The Zurich team published their results and drug companies began searching for ways to achieve the targeted cancer therapy without using a potentially dangerous virus.

Two years later, Chinese businessman Kenny Yo was diagnosed with stomach cancer. With a personal fortune of $11 billion and a life expectancy of less than one year, Yo offered Zurich University Virology Department $250 million to use their quarantine facility for his own course of SNorK treatment. The department said that using an unlicensed treatment was unethical, and illegal under Swiss Law.

But the determined billionaire found a group of Hangzhou-based genetic scientists who were seeking money to start their own gene-editing business. Most details of the Zurich University SNorK project had been published in a scientific journal, and they could use off-the-shelf gene-editing technology costing less than $10,000 to make a copycat version of SNorK.

Yo retreated to his country home, sealed himself away from friends and family and began dosing himself with SNorK. The treatment was successful, but while Yo kept himself isolated, the conditions were nothing like as secure as the viral containment lab at the University of Zurich.

It is believed that the first people to contract SNorK were Yo’s cleaner, and two men who came to vacuum the septic tank at his country home. SNorK is highly contagious, but its symptoms are mild compared to regular norovirus and the SNorK outbreak went unnoticed. Most patients were not sick enough to go to a doctor, and those that did were assumed to have a minor stomach infection.

Norovirus thrives in cool temperatures (another name for it is ‘winter vomiting bug’) and as cold weather set in a typical winter outbreak of norovirus began in the area around Hangzhou. At first, everything seemed normal, but shortly after Christmas patients started showing serious symptoms.

Instead of lasting less than twenty-four hours, patients were often sick for a week or more and many weaker patients died through severe dehydration. Norovirus is extremely contagious. It is mainly passed by touch, particularly in public restrooms and food-preparation areas. This makes the virus prone to spreading in heavily populated environments such as schools, prisons, cruise ships and hospitals.

As the Zurich scientists had feared, SNorK and regular norovirus had swapped genes and formed a deadlier strain. The recombined synthetic norovirus – now commonly referred to as SNor – mixes the longevity of SNorK and the unpleasant gastric effects of regular norovirus. In the eight months since SNor was first detected, it has appeared in every country on Earth, and is estimated to have infected one billion people.

In most cases SNor causes three to seven days of painful vomiting and diarrhoea. Patients are advised to continually drink water, to stay away from others as much as possible and not to seek medical attention, because of the risk of bringing the virus into contact with people with other illnesses.