Zoonosis
Host genetics plays an important role in determining which non-human viruses will be able to make copies of themselves in the human body.
"Approximately 1.67 million undescribed viruses are thought to exist in mammals and birds, up to half of which are estimated to have the potential to spill over into humans", says a study[18] led by researchers at the University of California, Davis.
The most significant zoonotic pathogens causing foodborne diseases are: Escherichia coli O157:H7, Campylobacter, Caliciviridae, and Salmonella.
[32] In Western countries, hepatitis E burden is largely dependent on exposure to animal products, and pork is a significant source of infection, in this respect.
Research has proved the importance for continued clinical veterinarian education on occupational risks associated with musculoskeletal injuries, animal bites, needle-sticks, and cuts.
[34] A July 2020 report by the United Nations Environment Programme stated that the increase in zoonotic pandemics is directly attributable to anthropogenic destruction of nature and the increased global demand for meat and that the industrial farming of pigs and chickens in particular will be a primary risk factor for the spillover of zoonotic diseases in the future.
[44] These markets, where diverse species converge, facilitate the mixing and transmission of pathogens, including those responsible for outbreaks of HIV-1,[45] Ebola,[46] and mpox,[47] and potentially even the COVID-19 pandemic.
[48] Notably, small mammals often harbor a vast array of zoonotic bacteria and viruses,[49] yet endemic bacterial transmission among wildlife remains largely unexplored.
Therefore, accurately determining the pathogenic landscape of traded wildlife is crucial for guiding effective measures to combat zoonotic diseases and documenting the societal and environmental costs associated with this practice.
Encephalitozoon cuniculi is a microsporidial parasite carried by many mammals, including rabbits, and is an important opportunistic pathogen in people immunocompromised by HIV/AIDS, organ transplantation, or CD4+ T-lymphocyte deficiency.
For instance, approximately 20% of domestic dogs, cats, and horses carry anti-hepatitis E virus antibodies and thus these animals probably contribute to human hepatitis E burden as well.
Hunting involves humans tracking, chasing, and capturing wild animals, primarily for food or materials like fur.
[60] Wildlife activities like hunting and trade bring humans closer to dangerous zoonotic pathogens, threatening global health.
[62] Although bushmeat provides protein and income for many, the practice is intricately linked to numerous emerging infectious diseases like Ebola, HIV, and SARS, raising critical public health concerns.
[63] Kate Jones, Chair of Ecology and Biodiversity at University College London, says zoonotic diseases are increasingly linked to environmental change and human behavior.
The disruption of pristine forests driven by logging, mining, road building through remote places, rapid urbanization, and population growth is bringing people into closer contact with animal species they may never have been near before.
[64] In a guest article, published by IPBES, President of the EcoHealth Alliance and zoologist Peter Daszak, along with three co-chairs of the 2019 Global Assessment Report on Biodiversity and Ecosystem Services, Josef Settele, Sandra Díaz, and Eduardo Brondizio, wrote that "rampant deforestation, uncontrolled expansion of agriculture, intensive farming, mining and infrastructure development, as well as the exploitation of wild species have created a 'perfect storm' for the spillover of diseases from wildlife to people.
"[65] Joshua Moon, Clare Wenham, and Sophie Harman said that there is evidence that decreased biodiversity has an effect on the diversity of hosts and frequency of human-animal interactions with potential for pathogenic spillover.
[66] An April 2020 study, published in the Proceedings of the Royal Society's Part B journal, found that increased virus spillover events from animals to humans can be linked to biodiversity loss and environmental degradation, as humans further encroach on wildlands to engage in agriculture, hunting, and resource extraction they become exposed to pathogens which normally would remain in these areas.
[68] In October 2020, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services published its report on the 'era of pandemics' by 22 experts in a variety of fields and concluded that anthropogenic destruction of biodiversity is paving the way to the pandemic era and could result in as many as 850,000 viruses being transmitted from animals – in particular birds and mammals – to humans.
The increased pressure on ecosystems is being driven by the "exponential rise" in consumption and trade of commodities such as meat, palm oil, and metals, largely facilitated by developed nations, and by a growing human population.
Southeast Asia is especially vulnerable as it has a large number of bat species that generally do not mix, but could easily if climate change forced them to begin migrating.
The authors suggest that climate-driven changes in the distribution and robustness of bat species harboring coronaviruses may have occurred in eastern Asian hotspots (southern China, Myanmar, and Laos), constituting a driver behind the evolution and spread of the virus.
[74][75] Zoonotic diseases contribute significantly to the burdened public health system as vulnerable groups such the elderly, children, childbearing women and immune-compromised individuals are at risk.
An example of this is the outbreak of Nipah virus in peninsular Malaysia, in 1999, when intensive pig farming began within the habitat of infected fruit bats.
[91] 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.
[citation needed] The first vaccine against smallpox by Edward Jenner in 1800 was by infection of a zoonotic bovine virus which caused a disease called cowpox.
