Wildfires ignite infection risks, by weakening the body’s immune defences and spreading bugs in smoke

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Over the past several days, the world has watched on in shock as wildfires have devastated large parts of Los Angeles.

Beyond the obvious destruction – to landscapes, homes, businesses and more – fires at this scale have far-reaching effects on communities. A number of these concern human health.

We know fire can harm directly, causing injuries and death. Tragically, the death toll in LA is now at least 24.

But wildfires, or bushfires, can also have indirect consequences for human health. In particular, they can promote the incidence and spread of a range of infections.

Effects on the immune system

Most people appreciate that fires can cause burns and smoke inhalation, both of which can be life-threatening in their own right.

What’s perhaps less well known is that both burns and smoke inhalation can cause acute and chronic changes in the immune system. This can leave those affected vulnerable to infections at the time of the injury, and for years to come.

Burns induce profound changes in the immune system. Some parts go into overdrive, becoming too reactive and leading to hyper-inflammation. In the immediate aftermath of serious burns, this can contribute to sepsis and organ failure.

Other parts of the immune system appear to be suppressed. Our ability to recognise and fight off bugs can be compromised after sustaining burns. Research shows people who have experienced serious burns have an increased risk of influenza, pneumonia and other types of respiratory infections for at least the first five years after injury compared to people who haven’t experienced burns.

Wildfire smoke is a complex mixture containing particulate matter, volatile organic compounds, ozone, toxic gases, and microbes. When people inhale smoke during wildfires, each of these elements can play a role in increasing inflammation in the airways, which can lead to increased susceptibility to respiratory infections and asthma.

Research published after Australia’s Black Summer of 2019–20 found a higher risk of COVID infections in areas of New South Wales where bushfires had occurred weeks earlier.

We need more research to understand the magnitude of these increased risks, how long they persist after exposure, and the mechanisms. But these effects are thought to be due to sustained changes to the immune response.

Microbes travel in smoky air

Another opportunity for infection arises from the fire-induced movement of microbes from niches they usually occupy in soils and plants in natural areas, into densely populated urban areas.

Recent evidence from forest fires in Utah shows microbes, such as bacteria and fungal spores, can be transported in smoke. These microbes are associated with particles from the source, such as burned vegetation and soil.

There are thousands of different species of microbes in smoke, many of which are not common in background, non-smoky air.

Only a small number of studies on this have been published so far, but researchers have shown the majority of microbes in smoke are still alive and remain alive in smoke long enough to colonise the places where they eventually land.

How far specific microbes can be transported remains an open question, but fungi associated with smoke particles have been detected hundreds of miles downwind from wildfires, even weeks after the fire.

So does this cause human infections?

A subset of these airborne microbes are known to cause infections in humans.

Scientists are probing records of human fungal infections in relation to wildfire smoke exposure. In particular, they’re looking at soil-borne infectious agents such as the fungi Coccidioides immitis and Coccidioides posadasii which thrive in dry soils that can be picked up in dust and smoke plumes.

These fungi cause valley fever, a lung infection with symptoms that can resemble the flu, across arid western parts of the United States.

A study of wildland firefighters in California showed high rates of valley fever infections, which spurred occupational health warnings including recommended use of respirators when in endemic regions.

A California-based study of the wider population showed a 20% increase in hospital admissions for valley fever following any amount of exposure to wildfire smoke.

However, another found only limited evidence of excess cases after smoke exposure in wildfire-adjacent populations in California’s San Joaquin Valley.

These contrasting results show more research is needed to evaluate the infectious potential of wildfire smoke from this and other fungal and bacterial causes.

Staying safe

Much remains to be learned about the links between wildfires and infections, and the multiple pathways by which wildfires can increase the risk of certain infections.

There’s also a risk people gathering together after a disaster like this, such as in potentially overcrowded shelters, can increase the transmission of infections. We’ve seen this happen after previous natural disasters.

Despite the gaps in our knowledge, public health responses to wildfires should encompass infection prevention (such as through the provision of effective masks) and surveillance to enable early detection and effective management of any outbreaks.

Christine Carson, Senior Research Fellow, School of Medicine, The University of Western Australia and Leda Kobziar, Professor of Wildland Fire Science, University of Idaho

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • Clams vs Oysters – Which is Healthier?

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    Our Verdict

    When comparing clams to oysters, we picked the clams.

