HAIRS risk assessment: Zika virus
Qualitative assessment of the risk that Zika virus presents to the UK population.
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Zika virus disease is a mosquito-borne infection caused by Zika virus (ZIKV), which is transmitted via the bite of Aedes mosquitoes. It was first isolated from a sentinel rhesus monkey in Uganda in 1947 and has circulated since then in many countries. ZIKV generally causes a mild infection in humans. ZIKV infection during pregnancy is a cause of congenital brain abnormalities.
In the UK, reported cases have been associated with travel to areas with active ZIKV transmission. Because the UK does not have established populations of invasive Aedes mosquito species competent at transmitting ZIKV, there have been no locally acquired infections. Although various life stages of invasive Aedes species were sporadically detected between 2016 and 2025, there is currently no evidence of population establishment in the UK.
This risk assessment was completed to assess the current risk that ZIKV presents to the UK population from exposure to infected vectors within the UK. The reader is reminded that this assessment does not consider the human-to-human transmission routes via sexual or vertical transmission.
Updates to this page
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Republished: unpublished in error.
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Added updated version of research: update of epidemiological and entomological data.
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Updated with latest epidemiology and vector information.
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Updated with latest epidemiology and vector information.
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Updated with v3 incorporating new evidence on sexual transmission.
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Updated (version 2) with current information including risk of sexual transmission.
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First published.