Before the COVID pandemic, the World Health Organization (WHO) had made a list of priority infectious diseases. These were felt to pose a threat to international public health, but where research was still needed to improve their surveillance and diagnosis. In 2018, “disease X” was included, which signified that a pathogen previously not on our radar could cause a pandemic.

While it’s one thing to acknowledge the limits to our knowledge of the microbial soup we live in, more recent attention has focused on how we might systematically approach future pandemic risks.

Former US Secretary of Defense Donald Rumsfeld famously talked about “known knowns” (things we know we know), “known unknowns” (things we know we don’t know), and “unknown unknowns” (the things we don’t know we don’t know).

Although this may have been controversial in its original context of weapons of mass destruction, it provides a way to think about how we might approach future pandemic threats.

Influenza: a ‘known known’

Influenza is largely a known entity; we essentially have a minor pandemic every winter with small changes in the virus each year. But more major changes can also occur, resulting in spread through populations with little pre-existing immunity. We saw this most recently in 2009 with the swine flu pandemic.

However, there’s a lot we don’t understand about what drives influenza mutations, how these interact with population-level immunity, and how best to make predictions about transmission, severity and impact each year.

The current H5N1 subtype of avian influenza (“bird flu”) has spread widely around the world. It has led to the deaths of many millions of birds and spread to several mammalian species including cows in the United States and marine mammals in South America.

Human cases have been reported in people who have had close contact with infected animals, but fortunately there’s currently no sustained spread between people.

While detecting influenza in animals is a huge task in a large country such as Australia, there are systems in place to detect and respond to bird flu in wildlife and production animals.

It’s inevitable there will be more influenza pandemics in the future. But it isn’t always the one we are worried about.

Attention had been focused on avian influenza since 1997, when an outbreak in birds in Hong Kong caused severe disease in humans. But the subsequent pandemic in 2009 originated in pigs in central Mexico.

Coronaviruses: an ‘unknown known’

Although Rumsfeld didn’t talk about “unknown knowns”, coronaviruses would be appropriate for this category. We knew more about coronaviruses than most people might have thought before the COVID pandemic.

We’d had experience with severe acute respiratory syndrome (SARS) and Middle Eastern respiratory syndrome (MERS) causing large outbreaks. Both are caused by viruses closely related to SARS-CoV-2, the coronavirus that causes COVID. While these might have faded from public consciousness before COVID, coronaviruses were listed in the 2015 WHO list of diseases with pandemic potential.

Previous research into the earlier coronaviruses proved vital in allowing COVID vaccines to be developed rapidly. For example, the Oxford group’s initial work on a MERS vaccine was key to the development of AstraZeneca’s COVID vaccine.

Similarly, previous research into the structure of the spike protein – a protein on the surface of coronaviruses that allows it to attach to our cells – was helpful in developing mRNA vaccines for COVID.

It would seem likely there will be further coronavirus pandemics in the future. And even if they don’t occur at the scale of COVID, the impacts can be significant. For example, when MERS spread to South Korea in 2015, it only caused 186 cases over two months, but the cost of controlling it was estimated at US$8 billion (A$11.6 billion).

The 25 viral families: an approach to ‘known unknowns’

Attention has now turned to the known unknowns. There are about 120 viruses from 25 families that are known to cause human disease. Members of each viral family share common properties and our immune systems respond to them in similar ways.

An example is the flavivirus family, of which the best-known members are yellow fever virus and dengue fever virus. This family also includes several other important viruses, such as Zika virus (which can cause birth defects when pregnant women are infected) and West Nile virus (which causes encephalitis, or inflammation of the brain).

The WHO’s blueprint for epidemics aims to consider threats from different classes of viruses and bacteria. It looks at individual pathogens as examples from each category to expand our understanding systematically.

The US National Institute of Allergy and Infectious Diseases has taken this a step further, preparing vaccines and therapies for a list of prototype pathogens from key virus families. The goal is to be able to adapt this knowledge to new vaccines and treatments if a pandemic were to arise from a closely related virus.

Pathogen X, the ‘unknown unknown’

There are also the unknown unknowns, or “disease X” – an unknown pathogen with the potential to trigger a severe global epidemic. To prepare for this, we need to adopt new forms of surveillance specifically looking at where new pathogens could emerge.

In recent years, there’s been an increasing recognition that we need to take a broader view of health beyond only thinking about human health, but also animals and the environment. This concept is known as “One Health” and considers issues such as climate change, intensive agricultural practices, trade in exotic animals, increased human encroachment into wildlife habitats, changing international travel, and urbanisation.

