Globalization and disease
, the flow of information, goods, capital, and people across political and geographic boundaries, allows infectious diseases to rapidly spread around the world, while also allowing the alleviation of factors such as hunger and poverty, which are key determinants of global health. The spread of diseases across wide geographic scales has increased through history. Early diseases that spread from Asia to Europe were bubonic plague, influenza of various types, and similar infectious diseases.
In the current era of globalization, the world is more interdependent than at any other time. Efficient and inexpensive transportation has left few places inaccessible, and increased global trade in agricultural products has brought more and more people into contact with animal diseases that have subsequently jumped species barriers.
Globalization intensified during the Age of Exploration, but trading routes had long been established between Asia and Europe, along which diseases were also transmitted. An increase in travel has helped spread diseases to natives of lands who had not previously been exposed. When a native population is infected with a new disease, where they have not developed antibodies through generations of previous exposure, the new disease tends to run rampant within the population.
Etiology, the modern branch of science that deals with the causes of infectious disease, recognizes five major modes of disease transmission: airborne, waterborne, bloodborne, by direct contact, and through vector. As humans began traveling overseas and across lands which were previously isolated, research suggests that diseases have been spread by all five transmission modes.
Travel patterns and globalization
The Age of Exploration generally refers to the period between the 15th and 17th centuries. During this time, technological advances in shipbuilding and navigation made it easier for nations to explore outside previous boundaries. Globalization has had many benefits, for example, new products to Europeans were discovered, such as tea, silk and sugar when Europeans developed new trade routes around Africa to India and the Spice Islands, Asia, and eventually running to the Americas.In addition to trading in goods, many nations began to trade in slavery. Trading in slaves was another way by which diseases were carried to new locations and peoples, for instance, from sub-Saharan Africa to the Caribbean and the Americas. During this time, different societies began to integrate, increasing the concentration of humans and animals in certain places, which led to the emergence of new diseases as some jumped in mutation from animals to humans.
During this time sorcerers' and witch doctors' treatment of disease was often focused on magic and religion, and healing the entire body and soul, rather than focusing on a few symptoms like modern medicine. Early medicine often included the use of herbs and meditation. Based on archaeological evidence, some prehistoric practitioners in both Europe and South America used trephining, making a hole in the skull to release illness. Severe diseases were often thought of as supernatural or magical. The result of the introduction of Eurasian diseases to the Americas was that many more native peoples were killed by disease and germs than by the colonists' use of guns or other weapons. Scholars estimate that over a period of four centuries, epidemic diseases wiped out as much as 90 percent of the American indigenous populations.
In Europe during the age of exploration, diseases such as smallpox, measles and tuberculosis had already been introduced centuries before through trade with Asia and Africa. People had developed some antibodies to these and other diseases from the Eurasian continent. When the Europeans traveled to new lands, they carried these diseases with them. When such diseases were introduced for the first time to new populations of humans, the effects on the native populations were widespread and deadly. The Columbian Exchange, referring to Christopher Columbus's first contact with the native peoples of the Caribbean, began the trade of animals, and plants, and unwittingly began an exchange of diseases.
It was not until the 1800s that humans began to recognize the existence and role of germs and microbes in relation to disease. Although many thinkers had ideas about germs, it was not until French doctor Louis Pasteur spread his theory about germs, and the need for washing hands and maintaining sanitation, that anyone listened. Many people were quite skeptical, but on May 22, 1881, Pasteur persuasively demonstrated the validity of his germ theory of disease with an early example of vaccination. The anthrax vaccine was administered to 25 sheep while another 25 were used as a control. On May 31, 1881, all of the sheep were exposed to anthrax. While every sheep in the control group died, each of the vaccinated sheep survived. Pasteur's experiment would become a milestone in disease prevention. His findings, in conjunction with other vaccines that followed, changed the way globalization affected the world.
Effects of globalization on disease in the modern world
Modern modes of transportation allow more people and products to travel around the world at a faster pace; they also open the airways to the transcontinental movement of infectious disease vectors. One example is the West Nile virus. It is believed that this disease reached the United States via "mosquitoes that crossed the ocean by riding in airplane wheel wells and arrived in New York City in 1999." With the use of air travel, people are able to go to foreign lands, contract a disease and not have any symptoms of illness until after they get home, and having exposed others to the disease along the way. Another example of the potency of modern modes of transportation in increasing the spread of disease is the 1918 Spanish Flu pandemic. Global transportation, back in the early 20th century, was able to spread a virus because the network of transmittance and trade was already global. The virus was found on crew members of ships and trains, and all the infected employees spread the virus everywhere they traveled. As a result, almost 50-100 million people died of this global transmission.As medicine has progressed, many vaccines and cures have been developed for some of the worst diseases that people develop. But, because the evolution of disease organisms is very rapid, even with vaccines, there is difficulty providing full immunity to many diseases. Since vaccines are made partly from the virus itself, when an unknown virus is introduced into the environment, it takes time for the medical community to formulate a curable vaccine. The lack of operational and functional research and data, which provide a quicker and more strategized pathway to a reliable vaccine, makes for a lengthy vaccine development timeline. Even though frameworks are set up and preparations plans are utilized to decrease the COVID-19 cases, a vaccine is the only way to ensure complete immunization. Some systems like the IIS, Immunization Information System, help give preliminary structure for quick responses to outbreaks and unknown viruses. These systems employ past data and research-based on modern world vaccine development successes. Finding vaccines at all for some diseases remains extremely difficult. Without vaccines, the global world remains vulnerable to infectious diseases.
