Changing nature of modern society on infectious diseases and pandemics.

During the twentieth century medical science made tremendous progress in defeating many diseases which had periodically ravished mankind over the millennia. While one disease after the other was outsmarted by science or contained through better management, changes in the way humans organize their societies introduced new diseases. In previous centuries diseases travelled with passengers on slow moving ships while the ill would often be quarantined when they arrived, however todays diseases spread with the speed of jetliners, travelling as uninvited guests on aircraft. The changing nature of modern transport has enabled epidemics to become pandemics at speeds unknown in previous generations.

The 2002–3 SARS pandemic is a perfect example of what would probably have remained a localized disease taking on global dimensions. Other changes to modern society have created new infectious diseases in the foods people consume. Population increases have necessitated industrialized food production as a means to keep prices down. As a result cattle and fish are being bred and fed in ways unknown to previous generations. In the 1990s industrialized cattle fed on a meal which included tainted waste meat products infected bovine with mad cow disease. Contaminated beef which was consumed by humans resulted in the deadly vCJD disease whose incubation period is so long, the full extend to the condition may still not be fully appreciated.

These diseases were similarly a byproduct of modern living. Industrialized aquaculture has similarly produced formerly unknown diseases occurring in farmed fish and prawns. Overpopulation, especially in poorer countries has compelled people to move into formerly uninhabited country where people have come into contact with wild animals. Ebola virus originated with bats who were likely hunted for their meat. While Ebola is not new the most recent outbreak threatened the entire planet after several cases appeared outside its African host countries. Likewise HIV/AIDS originated with primates and transferred to humans where changing social values allowed it to spread rapidly as a result of sexual promiscuity and intravenous drug taking. While treatments have dealt with modern diseases, diseases themselves have also evolved and in recent years superbugs which are immune to vaccines and treatments have emerged which threaten traditional remedies. Modern transport, population explosions, economic pressure and changes in social morals have all played their part in the spread and potential spread of today’s infectious diseases.

Today infectious diseases have the potential to explode into a global pandemic with the speed and ferocity of a Hollywood apocalyptic movie, thanks to the speed of air travel. In the 1995 movie 12 Monkeys (Gordinier 1995) a terrorist releases a virus at an international airport where the pathogen is instantly carried by other travellers on their flights across the globe. Elements of this far-fetched story actually occurred in 2002–3 when the severe acute respiratory syndrome (SARS) virus spread from its Hong Kong epicenter to distant locations by air travel, most notably Toronto and Singapore. Weeks after the first diagnosis 37 countries reported infected individuals of which 774 of the diagnosed 8096 cases resulted in fatalities (Smith 2006). Rapid containment in affected cities and global precautionary measures at airports are credited with containing the potential deadly pandemic.

While human deaths were relatively minimal the most significant casualty of SARS was international air travel with the travelling public avoiding high risk destinations in Asia or postponing travel altogether (Enserink 2013). A modern innovation, international air travel, had permitted SARS to threaten the world’s health, but another modern solution also contained and erased the same threat; sophisticated containment strategies. Prior to air travel SARS may have remained a localized disease restricted to southern China incapable of spreading with the speed that 21st century technology enabled it to. In the past similar diseases moved slowly or simply remained localized, something international air travel has put an end to.

Scientific and technological changes to farming techniques, especially made in the post-WWII era have fundamentally changed the nature of human diets with the introduction of factory farming and aquaculture. The industrialization of food production, necessitated by population growth and a need to reduce the cost of foodstuffs is both directly and indirectly responsible for the emergence of several new diet related diseases which have spread to humans. Mad cow disease (Ramasamy et al. 2003) and a variety of diseases spread through aqua-fisheries (Walker & Winton 2010) are directly associated with high density industrialized farming and the introduction of artificial or unnatural feedstock’s. Bovine spongiform encephalopathy (BSE) more commonly referred to as mad cow disease became epidemic in British cow herds in the 1990s and through the food chain spread as a human variant known as Creutzfeldt–Jakob disease (vCJD). It was established that BSE resulted from cows, which are naturally herbivores, receiving supplements whose ingredients included meat and bone meal (MBM) from other cattle.

It is believed MBM became contaminated with diseased sheep who had scrapie by being processed in the same meat works. BSE has an incubation period of 2.5–8 years with a correspondingly long incubation period in humans; consequently the full extent of vCJD may still not be fully known (Nathanson, Wilesmith & Griot 1997). Similarly aquatic species removed from their natural environments and farmed in high density and fed diets of processed fish meal which is unnatural to the species, experience environmental stress during their growth phases. As a direct consequence new marine borne diseases have emerged such as the hematopoietic necrosis virus (IHNV), viral haemorrhagic septicemia (VHS), spring viraemia of carp (SVC), infectious salmon anaemia (ISA), koi herpesvirus (KHV), epizootic haematopoietic necrosis and other ranavirus diseases (EHNV) and numerous other emerging diseases (Walker & Winton 2010).

Some of these diseases potentially affect the health of humans who consume diseased fish and products made with diseased fish. Of particular concern are diseases which have the potential risks associated with bioaccumulation. Ultimately diseases such BSE and the growing number of fish and shrimp variants are caused by human intervention in the diets and life cycles of these animals, which humans later ultimately consume. Changes in modern society have compelled mankind to intensify farming techniques which has potentially sown the seeds for infectious diseases spreading to humans through their modern diet.

