New data from the UK Health Security Agency (UKHSA) show that last year imported dengue cases in England, Wales and Northern Ireland (EWNI) reached their highest level since dengue surveillance began in 2009. All cases are linked to travel abroad.
In 2024, 904 dengue cases were reported in returning travellers across EWNI, up from 631 in 2023. Most cases were linked to travel to southern and south-eastern Asia. UKHSA is developing enhanced surveillance of dengue cases to better understand where people are acquiring infections and what mosquito bite precautions they were using, in order to help inform public health interventions in future.
Dengue cases have been increasing globally since 2010 with historic highs reported in 2019. In 2023, The World Health Organization (WHO) reported a post-pandemic global increase in both dengue cases and deaths, including in regions previously considered dengue-free, with significant increases particularly noted in Asia and the Americas. A range of factors, including climate change, changing distributions of the mosquito vector (Aedes aegypti pictured), and periodic weather events leading to rising temperatures, heavy rainfall and humidity are driving this increase globally.
The Joint Committee on Vaccination and Immunisation (JCVI) has recently recommended dengue vaccination for some travellers.
Imported cases of Chikungunya, another mosquito-borne infection, have also risen in EWNI. In 2024, 112 cases were reported, more than double the 45 cases in 2023, with most linked to travel in Southern Asia. These changing patterns may reflect several factors including differences in testing practices, disease burden, global epidemiology, clinician awareness and travel trends.
Zika virus disease cases increased to 16 in England, Wales and Northern Ireland during 2024, compared to eight cases in 2023, with most travellers returning from South-Eastern Asia. Although Zika virus cases are rarely reported and don’t often cause serious illness, the infection poses a significant risk to pregnant women, as it can be passed to the foetus. There is no drug or vaccine to prevent Zika virus infection, and the most effective way of preventing infection is minimising mosquito bites.