Evolution of disease presents a major threat in modern times. For example, the current "swine flu" or H1N1 virus is a new strain of an old form of flu, known for centuries as Asian flu based on its origin on that continent. From 1918 to 1920, a post-World War I global influenza epidemic killed an estimated 50–100 million peens, including half a million in the United States alone. H1N1 is a virus that has evolved from and partially combined with portions of avian, swine, and human flu.
Globalization has increased the spread of infectious diseases from South to North, but also the risk of non-communicable diseases by transmission of culture and behavior from North to South. It is important to target and reduce the spread of infectious diseases in developing countries. However, addressing the risk factors of non-communicable diseases and lifestyle risks in the South that cause disease, such as use or consumption of tobacco, alcohol, and unhealthy foods, is important as well.
Even during pandemics, it is vital to recognize economic globalization in being a catalyst in the spread of the coronavirus. Economic factors are especially damaged by increased global lockdown regulations and trade blockades. As transportation globalized, economies expanded. Internalized economies saw great financial opportunities in global trade. With increased interconnectivity among economies and the globalization of the world economy, the spread of the coronavirus maximized the potentiality of global recessions. The coronavirus pandemic caused many economic disruptions, which caused a functional disconnect in the supply chain and the flow of goods. As transportation modes are relevant to the spread of infectious diseases, it is important to also recognize the economy being the motor of this globalized transmission system.
Specific diseases
Plague
is a variant of the deadly flea-borne disease plague, which is caused by the enterobacteria Yersinia pestis, that devastated human populations beginning in the 14th century. Bubonic plague is primarily spread by fleas that lived on the black rat, an animal that originated in South Asia and spread to Europe by the 6th century. It became common to cities and villages, traveling by ship with explorers. A human would become infected after being bitten by an infected flea. The first sign of an infection of bubonic plague is swelling of the lymph nodes, and the formation of buboes. These buboes would first appear in the groin or armpit area, and would often ooze pus or blood. Eventually infected individuals would become covered with dark splotches caused by bleeding under the skin. The symptoms would be accompanied by a high fever, and within four to seven days of infection, more than half of the affected would die.The first recorded outbreak of plague occurred in China in the 1330s, a time when China was engaged in substantial trade with western Asia and Europe. The plague reached Europe in October 1347. It was thought to have been brought into Europe through the port of Messina, Sicily, by a fleet of Genoese trading ships from Kaffa, a seaport on the Crimean peninsula. When the ship left port in Kaffa, many of the inhabitants of the town were dying, and the crew was in a hurry to leave. By the time the fleet reached Messina, all the crew were either dead or dying; the rats that took passage with the ship slipped unnoticed to shore and carried the disease with them and their fleas.
Within Europe, the plague struck port cities first, then followed people along both sea and land trade routes. It raged through Italy into France and the British Isles. It was carried over the Alps into Switzerland, and eastward into Hungary and Russia. For a time during the 14th and 15th centuries, the plague would recede. Every ten to twenty years, it would return. Later epidemics, however, were never as widespread as the earlier outbreaks, when 60% of the population died.
The third plague pandemic emerged in Yunnan province of China in the mid-nineteenth century. It spread east and south through China, reaching Guangzhou and Hong Kong in 1894, where it entered the global maritime trade routes. Plague reached Singapore and Bombay in 1896. China lost an estimated 2 million people between plague's reappearance in the mid-nineteenth century and its retreat in the mid-twentieth. In India, between 1896 and the 1920s, plague claimed an estimated 12 million lives, most in the Bombay province. Plague spread into the countries around the Indian Ocean, the Red Sea and the Mediterranean. From China it also spread eastward to Japan, the Philippines and Hawaii, and in Central Asia it spread overland into the Russian territories from Siberia to Turkistan. By 1901 there had been outbreaks of plague on every continent, and new plague reservoirs would produce regular outbreaks over the ensuing decades.