Abstract
In immunocompromised patients with norovirus (NoV) gastroenteritis, the relationship between fecal NoV load and clinical complications has not been examined. In this study, a validated real-time quantitative PCR assay was used to determine viral loads for NoV genogroup I and II (GI and GII) in NoV-positive stool specimens of cancer patients. A total of 234 specimens from 152 patients were positive for NoV, including 201 of GII and 33 of GI. Geometric mean of logarithmic copies per gram of stool (w/w) of NoV-GII were 9.03 ± 1.71 (means ± SD), which was significantly higher than that of NoV-GI [7.87 ± 1.49; odd ratio (OR), 3.22; 95% CI, 1.33-7.76; P = 0.009]. Among 152 patients with gastroenteritis, the fecal NoV geometric mean of logarithmic copy was correlated with mild (n = 85; 7.97 ± 1.55), moderate (n = 23; 9.09 ± 1.38), and severe (n = 44; 10.39 ± 0.91) episodes of severity by modified Vesikari scoring system, respectively. Multivariate analysis revealed that high level of NoV load was correlated with GII infections (OR, 4.13; 95% CI, 1.62-10.55; P = 0.003) and associated with development of severe clinical symptom (OR, 5.53; 95% CI, 2.00-7.24; P = 0.001) at the time of diagnosis. Infection with GII strains was more common than GI infection in cancer patients with viral gastroenteritis.