"We must be one step ahead"

Text: Annika Lund, first published in Swedish in the magazine Medicinsk Vetenskap no 2/2012

In the summer of 2003, a heat-wave swept across Europe. The heat claimed many lives; up to 70,000 people, mainly the elderly and those suffering from heart disease, were estimated to have died as a direct result.

"It was a wake-up call for our politicians. It was suddenly clear that we need to have a plan for how our health is being affected by the changing climate", says Dr. Elisabet Lindgren, who researches climate health at the Institute of Environmental Medicine at Karolinska Institutet**.

Recurrent heat-waves are to be expected in Europe – even in Sweden. We can also expect extreme rainfall events which can flush contaminants into our drinking and bathing water.

Emerging infectious diseases will also pose new challenges for public health.

Expected to spread

Along with other researchers, Elisabet Lindgren has analysed more than 30 infections that are expected to spread throughout Europe as a result of climate changes. The analysis was conducted at the request of the European Centre for Disease Prevention and Control (ECDC) and was recently published in the academic journal Science.

A risk assessment was conducted, weighing up the infections' association with climate change against their impact on society. More prevalent infections or more serious symptoms were considered as having a significant impact on society. Using these criteria, seven climate-related infections were highlighted: vibrio, leishmaniasis, chikungunya fever, Rift Valley fever, dengue fever, TBE and Lyme disease.

"These climate change-sensitive infectious diseases are considered to be especially significant threats to society, due to the lack of appropriate surveillance", says Professor Jan Semenza, the senior investigator on the research team and an employee at ECDC in Solna.

All these diseases, apart from vibrio, are spread via vectors, i.e. insects or other animals that can carry disease. One example is the invasive tiger mosquito; the insect is currently established in Italy, France and Switzerland and has even been found in greenhouses as far north as the Netherlands.

Domestic tiger mosquitos

In 2007, Italy had an outbreak of chikungunya fever. It started with one man being infected abroad; when he returned to Italy, he was bitten by local tiger mosquitos which then infected over 200 other people, resulting in one death. Europeans have also contracted dengue fever at home, as a result of it being spread locally in France and Croatia by domestic tiger mosquitos.

In these cases, the authorities concerned were well aware that there was an abundance of tiger mosquitos in the area which made it possible to stop the spread of the infection by combating the mosquitos and isolating those who had been infected. Dr. Lindgren and her colleagues are now recommending vector surveillance to monitor the mosquitoes.

"We want to introduce a monitoring system, an obligatory control of the presence of certain vectors in Europe. This would allow us to get a better picture of where the risk areas are and to follow the development over time", she says.

Well-established vector

One vector that is already well-established throughout Europe is the tick. At the end of this century, they are expected to be thriving throughout almost all of Sweden, except for the mountainous regions in the north. This means that a dramatic increase in the number of cases of Lyme disease can be expected.

In order to better control the spread of the seven highlighted risk diseases, researchers suggest that a duty to report them be implemented across Europe. This, combined with vector control measures, should provide a very good picture of where outbreaks can be expected. This will allow local information and health care measures to be implemented quickly, in the event of an outbreak of the disease.

"We need to be one step ahead", says Dr. Lindgren.

The researchers' recommendations are currently being discussed by the European Commission.

**Note August 2021: Elisabet Lindgren is no longer a researcher at KI