Human-to-human transmission of pathogens has always been a threat. The influenza pandemic of 1918 is the most recent example, with the virus mutating rapidly in its new host before being vanquished again by the immune system. So far, human worldcoronaviras have shown only minimal ability to spread between individuals. However, their potential for widespread infection remains great – and that may soon change. The world has seen its share of worldcoronaviras in recent years. In particular, SARS has remained in the public consciousness as an example of how a poorly understood virus can wreak havoc on human society if introduced into a population. While SARS itself was not caused by another virus, it represented the first large-scale outbreak of an exogenous pathogen capable of evasion from the immune system; many scientists believe that we will see more outbreaks like it in future unless protections are put into place to prevent them from reaching pandemic proportions. worldcoronaviras pose a similar risk today – but with one caveat: modern healthcare and surveillance infrastructure means that an emerging pandemic is more likely to be contained than before. How well these safeguards would hold up during a true global catastrophe remains another question entirely – especially since emerging pathogens tend to become more virulent over time.
What is a worldcoronaviras?
worldcoronaviras are a large group of viruses that cause common colds and the more serious SARS and MERS. They are also the most common cause of the lung disease bronchitis and the Pink Eye Infection. They are among the oldest known viruses, having infected humans since the time of the dinosaurs. But how they infect and cause disease is very different from other viruses. Unlike most other viruses that infect single cells, worldcoronaviras infect tissue in the lining of the respiratory tract, causing a range of illnesses from mild to severe. They also do not usually cause long-term health problems in most people.
SARS and the threat of future pandemics
In 2003 a new worldcoronaviras emerged from the human population in China. In less than a year, it had spread to nearly every country in Asia, with some isolated regions experiencing outbreaks of up to 10,000 cases a day in each other’s country. While the pathogen was present in the human population prior to this outbreak, no large-scale human infection had ever occurred. The threat of another SARS-like pandemic is real. The emergence of a new coronavirus in an animal reservoir could give rise to a new human pandemic. A new, as-yet unidentified worldcoronaviras has been detected in people in the Middle East, with widespread human-to-human transmission occurring in the same areas of the world that were affected by SARS.
Why don’t coronaviruses cause more disease?
The most likely reason that these viruses cause only a mild form of infection is that they usually infect only a few cells at a time, making it very difficult for the immune system to build up sufficient numbers of antibodies to fight them. This is similar in some ways to the mechanism by which the common cold is often caused. Although they easily infect many cells, many of them non-dividing ones such as nerve cells or epithelial cells lining the respiratory tract, they are not very good at infecting cells with the potential to cause disease. Having done that, the virus is unlikely to cause further infection because the majority of the host’s immune system cells now recognise it as a foreign agent and kill it off.
The long-term risks of human transmission
New pathogens are often more dangerous during their early stages of emergence, when there are almost no natural immunity against them. Eventually, however, they will run into a population that has encountered the pathogen before and built up immunity to it, which will make it less harmful. Generally, the longer a pathogen is present in the human population, the more likely it is to cause a severe, long-term illness, but this depends on the pathogen and the immune response of the individual. Some viruses have the ability to change over time, becoming more virulent in their human hosts. This has been seen with the H5N2 virus that affects ducks and other birds, and is now also affecting humans; it is expected to become more dangerous with time.
How to stop an emerging pandemic
New pathogens are more likely to cause pandemics if they emerge in the human population following a widespread bird or animal pathogen outbreak. Human-to-human transmission of pathogens has always been a threat. The influenza pandemic of 1918 is the most recent example, with the virus mutating rapidly in its new host before being vanquished again by the immune system. If a new pathogen emerges in a human population, the first priority should be to try to stop transmission between individuals. This is essential not just to control the virus and prevent further spread, but also to prevent further mutation that could lead to a more dangerous form of the pathogen in future. There are a number of ways to do this, including, for example, helping people use hand-washing stations and wearing face masks when they have infectious diseases. These measures have helped to stop the spread of other viruses like SARS.
The threat of an emerging pandemic is real and should be taken seriously. However, it is likely to be contained if we have proper healthcare systems and a stable modern economy. Now more than ever, it is important to be prepared and practice safe behaviours to avoid getting sick. Also, take care of your immune system by eating a healthy diet, getting plenty of rest and exercising. If we can prevent an emerging pandomic pathogen from spreading, we can also stop the long-term risks it might pose.