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Human race has had strong quest to explore the World since ages. Human movement led to mixing of human races as well as flora and fauna. The mixing of races led to hybrid population all over the World. As explorers started discovering new continents, islands, exotic scenic areas, they started employing the indigenous population and grabbing their lands for economic activities. As the economic activities were increased in their areas the forests were cut to get the area cleaned for agricultural cultivation, economic activities and industrialization.
The virgin areas of land and sea were explored and exposed to human population. Beside the agricultural, economic and industrial activity the other scenario came up i.e. tourism. The tourism led to a lot of inconvenience to the local indigenous population, land, water and air pollution.
As the World population is growing the industrial activities are increasing and as a result of which the World forest cover and agricultural cultivation areas are decreasing which could result into great catastrophe in future.
The degradation of forest cover exposed the flora, fauna, microbes, insects and animals to the human population which led to emergence of new diseases in humans.
The Acquired Immunodeficiency Syndrome (AIDS)in preserved blood sample of man from Leopoldville in the Belgium Congowas unknown to human race before 1959. But it is widely believed that HIV originated in Kinshasa in the Democratic Republic of Congo around 1970 when HIV crossed species from Chimpanzee which are wild animals, though there was no need to disturb their habitat for any reason.
The African Continent is known for its forest cover, wild species and wide range of flora, fauna, microbes, insects and animals. Masai mara, Serengeti, Ngorongoro, Amboseli, Kruger, Chobe, Moremi, Tosha, among others, are famous wild life reserves of Africa.
Many reserves are there in India, China, South America, United States of America, South Asian countries and in the Australian continent. But now in these areas due to timber cutting, farming, and other industrial activities the forest cover is dwindling. The gas pipeline project in Canada, Palm oil project in Indonesia, mass oil drilling in US, artificial islands created by China, Belt and Road Initiative project of China, Exploration of Antarctica, etc. are glaring examples of human interference in nature. The uncontrolled animal hunting is also an issue of concern.
The Mainland China is the biggest market for animal parts in the World. It’s a lucrative business hence many people are involved in this. Even the dark web of internet is used to sell these products.
As the humans came close to unknown microbes, insects and animals the diseases in animals were transmitted to humans. It is also important to note that the wild animals were domesticated and kept as pets. The animal and human conflict also led to transmission of diseases in humans. The Table below shows few such examples:
| S.No. | Name of Disease | Origins | Remark |
| 1 | Malaria | August 20th, 1897 | From Secundrabad, India by Ross(Anopheles Female) Mosquito |
| 2 | Filaria | 1876 | Ervin von Badz in Tokyo(Culex) Mosquito |
| 3 | Dengue | 1780 | From Madras, but virologically proved in 1963-64 in Calcutta (Aedes aegpti) Mosquito |
| 4 | Chicken Guinea | 1952 | Southern Tanzania (Aedes aegpti) Mosquito |
| 5 | Kalazar | 1790-1835 | Bengal India (Sand Fly) |
| 6 | Leptospirosis | 1883 | Landouzy (bacterial disease): exposure to infected animals (both wild and domestic) and contaminated water. |
| 7 | Yellow Fever | 1648 | Africa by Aedes aegpti (found in primates) mosquito |
| 8 | Rabies | 1880 | Louis Pasteur by Rabid animals,especially mammals |
| 9 | JapaneseEncephalitis | 1871 | Japan (Culex) Mosquito |
| 10 | Influenza H1N1 | Mid-20th century | Pigs/Birds/Wild Birdsfrom China |
In several South Asian countries, China and now all over the World, non-vegetarian restaurants started selling live animals for dining. In some countries especially China, there are especially designated markets for selling these live animals. They include bats, foxes, different type of fishes, crabs, snakes, pythons, pangolins, tiger and lion body parts etc.
The destruction of natural flora, fauna, led to exposure of humans to unknown microbes and insects which results in emergence of new diseases in human.
Ebola virus was another tragic medical event which happened in Africa and which caused much human mortality and morbidity. It was suspected to be animal transmitted disease i.e. it was transmitted from bats to apes, monkeys, etc.
As per reports in public domain the miners got ill with mysterious illness in Wuhan China. They were treated very confidentially. The live animal market in Wuhan China is also under scanner because of animal to human transmission of novel corona virus. This was the perfect example of transmission of microbes from animals to humans. Some other reports claim that Wuhan virology lab was working on novel corona virus and accidently one bat bitten the scientist who got ill and transmitted the disease to others.
