatric patients at the hospital escuela, Honduras

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Abstract
Dengue is one of the most important arboviral diseases worldwide and is considered a reemerging infectious condition, posing a significant public health challenge, particularly among the pediatric population. The most effective diagnostic method during the acute phase of the illness (0–5 days), when viremia levels are high, is Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). However, some molecular techniques may detect viral RNA for up to seven days, depending on the viral load. The objective of this study was to determine the efficacy of RT-PCR in detecting viral RNA after the fifth day of illness in pediatric patients at Hospital Escuela, Honduras. A total of 101 paired serum samples were analyzed, with positive results within the first five days, and a second sample from the same pediatric patients was obtained on day six or later. Among the referred patients, 76.2% (n=77) were clinically classified as having dengue with warning signs; the predominant serotype was DENV-3 in 90.0% (n=91). The mean Ct (cycle threshold) in samples collected within the first 0–5 days was 29.5, with 43.5% (n=44) showing Ct values between 25.1 and 32.0. Of the samples obtained on the 6th and 7th days, 82.2% (n=81) tested negative for viral RNA regardless of initial viremia; only 18.8% (19/101) tested positive, with a mean Ct of 34.2. These findings indicate that RTPCR had reduced efficacy in detecting dengue virus beyond the fifth day of illness. RT-PCR should be used preferably during the first five days of the disease, highlighting the need to integrate it with serology in later stages. KEY WORDS: Viral load; dengue fever; pediatrics; molecular virus detection; late-stage; diagnosis.