The likelihood is that most people in the UK have never heard of dengue fever. Even those who have probably associate it with warmer climates, not something we should be concerned about in the UK. However, global warming is changing everything, and dengue fever in the UK is fast becoming a real possibility.

The fact is that the dengue virus is already on our doorstep, just across the Channel. That is because Europe is warming up, and that has allowed the mosquitoes which carry the virus to begin to breed way beyond the tropics. Recent research shows that the Aedes group of mosquitoes which transmit the virus are already spreading into central and southern Europe, places where we regularly go on holiday! As European average temperatures continue to climb, they are coming ever closer to the UK (see below).

Dengue fever is a particularly nasty viral infection, like a very severe case of flu, which can last more than two weeks. The main symptoms are prolonged high fever, rashes, nausea, pain behind the eyes, severe headaches, and muscle cramps. It can often result in victims requiring hospitalization. In the most serious cases, it can progress to dengue hemorrhagic fever, which can prove fatal.

In 2000, Dengue fever was confined to the tropics, but by 2023, that is no longer the case. There are increasing numbers of cases in developed countries, not just in Europe, but also in the USA, Australia, and China (see below).

Dengue cases have already been recorded in France, Spain, and Italy:

• These are locally acquired infections, not infections brought back from foreign travel.
• The numbers, although small at present, are increasing exponentially. The question is what will the figures for the period 2025–2030 look like? If the rate of increase in cases continues, we could be looking at thousands of cases!

The Aedes mosquitoes haven’t arrived yet, but when they do, the first dengue fever cases will not be far behind. The question that we should be asking now is whether we are ready to deal with dengue fever when that happens.

Communicable diseases are hazards in just the same way as extreme climatic events, wildfires, or earthquakes. They have measurable impacts and require governments to develop strategies to prevent them or mitigate their worst effects.

• If the dengue virus becomes established in the UK, we could be looking at as many as 200,000 cases a year on top of continuing COVID-19 cases and winter flu outbreaks. The NHS is already overstretched at key times of the year. Outbreaks of dengue fever will only make the situation worse, in terms of treatment costs, pressures on beds, medical staff, and the ambulance service.
• There will be an increase in the number of premature deaths, particularly in vulnerable populations, bearing in mind there is no acquired immunity to dengue in the UK.
• There will also be an economic cost in terms of working days lost and the knock-on impact on the economy through lost productivity.
• If current patterns of impact in the less developed world are repeated in the UK, it will be the less well-off who will be affected most by a dengue fever epidemic.

This is a disease that needs to be taken seriously by governments and populations across Europe, something that arguably didn’t happen in the early days of the global COVID-19 pandemic. So, the question is, what can we do to help prevent the spread of the virus and mitigate against its worst impacts?

Governments across Europe should be making contingency plans well in advance to deal with a potential dengue outbreak. This could also include some form of risk analysis identifying where the impact of a dengue outbreak would be most severe. It also makes sense for governments in Europe to learn from the experiences of health professionals and administrations in countries where dengue fever is endemic and to incorporate that information into detailed planning now.

Dengue Vaccines do exist. Dengvaxia is currently in use in the USA but only for children between the ages of 9 and 16, and only if they contract dengue. Qdenga is another vaccine that has been licensed for use in Europe. Both are effective in minimising the impact of the virus although both also are associated with side effects which can be unpleasant for some.

Governments including the UK government need to be putting in place now, plans to roll out mass vaccination programs should dengue fever become established in the UK:

• Governments should be encouraging increased funding for research into the treatment of patients with dengue fever, training of medical staff, and continued development of new vaccines.
• At the same time, it is important for authorities to continue to monitor the spatial spread of the Aedes group of mosquitoes to feed that information into government and for that information to be taken seriously.
• There also needs to be a public awareness campaign to educate the population not only on the nature of the infection but also ways to monitor the local environment and to look out for and destroy potential mosquito breeding sites.

Dengue Fever is a natural hazard, not as obvious perhaps as the various Atlantic storms we have experienced recently or the volcanic eruptions occurring in Iceland right now, but a hazard that requires urgent attention now, nonetheless. The COVID-19 pandemic showed that the UK has a sizable population that could be vulnerable to a new infection entering the country, and it also showed quite clearly what can happen when procedures to prevent or mitigate the hazard are not in place. If the UK is to avoid the major impacts that occurred as a result of the COVID-19 pandemic, then it needs to wake up to the threat now and not sleepwalk into the kind of disaster the country experienced in 2020/21.

The figure of 200,000 is an approximation arrived at by taking the number of current cases in Sri Lanka as a percentage of the total population and extrapolating the same percentage figure to the UK.

• Biology Factsheet 353. Mosquitoes vs. Mosquitoes: Curriculum Press
• Dengue on the rise in Sri Lanka (Geosrilanka.wordpress.com)
• Dengue will take off in Southern Europe, USA, and Africa: report from Reuters, October 2023