Methods, national trend graph. Annual national rates for HIV NAT, HBV NAT, HCV NAT, SYP RPR, and WNV NAT were taken from the yearly summary tables. For Babesia NAT, annual national rates were calculated from the screening-state-only worksheet by summing reactive donations and total screened donations across screening states for each calendar year, then computing reactive donations per 100,000 screened donations. Because Babesia NAT and WNV NAT are seasonal and the available 2026 data are incomplete, 2026 observations were excluded for those two parameters. Observed rates are shown as solid lines on a log-scale y-axis. Exploratory forecasts were generated using a log-linear model fit separately for each parameter; the dashed segments show the model-projected rates for the next three years after the last observed value. Forecasts should be interpreted as descriptive projections rather than definitive predictions.
Methods, state-level visualizations. State-level rates were taken from the state-by-year tables in the HIV NAT, HBV NAT, HCV NAT, SYP RPR, and WNV NAT worksheets. For Babesia NAT, state-level rates were calculated from the screening-state-only worksheet as reactive donations divided by total screened donations, multiplied by 100,000. Rates are shown for every available state-year. The choropleth displays the observed number of reactive or positive cases by state and year. The top-10 bar chart ranks states by number of positive cases for the selected parameter-year. The state-level bubble plot uses the same selected parameter and year as the map, with sample denominator on the x-axis, positive cases on the y-axis, rate per 100,000 as bubble color, and circle size proportional to the corresponding state population; each bubble represents one state. The compact trend panel shows the overall selected-parameter trend by default and switches to a state-specific trend when hovering over a state on the map or bubble plot. The k-means plot clusters states for the selected parameter-year using standardized positive cases and rate per 100,000, with circle size proportional to the corresponding state population, then labels the resulting groups as high count/high rate, low count/high rate, or low count/low rate based on each cluster centroid. The map and bubble plot display one parameter and year at a time using radio buttons and a year slider. To improve visual contrast in low-count years, the map color scale is rescaled dynamically for the selected parameter-year, with the upper color limit based on the 95th percentile of nonzero values for that selection.
HCV NAT shows the clearest long-term decline, falling from 17.35 per 100,000 in 2013 to 4.71 in 2025. Most of the decrease occurred before 2021, followed by a low, relatively stable plateau from 2021 through 2025. The forecast continues this downward direction, projecting rates of 3.32 in 2026, 2.94 in 2027, and 2.60 in 2028.
SYP RPR increased over the period, rising from 5.84 per 100,000 in 2013 to 9.31 in 2025. The highest observed rate was 10.34 in 2024, with a small decrease in 2025. The forecast suggests continued upward pressure, with projected rates of 10.25 in 2026, 10.87 in 2027, and 11.52 in 2028.
HBV NAT was comparatively stable, generally staying between about 4.4 and 6.5 per 100,000. It dipped in 2016 and 2021, then increased again through 2025. The forecast remains essentially flat, projecting 5.45 in 2026, 5.47 in 2027, and 5.48 in 2028.
HIV NAT declined from 2.63 per 100,000 in 2013 to a low of 0.75 in 2021. Rates then increased modestly from 2022 to 2025 but remained below the early-period levels. The forecast points to a slight decline, with projected rates of 1.07 in 2026, 1.02 in 2027, and 0.98 in 2028.
WNV NAT fluctuated more year to year than the other NAT measures. It dropped sharply in 2019 and 2020, rebounded in 2021 and 2023, and ended 2025 at 3.74 per 100,000. Because of this variability, the forecast should be interpreted cautiously; the model projects a gradual decline to 2.66 in 2026, 2.61 in 2027, and 2.55 in 2028.
Babesia NAT has higher observed rates than the other parameters in the years available, ranging from 19.42 to 30.69 per 100,000 between 2020 and 2025 after limiting the analysis to screening states and excluding incomplete 2026 data. The rate was highest in 2020, decreased through 2022, and rebounded in 2023 and 2025. With only six observed years, the forecast is especially tentative; it projects rates of 25.89 in 2026, 25.76 in 2027, and 25.64 in 2028.