One important lesson that the pandemic taught us is regarding the complex links between humans, animals and environmental health. Future pandemics, too, will witness this link. It is established that most pandemics are zoonotic in origin. More than 60% of new pathogens originate in the bodies of animals. Of late, we witnessed a dangerous emergence of multiple zoonotic diseases – infectious diseases caused by bacteria and viruses that jump from animals to humans. Some of them, like Covid, are new to humans, and we do not have immunity against them. One of the oldest known pandemics was Plague of Justinian (541 to 750 AD). Caused by bacterium Yersinia pestis, it possibly spread through fleas and rodents, and is believed to have originated in India or China to reach Egypt via trade routes. Historians say the plague, named after Byzantine emperor in Constantinople, Justinian I, could have led to deaths of about 100 million people during the two centuries.
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Other Outbreaks
SARS outbreak (2003; Severe Acute Respiratory syndrome-associated coronavirus) was first reported in Asia, before it spread to North America, South America and Europe. HIV AIDS (1981), Smallpox (1974), Asian flu pandemic (1957-58), Hong Kong flu pandemic (1968), Influenza pandemic (1918), Russia typhus (1918), Manchurian plague (1910), Black Death or bubonic plague (14th century), and The Great Plague of London (1665-1666) are some other examples of worldwide pandemics. The last major epidemic was the bubonic plague in England, which resulted in estimated 100,000 fatalities. The first case of bubonic plague in India that probably first emerged in Yunnan, China, in the mid-1800s, was reported in Mandvi district of Mumbai presidency in September 1896. It spread like wildfire. About one million persons died in 1903, with about half a million deaths in the first part of 1904. Outbreaks were reported frequently after that, with a few cases reported even now.
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There were about seven cholera pandemics in the past 200 years, with the first originating in India in 1817 near the-then Calcutta, and spreading to South and Southeast Asia, the Middle East, eastern Africa and Mediterranean coast. Fatalities were not estimated, but it’s believed that 30,000 people might have died in Bangkok, and 1,225 people in Java in a month in 1821, with the overall death toll at 100,000 in Java and 100,000 in Korea. Till date, cholera outbreaks continue. These include the one in 1991-1994 in South America, and the 2016-2021 one in Yemen.
According to WHO’s Public Health Emergency of International Concern (PHIEC), apart from Covid-19, the other PHIECs included H1N1 or swine flu pandemic (2009). The flu was first detected in Mexico and spread quickly across the United States and the world. A human respiratory infection caused by an influenza strain that started in pigs, swine flu’s origins reportedly lie in the 19th century.
No records exist of the first case of poliomyelitis, but known outbreaks were registered in the late Victorian times, along with major epidemics in Europe and the United States. The most recent case was reported in Cameroon, west-central Africa. It’s believed that WPV (wild polio virus) from Pakistan led to a spate of infections that included 36 cases in Syria and two in Iraq in 2013-2014. WHO said that Pakistan, Cameroon, and Syria “pose the greatest risk of further wild poliovirus exportations in 2014”.
The Ebola outbreak (2014), which resulted in viral hemorrhagic fever of humans and other primates, was caused by Ebola virus. It was first discovered in 1976 near Ebola River in Congo. In 2014, it surfaced in western Africa, beginning with Guinea. Other countries impacted were Sierra Leone, Liberia, Senegal, Nigeria and Mali, in addition to Spain and the US. The Zika virus (2015-16) was caused by a virus transmitted primarily by Aedes mosquito. It was first identified in monkeys in Uganda in 1947. It was later found in humans in Uganda and Tanzania. In 2015, Brazil had a large outbreak of rash illness which turned out to be Zika. Later in the year, the virus was found to be associated with the Guillain-Barré syndrome, a disorder in which a patient’s immune system attacks the nerves. In October 2015, Brazil reported an association between Zika and microcephaly (smaller head size).
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The 1918 influenza pandemic was the most severe pandemic in recent history. It was caused by the H1N1 virus with genes of avian origin. Although there is no universal consensus regarding where the virus originated, it spread during 1918-1919. In the US, it was first identified in military personnel in spring 1918. It is estimated that about 500 million people or one-third of the world’s population became infected. The number of deaths was estimated at 50 million worldwide with about 675,000 occurring in the US.
Since 2000, we have had three pandemics –SARS in 2003, H1N1 (swine flu) in 2009 and Covid-19. SARS and Covid-19 spread from civet cats/pangolin and bats in China, and swine flu from an intensive pig farm in Mexico. We had regional outbreaks of bird flu from poultry, the Middle East Respiratory Syndrome (MERS) from camels, Ebola from monkeys and pigs, Rift Valley fever from livestock, West Nile fever from birds, Zika from monkeys, and Nipah from bats. The primary reason for the new zoonotic diseases is environmental destruction. Due to deforestation and habitat loss, wild animals and humans are getting closer, leading to the spill-over of animal diseases into humans – Ebola, West Nile virus, Nipah and Zika. Livestock is coming in contact with wildlife, and transmitting pathogens to people, like the Rift Valley virus. Intensive animal farms are a contributor. The industrial farming of animals forces them to stay close to each other, apart from being pumped with growth promoters like antibiotics. Bird flu and swine flu both have origins in intensive animal farms. However, the most dangerous is Coronavirus because we know little about the virus and have no medicines. But it has yet to create fear like cholera, a pathogen that caused seven pandemics, and scientists predict that the eighth one is on its way. In the past 50 years, 300 new pathogens have emerged because of greed or carelessness.
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Though there was evidence of handwashing during Spanish flu, this could not be publicised due to lack of communication. There is ample evidence that years before the epidemic, handwashing among healthcare workers remained an area that needed improvement. Covid has seen a re-focus on handwashing. Along with hand sanitising, it is critical for preventing transmission of microorganisms.
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500 million, or one-third of world’s population, were infected by 1918—19 influenza
300 new pathogens have emerged in the recent past
100 million died during the Plague of Justinian (541—750)
60% of new pathogens originate in animals
Swadeep Srivastava, Founder & CEO, HEAL Health and HEAL Foundation
