A brief history of global pandemics

The novel coronavirus (Covid-19) has at last struck Bangladesh. Originating from the wildlife market of China's Wuhan city in December 2019, it has now become a global phenomenon within three months, with its presence felt in more than 100 countries, infecting over 100,000 people (mostly in China) and killing around 4,000.

Its spread has only highlighted the threats and vulnerabilities faced by mankind both at cosmic or macroscopic and atomic or microscopic levels. Physicists often explain the former through Einstein's theory of relativity and the latter through Quantum Mechanics. It is quite shocking that a miniscule new virus has once again succeeded in causing panic and mayhem in all continents of the globe minus Antarctica.

However, despite the global surge in coronavirus infections, the World Health Organisation (WHO) has refrained from labelling the crisis as 'pandemic' till now. The WHO director-general has claimed they could not do so unless they are convinced that Covid-19 was uncontrollable. The organisation fears using the word 'pandemic' might prompt governments to needlessly or prematurely change their strategies in ways that could undermine containment efforts. Many experts also support the WHO standpoint on the ground that use of the word 'pandemic' could rattle the markets, result in drastic travel-cum-trade restrictions, and stigmatise people living in affected places.

The WHO defines 'pandemic' as: "the worldwide spread of a new disease, where a new virus causes sustained community-level outbreaks in at least two world regions". And the US Center for Disease Control and Prevention offers the definition as "an epidemic that has spread over several countries or continents, usually affecting a large number of people". The WHO has, however, declared the coronavirus outbreak as a 'public health emergency of international concern' in late January, when it issued a broad set of recommendations for curbing its spread.

Alarmingly, the disease has been multiplying rapidly even in countries where strong public healthcare systems exist.

There are in fact two basic approaches to controlling such outbreaks: containment and mitigation. The first approach is pursued during initial stages of an outbreak by isolating at-risk populations (e.g. through quarantines) for preventing them from spreading the disease. This approach was by and large successful in tackling the spread of SARS in 2002 and the Ebola outbreak in West Africa in 2014 and 2016. The mitigation approach is adopted when isolating the disease is no longer practical. In that situation, the infections can occur anywhere and measures like closing schools or postponing/cancelling events are resorted to, for minimising contacts between large masses of people. Pandemics are considered to be best fought through mitigation, as was the case with the last WHO-declared pandemic of H1N1 'swine-flu' in 2009.

In fact, there is a long history of pandemics on a global scale since time immemorial, some of which are mentioned below. In ancient times, a typhoid fever killed a quarter of the Athenian troops and population from 430 to 426 BC during the Peloponnesian War. The Antoine Plague (165-180 AD) brought by soldiers returning from the Near-East killed up to five million people in Italian peninsula.

The second Plague outbreak of Cyprian (251-266 AD) resulted in deaths at the rate of 5,000 per day in Rome. Originating in Egypt, the first recorded outbreak of the bubonic plague or the Plague of Justinian (541-750 AD) reached Constantinople and killed 10,000 per day during its height, wiping out 40 per cent of the city's inhabitants. Ultimately, the plague wiped out a quarter to half of mankind across the known world and halved the European population between 550 and 700 AD.

The fatalities worldwide due to Black Death (1331-1353 AD) was estimated to be 75 million. The plague returned to Western Europe and the Mediterranean in 1348, killing a third of the European population in six years. Up to 87 per cent of the native Americans were said to have died of plague and small pox between 1620 and 1680.

A cycle of European plagues numbering 100 continued to bedevil the continent up to the 18th century. England's population was reduced by 50 per cent within 1370s. The Great Plague of London (1665-66) was the last outbreak of plague in England, devouring approximately 100,000 or 20 per cent of London's population. Originating in China in 1855, the third plague pandemic spread to India where 10 million people perished. The first pandemic outbreak in the USA was the San Francisco Plague (1900-04). After that, the Spanish Flue pandemic (1918-1920) infected 500 million people across the globe and led to the deaths of between 50 and 100 million people. Originating in Africa and spreading to the USA via Haiti between 1966 and 1972, HIV-AIDS is the present-day pandemic having the highest infection rates of 25 per cent in southern and eastern Africa.

The following diseases have mostly given rise to pandemics over the centuries: Cholera, Influenza, Typhus, Smallpox, Measles, Tuberculosis, Leprosy, Malaria, Yellow Fever, Ebola and Zika viruses. The Cholera pandemic of 1817-24 originated in Bengal and spread across the Indian sub-continent within 1820. Ten thousand British troops and innumerable natives died as a consequence. This outbreak spread to China, Indonesia (100,000 people dying in Java alone) and the Caspian Sea before receding. It is estimated that 15 million people died between 1817 and 1860, and another 23 million perished between 1865 and 1917 due to Cholera outbreaks in the Indian subcontinent. Originating in Indonesia, the latest Cholera pandemic (1961-75) reached Bangladesh in 1963, India in 1964, the Soviet Union in 1966, subsequently spreading to Africa, South and Central America.

At the current juncture, the following are considered to be potential causes of future pandemics: anti-biotic resistance; viral haemorrhagic fevers; coronavirus and atypical pneumonia, including SARS and Covid-19; and influenza, including avian flu and Zika viruses.

With regard to Bangladesh, the top priority in the backdrop of Covid-19 hitting the country would be deployment of adequate resources including front-line health-related funding for protecting people, taking care of the sick, and slowing the spread of the virus. The healthcare-related measures should be geared up on an urgent basis and the supply of medicines and clinical facilities should be at par with their demands for ensuring prompt containment and mitigation.

Dr. Helal Uddin Ahmed is a retired Additional Secretary and former Editor of Bangladesh Quarterly.

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