The term pandemic has its origin in the Greek word "pandemos", which when translated to English, denotes "pertaining to all people". Separately speaking "pan" in Greek means "all", while the Greek word demos denotes "people". Therefore, when we use the term pandemic, we actually mean the spread of a disease affecting a large section of the global population. This usually occurs with the emergence of a new virus among humans. The new virus not only results in grave ailment, but also spreads from one person to another (human transmissible) easily.
In simple words, a pandemic covers a vast geographical region, usually across the globe. In fact, a pandemic affects much more people compared to an epidemic. An epidemic may be confined to a particular city, area or a country. On the other hand, a pandemic covers a greater region, crossing national borders.
An infectious disease reaches epidemic proportions when it affects many more people in any region or a country than what is usually expected. In other words, an epidemic occurs when a disease spreads quickly affecting a vast populace. On the other hand, when a contagious disease affects people in numerous countries simultaneously, it is said to assume pandemic proportions.
Usually, a new virus strain or a virus sub-type is responsible for a pandemic. It is a novel virus against which humans do not have any immunity or, even if they have, the level of immunity is negligible. When there is no immunity or the immunity is very poor, it is likely that the virus will rapidly spread across the globe, especially it transmits easily from one human to another.
The seasonal outbreak of influenza is considered to be an epidemic because the virus subtype responsible for this condition is circulating among people from before. On the other hand, pandemics are usually caused by new virus subtypes which have never circulated among people earlier and, hence, they are not immunized against it. In addition, as in the case of influenza, pandemics may also be caused by viruses or virus subtypes, which are not in circulation among people for a prolonged period.
Compared to epidemics, many more people are affected by pandemics and even the casualties are much higher. In addition, pandemics are responsible for greater economic losses, social disruptions and general hardships than those caused by epidemics.
The influenza program of the World Health Organization (WHO) has been categorized in six different stages:
Over the centuries, people have witnessed several major pandemics, which killed millions of humans across the globe. Especially zoonoses like influenza and tuberculosis, which was introduced following the domestication of animals, affected several millions. Human history has recorded several major epidemic outbreaks, which not only killed millions of people, but destroyed many cities over the centuries. Some of them are discussed briefly below.
As many as 10 million people succumbed to the third plaque pandemic, which began in China in 1855 and subsequently reached India. The United States also suffered its first outbreak during this pandemic when the plaque afflicted residents of San Francisco between 1900 and 1904. Even today, isolated incidences of plague are reported from various western regions of the United States.
Cholera has claimed millions of human lives since its first pandemic outbreak in the 19th century.
The World Health Organization (WHO) has several phases of influenza pandemic alerts.
Influenza was explained for the first time in 412 BC by Hippocrates, the renowned Greek physician who is often referred to as the "Father of Medicine".
The first ever influenza pandemic was reported in 1580. Since then there has been influenza pandemics once in every 10 years to 30 years.
Often referred to as "camp fever", typhus emerged during the Crusades and in 1489 its first impact was felt in Spain, the first time in Europe. This disease is called "camp fever" because its outbreaks mostly occurred during strife. In addition, typhus is also referred to as "ship fever" and "gaol fever" as it spread wildly in the overcrowded quarters, for instance ships and jails. While only 3,000 Spanish people died in battles between the Muslims and Christian Spaniards in Granada, typhus claimed about 20,000 lives. Typhus is also said to be the reason behind the French losing 18,000 soldiers in 1528. As a result, France also lost its supremacy to the Spanish in Italy. In 1542, over 30,000 soldiers succumbed to typhus when they were fighting in the Balkans against the Ottomans.
An estimated 8 million Germans succumbed to typhus and bubonic plague throughout the Thirty Years' War, which lasted from 1618 to 1648. Moreover, in 1812, typhus was also responsible for devastating Napoleon's Grande Armée in Russia. On June 25, 1812, 450,000 French soldiers set out to conquer Russia crossing the Neman, but less than 40,000 could return home. Many more soldiers succumbed to typhus between 1500 and 1914 than those killed in fighting. Aside from this, more French troops succumbed to typhus compared to the personnel killed by the Russian soldiers when the former were retreating from Moscow. Towards the beginning of 1813, Napoleon replaced his losses in Russia by raising a new army of half a million troops. Another 219,000 men from Napoleon's army succumbed to typhus during their various campaigns that year. Typhus is also said to be largely responsible for the Irish Potato Famine. In addition, more than 150,000 people died due to typhus epidemics in Serbia during the World War I.
