New data published today by the UK Health Security Agency (UKHSA) shows a rise in Giardia cases across England. The number of laboratory-confirmed giardiasis cases increased by 11.4%, from 5,450 in 2024 to 6,069 in 2025. This marks the highest number of cases reported since 2016.
London registered the highest number of cases with 1,568, followed by the North West with 1,029. Cases peaked in autumn, with October recording 599 cases, September 580, and November 574.
The UKHSA is investigating the reasons for this increase, which has seen cases return to pre-pandemic levels in 2023 and rise further since. Possible contributing factors include new and more effective testing, increased international travel since the pandemic, and climate and environmental changes.
Giardia is a gastrointestinal illness caused by a parasite, with common symptoms including diarrhoea, abdominal cramps, bloating, and weight loss. Nicola Love, Senior Food Safety Surveillance Lead at UKHSA, stated that symptoms can last for weeks to several months and, if left untreated, can lead to serious complications, particularly in young children, the elderly, and those with weakened immune systems.