Last year, infectious disease experts warned of a shadowy killer that was preparing to strike - Disease X, an as yet unidentified pathogen that could cause a global pandemic and kill millions.
The warning from the World Health Organization (WHO) made headlines around the world and raised the profile of the threat posed by potentially deadly infectious diseases.
Disease X is what military planners call a “known unknown” and by including it on its list of the most dangerous pathogens, the WHO signaled that epidemics are inherently unpredictable and that surveillance was vital.
Now, a team of UK virus hunters has revealed how the country has faced down its own Disease X scenario on multiple occasions in recent years.
At the launch of its first ever strategy on infectious diseases on Wednesday, Public Health England (PHE) revealed that 12 "novel" infections and viruses have been identified in the UK in the last 10 years.
The diseases include tularemia, a life-threatening infection found in the US that is spread by rabbits and rodents; Crimean-Congo haemmorhagic fever, an Ebola-type illness that is prevalent in Africa and is spread by ticks; and monkeypox, a rare virus which is similar to human smallpox, three cases of which were identified in the UK last year.
While the majority of these outbreaks involved just one or two cases, there were 315 UK cases of Zika, a mosquito-borne virus that spread through South America between 2015 and 2016, leading to birth defects in babies born to mothers infected with the disease. The majority were associated with travel to affected countries while one was thought to have been sexually transmitted.
There have also been 250 cases of candida auris, a "shape shifting” fungal infection first identified in Japan which is thought to have killed eight patients in UK hospitals over recent years.
While all the outbreaks were successfully contained, they highlight how the threat from infectious diseases is changing. Ancient scourges such as tuberculosis are no longer a threat while diseases that have been brought to the UK by international travel are on the rise.
The threat of climate change also means we are more likely to "witness a global pandemic in the coming years", PHE warned.
Invoking the threat of Disease X, Professor Sharon Peacock, director of the national infection service, said: “Infectious diseases are evolving and we must continue to innovate and strengthen the science that keeps us safe - whether that’s whole genome sequencing to rapidly contain outbreaks of known infections or enhanced surveillance and preparedness for when an unknown disease strikes.”
One surveillance strategy employed by PHE virus hunters is scouring the internet for rumours of new diseases and unusual incidents. They monitor official sources such as reports from ministries of health and the WHO but they also constantly scan news websites and social media.
The scientists picked up “chatter” about an undiagnosed outbreak of fever and rash in Brazil in early 2015 - months before the Zika outbreak was officially confirmed in May 2015.
At the same time as new diseases are emerging the antibiotics doctors desperately rely on to keep epidemics at bay are losing their power.
PHE has identified 19 new superbugs in the last 10 years, the majority of which could not be treated with even last resort antibiotics such as colistin or carbapenems. Instead, doctors had to rely on experimental treatments and cocktails of different drugs.
In the last year three cases of “super gonorrhea” have also been identified in the UK - the first, described by PHE as the world’s worst ever case, was picked up in south east Asia, while the other two cases were acquired in the UK, prompting concerns over further spread of the disease.
None of the cases responded to the usual antibiotics and the patients had to be admitted to hospital and put on a drip.
Professor Chris Whitty, chief scientific adviser at the Department of Health, said: “Despite our arsenal of vaccines and antimicrobials infectious disease remains a real threat to public health. We are constantly faced with new threats and antimicrobial resistance is growing.”
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