Among 59,598 pregnant women screened at Peru's Instituto Nacional Materno Perinatal between 2023 and 2025, maternal syphilis prevalence held steady at 1.0–1.2%. Yet congenital syphilis incidence ranged from 383 to 526 cases per 100,000 live births across 36,094 births — seven to ten times the WHO elimination benchmark of 50 per 100,000. Paradoxically, reported treatment coverage exceeded 90% for mothers and reached 100% for infants, suggesting the bottleneck lies in timing and care-coordination rather than treatment availability per se.
The finding exposes a critical flaw in how elimination metrics are typically interpreted: high treatment coverage statistics can mask failures in early, antenatal diagnosis and seamless referral linkage. Over half of maternal infections were diagnosed at outside facilities before transfer, pointing to fragmentation between primary screening sites and the referral center as a key vulnerability. This mirrors patterns documented across Latin America and sub-Saharan Africa, where syphilis re-emergence has reversed decades of progress — driven by inconsistent first-trimester screening, supply-chain disruptions for penicillin, and stigma-related care avoidance.
For global health practitioners, the data underscore that near-perfect treatment rates are hollow without upstream diagnostic infrastructure. Limitations include the retrospective, aggregate design at a single national referral center — a high-risk population not representative of Peru broadly — and reliance on surveillance data that may undercount cases. As a preprint not yet peer-reviewed, findings require independent validation before informing policy revision.