Sin Nombre Viral RNA Load in Patients with the Hantavirus Cardiopulmonary Syndrome

To address the role of viral load 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 six patients we examined viral load in matched plasma, urine, and/or tracheal aspirate throughout the time when patients were in intensive care. Peak titers in plasma reached 1.8x106 copies/ml; none had viral RNA in urine. Titers in tracheal aspirates did not exceed 8x104/ml. We found a statistically significant association (P< 0.005) between plasma viral RNA levels at admission 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