    Why?

    Considering the macros first, clams have more than 2x the protein, while oysters have nearly 2x the fat, of which, a little over 5x the saturated fat. So, in all accounts, clam is the winner here.

    In terms of vitamins, clams have more of vitamins A, B1, B2, B3, B5, B6, B7, B9, B12, and C, while oysters are not higher in any vitamins. Another win for clams.

    The category of minerals is more balanced; clams are higher in manganese, phosphorus, potassium, and selenium, while oysters are higher in copper, iron, magnesium, and zinc. This makes for a 4:4 tie, though it’s worth noting that the margin of difference for zinc is very large, so that can be an argument for oysters.

    Nevertheless, adding up the sections makes for a clear win for clams.

    A quick aside on “are oysters an aphrodisiac?”:

    That zinc content is probably largely responsible for oysters’ reputation as an aphrodisiac, and zinc is important in the synthesis of both estrogen and testosterone. However, as the synthesis is not instant, and those sex hormones rise most in the morning (around 8am to 9am), to enjoy aphrodisiac benefits it’d be more sensible, on a biochemical level, to eat oysters one day, and then have morning sex the next day when those hormones are peaking. That said, while testosterone is the main driver of male libido, progesterone is usually more relevant for women’s, and unlike estrogen, progesterone usually peaks around 10pm to 2am, and is uninfluenced by having just eaten oysters.

    So, in what way, if any, could oysters be responsible for libido in women? Well, the zinc is still important in energy metabolism, so that’s a factor, and also, we might hypothesize that oysters’ high saturated fat and cholesterol content may increase blood pressure which, while not fabulous for the health in general, may be considered desirable in the bedroom since the clitoris is anatomically analogous to the penis, and—while estrogen vs testosterone makes differences to the nervous system down there that are beyond the scope of today’s article—also enjoys localized increased blood pressure (and thus, a flushing response and resultant engorgement) during arousal.

    Want to learn more?

    You might like to read:

    Does Eating Shellfish Really Contribute To Gout? ← short answer is: it can if consumed frequently over a long period of time, but that risk factor is greatly overstated, compared to some other risk factors

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  • Bushfire smoke affects children differently. Here’s how to protect them

    10almonds is reader-supported. We may, at no cost to you, receive a portion of sales if you purchase a product through a link in this article.

    Bushfires are currently burning in Australian states including Victoria, Tasmania, Western Australia and South Australia. In some areas, fire authorities have warned residents about the presence of smoke.

    Bushfire smoke is harmful to our health. Tiny particles of ash can lodge deep in the lungs.

    Exposure to this type of smoke may worsen existing conditions such as asthma, and induce a range of health effects from irritation of the eyes, nose and throat to changes in the cardiovascular system.

    Public health recommendations during smoke events tend to provide general advice, and don’t often include advice specifically geared at children. But children are not just little adults. They are uniquely vulnerable to environmental hazards such as bushfire smoke for a number of reasons.

    Different physiology, different behaviour

    Children’s lungs are still developing and maturing.

    Airways are smaller in children, especially young children, which is associated with greater rates of particle deposition – when particles settle on the surfaces of the airways.

    Children also breathe more air per kilogram of body weight compared with adults, and therefore inhale more polluted air relative to their size.

    Further, children’s detoxification systems are still developing, so environmental toxins take longer to effectively clear from their bodies.

    Meanwhile, children’s behaviour and habits may expose them to more environmental toxins than adults. For example, they tend to do more physical activity and spend more time outdoors. Higher levels of physical activity lead to more air inhaled per kilogram of body weight.

    Also, a normal and important part of children’s early play is exploring their environment, including by putting things in their mouth. This can result in kids ingesting soil, dust and dirt, which often contain environmental contaminants.

    For these reasons, it’s important to consider the specific needs of children when providing advice on what to do when there’s smoke in the air.

    Keeping our environments healthy

    The Australian government offers recommendations for minimising the health risks from exposure to bushfire smoke. The main advice includes staying indoors and keeping doors and windows closed.

    This is great advice when the smoke is thick outside, but air pollutants may still accumulate inside the home. So it’s important to air your home once the smoke outside starts to clear. Take advantage of wind changes to open up and get air moving out of the house with a cross breeze.

