Evolution of virus-related diseases: epidemic and pandemic

By: Dr. Rajkumar Singh

Newly emerging infectious diseases (EIDs) have been posing an increasingly significant threat to human health. The majority of EIDs are of zoonotic origin, for which human population increase and the intensification of animal farming as well as of wild animal environments are causative in part. Infections caused by viruses are common causes of illnesses: the common cold, many ear infections, sore throats, chicken pox, and the flu are caused by different viruses. Usually, these illnesses last only few days or, at most, a few weeks. Some virus infections like influenza are cleared from the body, and others such as the chicken pox virus remain in the body in an inactive state. However, some people may become quite ill when they are infected with a particular virus, possibly because part of their immune system does not respond properly to fight the virus. Researchers have discovered some reasons why a person may not be able to clear an infection caused by a virus. Some persons have changes in the genes that involve the immune system that result in the inability to properly control infection with a particular virus. Identifying changes in genes that involve the immune system should help scientists better understand how the immune system works to protect people from infection and may help develop new therapies. Humans have been battling viruses since before our species had even evolved into its modern form. For some viral diseases, vaccines and antiviral drugs have allowed us to keep infections from spreading widely and have helped sick people recover. But we’re a long way from winning the fight against viruses. In recent decades, several viruses have jumped from animals to humans and triggered sizable outbreaks, claiming thousands of lives. The viral strain that drove 2014-2016 Ebola out break in West Africa kills up to 90% of the people it infects, making it the most lethal member of the Ebola family. But there are other viruses out there that are equally deadly, and some that are even deadlier. Some viruses, including the novel coronavirus currently driving outbreaks around the globe, have lower fatality rates, but still pose a serious threat to public health as we don’t yet have the means to combat them. 

History of HIV/AIDS and Influenza

First identified in Democratic Republic of the Congo in 1976, HIV/AIDS has truly proven itself as a global pandemic, killing more than 36 million people since 1981. Currently there are between 31 and 35 million people living with HIV, the vast majority of those are in Sub-Saharan Africa, where 5% of the population is infected, roughly 21 million people. As awareness has grown, new treatments have been developed that make HIV far more manageable, and many of those infected go on to lead productive lives. Between 2005 and 2012 the annual global deaths from HIV/AIDS dropped from 2.2 million to 1.6 million. A category 2 Flu pandemic sometimes referred to as “the Hong Kong Flu,” the 1968 flu pandemic was caused by the H3N2 strain of the Influenza A virus, a genetic offshoot of the H2N2 subtype. From the first reported case on July 13, 1968 in Hong Kong, it took only 17 days before outbreaks of the virus were reported in Singapore and Vietnam, and within three months had spread to The Philippines, India, Australia, Europe, and the United States. While the 1968 pandemic had a comparatively low mortality rate (.5%) it still resulted in the deaths of more than a million people, including 500,000 residents of Hong Kong, approximately 15% of its population at the time. Asian Flu was a pandemic outbreak of Influenza A of the H2N2 subtype, that originated in China in 1956 and lasted until 1958. In its two-year spree, Asian Flu traveled from the Chinese province of Guizhou to Singapore, Hong Kong, and the United States. Estimates for the death toll of the Asian Flu vary depending on the source, but the World Health Organization places the final tally at approximately 2 million deaths, 69,800 of those infected.

Between 1918 and 1920 a disturbingly deadly outbreak of influenza tore across the globe, infecting over a third of the world’s population and ending the lives of 20 – 50 million people. Of the 500 million people infected in the 1918 pandemic, the mortality rate was estimated at 10% to 20%, with up to 25 million deaths in the first 25 weeks alone. What separated the 1918 flu pandemic from other influenza outbreaks was the victims; where influenza had always previously only killed juveniles and the elderly or already weakened patients, it had begun striking down hardy and completely healthy young adults, while leaving children and those with weaker immune systems still alive.

Cholera, Asiatic Flu and Plague

In its five previous incarnations, the Sixth Cholera Pandemic originated in India where it killed over 800,000, before spreading to the Middle East, North Africa, Eastern Europe and Russia. The Sixth Cholera Pandemic was also the source of the last American outbreak of Cholera (1910–1911). American health authorities, having learned from the past, quickly sought to isolate the infected, and in the end only 11 deaths occurred in the U.S. By 1923 Cholera cases had been cut down dramatically, although it was still a constant in India.

Originally the “Asiatic Flu” or “Russian Flu” as it was called, this strain was thought to be an outbreak of the Influenza A virus subtype H2N2, though recent discoveries have instead found the cause to be the Influenza A virus subtype H3N8. The first cases were observed in May 1889 in three separate and distant locations, Bukhara in Central Asia (Turkestan), Athabasca in northwestern Canada, and Greenland. Rapid population growth of the 19th century, specifically in urban areas, only helped the flu spread, and before long the outbreak had spread across the globe. Though it was the first true epidemic in the era of bacteriology, and much was learned from it. In the end, the 1889-1890 Flu Pandemic claimed the lives of over a million individuals.

From 1346 to 1353 an outbreak of the Plague ravaged Europe, Africa, and Asia, with an estimated death toll between 75 and 200 million people. Thought to have originated in Asia, the Plague most likely jumped continents via the fleas living on the rats that so frequently lived aboard merchant ships. Ports being major urban centers at the time, were the perfect breeding ground for the rats and fleas, and thus the insidious bacterium flourished, devastating three continents in its wake.

Bionic Plague and Antonine

Generally regarded as the first recorded incident of the Bubonic Plague, the Plague of Justinian left its mark on the world, killing up to a quarter of the population of the Eastern Mediterranean and devastating the city of Constantinople, where at its height it was killing an estimated 5,000 people per day and eventually resulting in the deaths of 40% of the city’s population. Also known as the Plague of Galen, the Antonine Plague was an ancient pandemic that affected Asia Minor, Egypt, Greece, and Italy and is thought to have been either Smallpox or Measles, though the true cause is still unknown.

Author is Professor and Head, University Department of Political Science, B.N. Mandal University, Madhepura

Madhepura-852113. Bihar, India.

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