UCSF

BACKGROUND: West Nile virus (WNV) infection is mostly asymptomatic (AS) but 20% of subjects report WNV fever and 1% of patients experience neurologic diseases with higher rates in elderly and immunosuppressed persons. With no treatment and no vaccine to prevent the development of symptomatic (S) infections, it is essential to understand prognostic factors influencing S disease outcome. Host genetic background has been linked to the development of WNV neuroinvasive disease. This study investigates the association between the ABO and D blood group status and WNV disease outcome. STUDY DESIGN AND METHODS: The distribution of blood groups was investigated within a cohort of 374 WNV+ blood donors including 244 AS and 130 S WNV+ blood donors. Logistic regression analyses were used to examine associations between A, B, O, and D blood groups and WNV clinical disease outcome. RESULTS: S WNV+ donors exhibited increased frequencies of blood group A (S 47.6%, AS 36.8%, p = 0.04; odds ratio [OR], 1.56; 95% confidence interval [CI], 1.01-2.40) and D- individuals (S 21.5%, AS 13.1%, p = 0.03; OR, 1.82; 95% CI, 1.04-3.18). CONCLUSION: The findings suggest a genetic susceptibility placing blood group A and D- individuals at risk for the development of S disease outcome after WNV infection.