King's College criteria and the Clichy-Villejuif criteria require adjustments for assessing acute liver failure due to yellow fever

Figure 1 Yellow fever is typically described as a biphasic disease. The initial phase is the viremia phase, which is characterized by the presence of the virus in the bloodstream and associated symptoms. Following this phase, there is a remission phase which is characterized by temporary symptom improvement. Only approximately 15% of patients progress to the toxic phase, which is characterized by severe symptoms and potential complications. The transitions between these phases reflect the progression and severity of the disease. AST: Aspartate aminotransferase; ALT: Alanine aminotransferase.

Figure 2 Analysis of international normalized ratio and factor V levels and clinical outcomes over time. This figure presents a comparative analysis of the international normalized ratio (INR) and factor V levels of patients, categorized by clinical outcomes and day of illness, categorized by the phases of yellow fever (viremia, remission, and toxicity). The figure includes two graphs: (1) One displaying INRs; and (2) The other showing factor V levels. Each data point represents the mean value for the specified day and outcome, with error bars indicating the standard deviation. The panels illustrate how INR and factor V levels vary across different clinical outcomes (transplantation, death, and clinical improvement) and days of illness. Trends reveal associations between elevated or decreased INRs and factor V levels with different clinical results, providing insights into their role in patient outcomes over time. INR: International normalized ratio. D4: Day 4; D5: Day 5; D6: Day 6; D7: Day 7; D8: Day 8; D9: Day 9; D10: Day 10; D12: Day 12; D14: Day 14.

Figure 3 Patient outcomes flowchart. This flowchart depicts the clinical outcomes of the 14 patients studied. Among these patients, 6 experienced clinical improvement. Among the 8 patients who experienced clinical deterioration, 4 did not receive a liver transplant and subsequently died. The remaining 4 patients who received a transplant were further divided into two groups: (1) 2 patients experienced clinical improvement; and (2) While the other 2 patients died despite the transplant.

Figure 4 Liver histopathological analysis. Histopathological features of explanted livers from Yellow fever (YF) patients who underwent transplantation. A and B: Microscopic examination showing a midzonal lesion (arrows) with acidophilic bodies, steatotic hepatocytes (asterisk), hyperplasia and hypertrophy of Kupffer cells, and mild inflammation, mainly in the portal tracts. Note the periportal preservation of hepatocytes; C: YF virus antigen positivity in midzonal hepatocytes with acidophilic degeneration or steatosis and in Kupffer cells.