    Kids are natural scientists, so get them involved. For example, you and your child can “rate” the air each hour by looking at a landmark outside your home and rating how clearly you can see it. When you notice the haze is reducing, open up the house and clear the air.

    Because air pollutants settle onto surfaces in our home and into household dust, an easy way to protect kids during smoky periods is to do a daily dust with a wet cloth and vacuum regularly. This will remove pollutants and reduce ingestion by children as they play. Frequent hand washing helps too.

    Healthy bodies and minds

    Research exploring the effects of bushfire smoke exposure on children’s health is sparse. However, during smoke events, we do see an increase in hospital visits for asthma, as well as children reporting irritation to their eyes, nose and throat.

    If your child has asthma or another medical condition, ensure they take any prescribed medications on a regular schedule to keep their condition well controlled. This will minimise the risk of a sudden worsening of their symptoms with bushfire smoke exposure.

    Make sure any action plans for symptom flare-ups are up to date, and ensure you have an adequate supply of in-date medication somewhere easy to locate and access.

    A mother talks to her child who is sitting on a bed.
    Children may be anxious during a bushfire.
    Media_Photos/Shutterstock

    Kids can get worried during bushfires, and fire emergencies have been linked with a reduction in children’s mental health. Stories such as the Birdie’s Tree books can help children understand these events do pass and people help one another in times of difficulty.

    Learning more about air pollution can help too. Our group has a children’s story explaining how air pollution affects our bodies and what can help.

    It’s also important for parents and caregivers not to get too stressed, as children cope better when their parents manage their own anxiety and help their children do the same. Try to strike a balance between being vigilant and staying calm.

    What about masks?

    N95 masks can protect the wearer from fine particles in bushfire smoke, but their use is a bit complicated when it comes to kids. Most young children won’t be able to fit properly into an N95 mask, or won’t tolerate the tight fit for long periods. Also, their smaller airways make it harder for young children to breathe through a mask.

    If you choose to use an N95 mask for your children, it’s best to save them for instances when high-level outdoor exposure is unavoidable, such as if you’re going outside when the smoke is very thick.

    N95 masks should be replaced after around four hours or when they become damp.

    If your child has an existing heart or lung condition, consult their doctor before having them wear an N95 mask.

    Our team is currently recruiting for a study exploring the effects of bushfire smoke in children. If you live in south east Queensland and are interested in participating in the event of a bushfire or hazard reduction burn near your home, please express your interest here.The Conversation

    Dwan Vilcins, Group leader, Environmental Epidemiology, Children’s Health Environment Program, The University of Queensland; Nicholas Osborne, Associate Professor, School of Public Health, The University of Queensland, and Paul D. Robinson, Conjoint Professor in Respiratory and Sleep Medicine, Child Health Research Centre, The University of Queensland

    This article is republished from The Conversation under a Creative Commons license. Read the original article.

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  • Can You Be Fat AND Fit?

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    The short answer is “yes“.

    And as for what that means for your heart and/or all-cause mortality risk: it’s just as good as being fit at a smaller size, and furthermore, it’s better than being less fit at a smaller size.

    Here’s the longer answer:

    The science

    A research team did a systematic review looking at multiple large cohort studies examining the associations between:

    • Cardiorespiratory fitness and cardiovascular disease risk
    • Cardiorespiratory fitness and all-cause mortality
    • BMI and cardiovascular disease risk
    • BMI and all-cause mortality

    However, they also took this further, and tabulated the data such that they could also establish the cardiovascular disease mortality risk and all-cause mortality risk of:

    1. Unfit people with “normal” BMI
    2. Unfit people with “overweight” BMI
    3. Unfit people with “obese” BMI
    4. Fit people with “normal” BMI
    5. Fit people with “overweight” BMI
    6. Fit people with “obese” BMI

    Before we move on, let’s note for the record that BMI is a woeful system in any case, for enough reasons to fill a whole article:

    When BMI Doesn’t Measure Up

    Now, with that in mind, let’s get to the results:

    What they found

    For cardiovascular disease mortality risk of unfit people specifically, compared to fit people of “normal” BMI:

    • Unfit people with “normal” BMI: 2.04x higher risk.
    • Unfit people with “overweight” BMI: 2.58x higher risk.
    • Unfit people with “obese” BMI: 3.35x higher risk

    So here we can see that if you are unfit, then being heavier will indeed increase your CVD mortality risk.