Overpopulation has resulted in humans colonizing parts of the planet where people formerly have not dwelt. This has resulted in humans deforesting large parts of the planet such as Brazil and Myanmar and building cities in deserts such as Saudi Arabia’s capital Riyadh. Human settlement is now found on the fridges of habitable existence, practically everywhere. As a result humans have come in contact with localized diseases which formerly had few possibilities of infecting people or may have been restricted to animals only. Poverty caused by overpopulation has further compelled humans to consume plants and wild animals that former did not form part of traditional diets, often with devastating consequences (Williams 2012). In Africa animal-to-human transmission of ebola hemorrhagic fever, more commonly known simply as Ebola came through the consumption of wild ‘bush meat’.

Bats are believed to the natural reservoir host of Ebola and human hunting of wild bats has resulted in periodic outbreaks of the disease since its first appearance in Southern Sudan in 1976. Ebola has repeatedly mutated with different strains appearing until the most recent epidemic in West Africa in 2014 (Centers for Disease Control and Prevention 2014). The present outbreak of the disease threatened to unleash a global pandemic as several cases escaped quarantined zones established in response to the crisis. Due to the contagious nature of the disease, ineffectiveness of treatments and possibility of transmission by foreigners sent to help the sick, global precautions were made to combat the disease in the event of a global outbreak. Consequently a disease originating from local bats spread to humans and through modern travel threatened the world’s population. This occurred because human’s encroached the domains of wild animals and poverty caused people to hunt them for food.

HIV/AIDS is another disease whose transmission from wild animals to humans has spread rapidly because of aspects of human society to became a global pandemic. The earliest known case of HIV dates to 1959 (Zhu et al. 1998) and the first US case may be from 1969 (Gilbert et al. 2007) yet HIV’s precursor virus dates back to the 1910s when HIV-1 and HIV-2, which were both present in central African primates, transferring from apes to humans, possibly through bush meat hunting or via some unknown high risk transmission channel. HIV is most commonly transferred through the exchange of bodily fluids, most commonly through sex, (particularly male to male) and intravenous drug use. Additionally studies have shown that uncircumcised men have a higher chance of become infected. Research conducted by de Sousa et al. (2010) suggests the emerge of HIV in Congo occurred because of the high rates of genital ulcer disease (GUD) combines with low rates of male circumcision during a period of high sexual promiscuity.

Ultimately by the time HIV hit the homosexual community in the early 1980s its rapid spread similarly resulted from high levels of sexual promiscuity in an era of unprotected sex. Some conservative religious groups observed that societies who maintained traditional family values and shunned sexual promiscuity and drug taking were effectively shielded from HIV. It could be argued that a 20th century relaxation of values which became a characteristic of contemporary human societies was a social factor which permitted the spread of HIV (Kerr 2011). This coupled with widespread movement of people through international travel permitted HIV to spread globally.

Today’s human societies are characterized by high levels of medical care in many advanced societies with substantial amounts of antibiotics and other medication taken regularly. Contagious diseases and viruses which once claimed millions have effectively been eliminated through universal vaccinations. Through a principle of herd immunity, global and national organizations have sought to immunize entire societies by vaccinating everyone. Smallpox, diphtheria, whooping cough, measles, neonatal tetanus, hepatitis B, tuberculosis and polio have all been effectively controlled through precautionary vaccination (Dowdle 1998). However diseases are becoming resistant to vaccinations and antibiotics which pose a potential threat to everyone whether they are treated or not. Diseases and viruses outmaneuver drug treatments, just as drugs seek to adjust to reflect mutations in diseases. An example of a resistant mutation is the New Delhi Metallo-beta-lactamase-1 (NDM-1) (Kumarasamy 2010). NDM-1 is an enzyme, belonging to a family of enzymes called carbapenemases which causes bacterial resistance to a wide range of beta-lactam antibiotics.

It has been described as a superbug as it renders many treatments ineffective. Although mutated treatment resistant super-bugs such as NDM-1 are yet to result in widespread deaths their potential to neutralise standard treatments is a serious concern to the medical profession. It is assumed the evolution of antimicrobial resistant superbugs resulted from exposure to regular drug treatments and vaccines (Cassir, Rolain & Brouqui 2014) which is a consequence of living in a heavily medicated society such as the one currently prevailing.

Advances in medical treatments have significantly reduced the risk of disease to global health, however similar advancements in transport have enabled their appearance and spread at lightning pace. Thanks to international air travel diseases which once might have remained confined to localized areas or would have spread at the speed of sailing ships can now appear in multiple locations in practically no time at all, as occurred with SARS in 2002–3. Soon after appearing in Hong Kong the disease was carried by an airline passenger to Toronto where it potentially could have spread through further contact with airline passengers. While technology enables some diseases to spread, unnatural industrialized farming has caused others. In the 1990s mad cow disease resulting from cattle consuming processed meal pallets containing diseased waste meat products caused some people who consumed beef to develop the human version of the disease, vCJD. Similarly industrialized fish farming has seen the unnatural life cycles and diets of farmed fish and prawns develop previously unknown diseases which have the potential to infect humans who consume diseased fish products.

The pressures of overpopulation which are ultimately responsible for causing industrialized farming have compelled others to move into unpopulated areas where they have come into contact with wild animals and their diseases, previously contained to non-humans. The animal-to-human transmission of diseases has occurred on many occasions with bats infecting humans with Ebola virus and primates infecting humans with HIV/AIDS. While Ebola has threatened mankind by its ability to infect travellers, HIV has spread through a mixture of sexual promiscuity and intravenous drug taking; both a characteristic of modern societies. While changing values facilitate the spread of some diseases and transport moves other, new superbugs have developed which threaten humanity by their resistance to current treatments. Just as mankind has outsmarted some viruses and diseases, many have outsmarted man. While modern society’s technological and scientific advances have dealt with many ailments some of these same advancements are a cause for the spread of infectious diseases and the launching of potential pandemics.

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