Respiratory virus activity associated with stroke rates in Victoria

Researchers conducted a population-level ecological study using statewide hospital admissions for stroke in Victoria, Australia, from June 2010 through December 2022, alongside representative respiratory PCR testing data. The analysis included 153,730 stroke events—61% ischemic, 25% hemorrhagic and 14% unspecified—and 6,180,896 respiratory specimens. Models accounted for population size, climate and air pollution, and estimated temporal and regional associations between virus activity and stroke.

Higher weekly levels of specific respiratory viruses were associated with increased stroke rates. The estimated fractions of strokes attributed to enterovirus and human metapneumovirus were 4.6% (95% CI, 2.5–6.6) and 1.3% (95% CI, 0.3–2.3), respectively; estimates rose during peak viral weeks. Associations also varied by stroke type: human metapneumovirus had an estimated attributable fraction of 3.7% for ischemic stroke, while enterovirus and parainfluenza estimates were 5.8% and 3.2% for hemorrhagic stroke.

Regional analyses found larger estimated effects in some areas, including outer-urban areas and areas potentially associated with agricultural or industrial activity. Because this was an ecological study, the findings are population-level associations and do not establish that infection caused individual strokes. The authors say further investigation is warranted.