In a world hyper-tuned to disease after more than two years of a global pandemic, every new outbreak attracts headlines.
The world is still struggling with COVID-19, but Australians have had to understand the symptoms and risks associated with a number of other new diseases.
Take the Japanese encephalitis virus (JEV), which was first found in the southeast of the country earlier this year.
Mosquito-borne virus is still rare and a cause for caution rather than an alarm.
But it is just one example of the kind of health challenges that scientists say we should expect to see more of as the planet continues to warm.
“Of course, not all of them are at the same level as COVID-19. But the frequency of pandemic events is certainly on the rise,” says Paul De Barro, senior senior researcher at CSIRO.
Mosquito-borne diseases improve as the world warms
Science is clear: human activity has warmed the world by about 1 degree Celsius since pre-industrial times. With that comes more extreme and unexpected weather events.
A major challenge facing the world is what is known as vector-borne diseases. With malaria, dengue and JEV, the vector is the mosquito.
“Simply put, vectors … do better in a warmer world,” he found in a 2020 report in the journal Nature Immunology.
JEV has been present in parts of the far north of Australia such as the Tiwi Islands and the Upper Cape York for years, but has never been detected further south until this year.
Most people experience no symptoms, but about 1% have a fever and headache, and in rare and severe cases, it can cause severe swelling of the brain. It has been linked to at least five deaths in Australia.
“Increased rainfall leading to flooding may create the preconditions for the main vector of Japanese encephalitis,” says Dr. De Barro.
“And that has two additional components: increased rainfall and waterfowl, which are intermediate hosts of the virus, and wild pigs do so much better.
“So you have more sources of viruses and many more mosquitoes that can spread it.”
It is the kind of event that scientists have been warning about for at least two decades.
Increased rainfall can result in higher mosquito populations, leading to a greater spread of vector-borne diseases. (Provided by: CSIRO)
The world’s largest climate science body, the Intergovernmental Panel on Climate Change (IPCC), has found that the prevalence of vector-borne diseases is already rising and could worsen.
There are other factors at play in the way any disease spreads, such as vaccination, insect control, quarantine, and even farming practices, and scientists want to make it clear that climate change is not the answer. ‘only cause.
“If there’s a mosquito vector part of this cycle, the mosquitoes could be alive one more week during the year,” says Nicholas Osborne, an associate professor at the University of Queensland.
“And that only increases the chance of someone getting infected with this mosquito.”
Australia has historically successfully managed the risk of deadly mosquito-borne diseases, such as malaria and dengue, which kill hundreds of thousands of people worldwide each year and are common in neighboring countries.
But this can be more difficult as the weather changes.
Viruses spread by animals are on the rise
Another new virus that has arrived in Australia this year is monkeypox, which causes flu-like symptoms and a distinctive rash after human-to-human contact.
Again, it is important to note that the outbreak of the virus is not a cause for panic.
And climate change is a factor: the increase in the number of outbreaks could be partly the result of declining levels of immunity to poxviruses in the general population.
The virus is known as a zoonotic disease, which is caused by germs that jump from animals to humans and then are transmitted from person to person.
All the evidence suggests that COVID-19 has zoonotic origins.
There are about 10,000 viruses currently circulating in wild mammals that have the ability to infect humans, a peer-reviewed study published in the journal Nature in April found.
According to the study, the potential for inter-species transmission increases as the climate changes and humans move to areas where they interact more with animals that were previously geographically isolated.
“What we’re seeing is an increase in frequency,” says Dr. De Barro.
“So we’ve seen, for example, in the last 20 years, a lot more outbreaks associated with zoonotic diseases than we’ve seen, for example, in the previous 20 years.”
This includes the swine flu pandemic, caused by the H1N1 virus, and the bird flu outbreaks, caused by the H5N1 virus.
Zoonotic diseases begin with animals, but unlike vector-borne diseases, they spread among humans. (ABC News: Margaret Burin)
One of the key findings of the April Nature study was that climate change could easily become a dominant force in interspecies transmission of viruses “which will no doubt have a downstream impact on human health and the risk of a pandemic “.
In a world that has already surpassed 1C degrees of global warming, the authors warned that much of this viral sharing between species could have already happened.
Mike Ryan, of the World Health Organization, warned earlier this month that rapidly changing weather conditions, such as drought, aggravated by climate change, were causing animals and humans to change their behavior.
Dr. Ryan noted recent outbreaks of monkeypox, an upward trend in cases of Lassa fever, spread by the common African rat, and an increase in the incidence of Ebola outbreaks.
“So I think that’s a lesson, these diseases will continue to emerge, they will continue to press, they will continue to cross the barrier of the species,” he said.
“The question is, are we in a position to respond collectively?”
There are opportunities to adapt
Of course, as the planet warms, we need to be prepared for the health impacts caused directly by this heat.
“Heat will affect our health in many different ways,” says Dr. Osborne of the University of Queensland.
“And I guess that’s where a changing climate is considered so important and why we strive to do something about it.”
The IPCC expects climate change to cause an additional 250,000 deaths a year from malnutrition, malaria, diarrhea and heat stress between 2030 and 2050.
Australia may initially escape the brunt of these challenges, with countries with more widespread poverty most likely to be the first to be affected, but they will not be saved at all.
Natural disasters can get worse with a changing climate. (AAP: Dean Lewins)
But there are some cracks of optimism amidst all the sadness.
Scientists are working hard to find ways to reduce the risk of health outcomes from environmental change, including the newly created Australian HEAL network, of which Dr Osborne is a member.
The April IPCC report found that the world already had the tools available to keep global warming below 1.5ºC. But he warned that there would have to be a “transformative change” immediately if that were to happen.
“I am encouraged by the climate action that is taking place in many countries. There are policies, regulations and market instruments that are proving to be effective. If they are expanded and implemented more broadly and equitably, they can supporting profound emission reductions and stimulating innovation “, IPCC. President Hoesung Lee said in April.
Posted 5 hours 5 hours ago Thu, June 16, 2022 at 8:27 PM, updated 3 hours, 3 hours ago, Thu, June 16, 2022 at 10:31 PM