As the summer holiday season begins, the UK Health Security Agency (UKHSA) is reminding travellers to take precautions against travel-associated infections overseas. UKHSA has today published provisional data for England, Wales and Northern Ireland on specific selected travel associated infections including mosquito-borne infections (dengue, Zika, chikungunya and malaria) and enteric fever (typhoid and paratyphoid fever).
Mosquito-borne infections can cause fever, headache, muscle and joint pain, nausea and vomiting, and can be serious although some people experience no symptoms at all. Typhoid and paratyphoid are serious but preventable illnesses caused by Salmonella bacteria, usually spread through contaminated food or water.
Travellers can protect themselves against these infections by taking steps to avoid mosquito bites, including using insect repellent, covering exposed skin and sleeping under a treated bed net where needed, as well as practising good food and water hygiene and getting vaccinations and malaria prevention tablets where appropriate.
The latest imported dengue data shows that a total of 137 cases were reported in England from January to June 2026. South-East Asia and South Asia remain the most common regions of exposure, with 27 cases linked to travel to Thailand and 19 to the Maldives.
A total of 8 Zika virus cases were reported from January to June 2026. This already exceeds the 7 cases recorded in 2025. Indonesia was the most frequently reported country of exposure, accounting for four of the eight cases in 2026 so far. Notably, only one travel-associated case linked to Indonesia had been reported between 2014 and 2025, which occurred in 2024.
Although Zika rarely causes serious illness in most people, it poses a significant risk during pregnancy as it can be passed to the unborn baby and can cause birth defects. There is no vaccine or treatment, so avoiding mosquito bites is the most effective form of protection.
A total of 59 chikungunya cases were reported from January to June 2026, with Sri Lanka being the most commonly reported country of travel, accounting for 18 cases.
Meanwhile, 557 malaria cases were reported in England, Wales and Northern Ireland from January to May 2026. Malaria is potentially fatal but almost entirely preventable when antimalaria tablets are taken correctly.
Today’s data shows that cases of dengue and Zika continue through spring and into the summer, with dengue recording its highest 2026 monthly total in June, and Zika cases reported throughout this period. This follows the pattern seen in previous years, where mosquito-borne infection cases are commonly reported during the spring and summer travel months.
In addition to mosquito-borne infections, a total of 287 travel-associated enteric fever cases (typhoid and paratyphoid fever) were reported from January to June 2026. The highest number of enteric fever cases is recorded between May and October in recent years, with September seeing a peak of 118 cases in 2025. These are serious but preventable illnesses caused by Salmonella bacteria, usually spread through contaminated food or water.
With the summer holiday season now underway, cases are expected to continue to rise and UKHSA is reminding travellers to take appropriate precautions before and during their trip.
Dr Hilary Kirkbride, Consultant Epidemiologist and Head of Travel Health at UKHSA, said
Summer is a popular time to travel – don’t let illness spoil your holidays. Good preparation and planning is important for a safe and enjoyable trip.
Check the TravelHealthPro website for the latest health advice for your destination, including which vaccines you may need and any important medications, such as antimalarial tablets. To protect against mosquito borne infections use insect repellent, cover exposed skin and sleep under a treated bed net where needed. For enteric fever and other stomach bugs make sure you take good food and water hygiene precautions.
Even if you have visited a country before, you do not have the same level of natural protection against infections as permanent residents, so it is important to take precautions every time you travel. And if you are pregnant or trying to conceive there are special precautions you should take, so please speak to a doctor, nurse or local travel clinic before planning your trip.
Meanwhile, measles continues to circulate in parts of the UK, with outbreaks also occurring worldwide. Measles spreads very easily and can lead to serious complications, including ear and chest infections and, in rare cases, inflammation of the brain.
Two doses of the MMR or MMRV vaccine is the best way to protect yourself and your family from measles. Babies under the age of 1 and some people who have weakened immune systems cannot have the vaccine and are at risk of more serious complications if they get measles. They rely on the rest of us getting the vaccine to protect them.
UKHSA is urging parents to ensure their children’s routine vaccinations are up to date before travelling, giving them the best possible protection ahead of their trip.
The TravelHealthPro website, supported by UKHSA, provides up-to-date health information for countries across the world.