As Mers hits the headlines, we have to ask: is this a golden age for pathogens?

It’s not just people who are at risk from the 21st-century way of life. Plants are suffering, too.

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With billions of human beings living in close proximity – and with so many of them travelling in mass transport all over the globe so frequently – these are good times for pathogens.

South Korea and China are trying to halt the spread of Middle East respiratory syndrome (Mers). The problem arose after a South Korean businessman picked up the pathogen on a trip to the Middle East and returned home. The man is known to have infected a couple of dozen people.

Worryingly, Mers was not known to be a particularly contagious disease. That is because the virus sits in the lower respiratory tract, making it difficult to pass on. It may be that the South Korean cases have arisen from a new strain that is more virulent than those encountered before. To investigate this possibility, researchers are sequencing the pathogen’s genome.

The Chinese government is particularly keen to get the outbreak controlled, as it has already arrived on the Chinese mainland. This occurred when a man who visited infected relatives at a hospital in Seoul flew to Hong Kong, then completed his journey to Guangdong Province by bus. The Chinese authorities have quarantined more than 80 people who might have been infected by the traveller.

It’s not just people who are at risk from the 21st-century way of life. Plants are suffering, too. Italian olive trees, for instance, are being plagued by the Xylella fastidiosa bacterium, a state of affairs so catastrophic that claims and counterclaims regarding the cause have led to a police investigation.

Xylella was first identified in Europe in 2013 after years of endemic status in South America, California and Costa Rica. It affects different plants in different ways, but in Puglia it has brought widespread withering and death to the region’s olive groves.

Local people have suggested that Italy’s agricultural scientists could be to blame. As a result, regional police have confiscated computers from research institutes and questioned several scientists about their practices. Even the country’s ministry of agriculture has had papers seized.

The chief concern is over whether the scientists imported the Xylella strain. Back in 2010, researchers brought in a sample of the Californian bacterium to carry out training for local agriculturalists. Their accusers claim that this was the source of the plague and that the scientists involved should be prosecuted. However, their science will almost certainly save them from a protracted investigation. Genetic analysis of the infected plants shows that the bacterium is identical to those found in ornamental coffee plants imported from Costa Rica.

Here’s another problem: consumer gardening. Researchers have traced the UK’s ash dieback problems to a similar desire for exotic ornamental plants. As with Xylella, the fungus involved in ash dieback peacefully coexists on many plants and is only a threat to some. Because of this, it can live undetected on plants being fast-grown for export in places such as China or southern Europe, then cause devastation when introduced to suburban gardens. Evolution also allows it to co-opt genetic resources available in the new environment, creating a pathogen never seen before.

We are unwittingly accelerating such developments. According to a paper by French researchers in the May issue of Annals of Forest Science, we are living in times when new diseases are occurring at an “unprecedented rate” because of human factors. They were writing about tree pathogens but the basics of biology dictate that it is true of all kinds: 21st-century life is convenient not only for human beings. 

Michael Brooks holds a PhD in quantum physics. His most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article appears in the 11 June 2015 issue of the New Statesman, Who owns the future?