The UK Health Security Agency (UKHSA) has issued a fresh warning to travellers visiting seven regions about the risk of mosquito-borne diseases, including dengue fever, Zika virus, chikungunya, and malaria. New data shows imported cases of these illnesses are rising in the UK, with some infections already exceeding last year's totals.
Key regions at high risk
The World Health Organisation identifies tropical and subtropical regions as highest risk for mosquito-borne viruses. The affected areas include Southeast Asia, South Asia, Sub-Saharan Africa, Central and South America, the Caribbean, and Pacific islands. Travellers to these destinations are urged to take precautions.
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.”
Rising case numbers in 2026
From January to June 2026, eight Zika virus cases were reported in England – already above the seven cases recorded in all of 2025. Four of these cases were linked to travel to Indonesia.
Some 137 cases of imported dengue were reported in England from January to June this year, with South-East Asia and South Asia remaining the most common regions where people caught it. Specifically, 27 cases were linked to travel to Thailand and 19 to the Maldives. For comparison, the overall number of cases by the end of June last year was 161, though cases tend to rise later in the year.
A total of 59 chikungunya cases were reported from January to June this year, with Sri Lanka being the most commonly reported country of travel, accounting for 18 cases. There were 73 in the same period last year. Meanwhile, 557 malaria cases were reported in England, Wales and Northern Ireland from January to May. Last year at the same point, there were 548.
Symptoms and severity
Dengue fever can feel similar to flu and symptoms include high temperature, severe headache, pain behind the eyes, muscle and joint pain and feeling sick. Chikungunya symptoms include fever, joint pain, headache, muscle pain, joint swelling and rash. Most people with Zika suffer a mild illness, but it is serious in pregnant women and can cause stillbirth, miscarriage, problems with development and unusually small heads. Malaria can prove fatal, with symptoms including fever, vomiting and pain.
As well as mosquito-borne illnesses, there were 287 cases of typhoid and paratyphoid fever between January and June this year. Typhoid and paratyphoid are caused by Salmonella bacteria, usually spread through contaminated food or water.
Prevention advice from UKHSA
The UKHSA advises travellers to reduce the risk of bites by applying insect repellent, covering arms and legs, and using an insecticide-treated mosquito net where appropriate. Travellers should also ensure travel vaccinations are up to date and check whether anti-malaria medication is recommended for their destination.
Dr Kirkbride added: “Check the TravelHealthPro website for the latest health advice for your destination, including which vaccines you may need and any important medications, such as anti-malarial 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.”
Choosing effective repellents
Natalie Hitchins, Which? head of home products and services, said: “If you’re travelling somewhere that has mosquitoes, it’s worth checking that your repellent will actually do the job before you go. Which? tests found that while some repellents provided effective protection for almost 10 hours, some trendy alternatives failed to prevent bites for longer than a few minutes. Look for products containing active ingredients such as Deet, Icaridin (picaridin) or PMD, rather than relying on marketing claims alone. Insect repellent can help protect against mosquito bites, but it should be used alongside – never as a replacement for – any vaccinations or medications recommended by a healthcare professional.”
