The era of voyages of discovery, about 500 years ago, is one of the most important chapters in world history. European navigators set sail, motivated by the need for a trade route to the east and the search for Spice Islands, or driven simply by a spirit of adventure.
Christopher Columbus, a Genoese in the employ of the king of Spain went westward in an effort to reach India, based on his assumption the world being round. One could go to the east by going west, he believed. Eight years later, the Portuguese navigator, Vasco da Gama, rounded the Cape of Good Hope and reached India in 1498, discovering the sea route to the east. The fleet of Ferdinand Magellan, another Portuguese navigator in the employ of the king of Spain, made the first circumnavigation of the world between 1519 and 1521. The discovery of new lands and people was a turning point in the history of the world, causing numerous encounters between new peoples and civilisations.
To celebrate the historic feat of Magellan, a training sailing vessel, Sagres, left Lisbon on 5 January 2020, on a world tour. It would have anchored in Mauritius on the 24 April before sailing to Tokyo, for the Olympic Games. Sagres had a laboratory for scientific research on oceans and climate change. However, this commemorative voyage was recalled due to the prevailing pandemic of Covid-19.
The Columbian Exchange: Diseases…
The narrative of Magellan’s voyage is well known. He set sail with a five-ship fleet from Seville in Spain, crossed the Atlantic, stopped at different places in Brazil. The fleet crossed the strait that came to be known as the Magellan Strait, and entered the Pacific Ocean, thus named by Magellan himself. Food and water become scarce and the scurvy ridden crew had to eat rats, ox hide and drink putrid water. They landed on an island in the Philippines where Magellan and some members of his crew were killed by the natives in a skirmish. Only one ship of the original fleet, commanded by Del Cano crossed the Indian Ocean and returned to Spain. The circumnavigation, gathering on its way considerable information about oceans and lands, symbolically opened the whole globe to travel and enterprise.
The voyages of Columbus and his successors caused considerable impact on both sides of the Atlantic. The historian, Alfred W. Crosby, coined the term ‘Columbian Exchange’ in 1972, to describe the movement of people, plants and animals, from the Old World to the New. However, Crosby considers that the exchange of infectious disease has been a main aspect of that encounter between civilizations. From the beginning, clashes with the Spaniards were disastrous for the natives. Indeed, the conquistadors had muskets, cannons and horses, but it was finally the transmission of infectious diseases, measles, smallpox or influenza, carried by the Spanish soldiers, that decimated Caribbean natives and Amerindians more swiftly than warfare and harsh treatment. Medical scientists call this form of transmission virgin soil epidemics. Diseases from the Old World were introduced to Amerindians who had lived isolated from the rest of the world, and who were therefore not immune to them. The most killing of the invisible invaders, smallpox, cleared the path of the conquistadors. In the 1520s, Cortez vanquished the Aztec empire of Mexico and Pizarro the Incan empire of Peru. Similar appalling narratives of deaths repeated throughout the Americas for the next two centuries.
On the other hand, Europeans introduced to the America, horses, cattle, pigs, as well as rice, wheat, and sugar. In return, they carried away to Spain potatoes, sweet potatoes, pineapples, chili pepper, tobacco, maize, manioc and cinchona for making quinine; all these spread worldwide.
When colonizers started to cultivate sugarcane in the Caribbean islands, few natives had survived to form a workforce. African slaves were therefore introduced, who in turn carried malaria and yellow fever. European trading companies had the monopoly to carry out the triangular trade, between Europe, Africa and the Americas. Cotton from America launched the Industrial revolution in England. Other goods included sugar, tobacco, cotton and rum shipped to Europe; in return, slaves, cloth, and household articles were shipped to the Americas. These voyages speeded the interchangeability of pathogens. In Europe, syphilis, a new disease appeared, which, some medical experts believe, was brought to Spain by the sailors of Columbus. 
At that time, Europeans themselves hardly knew the cause of infectious diseases, nor had they any effective form of treatment. They believed that miasma, noxious emanations, spreading in the air from polluted places, caused diseases.
