Recorded human leishmaniasis and notification gaps in Central Tuscany, Italy, 2014-2024: a multisource surveillance study

Objectives: To assess whether mandatory notification adequately captures recorded human leishmaniasis in Central Tuscany, Italy, by describing source-specific trends during 2014-2024 and evaluating notification completeness for 2022-2024. Methods: We conducted a retrospective multisource surveillance study using laboratory-positive records, mandatory notifications and first leishmaniasis-coded hospital discharge records. For 2022-2024, records from the three sources were deterministically linked at the individual level; observed notification completeness was defined as the proportion of linked individuals identified in at least one source who were present in the notification source, and three-source log-linear capture-recapture was performed. Results: During 2014-2024, 280 laboratory records, 89 notifications and 157 first leishmaniasis-coded hospital discharge records were identified. Counts increased from 2021, peaked in 2023 and remained elevated in 2024. In 2022-2024, linkage identified 185 unique individuals across the three sources; 65 (35.1%) were present in the notification source, 179 (96.8%) in laboratory records and 91 (49.2%) in hospital discharge records. Children aged 0-9 years were prominent, ranking first in notification and hospital sources. Capture-recapture estimated 214 cases (95% CI: 185-1,078), with imprecise estimates of unobserved cases. Conclusion: Mandatory notification incompletely represented individuals identified across the available routine data sources in this endemic Italian setting. Laboratory-linked notification and routine reconciliation of routine data sources could strengthen surveillance; recent increases should be interpreted as increases in recorded cases rather than as evidence of increased local transmission.