By Pascoal Carvalho

Mumbai, Sept. 28, 2021: Excerpt of the presentation by Mumbai-based Doctor Pascoal Carvalho at the general assembly of the Pontifical Academy for Life in Rome on September 27 on “Public Health in Global Perspective – Pandemic, Bioethics, Future.”

The Covid-19 Pandemic has been the greatest leveler in modern history. The Pandemic has affected all peoples – the first world and the developing world irrespective of healthcare infrastructure; the affluent as well as the poor; the educated as well as the unschooled. Even reputed Institutions like the WHO were brought under the scanner.

The big question remained. How could our technologically advanced world have missed this outbreak? This brings us to the issue of zoonosis.

Zoonosis is an infectious disease caused by a pathogen that has jumped from an animal to a human. The pathogens involved in causing Zoonotic diseases may be Bacterial, including anthrax, brucellosis and plague, or Viral including Covid-19, rabies, yellow fever, influenza and Zika or Helminthic, including roundworm, tapeworm and hookworm or Fungal, Protozoal.

Zoonotic disease can be spread through direct contact with the saliva, or other body fluids of an infected animal, or through indirect contact with areas where animals live and roam, or by carriers or vectors by being bitten by a tick, mosquito or a flea. Zoonotic diseases can be food and water borne by eating or drinking something unsafe.

Epidemics of zoonotic origin have regularly perplexed humans. Over 60 percent of existing human infectious diseases have animal origin. In the 14th Century, the plague “black death,” caused by a bacterium and transmitted from rat to man via rat flea, killed over 75 million people. In 1918, the Spanish flu caused by a virus infected 500 million people. India, in 1994, was ravaged by plague after an earthquake.

We had SARS (Severe Acute Respiratory Syndrome) with a fatality rate of 9.5 percent and MERS (Middle East Respiratory Syndrome) with a fatality rate of over 34 percent. Close on its heels came the Ebola virus in 2014 passed on from bats or monkeys killing over 11,000 people. HIV is also believed to have spilled over from chimpanzees to human.

As many as 75 percent of emerging diseases are zoonotic, with viral diseases being most common. Some of the recent zoonosis of deadly new or ‘novel’ viruses can be attributed to human being’s foray into the unknown and previously undisturbed forests and habitation, exposing humans to new plants, animals and new pathogens.

Our current pandemic disease Covid-19 (Coronavirus infectious disease 2019) is caused by the virus SARS-CoV-2 (Severe Acute Respiratory syndrome coronavirus 2). This virus has a close similarity to SARS-related coronaviruses. Coronaviruses are known to be evolved in animals and then jump to humans via an intermediate host. Many cases of common cold are due to coronaviruses.

The SARS-CoV-2 virus is believed to have originated in bats in Wuhan, China. Official hypothesis has it, that most probably a bat, or a pangolin that came in contact with food mixed with bat saliva, carried a deadly virus that went through an inter-species spillover and started infecting humans resulting in first an epidemic and then the current pandemic. However, there is also a strong lobby advocating that SARS-CoV-2 is a man-made virus which spilled over during collaborative studies being done in ‘Gain of function’ research – Government funded research aimed at increasing the virulence and lethality of pathogens and viruses.

Being a global crisis, it is important that there is a centralized global response in controlling the pandemic. An effort to stem the spread of a novel disease has to be a joint intervention between all concerned – the local population, the health and agriculture ministries, veterinary and animal health authorities and the government.

The “One Health” Initiative is an interdisciplinary movement to create collaborations between animal, human, and environmental health organizations. The WHO, the Food and Agriculture Organization of the United Nations and the World Organisation for Animal Health have published a Tripartite Zoonotic Guide to addressing zoonotic diseases in countries.

The Tripartite guide covers prevention, preparedness, detection and response to zoonotic threats at the animal-human-environment interface in all countries and regions, and includes examples of best practices and options based on the experiences of countries. In the Tripartite guide, all relevant sectors and disciplines across the human – animal – environment interface are involved to address health in a way that is more effective, efficient, or sustainable ensuring balance and equity among all the partners.

Key factors in sustainability of the initiatives include – A political will at the highest level and a commitment and engagement from all relevant sectors, sufficient and equitably distributed human and financial resources from domestic sources, strong governance and a strong and effective health system within the individual sectors.  

Experts opine that, given the evolving ecosystems and varied cultures, we will never be able to completely predict or prevent future outbreaks. Prevention methods for zoonotic diseases will differ for each pathogen. In-spite of the best efforts globally, there will always be areas of concern. Unregulated and non-hygienic wet markets may continue as potential spreaders and ready ground for spillovers. Poor access to hygiene in the developing world is another reality and an area of concern. The irrational use of antibiotics in animals bred for food is widespread, and increases the potential for drug-resistant strains of zoonotic pathogens capable of spreading quickly in animal and human populations.

There is always the grave risk of modified and dangerous zoonotic microorganisms being used as biological weapons. The possibility of non-disclosure or reluctance by governments to come clean on an outbreak in the early stages of the epidemic is always a concern. In the recent past, we have witnessed the effects of climate changes resulting in floods and fires and creating imbalances in the environment exposing newer organisms.

Despite all this, there is hope for the future. Though not good enough, the sharing of technical expertise and resources has brought the world closer together. It is our belief that Diseases and Pandemics will in no way deter us in building a safer and a healthier world.

(Pascoal Carvalho has a doctorate in Microbiology with a post doctorate in Immunology on a WHO Fellowship. He is a member of the Pontifical Academy for Life, Vatican City, and actively involved in Bio-Medical Ethics. He is currently involved in developing products and facilities for the Agro, Pharma and Diagnostic Industry. He is responsible for launching new drugs and Innovative diagnostic tests and devices in India in collaboration with European companies.)