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.

Has your doctor asked you to stick out your tongue and say “aaah”? While the GP assesses your throat, they’re also checking out your tongue, which can reveal a lot about your health.

The doctor will look for any changes in the tongue’s surface or how it moves. This can indicate issues in the mouth itself, as well as the state of your overall health and immunity.

But there’s no need to wait for a trip to the doctor. Cleaning your tongue twice a day can help you check how your tongue looks and feels – and improve your breath.

What does a healthy tongue look like?

Our tongue plays a crucial role in eating, talking and other vital functions. It is not a single muscle but rather a muscular organ, made up of eight muscle pairs that help it move.

The surface of the tongue is covered by tiny bumps that can be seen and felt, called papillae, giving it a rough surface.

These are sometimes mistaken for taste buds – they’re not. Of your 200,000-300,000 papillae, only a small fraction contain taste buds. Adults have up to 10,000 taste buds and they are invisible to the naked eye, concentrated mainly on the tip, sides and back of the tongue. https://www.youtube.com/embed/uYvpUl7li9Y?wmode=transparent&start=0

A healthy tongue is pink although the shade may vary from person to person, ranging from dark to light pink.

A small amount of white coating can be normal. But significant changes or discolouration may indicate a disease or other issues.

How should I clean my tongue?

Cleaning your tongue only takes around 10-15 seconds, but it’s is a good way to check in with your health and can easily be incorporated into your teeth brushing routine.

You can clean your tongue by gently scrubbing it with a regular toothbrush. This dislodges any food debris and helps prevent microbes building up on its rough textured surface.

Or you can use a special tongue scraper. These curved instruments are made of metal or plastic, and can be used alone or accompanied by scrubbing with your toothbrush.

Your co-workers will thank you as well – cleaning your tongue can help combat stinky breath. Tongue scrapers are particularly effective at removing the bacteria that commonly causes bad breath, hidden in the tongue’s surface.

What’s that stuff on my tongue?

So, you’re checking your tongue during your twice-daily clean, and you notice something different. Noting these signs is the first step. If you observe any changes and they worry you, you should talk to your GP.

Here’s what your tongue might be telling you.

White coating

Developing a white coating on the tongue’s surface is one of the most common changes in healthy people. This can happen if you stop brushing or scraping the tongue, even for a few days.

In this case, food debris and microbes have accumulated and caused plaque. Gentle scrubbing or scraping will remove this coating. Removing microbes reduces the risk of chronic infections, which can be transferred to other organs and cause serious illnesses.

Yellow coating

This may indicate oral thrush, a fungal infection that leaves a raw surface when scrubbed.

Oral thrush is common in elderly people who take multiple medications or have diabetes. It can also affect children and young adults after an illness, due to the temporary suppression of the immune system or antibiotic use.

If you have oral thrush, a doctor will usually prescribe a course of anti-fungal medication for at least a month.

Black coating

Smoking or consuming a lot of strong-coloured food and drink – such as tea and coffee, or dishes with tumeric – can cause a furry appearance. This is known as a black hairy tongue. It’s not hair, but an overgrowth of bacteria which may indicate poor oral hygiene.

Pink patches

Pink patches surrounded by a white border can make your tongue look like a map – this is called “geographic tongue”. It’s not known what causes this condition, which usually doesn’t require treatment.

Pain and inflammation

A red, sore tongue can indicate a range of issues, including:

• nutritional deficiencies such as folic acid or vitamin B12
• diseases including pernicious anaemia, Kawasaki disease and scarlet fever
• inflammation known as glossitis
• injury from hot beverages or food
• ulcers, including cold sores and canker sores
• burning mouth syndrome.

Dryness

Many medications can cause dry mouth, also called xerostomia. These include antidepressants, anti-psychotics, muscle relaxants, pain killers, antihistamines and diuretics. If your mouth is very dry, it may hurt.

What about cancer?

White or red patches on the tongue that can’t be scraped off, are long-standing or growing need to checked out by a dental professional as soon as possible, as do painless ulcers. These are at a higher risk of turning into cancer, compared to other parts of the mouth.

Oral cancers have low survival rates due to delayed detection – and they are on the rise. So checking your tongue for changes in colour, texture, sore spots or ulcers is critical.

Dileep Sharma, Professor and Head of Discipline – Oral Health, University of Newcastle

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