Why are infectious disease outbreaks so common?

SARS-CoV-2. Monkey smallpox. Polio. Marburg. These viruses are no longer familiar only to public health professionals but are household names around the world, thanks to their recent incursions into human populations. Humans are always faced with all kinds of pathogens, but attacks are becoming more common and more intense than ever.

“We are going through an era of epidemics and pandemics, and they are going to be more complicated,” said Jeremy Farrar, director of Wellcome, a global health charity that tackles health challenges. and more often. “We tend to watch each [outbreak] in its own right, as a single volume. But the truth is that they are almost all a symptom of underlying drivers, all part of 21st century living.”

For instance, the world has seen previous outbreaks of polio, as well as clusters of smallpox in monkeys and the case of Marburg, a cousin of the dead. Ebola virus. We have even seen previous versions of SARS-CoV-2 during the coronavirus outbreaks of 2002 and 2012. So why are these outbreaks piling up, seemingly suddenly, all at once?

The explanation lies in bringing together a perfect storm of factors that influence almost every way we live our contemporary lives — from the ubiquity of worldwide travel to deeper encroachment. humans into previously unspoiled natural habitats, and modernization leads to climate change, urbanization, and overpopulation. Even the way we communicate instantaneously and unfiltered on social media plays a big part, as misinformation is often shared, trusted, and promoted as much as trusted messages. . Subsequently, the increasingly unstable and ruthless geopolitical balance has driven millions from their homes, into refugee camps and migrant homes, which are fertile ground for refugees. infectious diseases spread.

Simply put, the multitude of infectious diseases facing the world today “are just microbial evolution and humans about to collide”, says Michael Osterholm, Director of the Center for Research and Policy in Infectious Diseases at the University of Minnesota.

Read more: A hotter world means more disease outbreaks in our future

That look takes place more often as people get closer to nature. For example, coronavirus lives in bats, while influenza virus lives in bird populations; Both viruses are spread wherever animals roam, which is increasingly related to areas where they come into contact with humans.

Deforestation, climate change and urbanization make such interactions more likely. In the case of Ebola, experts say, the largest outbreak in West Africa in 2014 was likely amplified by the fact that urbanization has concentrated more people to more crowded cities. compared to cases of the virus first reported in people in the 1970s. “In the 1990s and 2000s, Ebola remained unchanged; What has changed is that Ebola used to be a rural disease that used to affect isolated villages, but has not yet reached major urban centers,” said Osterholm. Urbanization and overcrowding in large cities, where sanitation and social distancing are not always practical, mean that viruses and bacteria find new hosts more easily.

Travel has also improved with urbanization. And air travel doesn’t just transport people; it also carries any viruses and bacteria that might be hiding in other parts of the world for a few hours. The recent outbreak of monkeypox, spread to 94 countries in three months, for example. The virus, endemic to Central and West Africa, rode people from that region to festivals around the world, then landed in rarely reported countries. “If monkeypox had occurred 100 years ago, the world would be unlikely to see any real global challenge, because transportation is so slow and incomplete it would be,” Osterholm said. won’t spread the way modern air travel can,” said Osterholm.

There may be another powerful force at work that makes such confrontations between humans and pathogens more significant and even more lethal. Viruses and other bacteria are not individual pathogens, but exist as a dynamic and ever-evolving community. Every encounter with humans is an opportunity for pathogens such as viruses to become more active and more sophisticated in infecting and causing disease in humans. That may be the case with the coronavirus; For example, SARS and MERS cause infections with high mortality but are not effectively transmitted from person to person. However, the next-generation virus SARS-CoV-2 has finally found a way to spread easily from a human host to another.

Something similar could happen with monkeypox. US scientists, working with their partners in Nigeria, where the virus is endemic, started noticing changes in the virus a few years ago. “They found that the virus was more effective at transmitting disease from person to person,” said Dr Raj Panjabi, senior director for global security and biosecurity at the White House National Security Council. . “It was an alarm bell. It signals that maybe the transmission has changed because the virus is better adapted to [live] between us.” Farrar noted that with each previous outbreak of monkeypox in Africa, the chain of infection — one person to another — got progressively longer, “and the infection lasted longer, “Instead of one or two people infected, now five to six people, then 10 to 12 people,” he said.

All of these converging factors, Osterholm says, put the world in jeopardy. “Any of these is a problem for public health,” he said. “Add them all together, and you have a crisis.”

Do people have a chance? “I think we’re in the most vulnerable moments we’ve ever had in our professional careers,” Farrar said. He sees the greatest threat to everyone’s ability to prevent major pandemics from our inability to cooperate, share public health information, and build a defense system. effective defense against infectious diseases. “Ignoring biodiversity, land use, habitat protection and social media, the biggest challenge is geopolitics,” he said, citing invasions in Eastern Europe, tensions East-West and inequalities in health resources and health infrastructure between developed and developing countries. “Unless we address the geopolitical issues, I am afraid we will not see what is emerging from China, Europe, Africa, the Americas and Southeast Asia. We have to come back to understand that the world is very small, and we are all interconnected. “

Read more: Virus hunters are trying to prepare for the next pandemic

He is optimistic that COVID-19 and other ongoing outbreaks may have finally awakened global awareness of this need for cooperation. The World Bank recently raised a $10 billion annual fund dedicated to helping countries in the developing world improve surveillance methods to detect and – most importantly – share Share information about unusual infectious disease cases that may pose new public health threats. These funds will support these countries’ networks of public health workers and lab testing capabilities, as well as their access to tests, vaccines and treatments. Farrar noted that global donations to the fund, including from China, are hopeful signs that “maybe this is a way to bring the world together again” in the face of challenges. preparedness for the pandemic.

But developed countries need to lead by example. The United States is making some progress; President Biden revived the Biodefense and Global Health Security Directorate, headed by Panjabi, after it was dissolved under the Trump Administration. Biden has proposed a record $88 billion investment to prepare the country against the next pandemic threat, spreading in five years, which would prioritize investments in research, testing, vaccines and therapeutics. treatment, as well as monitor new diseases and build a supply of personal protective equipment and trained healthcare workers who can be deployed during a public health emergency. “Never before has so much money been requested for pandemic preparedness and global health security,” Panjabi said.

Securing that amount will be a huge challenge. But such an investment is ultimately the most cost-effective way to combat public health threats, before new disease cases swarm – then outbreaks, epidemics and pandemics. “The more we do to strengthen national public health institutions — not just in the United States but around the world — the better prepared we will be,” says Panjabi. “These investments are geared toward ambitious goals, such as developing effective vaccines and treatments within 100 days of threat identification, producing sufficient quantities to inoculate the US population within 130 days and support increased production to rapidly respond to global demand.”

Responding quickly and effectively will have to become routine if we are to deal with the onslaught of outbreaks that are bound to come our way. “Microbiological evolution is alive and well,” says Osterholm. “We are fighting an enemy that is growing and changing daily to adapt as the world changes.”

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