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What Is The Influence Of The Environment On Human Diseases And Pandemics?


Earth Day during a pandemic is a different celebration as many of us are in quarantine. The pandemic has also made us look at the world differently. Eco Minute host, Dr. Enid Sisskin shares some insight on how the environment has been impacted by the pandemic. 

According to the CDC, most infectious diseases in humans are zoonoses – diseases that originate in animals and can infect humans - think rabies, the plague, salmonellosis, Lyme disease and Ebola, to name a few. But, how does the state of the environment influence these diseases?

Degradation of the natural environment:

Most experts believe there is an increase in zoonotic diseases due to environmental degradation – deforestation and habitat destruction for homes, urban sprawl and farming. The loss of habitat increases the opportunity for contact between humans and animal species, which also changes the dynamics of the transmission of viruses. One study of Ebola found that the disease was more prevalent in areas that had recently been deforested. “When we encroach on nature, when we destroy forest, when we degrade the environment, then we are disturbing what is supposed to be left undisturbed," echoes Inger Anderson, the Executive Director of the United Nations Environment Programme, when she spoke with Business Insider

"We disrupt their ecosystems, hunt them, build houses next to them, grow livestock right next to their populations..." "We allow the viruses they carry, that we've never been exposed to in our history, to emerge into our own populationsm," said Dr. Peter Daszak, a professor at Columbia University and president of the EcoHealth Alliance in a CBS News article. 

Climate change 

The destruction of biodiversity from climate change disrupts the predator-prey balance. "When predators disappear, often their prey, such as rats and mice, increase. Rats and mice are the sources of many of the pathogens that jump from wildlife to humans," said Dr. Richard Ostfeld, a disease ecologist from the Cary Institute of Ecosystem Studies, in New York's Hudson Valley. Human-caused climate change can make the issue worse as animal populations are forced to move into different areas. 

Waste management, sanitation and infrastructure

The coronavirus crisis is also impacting waste streams as more face masks and medical gowns are used and then thrown away, says Anderson. Many countries may not have the infrastructure or capacity to properly dispose of this waste allowing it to infect the environment and people. 

Credit Jennie McKeon/WUWF
Dr. Enid Sisskin

Factory farms are another problem. "When we house these animals in unsanitary conditions with many other species of animals, we can create ideal conditions for these pathogens to jump to us," said Ostfeld. 

Last, but certainly not least, wet markets

A wet market is a marketplace that sells unpackaged fresh meat, fish, produce and other perishable goods. And they can be a hotspot for viruses as animals are removed from their natural habitats and transported in crowded conditions among other wild and domestic animal.

"Both wet markets and the wild animal trade have been implicated in species jumps and epidemics," said Ostfeld. "If you were a virus, you'd be very happy in this situation, because jumping to new hosts would be a piece of cake, opening up tremendous opportunities for infection and further transmission."

How does the virus get from animals to humans? People can be directly exposed to animal fluids or feces, by hunting, killing or butchering them or simply through contaminated surfaces or food or drink. Or other animals can act as intermediate hosts, such as the civet cat, pangolin, or domestic livestock. 

What has been the effect of the Pandemic on the Environment?

Quarantining, the decrease in transportation and industry has led to a decrease in air and water pollution worldwide. In Wuhan, the city that started it all, a city usually blanketed by air pollution, the skies are blue and nitrous oxides have decreased all over China, as well as Italy, and many other countries.

Catch Dr. Sisskin's Eco Minute every weekday at 4 p.m. or download the podcast