Dengue Fever Prevention in Thailand: What Every Traveller Needs to Know

Dengue fever is a mosquito-borne viral illness that affects tens of thousands of people in Thailand every year, including a significant number of foreign travellers. Unlike malaria, dengue is present in urban as well as rural areas — Bangkok's high-rise neighbourhoods, Chiang Mai's old city, and beach resorts all report cases. There is no curative treatment; prevention and early detection are everything. Understanding the risk: dengue is transmitted by the Aedes aegypti mosquito, which bites primarily during daylight hours — especially in the two hours after sunrise and two hours before sunset. Peak season is the rainy season (July–November) when standing water creates extensive breeding grounds. Symptoms: dengue presents 4–7 days after a bite with sudden high fever (39–40°C), severe headache, pain behind the eyes, joint and muscle pain (earning the nickname "breakbone fever"), and a skin rash appearing 3–5 days into illness. Severe dengue (dengue haemorrhagic fever) develops in a minority of cases and can be life-threatening — symptoms include persistent vomiting, abdominal pain, bleeding from the nose or gums, and blood in urine. Seek emergency care immediately if these develop. Prevention: no repellent provides 100% protection. Use DEET 30–50% based repellent — apply to all exposed skin. Reapply every 4 hours in heavy mosquito areas. Wear long sleeves and trousers in the evenings and jungle areas. Sleep under a mosquito net if your accommodation lacks screens. Remove standing water from your immediate environment — even a bottle cap of water can breed hundreds of mosquitoes. Dengue vaccine (Qdenga): a dengue vaccine became available in Thailand from 2024 for travellers aged 4+. It offers approximately 80% protection against dengue types 2 and 3 and partial protection against types 1 and 4. Suitable for travellers with extended stays. Available at Bumrungrad and major Bangkok hospitals from approximately ฿3,500–5,000 for a two-dose course. Testing and treatment: if you develop fever in Thailand, get a dengue rapid test (available at any clinic, cost ฿300–800). The test is most reliable from day 4 of fever. If positive, treatment is supportive: rest, fluids, paracetamol (never ibuprofen or aspirin with dengue — risk of bleeding). Monitor platelet count daily if confirmed dengue.