ECDC raises Aedes albopictus surveillance tier for Lombardia and Emilia-Romagna
West Nile virus detected in mosquito pools across Pavia and Milan provinces. One human seroconversion confirmed in Lombardia, the earliest in the region's recorded surveillance history.
title: "ECDC raises Aedes albopictus surveillance tier for Lombardia and Emilia-Romagna" date: "2026-04-20" author: "Mosticare Editorial" authorRole: "Science Editor · Mosticare" mins: 4 region: "Italy" alert: null excerpt: "West Nile virus detected in mosquito pools across Pavia and Milan provinces. One human seroconversion confirmed in Lombardia, the earliest in the region's recorded surveillance history." sources:
- text: "ECDC · Rapid Risk Assessment, Italy WNV 2026" href: "https://www.ecdc.europa.eu"
- text: "Ministero della Salute · Bollettino WNV settimana 16" href: "https://www.salute.gov.it"
- text: "Angelini et al. 2004 · West Nile in northern Italy: first report" href: "https://doi.org/10.2807/esm.09.11.00490-en" correctionEmail: "corrections@mosticare.org"
ECDC has raised its Aedes albopictus surveillance tier for Lombardia and Emilia-Romagna to Enhanced Monitoring, effective 18 April 2026, the earliest calendar date this tier has been triggered in either region.
The decision follows the detection of West Nile virus RNA in sentinel mosquito pool samples from Pavia and Milan provinces, and the confirmation of one human case: a 67-year-old resident of Lodi who presented with neurological symptoms on 16 April and has since been discharged from hospital.
Why the timing matters
West Nile surveillance in northern Italy typically begins recording positives in late June or early July, when Culex pipiens populations peak after sustained warm weather. The current positives in April are ten to twelve weeks ahead of the 2015–2023 average onset date.
The mechanism is straightforward. The 2025–26 winter across the Po Valley was approximately 1.8°C above the 30-year mean. Overwintering Culex populations experienced lower cold-knockdown mortality, and spring amplification of the avian-mosquito-human transmission cycle began from a higher baseline.
The Ministero della Salute's integrated surveillance network, which monitors bird mortality, equine cases, mosquito pools, and human cases in parallel, is now at full operational status for the Lombardia-Emilia corridor, eight weeks ahead of the standard activation date.
What this means for residents
Culex pipiens is a night-biter that primarily feeds on birds but will take human blood meals when bird hosts are scarce. Standard protective measures apply:
- Use physical-barrier window screens, particularly in bedrooms and on ground floors near gardens or water features.
- Drain standing water weekly, bird baths, pot saucers, rain barrels without sealed covers.
- If you develop sudden fever, stiff neck, or confusion within a fortnight of mosquito exposure in the Po Valley, seek medical assessment.
West Nile neurological disease is rare but severe. The elderly and immunocompromised carry disproportionate risk. There is no licensed human vaccine available in the EU.
The Lombardia-Emilia corridor in context
This corridor has recorded West Nile human cases every summer since 2008. The long-term trend is upward: the 2018 season produced 610 human cases nationally, the highest before 2025's 743. The early 2026 signal does not guarantee a record year, but it narrows the window in which preventive infrastructure, breeding-site management, public awareness, hospital preparedness, can be put in place without incident driving the timeline.
Mosticare's threat map is tracking this signal with daily pool-sample updates. The Lombardia regional dossier is available at mosticare.org/threat-map.