It led to COVID-19 pandemic all over the World which caused millions of deaths and a very high rate of morbidity. This led to economic slowdown, unemployment, and closure of business establishments. Millions of people went below the poverty line due to lockdowns.
Recently, scientists found similar virus like corona in the bats found in the caves of Maharashtra. It clearly indicates that human to animal conflict not only results in killings and destruction but it has a larger dimension of transmission of unknown diseases to humans.
The exposure of humans to wild birds especially migratory, uncontrolled and low maintained quality poultry and pig farming led to transmission of H1N1 virus to humans. The infection in these birds and pigs were not known before this disease so the exact cause is unknown.
Recently in Maharashtra (Mahabaleshar Caves), the scientists have taken samples from bats. In these bats, some strains of Nipah virus were found. Scientists from the Pune-based National Institute of Virology (NIV) identified the virus in bats from a cave in Mahabaleshwar in Satara in March 2020. It shows vulnerability of humans to these strains, thus, coming in contact with these animals could lead to contracting several unknown diseases. The samples taken by scientists from bats indicate that corona virus did not originate in India. The virus, usually found in bats and transmitted through them, features in the top 10 priority list of pathogens identified by the World Health Organization (WHO), and its transmission to humans has resulted in deadly outbreaks across the World.
A major factor contributing to the appearance of new zoonotic pathogens in human populations is increased contact between humans and wildlife. This can be caused either by encroachment of human activity into wilderness areas or by movement of wild animals into areas of human activity. An example of this is the outbreak of Nipah virus in peninsular Malaysia in 1999, when intensive pig farming began in the habitat of infected fruit bats. Unidentified infection of the pigs amplified the force of infection, eventually transmitting the virus to farmers and causing many human deaths.
Similarly, in recent times Avian influenza and West Nile virus have spilled over into human populations probably due to interactions between the carrier host and domestic animals. Highly mobile animals such as bats and birds may present a greater risk of zoonotic transmission than other animals due to the ease with which they can move into areas of human habitation.
Because they depend on the human host for part of their life-cycle, diseases such as African schistosomiasis, river blindness, and elephantiasis are not defined as zoonotic, even though they may depend on transmission by insects or other vectors.
The WHO works with National governments, academia, non-governmental and philanthropic organizations, and regional and international partners to prevent and manage zoonotic threats and their public health, social and economic impacts. These efforts include fostering cross-sectoral collaboration at the human-animal-environment interface among the different relevant sectors at regional, national and international levels. The WHO also works to develop capacity and promote practical, evidence-based and cost-effective tools and mechanisms for prevention of zoonotic infection, surveillance and detection through reporting, epidemiological and laboratory investigation, risk assessment and control, and assisting countries in their implementation.
As part of the One Health approach, the World Health Organization collaborated with the Food and Agriculture Organization (FAO) of the United Nations and the World Organization for Animal Health (OIE) on the Global Early Warning System for Major Animal Diseases (GLEWS). This joint system builds on the added value of combining and coordinating alert mechanisms of the three agencies to assist in early warning, prevention and control of animal disease threats, including zoonoses, through data sharing and risk assessment.
Conclusion
Many infectious diseases of recent concern, including malaria, Influenza, Dengue, Japanese Encephalitis and Covid-19 have emerged from complex ecological communities involving multiple hosts and their associated parasites. Several of these diseases appear to be influenced by human impacts on the environment, for example intensive agriculture, deforestation, habitat loss, contamination of air, water and soil. Such environmental impacts may affect many species at trophic levels below or above the host community. Thus, the prevalence of both human and wildlife diseases may alter in unanticipated ways as a result of changes in the structure and composition of ecological communities. Despite lot of advancement in understanding and management of these diseases, morbidity and mortality incurred are still sporadically higher in many parts of the world especially in low and middle income countries. Unfortunately, the human generations are still not able to understand that very existence and well-being of human race is directly depends upon healthy equilibrium between human and environment.
India has always an environmentally sensitive philosophy since ages. The Mahabharata, Ramayana, Vedas, Upanishads, Bhagavad Gita, Puranas and Smriti contain the earliest messages for preservation of environment and ecological balance. Nature, or Earth, has never been considered a hostile element to be conquered or dominated. In fact, man is forbidden from exploiting nature. He is taught to live in harmony with nature and recognize that divinity prevails in all elements, including plants and animals. The Bhagavad Gita advises us not to try to change the environment, improve it, or wrestle with it. If it seems hostile at times tolerate it. Therefore, to provide healthy and safe environment to coming generations that is free from sufferings, current generation must be honest and dedicated towards our own planet.