Climate Action | Adaptation to climate change

Health

Climate change could have major impacts on public health in the future. Combined with other factors, it is likely that diseases previously found only in warm and humid regions of the world will become more common in Europe. The authorities in northern Italy are improving their efforts to counter rising threats of ‘vector-borne’ diseases – those spread by insects such as mosquitoes.

When an epidemic of Chikungunya virus hit the Ravenna province of Italy in the summer 2007, it was the first recorded outbreak of the disease on the European continent.

“It was a big surprise for us,” says Romeo Bellini, a medical entomologist and head of the Centro Agricoltura Ambiente “Giorgio Nicoli” (CAA) in North Italy, which has been involved in the monitoring and control of mosquitoes for over 20 years.

The species of mosquito that carries Chikungunya – the tiger mosquito (Aedes albopictus) – first arrived in Italy in the 1990s, says Bellini. However, prior to 2007, the virus had only spread in parts of East Africa, the Indian Ocean region and South-East Asia.

For disease control experts, it confirmed predictions that Chikungunya was able to survive in European climates. This means that other European areas where tiger mosquitoes are already present, including parts of southern French coastlines, Spain, southern Switzerland, Croatia, Albania and Greece could also be vulnerable.

Rising mosquito populations

Although Bellini believes that climate change was not a major factor in this particular outbreak, he states that it may play an increasingly important role in the spread of such vector-borne diseases in the future.

Many experts believe that predicted climatic changes, such as warmer and longer summers, milder winters or increased annual rainfall, are all factors that could enable the insects to expand their habitats. This brings greater potential to introduce diseases to areas where they did not previously exist.

“Data collected in laboratories show that higher temperatures will increase mosquito populations,” says Bellini. “However, in reality it is not that simple. We see large year-on-year fluctuations [in populations] and there are a number of factors combining together. Also relevant are many ecological changes and it is a complex and very dynamic situation.”

Ultimately, for experts such as Bellini, the causes of changes in mosquito populations are less important than finding effective ways to assess and detect the threats they pose as early as possible.

“We concentrate on how we can better monitor and predict seasonal dynamics in insect populations and vector-borne disease activity. Then we can make a risk estimation of virus threats and take adequate measures,” he says.

Changes in surveillance

The 2007 outbreak was a wake-up call in many ways, adds Bellini, focusing attention on how to improve monitoring systems for Aedes albopictus in the Emilia-Romagna region. “An outbreak like this has serious impacts on tourism and the country as a whole,” he says.

“We have realised that we need to pay greater attention to the risk to public health that mosquitoes pose,” he continues. “In the last few years we have become more and more concerned with risk assessment.”

The centre has drafted in the most advanced GIS (Geographic Information System) technology in its efforts to coordinate more effective monitoring and vector control activities. This should enable the detection of potential epidemic threats sooner than previously.

The first step is detailed annual mapping of mosquito breeding sites. These sites range from large areas of natural wetlands to small puddles in drains or sewers. Researchers take water samples so that they can classify and count mosquito larvae in each potential breeding site. Data such as the density and species of the mosquitoes found is then fed into a database which GIS and satellite navigation applications use to guide disinfection efforts to the correct locations.

“More accurate data enables better understanding and earlier detection, so we can have more effective and cost-beneficial control efforts,” says Bellini.

Systems such as this which enable authorities to monitor and react quicker to public health threats will become more important as climatic conditions change across Europe.