On this side of the world, in the Indian Ocean, the voyage of Vasco da Gama had opened the sea route to India in 1498. The Indian Ocean world was different from that of the Atlantic. Indians, Arabs and Chinese merchants had established a network of coastal trade. Moreover, trade links between India and the Mediterranean had existed since the Roman times. Portuguese explorers, during the early 16th century, discovered several uninhabited islands of the Indian Ocean, including Mauritius. Competition among Europeans to establish trading posts in India and the Indies was rife. Cargoes of silk, cotton, porcelain and tea were shipped to Europe, although Europeans had little to offer to Indian and Chinese markets. In Asia, Europeans met the same infections such as cholera, smallpox, and malaria, known to them in their own countries. Epidemics erupted sporadically, and spreading along sea and land routes became pandemics. However, traditional Asian civilisations in China, India and Arabia had developed sophisticated health systems. Europeans learnt from the Asians the practice of inoculation against smallpox, which was introduced in Europe in the early 18th century, long before Edward Jenner’s vaccination was propagated which in a short time reached both sides of the world. However, European soldiers and officers were most vulnerable in the tropical climates of India and North Africa, where malaria was among the killer diseases. Europeans therefore preferred to form colonies in the temperate zones of South Africa and Australasia.
In the southern Indian Ocean, navigators such as the Dutch Abel Tasman followed by Captain James Cook enlarged the picture of the known world to include Australasia. Again, history repeated itself. Following encounters between Europeans and the Aborigines of Australia and the Maoris of New Zealand, smallpox broke out amidst the natives. Introduced in the midst of a virgin population, living in geographic isolation, ‘European’ diseases were catastrophic. On his visit to Australasia in 1836, Charles Darwin wrote ‘Wherever the European had trod, death seems to pursue the aboriginal.’
Increased maritime travel, trade, and colonisation created the first era of globalisation, provoking at the same time numerous pandemics. The nineteenth century is marked by several cholera pandemics that criss-crossed the world. Starting from India, Asiatic cholera travelled by commercial vessels up to America and followed land routes to remote places in Russia. Plague broke out in China in 1894 reaching Bombay in 1896, it spread from port to port reviving memories of the Black Death of the medieval times. Since it was an era of mass migrations, Indian and Chinese indentured labourers, European migrants to America and convicts to Australia, were all moving with specific pathogens infecting virgin populations. In each host country, quarantine stations were built to control infected ships. Early ‘international’ conferences were held from 1852 onwards to prevent diseases from Asian countries from entering Europe. Maritime communication between certain countries was sometimes banned during the duration of epidemics. Mauritius, importer of indentured labourers for cane cultivation, was visited by at least five cholera outbreaks in the mid nineteenth century. Malaria became endemic for one hundred years and plague reached its shores on two occasions. Apart from Crosby, other historians, such as Le Roy Ladurie, also stressed on the unification of the world by disease.
It is only after the mid-19th century that the mystery of infections started to be unravelled, when scientists like Louis Pasteur and Robert Koch and their disciples discovered by means of microscopes how diseases were caused by the invasion of the body by tiny organisms. New fields of medical science such as bacteriology developed. Research found that infection can be stopped by the body’s natural immune system, but disease can occur when immunity is low, as it is among the elderly, or it is impaired, as in the case of HIV patients. Vaccines were developed to help the immune system to react. However, disease occurs and spreads when a novel virus enters the body and the immune system cannot react. Thus, the urgency for a vaccine, as it is the case with Covid-19.
Time and again, human history has been marked by outbreaks of new diseases which has often hit communities unawares. History shows that lessons are learnt, but seem to be soon forgotten. Instead of preparedness, complacency always sets in. Let us hope the present pandemic bring changes in the mind-set of decision makers throughout the world, who need to bear in mind what experts have always affirmed that diseases caused by novel viruses are not always predictable. Only an active global surveillance system, early detection and rapid information sharing can help countries to be prepared and create resilient health systems.
Infectious Disease and Public Health Mauritius 1810-2010, ELP 2019
Crosby A. Ecological Imperialism The biological imperialism of Europe CUP 1986