Viral kinetics in sylvatic yellow fever cases.

<bold>Background: </bold>Yellow fever is a mosquito-borne zoonotic disease, caused by yellow fever virus (YFV). Between 2017-2019 more than 504 human cases and 176 deaths were confirmed in the outskirts of São Paulo city. Throughout this outbreak, studies suggested a potential association between YFV viremia and mortality.<bold>Methods: </bold>Viral RNA was measured using RT-qPCR in plasma samples collected at up to 5 time points, between 3-120 days after symptoms onset.<bold>Results: </bold>84 patients with confirmed YFV infection were included. Most were males; median age was 42, and 30 (36%) died. Deceased patients were older than survivors (p = 0.003) and had a higher viremia across all time points (p = 0.0006). Mean values of viremia had a positive, statistically significant correlation with peak values of neutrophils, indirect bilirubin, AST, INR and creatinine. Finally, a Cox proportional hazards model adjusted for age and laboratory variables showed that viremia is independently associated with death, with a mean 1.84-fold increase (84%) in the hazard of death (p < 0.001) for each unit increase in mean log10 viremia.<bold>Conclusion: </bold>Our results raise the importance of monitoring YFV viremia and suggest a potential benefit of antiviral drugs or neutralizing monoclonal antibodies early in the course of this infection to improve disease outcomes. [ABSTRACT FROM AUTHOR]