An extremely infectious disease, smallpox is attributed to the variola virus. Towards the end of the 18th century, this killer disease claimed about 400,000 lives in Europe every year. According to rough estimates, smallpox killed anything between 300 million and 400 million people as recently as the 20th century. More recently, in the beginning of the 1950s, there were an estimated 50 million incidences of smallpox throughout the world each year. This led to widespread vaccination campaigns during the 19th and 20th centuries across the world. The success of these campaigns led the World Health Organization (WHO) to certify in December 1979 that smallpox has been eradicated from the planet. As of now, smallpox is the sole human contagious disease that has been eradicated completely. In fact, this is one of the two contagious viruses that have been successfully wiped out from the face of the globe.
In the olden days, measles was widespread all over the world since this is an extremely infectious disease. The National Immunization Program reports that 90 percent people are infected by this disease by the time they are 15 years old. Prior to the introduction of the measles vaccination in 1963, an estimated 3 million to 4 million people were infected by this disease every year in the United States alone. During the last 150 years, about 200 million people succumbed to measles across the globe. It is shocking to note that in 2000 itself, measles claimed about 777,000 lives worldwide.
Measles is considered to be an endemic disease. In other words, this disease has always existed in a community and over the years numerous people have developed resistance against it. However, in places where people are yet to be exposed to this disease, it may be devastating when they are exposed to a new disease. In fact, a measles outbreak in Cuba in 1529 wiped out about two thirds of the native population, though they have successfully endured a smallpox outbreak earlier. Aside from Cuba, measles has also devastated Central America, Mexico and the Inca civilization at different times.
It may seem to be incredible, but about a third of the world's population is currently infected with the bacteria called Mycobacterium tuberculosis. The rate of infection too is also alarming - one person every second. What is even worse is that about 5 to 10 percent of all such latent infections eventually develop into active tuberculosis (TB). If the disease is not treated or treated timely, it may result in the death of 50 percent victims. According to available records, an estimated 25 percent of the population in Europe was succumbed to tuberculosis during the 19th century. In fact, one in every six persons died in France due to tuberculosis by the year 1918. In the 20th century, a whopping 100 million people succumbed to tuberculosis. Even today, tuberculosis is a major health issue worldwide, especially in the developing nations.
Also known as Hansen's or Wopat's disease, leprosy is attributed to a bacillus called Mycobacterium leprae. Leprosy is a chronic health condition that has an incubation period of a maximum of five years. The good news is that more than 15 million leprosy patients worldwide have been cured since 1985.
From the historic point of view, people have been afflicted by this disease since way back in 600 BC. However, leprosy outbreaks were first seen in the western regions of Europe sometime around 1000 AD. During the Middle Ages, many leprosy hospitals called leprosaria came into existence. According to Matthew Paris, a Benedictine monk and English chronicler, there were about 19,000 leprosy hospitals all over Europe during the beginning of the 13th century.
Malaria (Plasmodium falciparum) is prevalent in the tropical as well as sub-tropical regions of the world, which includes several parts of Africa, Asia and the two Americas. Every year, about 350 to 500 million cases of malaria are reported from across the globe. Treatment of malaria has become difficult during the 21st century owing to drug resistance. In fact, malaria has become resistant to all types of anti-malarial medications, save for artemisinins.
There was a time when malaria was widespread in most of the regions of Europe as well as North America. However, currently this disease is non-existent in these regions. It is assumed that malaria may have been responsible for the downfall of the mighty Roman Empire. This is perhaps the reason why malaria was also called "Roman fever". In fact, Plasmodium falciparum or malaria had turned out to be a real menace for colonists as well as the indigenous people, when the disease reached the Americas via slave trade. For instance, malaria was responsible for the devastation of Jamestown colony and the disease continued to ravage the Midwest and South regularly. Malaria had arrived in the Pacific Northwest by 1830. More than 1.2 million soldiers on both sides of the American Civil War were affected by malaria. Millions of people were afflicted by malaria in the southern United States and this continued until 1930s.
Yellow fever (also referred to as yellow jack) has been responsible for numerous ravaging epidemics. In fact, yellow fever epidemics have devastated several cities in the north, including Boston, Philadelphia and New York. A major, perhaps the largest in America's history, yellow fever epidemic appeared in the United Sates in 1793 claiming about 5,000 people just in Philadelphia, roughly 10 percent of the region's population then. The devastation was so severe that nearly 50 percent of the residents of the region, including President George Washington, had fled the region. During the days of colonization, the devastation caused by malaria and yellow fever led to West Africa being referred to as "the white man's grave".
