From Ebola to Zika, to SARS and so on, infectious diseases periodically populate our headlines; it seems that tackling them will forever be on the global agenda. But how can we deal with them? Are some strategies better than others? And what is the real risk? I spoke to Professor David Heymann, head of the Centre on Global Health Security and Chatham House and chairman of Public Health England, to talk about the challenges of global health today.

Heymann proposes that we should look at health security from two perspectives: “both the collective, which means protection against cross-border events such as epidemics and pandemics,” and the individual, through “access to medicines and vaccines and other health interventions, which is really a universal health coverage activity.” This view, he suggests, is because during an outbreak both the individual person and the general population must be considered: “You have to take care of the patients; you have to isolate them. You need to have a good health facility so you don’t spread it, as well as having detection and response systems in the field. So it all fits together in a global health security agenda.”

“It is health facilities, improper infection control, that drive outbreaks such as Ebola”

Professor David Heymann

The horror of the 2014 Ebola epidemic is still clearly remembered across the globe. This wasn’t, however, our first sighting of the disease. Heymann expresses that “since the first outbreak in 1976, when I was present at the epidemiological investigation with the Centers for Disease Control and Prevention (CDC/Atlanta), where I was working at the time, and from studies afterwards, it became clear that Ebola did not usually become an outbreak. In fact, in the first outbreak transmission was amplified by the use of unsterilized needles and syringes...it was mainly a hospital outbreak.” The same story unfolded in the subsequent epidemics, including those in the Democratic Republic of Congo and other parts of Africa: hospital environments with sub-standard infections control amplified the transmission of the disease. Heymann explains that “it is health facilities and improper infection control that drive outbreaks such as Ebola, first of all among health-workers, then out into the communities. These outbreaks would not occur if transmission were not amplified in hospitals with poor infection control.” Strengthening hospital infection control seems easy in theory, but in practice, it a serious challenge. To avoid “supporting hospitals to strengthen infection control is very difficult. It’s very difficult to change behaviour and to get people to change their behaviour in a way that prevents infections spreading in hospitals.”

Our world is full of debilitating endemic diseases and it has long been the aspiration of global health to eradicate them. “Eradication is very useful” Heymann comments, “not only because it gets rid of the disease, but because it also gets rid of the need to use antimicrobial drugs to treat these infections. This then decreases the risk of antimicrobial resistance.” Such an aspiration was achieved in 1980 by the complete eradication of smallpox, an effort led by the World Health Organisation (WHO). “For smallpox, clearly eradication was a good use of resources. The whole programme costs about $600 million. It was a very easy strategy to follow and was very cost effective. When the US looked back at their investment in smallpox eradication globally, they determined in 1983 that they were saving their investment every 30 days by not having to vaccinate their populations or deal with the side effects from the vaccines.” At the WHO, where Heymann was once the representative of the director-general for polio eradication, an effort is trying to emulate smallpox’s success. However, he warns that “polio has been a different story. Today it’s cost over $15 billion and will probably cost $20 billion before it’s finished. But still, in today’s terms, that’s a great investment and it’s one that will get rid of the disease that causes paralysis.”

“I think that Dr Tedros is on the way to a very successful term because he understands political issues”

Professor David Heymann

In July this year, Dr Tedros Adhanom Ghebreyesus took over from Dr Margret Chan as the director-general of the WHO, becoming arguably the most important figure in global health. Heymann seems optimistic about the future of this eminent institution:“I think he’s got his priorities right. One of his priorities is universal health coverage, and the second is to help countries develop their capacity to deal with disease outbreaks where they occur.” Heymann acknowledges that public health is not just about people and disease, but also about the surrounding halo of politics, adding that “I think Dr Tedros is on the way to a very successful term because he understands political issues. He’s been a politician himself and he understands health issues. Hopefully he will be able to succeed in bringing developing countries along with his agenda.”

So what does the future of global health look like? Everyone talks about the ‘Big One,’ a disease so transmissible and virulent that it exterminates the majority of our world. I asked Heymann what he reckons this will look like: “What the ‘Big One’ might be in the future is impossible to say. We just don’t have a way of predicting.” He suggests that these are “Swiss cheese events, as described by James Reason in the early 1990s. When you have four pieces of Swiss cheese with holes and you want to pass a pencil through those four pieces, you have to line up the four holes. In public heath those holes are risk factors and when risk factors align in such a way that leads to an event of public health panic.” These risk factors are however frustratingly elusive and whilst a lot can be done to minimize the risks, such as “good hospital infection control, good sanitation among animals, and many other interventions to decrease risk”, we can’t completely eliminate the risks.

Furthermore, these ‘Big Ones’ are not just some future speculation but also a present threat. “Certainly some of the ‘Big Ones’ are already here. We know that antimicrobial resistance is occurring. It’s increasing.”, Heymann explains. Another is influenza, which has the potential to wreak extreme havoc, much like it did in the 1918 Spanish flu epidemic. This time, however, Heymann suggests we will be armed with a new weapon: “Hopefully there will be a vaccine by that time. We know that there are about eighteen different flu strains in waterfowl that cause a risk to humans. If a vaccine could be made that would neutralize those eighteen strains and provide long-lasting immunity in humans, it would prevent outbreaks of influenza in the future. We don’t have that holy grail of vaccines yet so what we need to do is have good surveillance and good response mechanisms in place.” We need not fear the likes of Ebola and many other outbreaks if health facilities and health workers understand and apply good infection control measures but, “if these pathogens get into hospitals where there is very weak infection control, outbreaks will occur.”

Dealing with infectious disease will always remain an uphill struggle, with the next deadly pathogen always on the horizon. Yet, combining our knowledge of their evolution and molecular biology with an understanding of how people interact with disease, both on a personal and general level, will help to minimize the devastation they cause.