Highlights
COVID-19 diagnosis; high sensitivity and specificity qualitative rapid chromatographic immunoassays; can be used for the diagnosis of RT-PCR-negative patients.
BACKGROUND Despite a highly efficacious vaccine, yellow fever (YF) is still a major threat in developing countries and a cause of outbreaks. In 2018, the Brazilian state of São Paulo witnessed a new YF outbreak in areas where the virus has not been detected before.
OBJECTIVEThe aim is to describe the clinical and laboratorial characteristics of severe cases of YF, evaluate viral to determine markers associated with fatal outcome. METHODS Acute severe YF cases (n = 62) were admitted to the Intensive Care Unit of a reference hospital and submitted to routine laboratorial evaluation on admission. YFV-RNA was detected in serum and urine by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and then sequenced. Patients were classified in two groups: survival or death. FINDINGS In the univariate analysis the following variables were associated with outcome: alanin aminotransferase (ALT), aspartat aminotransferase (AST), AST/ALT ratio, total bilirubin (TB), chronic kidney disease epidemiology collaboration (CKD-EPI), ammonia, lipase, factor V, international normalised ratio (INR), lactate and bicarbonate. Logistic regression model showed two independent variables associated with death: lipase [odds ratio (OR) 1.018, 95% confidence interval (CI) 1.007 to 1.030, p = 0.002], and factor V (OR -0.955, 95% CI 0.929 to 0.982, p = 0.001). The estimated lipase and factor V cut-off values that maximised sensitivity and specificity for death prediction were 147.5 U/L [area under the curve (AUC) = 0.879], and 56.5% (AUC = 0.913).MAIN CONCLUSIONS YF acute severe cases show a generalised involvement of different organs (liver, spleen, heart, kidneys, intestines and pancreas), and different parameters were related to outcome. Factor V and lipase are independent variables associated with death, reinforcing the importance of hemorrhagic events due to fulminant liver failure and pointing to pancreatitis as a relevant event in the outcome of the disease.
The host immune response, including innate and adaptive immunity, plays a critical role in determining the outcome of viral infection. Nevertheless, little is known about the exact reasons for the failure of the host immune system in controlling hepatitis C virus (HCV) infection. Impairment of dendritic cells (DCs) function is probably one of the mechanisms responsible for immune evasion of HCV. In this study, the frequency and phenotype of DCs subsets were analyzed in three groups: HCV-infected individuals who developed viral persistence (1), HCV-infected individuals who spontaneously cleared the virus (2) and HCV-seronegative uninfected subjects (3). The results showed that the frequency of DCs subsets was not statistically significant between groups. Plasmacytoid DCs circulating exhibited an immature phenotype characterized by low expression of CD86. On the other hand, CD86 expression in myeloid DCs was significantly higher in chronic infected individuals compared to healthy controls (P=0.037). A positive correlation was observed between CD86(+) myeloid DC (mDC) and HCV viral load (r=0.4121, P=0.0263). These results suggest that HCV did not have an inhibitory effect on mDC maturation and the HCV viremia drives the increase of CD86 expression in mDC. The regulation of DCs maturation and migration lies at the level of intracellular signaling. HCV can activate or block intracellular signaling pathways and alter DC function. In conclusion, the present study suggests that imbalance of DC maturation by the virus represents a mechanism of evasion of the immune system despite the fact that HCV viremia appears to exert a "stimulatory" effect on cell-surface immune phenotype.
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