In Australia, urbanisation is bringing animals and diseases closer to home

This little guy could give you leptospirosis, toxoplasmosis, hantavirus infection, or the plague. Image: Getty.

Our world is becoming increasingly urbanised. In 1950, just 30 per cent of the world’s population lived in urban areas. This number is now over 50 per cent and rising. By 2050, two-thirds of the world’s population are expected to be urban dwellers. Although much of this growth will occur in developing regions, northern Australian cities are likely to see significant expansion.

The successful growth of cities will undoubtedly be critical to the economic health of Australia and the surrounding region. However, the increasing size and density of human populations are creating challenges for human health. A report published this week by Australia's national science agency CSIRO, Australia’s Biosecurity Future: Preparing for Future Biological Challenges, highlights the biosecurity risk of urbanisation as cities become hotspots for new and emerging infectious diseases.

Animal hosts

The number of emerging infectious diseases that infect people has more than tripled since the 1940s. Around two-thirds of these are zoonotic, which means that they have spilled over into human populations from animals. The number of emerging diseases is likely to continue to increase, driven by the globalisation of travel and trade, climate change and, of course, urbanisation.

Urbanisation modifies the environment rapidly and permanently, creating irreversible changes in biodiversity. Animal species that can adapt to disturbed or fragmented environments (urban adapters) or thrive when living closely with people (urban exploiters) will prosper in cities. But those that cannot adapt (urban avoiders) may die out. This process contributes to the reduced biodiversity seen in urban environments.

In Australia, urban adaptors include familiar species such as the noisy miner bird and the common brushtail possum; urban exploiters are often invasive species, such as rats and pigeons.

The high prevalence of urban adapters/exploiters in city environments means people may be at risk from the diseases they carry. Possums have already been identified as potential sources of zoonotic bacteria in drinking water in Australia, while rats have been associated with many zoonotic diseases, including leptospirosis, toxoplasmosis, the plague and hantavirus infection.

Insects, such as mosquitoes, also differ in their ability to colonise urban environments. Mosquitoes that breed in small amounts of standing water and prefer to feed on humans are often abundant in urban environments. They have been instrumental in the emergence and spread of viruses like dengue and Chikungunya.

A warming climate is predicted to increase the geographic range of some of these urbanised mosquitoes. Growing cities will increase the number of people at risk from the diseases they carry.

Animal-to-human transmission

Why some diseases spill over from animal to human populations while others do not depends on many factors, including the genetic, cellular and behavioural characteristics of the pathogen, animal and human host. But, although scientists are still trying to unravel the complexity of this process, we do know that the frequency of contact between animal and human populations is a significant contributor to the probability that cross-species transmission occurs.

Processes such as deforestation and urbanisation can change the way human and animal populations interact. Land-use changes such as these have been associated with the emergence of many significant zoonotic diseases, including dengue, malaria, severe acute respiratory syndrome (SARS) and Ebola.

Mosquitos adapt easily to urban environments, preferring to stick close to hubs of human activity where there is plenty to eat. James Gathany/AAP

Although we tend to focus on pathogens that have successfully jumped species to transmit and cause disease in a new host (such as dengue and SARS viruses), most cross-species transmission events go no further than the first infected individual. In these cases, which include hantavirus and rabies virus infection, people are dead-end hosts.

It is not yet clear why some zoonotic pathogens are able to cause sustained human disease, while others are never transmitted between people. We need to unravel the complex interactions between pathogens, their hosts and the environment to begin to predict which diseases carried by animals pose the greatest threat to human health in an increasingly urbanised world.

Reducing the risks

Zoonotic disease outbreaks place significant burdens on public health systems, as well as on local and global economies. Despite the relatively localised scale of the current Ebola outbreak, the World Bank is forecasting costs as high as US$33 billion by the end of 2015, a number approaching the estimated US$40 billion price tag of the SARS epidemic.

Given the extraordinary costs associated with outbreak response and control, it is clear we need to focus on prevention and surveillance to reduce the incidence of emerging infectious diseases in the future.

Despite the challenges of an increasingly urbanised world, the concentration of people in cities also provides opportunities to reduce and control new and emerging infectious diseases. Compared with rural areas, the centralisation of money, power and knowledge can greatly improve surveillance and intervention measures in cities. This includes increasing access to clean drinking water, improved sanitation and urban flood reduction.

Good hygiene practices can decrease the spread of infectious diseases. Brandon Otto/ Flickr, CC BY-NC

City dwellers also often have greater access to mass media than people in many rural areas. This provides a platform for public health campaigns aimed at increasing awareness of behaviours that reduce the risk of acquiring infectious diseases. These include the importance of vaccination, hand-washing, insecticide use and waste management, among others.

Taking steps to improve urban disease surveillance, developing effective prevention measures and initiating appropriate education campaigns will allow us to significantly reduce the impact of emerging infectious diseases.The Conversation

Kurt Zuelke is a director, and Cadhla Firth a research scientist, at the Commonwealth Scientific & Industrial Research Organisation (CSIRO), the national science agency of Australia.

The authors do not work for, consult to, own shares in or receive funding from any company or organisation that would benefit from this article. They also have no relevant affiliations.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

It’s not all cool bridges and very real concerns: In defence of Teesside

Just one of the many interesting bridges you’ll find in Teesside. Image: Stephen Jorgensen-Murray.

The latest entry in our ‘In Defence Of’ series...

I have to start this with a disclaimer: I’m not writing this from anywhere in Teesside. I’m writing this from Germany, where I live and work. Some of you may remember being told by Norman Tebbit, that instead of complaining that we can’t find jobs, we should get on our bikes (or, more recently, by IDS to get on a bus), and I did. I’m paid well here, to do a job that doesn’t really exist in Teesside. And yet, every time I go home to visit my family, I almost wish I’d stayed.

