Chikungunya virus RNA PCR is a molecular diagnostic test that detects the presence of chikungunya virus RNA in a patient's blood sample. It's a highly sensitive and specific test that can confirm chikungunya infection within the first week of symptoms, when other diagnostic methods may be inconclusive. The test involves extracting viral RNA from the blood sample, amplifying it using a technique called reverse transcription-polymerase chain reaction (RT-PCR), and detecting specific viral sequences using fluorescent probes. A positive result indicates active chikungunya infection, while a negative result does not rule out the possibility of infection, especially if the sample was collected after the first week of illness.