COVID, bird flu, MPox – a virologist on why so many viruses are emerging

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From the widespread outbreak of Mpox (formerly known as monkeypox) in 2022, to the evolution of bird flu, to the recent cases of Marburg virus in Equatorial Guinea, COVID is not dominating the headlines as much as it used to be. Instead, we regularly hear about outbreaks of emerging or re-emerging viruses.

So is the frequency of virus outbreaks increasing? Or have we just gotten better at spotting outbreaks thanks to improved technology developed during the COVID pandemic? The answer can be a little bit of both.

Read more: Three years later, the COVID pandemic may never end – but the public health impact is becoming increasingly manageable

An estimated 1.67 million viruses currently infecting mammals and birds have yet to be identified. Up to 827,000 of these are believed to have the potential to infect humans.

To understand how viruses come about, we need to go back to the beginning of life on Earth. There are several theories as to how the first viruses came about, but all agree that viruses have existed for billions of years and evolved along with living things. If this stable co-evolution is disrupted, we can get into trouble.

The main drivers of viral emergence in the human population are people and their actions. Farming became a common practice more than 10,000 years ago, and this is how humans began to come into close contact with animals. This provided an opportunity for the viruses that naturally infected these animals to “species jump” onto humans. It’s called zoonosis. Around 75% of newly emerging infectious diseases are due to zoonoses.

As human civilization and technology advanced, the destruction of animal habitats forced animals into new areas in search of food sources. Different species that normally would not have been in contact now shared the same environment. Add humans to this equation and you have the perfect recipe for creating a new virus.

Urbanization leads to high population density and creates an ideal environment for the spread of viruses. The rapid development of cities often outstrips adequate infrastructure such as sanitation and health care, further increasing the likelihood of virus outbreaks.

Climate change also contributes to the spread of viruses. For example, arboviruses (viruses transmitted by arthropods such as mosquitoes) are being detected in new areas as the number of countries where mosquitoes can survive increases.

We have known about these factors for a long time. The emergence of SARS-CoV-2 (the virus that causes COVID) has not surprised any virologist or epidemiologist. It was a question of when – not if – a pandemic would occur. What was unexpected was the scale of the COVID pandemic and the difficulty in effectively containing the spread of the virus.

Nor could we anticipate the impact misinformation would have on other areas of public health. In particular, anti-vaccination sentiment has become increasingly prevalent on social media in recent years and we are seeing increasing hesitancy to vaccinate.

There have also been disruptions to routine childhood immunization programs, increasing the risk of outbreaks of vaccine-preventable diseases like measles.

lessons in surveillance

Science has moved at an unprecedented pace during the COVID pandemic, leading to the development of new and improved virus detection methods to monitor outbreaks and the development of the virus. Now many of the scientists involved in tracking SARS-CoV-2 are turning their attention to monitoring other viruses as well.

For example, wastewater monitoring has been used extensively during the pandemic to detect SARS-CoV-2 and could similarly help detect other viruses that pose a threat to human health.

Normally, when a person is infected with a virus, some of that virus’s genetic material is flushed down the toilet. Sewage has the power to show if the number of infections is increasing in an area, usually before hospital case counts begin to rise.

Adapting this technology to look for other viruses such as influenza, measles or even polio could give us valuable data on the timing of virus outbreaks. Some of this is already happening – in London, for example, the polio virus was detected in wastewater in 2022.

Read more: We measured vaccination confidence before the pandemic and in 2022 – it’s dropped significantly

Of course, this increase in virus surveillance will result in more virus outbreaks being reported. While some people see this as scaremongering, information like this could hold the key to containing future pandemics. If an outbreak occurs in an area that does not have adequate virus surveillance, the infection is more likely to spread too far to be easily contained.

However, surveillance is only part of pandemic preparedness. Governments, health and scientific agencies around the world need to have (regularly updated) logs of virus and pandemic occurrences so we don’t make the effort to understand a situation when it may already be too late.

COVID will likely not be the last pandemic many people alive today will experience. Let’s hope we’ll be better prepared next time.

This article was republished by The Conversation under a Creative Commons license. Read the original article.

The conversation

The conversation

Lindsay Broadbent has previously received funding from The Wellcome Trust.

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