Are Pandemics on The Rise?

While the world is being ravaged by the COVID-19 pandemic, modeling taking several factors into account shows that the next pandemic could be much closer than we think, and pandemics will be more frequent.

The World Health Organization warned in its 2007 report that infectious diseases are emerging at a rate that has not been seen before. Since the 1970s, about 40 infectious diseases have been discovered, including SARS, MERS, Ebola, avian flu, swine flu, Zika, and SARS-CoV-2.

Climate Change

Climate change is dominating our lives and causing a high level of distress. Countries all over the world are struggling to survive the damage caused by extreme events. They are trying to control wildfires, rebuild roads and houses damaged by floods, and learn to survive in a hotter and more dangerous world. However, there is also a new threat that is being overlooked—the interaction between climate change and infectious diseases.

Climate change could aggravate more than 50% of known human pathogens. Pathogens frozen in the permafrost, for which no immunity currently exists, may be released as the climate continues to warm. Such a notion may be considered alarmist.

There are several ways that climate hazards aggravate infectious diseases, both directly and indirectly. These include the slow rise in temperature; changes in environmental conditions that increase the dispersal of disease vectors such as mosquitoes, rodents, and ticks; and the sudden appearance of extreme events such as floods, which contaminate drinking-water sources and trigger the displacement of humans and animals, which can carry and transmit pathogens.

Climate change can also drive populations to migrate, causing more interactions with wildlife and increasing the risk of spillover of pathogens. Scientists anticipate that 2024 will be an even warmer year because of an El Niño event (a climate pattern that results in the warming of surface waters in the eastern Pacific Ocean). This will likely produce severe drought in some regions of the world, potentially spurring mass migrations.

Refugees

About 50 million people were either displaced or refugees, due to wars or natural calamities. Refugee camps and shelters are fertile soil for an outbreak, being very like slums in their lack of basic hygiene facilities, accumulating people from multiple regions, overcrowding, poor medical care, and susceptibility to vectors as well as animals that spread disease. For example, half a million refugees from Rwanda died in just one month due to cholera and dysentery in the Zaire camp – accounting for approximately one in ten of those who arrived at the camp.

Travel

A huge increase in globalization and connectivity has meant that disease agents can spread from one side of the world to another within a few hours. While infectious pathogens are spread by travelers, the latter also introduce other types of disease factors, related to new farm technology, novel drugs, and medical treatments, and the use of chemicals and pesticides. These often produce a long-term effect on the region that lasts for generations.

Signs of development such as clearing old forest, building dams for power and irrigation, and cutting roads into remote locations, are all linked with large-scale movements of people, along with shifts in the range and prevalence of infectious diseases in those regions, including schistosomiasis, sexually transmitted disease, and malaria.

The means of transportation, such as ships or aircraft, provide space for microbes to spread, either on a large scale such as cholera and other foodborne infections or from one individual to another, such as tuberculosis or the flu.

Urbanization

The world is transitioning to being more urban. In many cases this means an increasing number of people living in overcrowded and unhygienic environments in which infectious diseases can thrive, without adequate health systems that can deal with these threats.

We are experiencing the process of global large-scale urbanization and nearly 70% of the world’s population will live in urban areas by 2050 according to the World Urbanization Prospects issued by the United Nations. Urbanization has the pros and cons like a double-edged sword. Improved health services, better infrastructure and more employment opportunities benefit people a lot, but the overcrowding, environmental pollution, dietary changes, and traffic jam may cause health problems.

As a complex dynamic process, urbanization is associated with human, domestic poultry, wild birds, environment and even expanded interfaces of contacts among them, which may all result in increased vulnerability to infectious disease. The influence of urbanization on infectious diseases will be very heterogeneous and the local diseases and health challenges can greatly differ.

Shortage of Health Workers

Healthcare workforce shortage is a worldwide problem. Healthcare is one of the most complex public systems of the modern era, under constant intense pressure from changes in biomedicine and society. The coronavirus disease 2019 (COVID-19) pandemic has once again shown how the health status of the population is reflected in all segments of society. It has also shown the importance of comprehensive and sustainable human resources management in health care.

Constant migration of health workers from low- and middle-income countries to high-income countries depleted the health workforce in many nations in the regions where epidemic diseases, with the potential to become pandemics, are most likely to originate. Countries with inadequate health workforce in the health systems can easily be vulnerable to the increasing threat of disease outbreaks.

Bats and The Next Pandemics

Viruses that jump from animals to humans are the likely sources of major health threats. Viruses that spill over from bats to humans have caused some of the world's deadliest outbreaks. The latest COVID-19 pandemic is potentially just one example, as a virus related to coronaviruses in bats.

Widespread deforestation, mining for minerals and metals, and building roads and railways have meant that we are constantly invading bat habitats, making it much more likely that humans and bats will come into contact.

Bats are super-incubators for viruses. The way that bats live means they are the perfect species to allow viruses to multiply. They often roost close together with other bat species, meaning that the viruses can spread and evolve, and as bats fly hundreds of kilometers hunting for food, they can spread those viruses far and wide.

Even before COVID-19, viruses carried by bats, such as Ebola, Marburg, SARS, and Nipah, together have triggered more than 90 outbreaks, infecting about 44,000 people and killing more than 16,000. COVID-19 alone has killed nearly seven million, which is a conservative estimate, as the real number is likely to be much higher.

Bats scatter viruses in their saliva, urine, blood and excrement. These can then infect people either directly when they come into contact with these substances, or via an animal that gets infected.

Bats are getting stressed as we are disrupting their habitats and affecting their food supply. We are stressing out bats in a variety of different ways, and that makes them more prone to illness and makes them more likely to shed viruses that can then go on to infect people. Just like when we're stressed, we're more likely to get sick. The same goes for bats.

Countries that are densely populated and that are pursuing industrial development at breakneck speed are likely to be hotspots for virus spillover.

Antimicrobial Resistance

Antimicrobial resistance is the acquired resistance of pathogens to antimicrobial medications such as antibiotics. Bacteria, viruses, and other microorganisms can change over time and develop a resistance to the drugs used to treat diseases caused by the pathogens. Therefore, drugs that were effective in the past are no longer useful in controlling disease.

Decline in Vaccine Coverage

Even when a safe and effective vaccine exists, a growing number of people choose not to become vaccinated. This has been a particular problem with the measles vaccine. Measles, a highly contagious and serious infection that was eliminated from the U.S. in 2000 and from the Western Hemisphere in 2016, has returned in certain areas due to an increase in the number of people opting to take nonmedical vaccine exemptions for reasons of personal and philosophical belief. This has been driven by an anti-vaccine movement that was founded largely on an invalid and discredited study that claimed a link between a vaccine against measles and autism. As a result of the decline in vaccine coverage, measles cases are highest by far this decade with more than 1,000 cases of measles reported in the U.S. in the first half of 2019.

Four million deaths worldwide are prevented by childhood vaccination every year. The Covid-19 pandemic lockdowns, misinformation campaigns, conflicts, climate crises and other problems diverted resources and contributed to the largest backslide in routine immunization in 30 years. Combined with rapidly rising rates of malnutrition, it has created conditions that could threaten the lives of millions of young children.