The UK Health Security Agency reported on 26 August 2026 that laboratory-confirmed Giardia cases in England rose from 5,450 in 2024 to 6,069 in 2025, an increase of 11.4% (619 cases) and the highest annual figure since 2016. London recorded the highest regional total at 1,568 cases, followed by the North West with 1,029. Reports peaked in autumn, led by October (599), September (580) and November (574).

Annual case numbers returned to pre-pandemic levels in 2023 and have risen since. UKHSA said it was investigating the reasons, possibly a mix of more effective testing, increased post-pandemic travel, and climate and environmental changes. The agency noted infection can be acquired in the UK or abroad, spreading through contact with infected people or animals, contaminated food or water, and sexual transmission, with cases also seen in travellers returning from Southern Asia, South-Eastern Asia, Africa and South America.

Nicola Love, Senior Food Safety Surveillance Lead at UKHSA, said symptoms can last weeks to months and may cause serious complications, especially in young children, the elderly and people with weakened immune systems. She advised handwashing with soap and water and said people with infection should stay hydrated and see a GP, avoiding swimming until two weeks after diarrhoea stops.