We Scots are well accustomed to the plague of midges that can often blight our enjoyment of summer. Now we may have to adjust to a much more serious threat. The climate crisis has emerged as a critical factor in the spread of deadly infectious diseases, posing significant health risks to global populations. Rising temperatures, changing rainfall patterns, and extreme weather events driven by climate change have created ideal conditions for the proliferation and transmission of infectious organisms that cause disease in humans, including viruses, bacteria, and parasites. 

There is even a risk that malaria could soon be a disease hazard in Scotland. Researchers at Glasgow University have been awarded a £1.25 million grant to investigate how climate change could increase the risk of the mosquito-borne disease in this country. Their 3-year research programme in collaboration with the UK Health Security Agency (UKHSA) and UK Centre for Ecology & Hydrology, will examine the menace of mosquito-borne pathogens emerging in Scotland for the first time, because of changes in our weather patterns. Malaria was endemic in America until the 1950s but was considered eliminated from the country by 1951. Now, the first cases of homegrown malaria in years have been reported in Texas, Florida and Maryland. Its re-emergence has been blamed on climate change. It is feared the same thing may happen here.

The Westminster government’s Department for Environment, Food and Rural Affairs (Defra) has launched a £7 million research package that will also investigate diseases caused by ticks, fleas and lice, which are thriving in the increasingly warm and wet conditions in Scotland. It is feared that as temperatures rise, major changes occur, and disease can ensue. Following the coronavirus pandemic that took 10,000 lives in Scotland, the dual challenge posed by climate change and the spread of infectious diseases is of great concern. 

Globally, the impact of climate change on the behaviour of animals is evident. As temperatures rise, the thick ice in the Arctic is melting and minke, bottlenose, fin and sperm whales are heading north for the first time, just as grizzly bears, white-tailed deer, coyotes and other animals and birds head south. New types of beetle have headed northwards in the warmer conditions, causing devastation to Siberian forests, while new ticks have caused problems with Alaskan mammals and new insects are plaguing humans in northern Norway. Deadly and debilitating diseases are now killing reindeer in Scandinavia and Russia, musk oxen in Arctic Canada, and polar bears and seals off the coast of Alaska, where temperatures have risen by 4 degrees centigrade in the past 60 years. Strange new pests have appeared on maize crops in Malawi and a new bacteria has caused the fruit of lemon trees to shrivel in Florida. 

The World Health Organization (WHO) says that despite the Covid-19 pandemic, climate change may now become the defining global threat to public health of the 21st century. Human illnesses caused by parasites, viruses and bacteria that are transmitted by mosquitoes, ticks and other vectors in warmer and wetter environments, spread infections like malaria, dengue fever, Zika virus and Lyme disease beyond their traditional geographic boundaries, to regions that were previously unaffected. 

At the same time, wildlife hosts, like the species of bat that many claim was the origin of Covid-19, are affected by rising temperatures and extreme weather events, displacing them to new areas, exacerbating the risk of transmission of diseases like Sars and Ebola from animals to humans. Increased rain can cause flooding and, as we’ve seen on the recent UK news, this can lead to the overflow of sewage systems, contaminating rivers and freshwater sources with human faeces, spreading water-borne diseases like cholera and cryptosporidiosis, a particularly nasty illness that causes watery diarrhoea and stomach pains.

According to the WHO, Dengue fever, which can cause a high fever, headache, vomiting and muscle and joint pains, will become a major threat in southern Europe, the southern United States and new, previously unaffected parts of Africa this decade, as warmer temperatures create the ideal conditions for mosquitoes that carry the infection to spread. The illness has long been a scourge in much of Asia and Latin America, causing an estimated 20,000 deaths every year. But rates of the disease have already risen eight-fold globally since 2000, driven largely by climate change as well as the increased movement of people and urbanization.

Meanwhile, those families planning hill-walks and spring or summer picnics in Scotland, may be wise to wear clothing that covers their arms and legs, to protect them from tick bites that can cause Lyme disease. Researchers predict that the rise in global temperatures will increase the risk of coming into contact with ticks. The Highlands and Tayside are thought to be particularly impacted, although there are areas of forestry and grassland in many parts of Scotland where infected ticks can be found. Lyme disease can cause joint and muscle pains, abnormal tiredness, persistent headaches and palpitations, with long-term problems sometimes associated with the tick-borne infection. The tick season is starting earlier and with more active ticks, this means that the number of tick bites is going up and with it, the tick-borne diseases. Anyone finding a tick attached to their skin should remove it carefully with tweezers as quickly as possible.

Extreme weather events are also a risk to health. The increasing prevalence of wildfires, caused by prolonged droughts and higher temperatures, can release dust particles and toxic pollutants into the air, increasing the risk of respiratory infections. The prolonged warm, dry and windy weather last summer caused a wildfire near Cannich in the Highlands, that burned an area of more than 30 square miles, with plumes of smoke that were detected from space by Nasa satellites. Firefighters said it was the largest wildfire ever recorded in the UK.

António Guterres, the United Nations Secretary-General told the COP 27 Climate Change Summit in Egypt that: “Our planet is fast approaching tipping points that will make climate chaos irreversible. We are on a highway to climate hell with our foot on the accelerator.” As we reflect on his words, we may yet come to realise that the Scottish midge is the least of our problems.