Fig. 3: Persistent maternal–infant attachment in ZIKV-exposed infants at 12 months of age.

Mother-infant dyads (ZIKV n = 26, control n = 9) were videotaped in their home enclosure, and the durations spent in nipple contact, togetherness, ventral contact, and locomotion were recorded as a percentage of the total observation time (a). Significant differences between ZIKV-exposed and control groups were assessed using two-sided Wilcoxon rank-sum tests: mutual ventral contact (Z = 2.49, p = 0.0127, ZIKV median = 36.3%, control median = 0.0%), togetherness (Z = 2.43, p = 0.0149, ZIKV median = 74.8%, control median = 50.4%), and nipple contact (Z = 2.60, p = 0.0093, ZIKV median = 33.3%, control median = 0.0%). b Mutual ventral contact duration by inoculation group. A significant difference between ZIKV-PR 45gd and control groups was observed (49.4% vs 0.0%; two-sided Wilcoxon rank-sum test, Z = 2.43, p = 0.0104). The association between mutual ventral contact duration and maternal infection variables were assessed using linear regression, including plasma viremia duration (c), area under the curve plasma viral load (d), maternal-fetal interface biopsies that were vRNA positive (e) and PRNT90 titer (f). For box plots (a, b), the center line represents the median, box bounds represent the 25th and 75th percentiles (interquartile range), and whiskers extend to the minimum and maximum values excluding outliers (values beyond 1.5× IQR), with individual data points overlaid. For scatter plots (c–f), data are presented as individual values with linear regression lines; shaded areas represent the 95% confidence interval of the regression. Linear regression statistics (R², t-statistic, and p value) are displayed on each graph.