This has implications not only for where to look for new infectious diseases, but also how we can reduce the risk of “spillover” from animals to humans. This might include targeted testing of animals and people who work closely with animals. Currently, testing is mainly directed towards known viruses, but new technologies can look for as yet unknown viruses in patients with symptoms consistent with new infections.

We live in a vast world of potential microbiological threats. While influenza and coronaviruses have a track record of causing past pandemics, a longer list of new pathogens could still cause outbreaks with significant consequences.

Continued surveillance for new pathogens, improving our understanding of important virus families, and developing policies to reduce the risk of spillover will all be important for reducing the risk of future pandemics.

This article is part of a series on the next pandemic.

Allen Cheng, Professor of Infectious Diseases, Monash University

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

Cold, flu, COVID and RSV have been circulating across Australia this winter. Many of us have caught and recovered from one of these common upper respiratory tract infections.

But for some people their impact is ongoing. Even if your throat isn’t sore anymore, your voice may still be hoarse or croaky.

So what happens to the voice when we get a virus? And what happens after?

Here’s what you should know if your voice is still hoarse for days – or even weeks – after your other symptoms have resolved.

Why does my voice get croaky during a cold?

A healthy voice is normally clear and strong. It’s powered by the lungs, which push air past the vocal cords to make them vibrate. These vibrations are amplified in the throat and mouth, creating the voice we hear.

The vocal cords are two elastic muscles situated in your throat, around the level of your laryngeal prominence, or Adam’s apple. (Although everyone has one, it tends to be more pronounced in males.) The vocal cords are small and delicate – around the size of your fingernail. Any small change in their structure will affect how the voice sounds.

When the vocal cords become inflamed – known as laryngitis – your voice will sound different. Laryngitis is a common part of upper respiratory tract infections, but can also be caused through misuse.

Catching a virus triggers the body’s defence mechanisms. White blood cells are recruited to kill the virus and heal the tissues in the vocal cords. They become inflamed, but also stiffer. It’s harder for them to vibrate, so the voice comes out hoarse and croaky.

In some instances, you may find it hard to speak in a loud voice or have a reduced pitch range, meaning you can’t go as high or loud as normal. You may even “lose” your voice altogether.

Coughing can also make things worse. It is the body’s way of trying to clear the airways of irritation, including your own mucus dripping onto your throat (post-nasal drip). But coughing slams the vocal cords together with force.

Chronic coughing can lead to persistent inflammation and even thicken the vocal cords. This thickening is the body trying to protect itself, similar to developing a callus when a pair of new shoes rubs.

Thickening on your vocal cords can lead to physical changes in the vocal cords – such as developing a growth or “nodule” – and further deterioration of your voice quality.

How can you care for your voice during infection?

People who use their voices a lot professionally – such as teachers, call centre workers and singers – are often desperate to resume their vocal activities. They are more at risk of forcing their voice before it’s ready.

The good news is most viral infections resolve themselves. Your voice is usually restored within five to ten days of recovering from a cold.

Occasionally, your pharmacist or doctor may prescribe cough suppressants to limit additional damage to the vocal cords (among other reasons) or mucolytics, which break down mucus. But the most effective treatments for viral upper respiratory tract infections are hydration and rest.

Drink plenty of water, avoid alcohol and exposure to cigarette smoke. Inhaling steam by making yourself a cup of hot water will also help clear blocked noses and hydrate your vocal cords.

Rest your voice by talking as little as possible. If you do need to talk, don’t whisper – this strains the muscles.

Instead, consider using “confidential voice”. This is a soft voice – not a whisper – that gently vibrates your vocal cords but puts less strain on your voice than normal speech. Think of the voice you use when communicating with someone close by.

During the first five to ten days of your infection, it is important not to push through. Exerting the voice by talking a lot or loudly will only exacerbate the situation. Once you’ve recovered from your cold, you can speak as you would normally.

What should you do if your voice is still hoarse after recovery?

If your voice hasn’t returned to normal after two to three weeks, you should seek medical attention from your doctor, who may refer you to an ear nose and throat specialist.

If you’ve developed a nodule, the specialist would likely refer you to a speech pathologist who will show you how to take care of your voice. Many nodules can be treated with voice therapy and don’t require surgery.

You may have also developed a habit of straining your vocal cords, if you forced yourself to speak or sing while they were inflamed. This can be a reason why some people continue to have a hoarse voice even when they’ve recovered from the cold.

In those cases, a speech pathologist may play a valuable role. They may teach you to exercises that make voicing more efficient. For example, lip trills (blowing raspberries) are a fun and easy way you can learn to relax the voice. This can help break the habit of straining your voice you may have developed during infection.

Yeptain Leung, Postdoctoral Research and Lecturer of Speech Pathology, School of Health Sciences, The University of Melbourne

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