It was an incredible experience with a stellar lineup of panel experts who engaged in the best discussion I heard all weekend. And I figured that I needed a whole post here to really do it justice. So you’ll be reading about why epidemics are so dangerous to modern medicine, how we can deal with them, animal reservoirs for disease, and even bioterrorism!
The session started with an overview of some of the major epidemics and diseases from history, which I’ll briefly summarise for you:
- Also known as the Black Death
- It killed 60% of Europe’s population
- Between 75-200 million total deaths (1340-1770)
- Spread along trade routes
- It’s still around today
- Caused 50 million deaths
- Major impact from 1918-1920 due to travel after WW1 along railroads and ships
- 1900-2000 mainly
- Paralysed hundreds and thousands of children every year
- Still active in areas where there is conflict and little access to vaccination
- Other polio-like diseases are active today even in countries like Australia
What’s interesting is that more than half of human diseases are from animals and many arose with the rise in agriculture in early history. In fact, one of the panelists noted that any time that society changes the way we live (in terms of our relationship with animals, environment or other major areas of life), new diseases arise.
But going back to the point about animals, many modern diseases have animal reservoirs, or animal species that the disease infects so that it maintains having hosts even when it can’t prey on humans at that time (for example, if a population is vaccinated, or dies out completely, the disease retreats to animal hosts). In fact, measles began as a cattle disease (however it no longer infects cattle due to the abundance of human hosts). HIV also arose first in chimpanzees and now only infects humans.
Bats are reservoirs for several serious diseases, including SARS, Ebola, types of rabies. This means we would struggle to ever eradicate these diseases because they can ‘stick around’ in the animals they infect. In the case of SARS, it wasn’t traced to bat carriers for some time. In fact, in China where it arose, people would eat bats and spread the disease this way. MERS, which is similar to SARS, is a middle-eastern disease and infects camels instead of bats.
While not directly an animal reservoir, mosquitoes also act as part of the malaria life cycle and have been for as long as recorded history. Malaria itself is responsible for between 150-300 million deaths in the 20th century alone. However, it stands to reason that getting rid of the mosquitoes, or protecting people from their bites, will help prevent the spread of malaria, and it has done so very effectively in many countries.
This is where the session got really interesting. With today’s biotechnologies, we can create viruses from scratch (biosynthesis) or modify existing viruses, both often employing the use of the recently-developed CRISPR-Cas9.
CRISPR tools are so powerful that a group engineered a smallpox virus that was resistant to vaccination (by accident, too!). Not only that, but they managed it with a budget of only $100,000. And then they went and published their results online. So many people can see exactly the methods they used and could probably replicate the results without too much trouble. And voila, bioterrorist play-time!
The story gets worse from here. Due to fairly high levels of immune suppressing drugs, about 17% of Sydney’s population and 19% of New York’s are immune-compromised. So we have a deadly virus, no vaccine, and immune-compromised people to go infect everyone.
You’d hope that we have a grand plan to stop it happening. But realistically, we don’t really. Remember how the results of these virus modifications are published online? The panelists likened it to writing a paper on how to hack a bank account, and then hoping that no-one will!
Researchers and public health experts are working towards how we’d deal with such an outbreak. We’ve learnt from recent epidemics, such as Ebola in 2014, that we are highly unprepared to deal with such massive-scale outbreaks. But the Ebola epidemic is still being intensely studied, as people are working to understand how we can deal better with a future epidemic of any kind, learning from our mistakes, and preparing for the future!