Infectious Disease · Public Health · 1 h ago
West Nile virus detected repeatedly in Aedes caspius in Lombardy
A surveillance investigation in Lombardy, Italy, detected West Nile virus lineage 2 in six of seven archived Aedes caspius mosquito pools collected in July 2026. The findings coincided with an early human transmission season, but do not establish that this mosquito species transmitted the virus.
- WNV lineage 2 was detected in six of seven mosquito pools.
- Positive pools came from three independent sites.
- Mosquito and human virus sequences were highly similar.
- Vector competence remains unproven.
In Lombardy, northern Italy, the first neuroinvasive West Nile virus (WNV) case of 2026 was reported on 7 July. At several surveillance sites, investigators observed high numbers of Aedes caspius and low numbers of Culex pipiens. They tested seven archived pools of A. caspius collected in July for WNV.
WNV lineage 2 was detected in six pools from three independent sites. A sequence from A. caspius shared more than 99.94% nucleotide identity with sequences obtained from contemporaneous human cases.
The findings document repeated WNV detection in A. caspius during an unusually early human transmission season. They do not demonstrate vector competence or establish that this species contributed to human infections; the authors call for further investigation, particularly of its ability to transmit lineage 2.
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Eurosurveillance: Repeated detection of West Nile virus in Aedes caspius during an unusually early transmission season in humans in northern Italy, 2026 ↗This is an automated AI-condensed summary that has not yet been reviewed by an editor. Always consult the full item at the original source.