A storm is brewing in the Democratic Republic of CongoA country in central Africa with a population of 99 million. (DRC). Mpox - a contagious disease spread by human contact - is spreading more rapidly than ever before.

There have been more than 17,500 recorded cases in Africa so far this year, more than all of 2023. The virus has moved from the DRC to 12 neighbouring countries.¹ International travel could see it grow far further - on Thursday evening, Sweden announced the first case of the new variant outside of Africa.

On Tuesday, the World Health OrganisationThe United Nations agency responsible for global public health. (WHO) declared mpox a public health emergency. It released $1.5m (£1.2m) from its own funds and asked donors to provide $15m (£11.7m) more to aid response.

WHO outbreak leader Maria Van Kerkhove called for rapid action: "We do not want the world to sit and watch and wait. The time [to act] is now." The global risk is moderate. But the disease must be defeated before it can spread further.

Mpox is closely related to smallpoxA disease estimated to have killed 300 million people in the 20th Century..² It is caused by a virusA very small piece of material that causes disease. previously known as monkeypox, which was discovered after it broke out among lab monkeys in 1958. A human case was first recorded in 1970 in the DRC. There have since been outbreaks in several countries, including Nigeria, Britain and the United States.

The disease has a range of symptoms: fevers and chills, muscle aches and exhaustion, headaches and sore throats. But its most notable outward sign is a skin rash. Some sufferers develop lesionsAn area of abnormal tissue in the body, caused by injury or disease. over their whole body.  

Most patients recover. But it can prove fatal. There have been 460 recorded deaths this year so far in Africa.

Doctors believe this spread is due to Clade 1b, a mutantAn organism that is different to others in the same species due to genetic changes. variant that can spread through short contact, especially among young children. Jean Claude Udahemuka of the University of Rwanda claims: that it is "undoubtedly the most dangerous" strain so far.

All infectious diseases come from an interaction between our bodies and the environment. The mpox virus is endemicCommon to a particular place or community. to the dense, humid forests of central Africa.

The plagueA deadly disease that spreads between people. was spread by a bacteria that lives in fleas, which themselves live on rodents.³ Medieval Europe's rat-ridden cities provided the perfect breeding ground. Humans catch malariaA serious parasite infection transmitted by mosquito bites. It is one of the world's most lethal diseases. from female marsh mosquitos, which can develop the disease after living for a certain length of time.⁴ To do so they need warm temperatures and high rainfall.

Many scientists believe that our changing planet is making disease worse. As one paper in Nature declares: "Over half of known human pathogenicAble to cause disease. diseases can be aggravated by climate change."

Environmentalists have begun to use the term One Health to describe the connectedness between humans, other living things and the planet. Our actions affect other beings and they affect us.

Warmer winters and longer summers are causing insect-based diseases to flourish. Ticks, which can spread Lyme diseaseAll illness caused by bacteria-carrying tick bites., have begun to spread further north. The season in which they are active has become longer.

Changes in rain patterns and water temperature can affect the spread of waterborne diseases such as E. coli, which has recently been spotted in both the Thames and the Seine. And deforestation in tropical regions has increased the spread of vector-borneDiseases transmitted by animals. disease.⁵

Others think that the connection is not so clear. Climate change is complex and connected to many other processes, such as migration and urbanisation. It is difficult to identify a single cause for an outbreak.

Our ability to tackle disease has grown as technology develops. Modern medicine has allowed us to cure many once-deadly afflictions, from plague to scrofulaAn infection in the lymph nodes of your neck., typhoidA dangerous bacterial infection. to choleraA dangerous infection, still present in some parts of the world that is usually caught from drinking unclean water.. Many of these remedies would be difficult to achieve without exploiting - some would say abusing - the Earth's resources.⁶

Is our abuse of the planet to blame?

Yes: We reap what we sow. As temperatures rise, summers extend and forests fall, infectious diseases crop up in newly warmer locations. The links are obvious. To ignore it is a form of climate change denial.

No: PestilenceDeadly diseases that affect entire communities. featured in human history long before global warming and will exist after we are gone. Climate change offers a convenient excuse for some outbreaks. But the true picture is even darker. Disease is always with us.

Or... Blame is a strong word. There is almost certainly a relationship between our changing environment and the spread of illness. But the illnesses are often unwanted side effects of things done to improve lives. And cause and effect are rarely clear.

FOR YOUR SUMMER READING CHALLENGE CLUE GO TO STEP SIX IN THE SIX STEPS TO DISCOVERY BELOW.