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The idea of ‘new’ infectious diseases seems absurd – shouldn’t we have discovered and eradicated all of them by now? The Zika virus is proof that’s not the case. According to the World Health Organisation (WHO) up to four million people could contract the virus in 2016. It might seem like this rapidly spreading mosquito-borne virus appeared out of nowhere, but its existence was known as early as 1947, when it was found in Uganda. But why has it re-emerged now? And if it’s existed all that time, why isn’t there a vaccine? Deakin University Professor Soren Alexandersen, Director of the Geelong Centre for Emerging Infectious Diseases (GCEID), which opened in October 2015, has the answers.
Where do infectious diseases come from?
‘Infectious diseases come from animals and spread to people or spread geographically,’ Prof. Alexandersen explains. He says that when a disease is isolated or occurs where people aren’t susceptible, not too much damage is done. But when it moves to new territories through travelling people or via animals, it has the potential to spread faster and wider through vulnerable people such as pregnant women or the elderly. He says new infectious diseases travel because humans travel internationally and live closely with animals. In the case of Zika, medical professionals believed it was isolated and therefore wasn’t likely to cause harm. ‘We had 65 years and now we need answers in a matter of weeks,’ Prof. Alexandersen says.
What’s being done to prevent infectious diseases?
Prof. Alexandersen says a key to stopping the spread of infectious diseases is to get to them early. ‘We need to look at animal disease and ecology. If you can get to viruses before they get to domestic animals, you can stop them from getting to humans,’ he says. In order to find a solution, a sample of the pathogen – the biological agent that can produce the disease – is required. Researchers have a good idea of which diseases may eventually cause problems and the GCEID will soon facilitate and coordinate pilot studies that help them to put preventative measures in place. They will also look at pathogens in animals, as well as humans, to increase awareness of worrying pathogens well before humans are in danger. ‘The way it’s done now, we wait until there’s a problem with humans and then react,’ he points out. His team will now work to ‘be nimble and act quickly.’
'We need to look at animal disease and ecology. If you can get to viruses before they get to domestic animals, you can stop them from getting to humans.'
Professor Soren Alexandersen,
Some infectious diseases have been eradicated. Prof. Alexandersen highlights the success in eradicating smallpox and rinderpest, a cattle plague that struck cows around the world. However, it’s not possible to know about the potential for disease in every microorganism. ‘You cannot get rid of all of them because there are hundreds and thousands of pathogens.’ Prof. Alexandersen says. In addition, there’s no guarantee that a disease has been completely eradicated. ‘International organisations will go out and declare a disease eradicated, but maybe it’s in a remote location and hasn’t been seen.’ This is why diseases can re-emerge some time later. However, Prof. Alexandersen and his team are working to grow their understanding of ‘virus families’ that have similar attributes so that they can be better equipped to manage new and re-emerging diseases.
Australians have contracted the Zika virus, and the WHO has declared the spread of the virus a public emergency, but there’s no need to panic in Australia. WHO’s advice for prevention applies mostly to pregnant women and people travelling to Africa, the Americas, Asia and the Pacific. According to WHO, the best prevention for travellers is to avoid mosquito bites. Use insect repellent, sleep under mosquito nets and remove any mosquito breeding sites that store water such as buckets and pots.
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