How is Seoul virus diagnosed in humans?

• A. Serology
• B. PCR
• C. Serology and PCR
• D. Blood culture

Answer: (C)

Diagnosis relies on detecting both the immune response to the virus and the virus itself. Early in infection, viral RNA is present in the blood, so PCR can directly detect the infection. As illness progresses, the body produces hantavirus-specific antibodies (IgM and later IgG), which serology tests can identify. Using both approaches—serology to catch the antibody response and PCR to detect viral RNA—gives the most reliable diagnosis across different stages of illness. Blood culture isn’t used for Seoul virus because viruses do not grow in standard bacterial culture, and viral culture is not routine for clinical diagnosis. So combining serology and PCR provides the best overall diagnostic accuracy.