Sin Nombre viral RNA load in patients with hantavirus cardiopulmonary syndrome.

To address the role that viral load plays in pathogenesis in patients with hantavirus cardiopulmonary syndrome (HCPS), we quantified Sin Nombre virus S segment viral RNA in plasma samples from 27 acutely ill patients. For 6 patients, we examined viral load in matched plasma, urine, and/or tracheal aspirate throughout the time when the patients were in intensive care. Peak titers in plasma reached 1.8 x 106 copies/mL; none of the patients had viral RNA in urine. Titers in tracheal aspirates did not exceed 8 x 104 copies/mL. We found a statistically significant association (P < .005) between plasma viral RNA levels at admission to the hospital and the severity of disease. Of those with plasma viral RNA titers above the threshold for assay sensitivity (5000 copies/mL), those with mild-moderate and severe disease had an average of 27,800 and 438,545 copies/mL, respectively. These results suggest that patients with high viral loads on admission are more likely to have severe disease.