How climate change can spread respiratory infection - Featured Image

SCIENTISTS and policymakers worry about the economic havoc that climate change will wreak, thanks to rising sea levels, extreme weather events or desertification. But there’s been less emphasis on the effect it is already having on the spread of infectious diseases across human populations.

This is a subject dear to the heart of leading US respiratory specialist Dean Schraufnagel, a Professor of Medicine at the University of Illinois, Chicago. Professor Schraufnagel was in Australia in November 2017 to give a fascinating talk on respiratory infection and climate change at the plenary session of the Asian Pacific Society of Respirology (APSR) Congress, held in Sydney.

“It’s not a question of whether climate change will affect human health. It already has, by altering the epidemiology of climate-sensitive pathogens,” Professor Schraufnagel told MJA InSight.

“When we change the climate, we also change habitats and bring wildlife, crops, livestock and humans into contact with pathogens to which they may have had less exposure and less immunity,” he says.

As a case in point, Professor Schraufnagel points to an outbreak of respiratory disease caused by hantavirus in Panama. Hantavirus is found in the saliva, urine and faeces of rats, the population of which had increased exponentially due to an episode of warm, rainy weather.

“Climate variation had boosted the rat population, which put them in closer proximity to humans, who then picked up the virus from the rats,” Professor Schraufnagel explains.

“The way that climate change acts on the spread of infectious diseases is very complicated, and can involve the migration of wild animals, livestock or humans, and each time there’s a change in habitat, you come into contact with new vectors and situations that can lead to infection. So, as the environment changes, we’re more likely to come into contact with infectious agents.”

In an example closer to home, an Australian study looked at how fluctuating temperatures — another measure of global climate change — can affect pneumonia incidence. It found a correlation between sharp temperature drops from one day to the next and increased emergency visits for childhood pneumonia.

Fungal infection is another area where climate change can play a significant role in the incidence of respiratory diseases.

“Endemic fungi are found in the soil. There was a well documented case, in California, where there was an outbreak of coccidioidomycosis, which is transmitted by inhaling spores and can’t be transmitted from person to person. The cases developed 2 weeks after a severe dust storm, which released the spores from the soil.”

Professor Schraufnagel says risks will vary from region to region, and some regions will be at greater risk than others.

“Borderline areas will be more affected. So arid areas at risk of desertification, or low-lying areas at risk of flooding might be the ones at most risk of respiratory infection.”

He says one of the challenges of dealing with the effect of climate change on infectious diseases is its very complexity.

“If you have a cyclone or an earthquake, you know what the damage is right away. But with climate change, it’s not so straightforward, which allows for deniers and industry lobbyists. I’m from the US, so I’m particularly hard hit by the election of Donald Trump in this regard. But I’m heartened to see the rest of the world and much of the US are still trying to do something about climate. I think we need to educate the public. Doctors and scientists and the media need to get the message out.”

At the APSR Congress, Professor Schraufnagel also chaired a workshop on another controversial topic: electronic cigarettes and respiratory health. He is of the view that e-cigarettes need a tighter regulation than they’re getting now.

“Nicotine is one of the most addictive substances in use. So, I think you have to be very conservative and I’m quite opposed to these nicotine delivery devices. The exception might be if they could be used to help people stop smoking, but that should be done through regulatory agencies. It should be prescribed medicine, or if not prescribed, at least shown to be safe in clinical trials. If the makers want to claim e-cigarettes are useful for smoking cessation, fine. Just do the trials and see what happens.”

He says there has been an increasing amount of research into the harm e-cigarette vapours can do to the lungs.

“All the potential harms of combustible cigarettes are pretty much present, although in a much smaller degree, in e-cigarettes. People say the flavouring they use is safe because they’re already used in foods, but what’s safe for eating is not necessarily safe for breathing.”

He points to diacetyl, a buttery-flavoured chemical in foods like popcorn, which is safe to eat, but when inhaled by workers in food factories was found to cause a fatal bronchitis.

“There are dozens or even hundreds of flavourings used in e-cigarettes and we just don’t know how safe they are. The harm reduction argument for e-cigarettes is fundamentally faulty, because smoking is one of the most dangerous, toxic things you can do to your lungs. To say it’s better to use e-cigarettes is like saying that getting shot with a 22-calibre gun is better than getting shot with a 35-calibre gun. When actually it’s best not to get shot at all!”


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16 thoughts on “How climate change can spread respiratory infection

  1. Anonymous says:

    While changes in weather may have an impact on illnesses, “climate change” is not an established fact.

  2. Anonymous says:

    As far as rats are concerned regarding cause and spread of disease, little has changed over centuries, e.g. the bubonic plague in England in the 17th. century. Control the animals and parasites and then you control the disease.
    Despite the so called experts and their global warming theories and yes they are only theories suggested by computer modelling and still to be proven, people today still live twice as long on average in a temperate climate than they did in the ice ages of the past. In fact the average age of longevity has changed little in the past 400 years and is only maintained today by good quality medicine, technology and until recently, effective antibiotic treatment.

  3. Rudolph Pitman says:

    Title should be cahnged to “How weather can spread respiratory infection”.

    As to e-cigs, I think the author means that there should be *fewer* regs, in order to allow for prescriptions for the devices, since currently they are banned. The fact remains that the available evidence supports the notion that they are far, far safer than cigs, and there is no evidence that people use them as a so-called ‘gateway’ to smoking.