    For all-cause mortality risk of unfit people specifically, compared to fit people of “normal” BMI:

    • Unfit people with “normal” BMI: 1.92x higher risk.
    • Unfit people with “overweight” BMI: 1.82x higher risk.
    • Unfit people with “obese” BMI: 2.04x higher risk

    This time we see that if you are unfit, then being heavier or lighter than “overweight” will increase your all-cause mortality risk.

    So, what about if you are fit? Then being heavier or lighter made no significant difference to either CVD mortality risk or all-cause mortality risk.

    Fit individuals, regardless of weight category (normal, overweight, or obese), had significantly lower mortality risks compared to unfit individuals in any weight category.

    Note: not just “compared to unfit individuals in their weight category”, but compared to unfit individuals in any weight category.

    In other words, if you are obese and have good cardiorespiratory fitness, you will (on average) live longer than an unfit person with “normal” BMI.

    You can find the paper itself here, if you want to examine the data and/or method:

    Cardiorespiratory fitness, body mass index and mortality: a systematic review and meta-analysis

    Ok, so how do I improve the kind of fitness that they measured?

    They based their cardiorespiratory fitness on VO2 Max, which scientific consensus holds to be a good measure of how efficiently your body can use oxygen—thus depending on your heart and lungs being healthy.

    If you use a fitness tracker that tracks your exercise and your heart rate, it will estimate your VO2 Max for you—to truly measure the VO2 Max itself directly, you’ll need a lot more equipment; basically, access to a lab that tests this. But the estimates are fairly accurate, and so good enough for most personal purposes that aren’t hard-science research.

    Next, you’ll want to do this:

    53 Studies Later: The Best Way to Improve VO2 Max

    Take care!

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  • Recognize The Early Symptoms Of Parkinson’s Disease

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    Parkinson’s disease is a degenerative condition with wide-reaching implications for health. While there is currently no known cure, there are treatments, so knowing about it sooner rather than later is important.

    Spot The Signs

    There are two main kinds of symptoms, motor and non-motor.

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  • Can You Step Backwards Without Your Foot Or Torso Turning Out?

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    Walking backwards is often overlooked, but research shows it can enhance forward walking, especially in stroke patients; it has other benefits for everyone else, too. The physiotherapists at Fitness4Life Physical Therapy explain:

    …and one step back

    How it works: walking backwards heightens proprioception and stimulates muscles, improving balance and posture. Additionally, our daily lives tend to involve forward-leaning postures, causing upper back bending, and walking backwards helps counterbalance this.

    Extra benefits: training to walk backwards can reduce the risk of falls, as stepping back is a common movement that is often untrained.

    Exercise: try doing backwards lunges, to assess your skill and balance while moving backward. If foot rotation or torso rotation occurs during the exercise, then there’s room for improvement. Correcting these movements is then simply a matter of practicing backward lunges without turning.

    10almonds tip: any exercise is only as good as your will to actually do it. For this reason, dancing is a great exercise in this case, as almost all forms of dance involve stepping backwards (in order to have steps without travelling somewhere, forwards steps are usually balanced with backwards ones)

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  • Beetroot vs Eggplant – Which is Healthier?

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    Our Verdict

    When comparing beetroot to eggplant, we picked the beetroot.

    Why?

    It’s close!

    In terms of macros, they’re equal on fiber, while beetroot has slightly more protein and carbs. In both cases, despite being quite firm vegetables when raw, they are nevertheless both mostly water. We’re calling this category a tie.

    In the category of vitamins, beetroot has more of vitamins A, B2, B9, and C, while eggplant has more of vitamins B3, B5, B6, E, and K. That’s a marginal victory for eggplant.

    When it comes to minerals, however, beetroot has more calcium, copper, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc, while eggplant is not higher in any minerals. A clear and easy win for beetroot this time.

    In terms of polyphenols, both have good-but-different health-giving polyphenols to share, including the quercetin in beetroot and caffeic acid in eggplant—nothing that would tip one ahead of the other, though.

    All in all, the categories added up are balanced, but beetroot won the minerals category much more convincingly than eggplant won the vitamins category, so we’re giving this one to beetroot, even if only on tie-breakers!

    Of course, enjoy either or both; diversity is good 😎

    Want to learn more?

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    Beetroot For More Than Just Your Blood Pressure ← more beetroot benefits

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