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Tuesday, 11 December 2012

Invasive Pathogens and Infectious Diseases

Plenary Five: Emerging Pathogens in the Environment

Blog from Global Forum On Biotechnology - The Evolving Promise Of The Life Sciences

Invasive pathogens and infectious diseases have been with us through the ages from the bubonic plague to the yellow fever outbreak in the US to the more recent SARS and H1N1 swine flu pandemics. But with increasing global travel and trade, invasive pathogens are ever emerging and are ever more threatening.

The truth is that we don’t know what exists and we need to create models and policies to deal with those threats that we cannot prevent.

How can we translate emerging information into effective and pragmatic public policy? And how can it be done without limiting prosperity through trade and travel?

These were the questions posed by Professor David Ingram as the chair of Plenary Five: Emerging Pathogens in the Environment.

The first speaker was Professor Jan Semenza from the ECDC (European Centre for Disease Control). Professor Semenza began by giving the audience a bit of background about the ECDC. The ECDC was set up in the wake of the SARS pandemic when Europe realised that it couldn’t solely depend on the US’ CDC in the fight against infectious diseases. As a public health agency, the ECDC has a specific mandate covering infectious disease control, especially cross border infection potential. It monitors infectious diseases in Europe and all EU member states must report specific outbreaks and prevalence of certain conditions to ECDC. The ECDC is also tasked to give scientific advice in the wake of infectious disease situations.


Semenza stated that no one has a crystal ball to predict the future; no one can guess what could be coming in the way of infectious diseases. The ECDC try to look for the unanticipated diseases - what could be a threat to the public health infrastructure?

The ECDC worked on a foresight study which brought experts together to ask, “What can we predict about the future and can we identify key potential drivers?” The study developed possible scenarios and considered the fact that Europe is an infectious diseases ‘hotspot’ due to the vast cross border opportunities. They also looked at public health strategies and what public health actions can be taken. What more can be done to anticipate future disease outbreaks?

The study identified three main categories of drivers:

  • Global and environmental change – climate change, increasing travel and migration
  • Social and demographic change eg social inequality, human trafficking
  • Public health systems – surveillance, animal health, healthcare structures, research and development
The economic crisis was identified as a ‘super driver’. All the different drivers interact in a myriad of complicated scenarios and we must try to be as prepared as possible for each and every one.

Next up was Dr Penny Wilson from the UK’s Technology Strategy Board. Dr Wilson referred to the Foresight – The Detection and Identification of Infectious Disease project in the UK. Formed in the wake of the Foot and Mouth crisis, the project was set up to see how we can be better prepared for future infectious disease outbreaks.  The project reviewed potential future risks, evaluated future science and explored future capabilities and contexts.

Nine future threats were identified which included HIV, zoonoses and new diseases. It was found that the area that would make the most impact would be the area of point of care diagnostics. As a result, the Detection and identification of Infections Agents Innovation platform (DIIA) was set up as an investment into innovative research and development into diagnostic tests that will help to reduce the impact of infectious diseases on the population. Developments in this area will come from converging technologies (e.g. biomarker discovery, biosensors, novel chemistries, genomics, proteomics, sequencing technologies etc).

Diagnostics don’t always have to be the high tech solution and they range from a basic lateral flow device to the other end of the spectrum e.g. high-end mobile phone tech. There are currently many technologies that are on the verge of going to market.

The Technology Strategy Board has supported and is supporting many projects in preparation for threats from infectious diseases.

Dr Bethan Purse from the Centre for Ecology & Hydrology in Scotland was next to speak. There is an increasing emergence of vector-borne pathogens worldwide with huge impacts on livelihoods and economies. What are the challenges we face and what weapons do we have to battle against this?

How can we better understand and predict disease emergence? Statistical and biological models need to be better used.

How can we integrate this improved understanding into frameworks for risk communication and disease management? We need to use trait-based models of disease, factor in the ecosystem in disease management and put in policy relevant early warning frameworks.

