Historical records show that pandemics have long been a catastrophic threat to the health of human populations around the world, shaping the destiny of mankind. For instance, the Black Death (Yersinia pestis) is estimated to have killed between 30 and 60% of Europeans in the 14th century, and the Spanish influenza pandemic of 1918-19 claimed the lives of more people than the two world wars combined. Despite our continuous progress in eradicating or controlling infectious diseases, microbes constantly evolve ways to bypass or find loopholes in current therapies, posing a ticking time bomb for human health. Along with atomic weapons and looming climate change, they represent the greatest threat to our species.
The fight against infectious diseases requires worldwide research and surveillance by scientists, physicians, and public health officials who gather information, report new or resurgent outbreaks, and develop therapies, regimens and guidelines for treating and controlling disease. Immunisation has long been the most effective way to prevent the spread of infectious diseases. Yet, vaccines exist only against a limited number of pathogens, and despite decades of intensive research there is still no efficient vaccine against tuberculosis (TB), malaria, or HIV. Moreover, controversies about established vaccines have erupted time and again throughout the twentieth century, and continue to this day. Opponents question their effectiveness, safety, and necessity. They also argue that mandatory vaccinations violate individual rights to make medical decisions and follow religious principles. To be effective immunisation programmes depend on public confidence. A modern and infamous example of anti-vaccine propaganda is the scientifically disproven claim of vaccines causing autism. Loss of public confidence as a result of such unsubstantiated claims is contributing to a significant increase in preventable infectious diseases today.
A second pillar of public health has been the development of anti-infective drugs. Their poster child, antibiotics, has been instrumental in the fight against infectious diseases, a major achievement of modern medicine in the twentieth century. Yet alarmingly, an increasing number microorganisms that are resistant to most or even all current medication have emerged in the past two decades, rendering diseases that were once treatable deadly again, and posing an imminent threat to public health. In this post-antibiotic era, development of new therapies is imperative for us to maintain our current living standards and life expectancy. However, knowing how difficult it is to develop new antibiotics, stewardship of current available medication is equally vital in this fight against pathogens. Physicians must prescribe antibiotics carefully, and use of antibiotics in food production must be closely monitored. The more widely anti-infectives are used the more likely it is that resistant strains of microorganisms will emerge. Without a global effort to halt the spread of resistance and increase support for the development of new antibiotics situations unseen since the early 1900’s may arise, where a simple cold or wound could prove deadly.
It is important to remember that when it comes to infectious diseases, sadly those living in the poorer parts of the world are still much more susceptible than those living in the wealthier parts. Infectious diseases are responsible for half of all deaths in the developing world, and almost exclusively for infant mortality. In a very real way, many infectious diseases are diseases of poverty. Today, malaria, TB and cholera are endemic only in the developing world, and while medication to treat them exists, this is often unattainable to those in need, or inefficient because resistance has emerged. Poor sanitary conditions exacerbate the situation, and effective vaccines are still lacking for malaria and TB. Similarly, while most people in the developed world have access to drugs that can now enable them to live relatively ‘normal’ lives with HIV/Aids, it remains a death sentence in poor countries. The drugs that suppress the virus and keep people well in the affluent north are still too expensive for most of the 40 million infected with HIV throughout the rest of the world.
Finally, we may have to face a man-made, entirely new dimension of threat from epidemics: bioterrorism. This refers to the deliberate release of viruses and bacteria to cause illness or death in people, animals, or plants. These agents are typically found in nature, but could be genetically mutated or altered to increase their ability to cause disease, make them resistant to current medicines, or to increase their ability to be spread into the environment.