  4. Anonymous says:

    I always knew there was a reason for rising pneumonia rates! Great news.

  5. Anonymous says:

    Earth has been in and out of ice ages for millennia, and on any one day the surface temperature varies from about -50 to +50°C with significant variation in temperature, rainfall and every other weather variable on every timeframe from hours to months, seasons, decades and centuries. The only constant is huge variability. The idea that the earth has never warmed a degree or so in any prior century is just ridiculous. In March 2009 the MJA published a paper debunking the idea that dengue fever was related to temperature change, and the global expert Paul Reiter said the same about malaria. He resigned from an IPCC committee because no one on it knew anything about the subject matter. As a result of the research into cigarette smoking causing lung cancer, the criteria for establishing a cause and effect relationship between two variables were documented in the 1960s by Bradford Hill. Each of the examples given in the article above does not meet the criteria for a cause and effect relationship. This is just politically correct speculation.

  6. David says:

    Sorry Anonymous, but climate change is an established fact, and it is changing weather patterns. The warming that we are observing is consistent with the predictions of the models, so the theory is being supported by all but a few fragments of cherry picked evidence. You can have your beliefs, but it is not possible to have ‘alternative facts’. I really can’t see what is politically correct about such facts of a warming world and the likely impacts on health – I’m a sceptic about your choice of what is a politically correct view, please convince me as to why this is the case.

  7. Anonymous says:

    I laugh every time I read MJA Insights weekly curated list of ‘articles,’ and the associated comments. I eagerly anticipate the piece on transgender youth or women being harassed, or climate change, etc. etc. I can only assume that the sane 90% of doctors are not on this forum.

  8. Cate Swannell says:

    EDITOR’S NOTE: It never ceases to amaze me that the most critical, the ones who cannot see the value of what we or our external authors write about, are also the ones who can’t seem to bring themselves to unsubscribe.

  9. Anonymous says:

    Because it is not healthy to ‘unsubscribe’ to that to which you do not agree, and it is important to participate in conversation. I was merely making an observation. I’m sorry if it offended you.

  10. Ian F says:

    Dear Editor: 7 of the above 9 comments have been critical of this piece. I don’t think it’s a question of ‘critical people’ out there unsubscribing. I think rather the majority of your highly educated peers are prone to sneer at any article that grabs at straws if otherwise inconsequential evidence to construct a political case. They indeed must be very critical readers.
    Dr. Ian F.

  11. Joe Kosterich says:

    The climate has been changing for 4.5 billion years. Every prediction made on the basis of “man made” climate change has failed to materialise. Funny that!

  12. Sydney GP says:

    This website, and for that matter the entire MJA (especially in the last few years) has begun to sound like a lefty agenda pushing organ, and no doubt editors are to blame. Oh for the glory of a publication such as the NEJM, or for GPs like me, the American AFP. I pick them up and (I cannot express how wonderful this is), they are about medicine!! I learn so much, and I can help my patients. Their rising circulation strongly attests to their practical usefulness to real doctors.

    I’ll be honest dear editor, I could not give a rats arse if someone thinks the changing climate will lead to some more respiratory infections, especially when they don’t have an argument as to what to do to fix this awful thing. Perhaps shutting down a few hospitals might help the coal load, but then again I suppose that might lead to a few more mortalities from respiratory infections …

    Sydney GP.

  13. Anonymous says:

    MJA Impact factor.
    2013: 3.789.
    2014: 4.089.
    2015: 3.369.
    2016: 2.872.

  14. Cate Swannell says:

    EDITOR’S NOTE: Dear anonymous, your information is out of date. Due to an error by Thomson Reuters in the way in which they calculated the MJA impact factor, our IF has been amended. The MJA’s 2016 impact factor is 3.68, with a 5-year impact factor of 4.10. It received a record 10 610 citations during 2016, ranking the MJA among the top 20 general medical journals in the world. Editor-in-Chief Nick Talley will be further addressing this issue in his year-ending editorial in the 11 Dec MJA. Thank you so much for opportunity to talk about this. CS

  15. Anonymous says:

    OK Cate, let me put things in perspective for you.

    1. I was quoting the Scimago Impact Factor, which takes into account the WEIGHT of each citation (i.e. a citation in NEJM is more heavily weighted than a citation in a tiny isolated journal). This number is correct and remains unchanged. MJA has been falling dramatically over the past 5 years.

    2. If you would like to base your impact on the pure CITATION ONLY method as per Thomson Reuters, it only makes MJA look more ridiculous.

    Compare 2016 impact factors according to your method for 216.

    NEJM: 33.9.
    Lancet: 25.8.
    JAMA: 13.82.

    MJA is listed as 1.88, you tell me it is really going to be corrected to 3.68. Granted.
    This puts you in league with such journals as:

    The (Canadian) Journal of Medical Internet Research: 4.06.
    PLoS: Neglected Infectious Diseases: 3.90.
    The (Denmark) Journal of Indoor Air: 3.85.
    The (Australian) Journal of Clinical and Experimental Gastroenterology: 3.69

    All of which are ranked more highly than your own quoted revised estimate. They all double your currently listed one.

  16. Cate Swannell says:

    EDITOR’S NOTE: Dear Anonymous … It’s not “really going to be corrected”, it has been corrected. As I said, Prof Nick Talley will be elaborating on this in his 11 December MJA editorial.

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