A method of detecting presence of a dengue virus in a biological sample comprises the steps of isolating ribonucleic acid specimen from the biological sample; subjecting the isolated ribonucleic acid specimen to a reverse transcription-loop-mediated isothermal amplification in a single-tube reaction using primers with nucleic acid sequence as set forth in SEQ ID NO. 1, SEQ ID NO. 2, SEQ ID NO. 3, SEQ ID NO. 4, SEQ ID NO. 5, SEQ ID NO. 6, SEQ ID NO. 7, and SEQ ID NO. 8 throughout a constant temperature involving a forward outer primer, a backward outer primer, a forward inner primer, and a backward inner primer; and ascertaining presence of the dengue virus in the biological sample upon acquiring an amplicon of predetermined sizes. The disclosed method further comprises a primer with nucleic acid sequence as set forth in SEQ ID NO. 9 as the loop primer. The disclosed primers are derived from the 3 untranslated region of the dengue virus genome.