Chronicle of a death foretold

IN PERSPECTIVE

More than 300 infectious diseases have either newly emerged or re-emerged over the last half a century, in virgin territories. The US Institute of Medicine’s influential 1992 report—”Emerging Infections: Microbial Threats to Health in the United States” put the onus on human movement, crowding, climate, environmental damage, and inter-related factors for this. The majority of epidemiologists kept on warning that one of them might well snowball into a deadly pandemic anytime. Human foray into the complex dynamic ecosystems in which men and microbes co-exist is held to be the trigger.

The unknown spectre of what would constitute as the ‘next’, the scientists kept telling us until the new outbreak took us by storm, could be Ebola, avian flu, a drug-resistant superbug, or something completely new. By unravelling how some deadly and disruptive pathogens have caused pandemics in the past and by exploring the origins of contagions, they have tried to predict a model of the new diseases that may stalk humankind today. If we know what the next global contagion might look like ― and what we can do to prevent it, we can save our precious resources, the foremost of which are human resources.

A deadly virus emerged from the Congo forest and came as swiftly as it disappeared without a trace in 1976, only to emerge sporadically over the four decades since, almost always with sanguinary effect – killing up to 90% of its victims – until 2013–2014 when the Ebola epidemic presaged an apocalypse with a promise of more such epidemics to strike mankind at any time and place of their choosing.

With roads and towns cut deep into the jungles of equatorial Africa or into the Brazilian Amazon, viruses both familiar and undiscovered are being unleashed into more densely populated areas than ever before. Thus, a little more than 30,000 miles of new roads through the rain forest in the Brazilian Amazon built in just three years not only contribute to deforestation and habitat loss in one of the planet’s most biologically diverse regions, but also become a route to a veritable virosphere, the deadly potential of which is unfolding in the form of pathogens like the novel coronavirus. That our lure for an interconnected world glosses over the possibility of many such viral outbreaks is thus just incidental to the plot.

As a chronicle of human rapacity, instances of man’s invasion of new ecological niches in recent history are too many to be documented: the clearing of savannah in Africa and Asia unleashed deadly arenaviruses such as Lassa and Hanta; the increase in agricultural settlement in the Bolivian rain forest had set off Machupo; the ploughing of the pampas in South America in preparation for maize growing and cattle ranching unleashed the Junin virus; the building of the Aswan Dam in Egypt that elevated the water table allowed mosquitoes to breed and Rift Valley fever afflicted 300,000 people; and forest clear-cutting prised open the Kyasanur Forest Disease, a tick-borne viral haemorrhagic fever endemic to South India. The yellow fever, the unpleasant mosquito-borne viral illness, killed tens of thousands in the Americas and Europe from the 17th to early 20th centuries only when the craving of humans for sugar led to mass deforestation of Caribbean islands in order to plant cane. The mosquitoes that fed from birds and monkeys, who had lost their habitat, were forced to find new hosts in the shape of the slaves and settlers who were clearing the land.

Exactly like the predatory humans seeking to colonise every pasture they come across, a microbe finds in a city a target-rich environment, for urban life facilitates the four major modes of disease transmission—waterborne, vector borne, airborne, or direct contact. And an urban life – with a vast repository of stored food and a huge store of human and animal waste lying around, with its puddles and cisterns harbouring mosquito larvae carrying malaria, yellow fever, encephalitis, and dengue, its cats spreading toxoplasmosis and rats carrying plague – with too many people living too close together with too many wild animals, is truly the happy hunting ground for bacteria and viruses.

In recent decades SARS and Ebola, besides AIDS, remain examples that interchange of disease still occurs. But, unlike in the past, our capacity to conduct a thorough analysis of the historic spread of these diseases may be useful in preventing new epidemics. Thus, we see upon examining each stage of cholera’s dramatic journey, from its emergence in the South Asian hinterlands as a harmless microbe to its rapid dispersal across the 19th century world, all the way to its beachhead in Haiti in 2010 and Yemen in 2016 (reported as late as in January this year), pathogens coming close on its heels from the MRSA bacterium to the unforeseen killers coming out of China’s wet markets, the surgical wards of New Delhi, and the suburban backyards of the East Coast.

Let’s face it. Our mastery of the microbial world is less comprehensive than we might imagine and more susceptible to chance interactions in the environment than we might care to own up. The ongoing outbreak does teach us that it is imperative to a put a brake on human greed to stave off the spread of deadly pathogens because naked commercial greed brought diseases with disastrous consequences both to and from the New World. Like an enduring old adage, human intervention in the environment has been an age-old source of exposure to new microbes. China’s vast societal shifts, from rural to urban, from agricultural to industrial, from cooperative economy to consumer society, caused severe dislocations powerful enough to tear at nature’s fabric that serves as a model for the rest of the world about what not to do on the plea of economic ‘development’.