She warned that we to need to be wary about linking disease emergence with climate change, stressing the need to have specific time based correlations e.g. in the case of Tick Borne Encephalitis in Eastern Europe. Socio-economic factors determined human exposure to the disease.

How does exposure to infection depend on how individuals use ecosystems? Looking at the case study of Malaria in Camargue; socio-economic surveys and agent-based models of people’s movements concluded that hunters were most exposed due to activity at sunset and the contact rate highest in populations close to rice fields.

Dr Purse went on to say that ecological understanding needs to be integrated into frameworks for risk communication and disease management e.g. in the case of Lyme Disease, influencing human behaviour was the best way to mitigate the disease.

So how do we improve the weapons in the battle against emerging disease? All the tools we have need to be linked in order to strengthen their effect. Modellers need to work with social scientists to gain a better understanding of human decisions with regards to exposure and environmental change.

The final speaker of the session was Dr Matthew Fisher from the Department of Infectious Diseases at Imperial College London. The topic for his presentation was Emerging Fungal Threats to Animal, Plant and Ecosystem Health. Using the cases of Batrachochytrium dendrobatidis (Bd) in frogs and Geomyces destructans (White nose syndrome) in bats, Dr Fisher explained that the threat appears to be widespread. Other examples included the Crayfish Plague and the current Ash Dieback problem in the UK. There is widespread consensus that fungi are causing more diseases than before.

Looking at data from ProMED, HealthMAP and species extinction catalogues by Web of Science, fungal alerts are increasing in relation to other pathogen taxa in both databases (animal and plant). Fungi comprise the highest threat for both animal (72% of extinctions) and plants (64% of extinctions) and this threat is increasing.

But why is this? Fungal disease dynamics predispose them to emergence and drive extinction processes. They are highly virulent and long-lived. They’re high generalist pathogens and they are ‘hopeful monsters’ – recombining, accelerating evolution and increasing potential for change.

Dr Fisher returned to the case of Bd in frogs. Revealing data from www.bd-maps.net and www.bd-maps.eu , we were shown a map of global Bd outbreaks and the dominance of spots all over the map really showed why Bd is the cause célèbre for mycotic outbreaks. The data were gathered, to an extent, by citizen science (build a website where people can contribute data and you get global coverage).

The Bd case study has shown that trade is forcing some of these infections in new environments. It’s also revealed that Bd’s genome is highly dynamic (let’s scan for genes that drive virulence?). The Bd case has clearly demonstrated the increasing risk that fungi pose to biodiversity, the wider ecosystem impact has not been adequately assessed and that the vectors and routes of introduction are not sufficiently understood.

But our borders are wide open to invading fungal threats. Do we have the political will to initiate the levels of quarantine that are necessary to prevent further invasions? No! Do we have the rapid diagnostics to test for fungal EIDs at borders? No! Do we know the full economic cost of emerging fungi? No!

And on that note, the presentations were over and it was time for a few questions from the audience. The first question asked, what I’m sure was on the mind of many in the room:”Is there anything positive coming out of this?” Professor Semenza responded by saying that there are pros and cons to every situation so it’s not just bad news. Dr Fisher went on to say climate change can dry out the environment and kill diseases (instead of just propagating them). In terms of the frogs, as it gets warmer, the fungus die (but so may the frogs). Dr Wilson said “Are we better prepared? We are getting there, but it all takes time. There is certainly good news, but we still have a long way to go.”

The final question was, “Are governments promising to buy better diagnostic tools? Are there any incentives for industry/technologists to improve things” Professor Semenza took the question and said that it’s a complicated issue and he’s not aware of any specific policy in place to incentivise development.

So it’s not entirely bad news but there are many known and unknown pathogens emerging in our midst which pose a threat to humans, animals and plants. We’re a long way off being completely prepared but the good news is that we are working on it.

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