This isn’t going to be a very straightforward take – I’m hoping to pay my respects to Stockton, Middlesbrough and Hartlepool as well as my native Billingham – but Teesside isn’t a very straightforward place. What county is it in? Cleveland, Stockton-on-Tees, Durham or North Yorkshire depending on how old you are and where you’re standing. I always had great fun ordering online and trying to guess which of the unfamiliar options on the dropdown menu would get my parcel to me.

But regardless of where you draw the lines, Teesside is still there.

Our accent is similarly hard to pin down: Geordie, Mackem, Yorkshire, even Scouse, depending on who’s imitating us. I’ve been pegged as Irish, American and South African by determined people in the past. Our slang is stolen from Scotland, Northumberland, Newcastle and Yorkshire, and, not satisfied, some words are purely our own. Hoy, shan, howay, dinner nanny. We have as many words for classless people as the Romans did for murder.

But regardless of how it sounds to you, Teesside still talks.


On a map of the UK, Teesside sits as an isolated blob of civilisation between the Dales and the sea. Half-urban, half-rural, half-seaside, half-inland, half industrial estate and half nature reserve. A Labour heartland with a Tory mayor. Places that sprang up fully formed in the ICI rush of the 1950s, but that still have Viking place names.

We’ve been portrayed in fiction by Richard Milward, in song by Maximo Park, in statistics by Lady Florence Bell and in cinema by Sir Ridley Scott (our chemical works and power plants inspired the look of Blade Runner). More recently, we’re being portrayed in documentary in The Mighty Redcar, and in the media as an area of left-behind, white working class racists who all voted Leave. But while most of the area is whiter than the average, Middlesbrough mirrors the UK average for racial diversity and has been assigned to resettle more refugees than any other town in the UK – and more than its cut-back council can look after.

And when you look at the numbers, the proportion of the population of Teesside who voted to leave the EU is much less than many other areas. (And yes, of course I voted Remain from my now slightly more precarious home in Frankfurt, joining 100,000 other Teesside Remainers.)

We’re pitied for the loss of the Teesside steelworks and derided for blaming the EU for it (when of course it was our own government’s sabotaging of EU attempts to block Chinese steel dumping that drove that knife in). Even the people who profess to be on our side take our angry, uneducated racism as fact, baking it into the premises of their arguments, which consist of addressing our “racist but real concerns”, and how to reach us.

But whether you understand us or not, whether you miss the point or not, we’ll continue to exist, long after we’ve been forgotten again.

Billingham town centre. One of the first pedestrianised town centres in the UK. Image: Stephen Jorgensen-Murray.

Still, while we’re in the spotlight, why not see what we have to offer? Come to see our rather wonderful collection of interesting bridges. See where the first public steam train ran, from Stockton to Darlington. Visit Mima, the modern art gallery in Middlesbrough and the 1960s utopia of Billingham’s pedestrianised town centre. Feel slightly uncomfortable around all the things that are named for Captain Cook (though the replica of the Endeavour at Stockton riverside is impressive regardless on your thoughts on its captain – and it’s the best you’ll see until they work out whether they’ve found the real one yet). Wander Middlesbrough’s thriving student/hipster district on Linthorpe RoadD – despite being a punchline during my youth, Teesside University has become a respected institution. Visit Billingham’s Folklore Festival in August, where as schoolchildren we’d watch troupes of folk dancers from across the world open-mouthed, and get their autographs afterwards as though they were celebrities.

Fried chicken, white sauce and cheese make the Teesside parmo. Perfect. Image: Stephen Jorgensen-Murray.

Try a parmo. Try the Billingham Catholic Club’s real ale, and stay for the bingo, which is called by a man with the most acrobatic mental arithmetic skills I’ve ever seen. Try a lemon top ice cream from Pacitto’s in Redcar and wonder why no one else has ever done this before. Lemon sorbet and vanilla ice cream! Together at last!

While you’re at the beach, take a ride on the Saltburn Cliff Lift, the oldest operating water-balance cliff lift in the UK. Pretend Saltburn is sort of in Teesside while you’re enjoying the view. Look out on beaches black with sea coal, washed up from undersea seams and nearby coal mines. Visit the golf course by Seaton Carew to catch a glimpse of a curlew or two, and watch the young seagulls pick up golf balls to crack them open by dropping them from a great height. Visit Seal Sands, whose owners can be observed lazing on the estuary banks whenever the tide is out. Or visit Saltholme, the RSPB nature reserve, where you can see avocets, Britain’s weirdest-looking and most beloved seabird.

Nature coexists with industry on Teesside. Image: Stephen Jorgensen-Murray.

Go white water rafting, bell boating or paddleboarding at the Tees Barrage, where there are so many seals that they’ve had to put up guards to keep them out of the way. The Tees used to be too polluted even to support salmon and trout, and now we have too many of one of Britain’s largest native mammals. The return of the seals to the Tees was the first documented case of seals returning to an industrial area. You’d be surprised at how well nature can thrive in the shadow of industry, colonising the quiet fields and marshy ponds on private land that are never disturbed, haunted by sika deer and shelducks, redshanks, knots, stonechats.

Teesside has plenty to offer. What it doesn’t have is the jobs to keep its younger generations from having to get on their bikes and leave. We aren’t aliens, or Jacob Rees-Mogg’s army of goblin henchbrexiteers. We’re just like you, but with more seals and fewer employment opportunities.