The modification of wildlife habitats has resulted in the proliferation of zoonoses
Mexico.- The zoonotic diseases, which are transferred from animals to humans, have gained international attention in the past decades, the ebola, the avian flu, the swine flu (H1N1), the respiratory syndrome Middle East (MERS), the Rift Valley fever, severe acute respiratory syndrome (SARS), West Nile virus, the virus Zika and the new COVID-19 have caused pandemics or have threatened to be the cause of it, and left thousands of deaths and large economic losses.
Investigators still have not identified the exact point at which the virus SARS-CoV-2 was transmitted from animals to humans and are presented as the COVID-19, but it does ensure that will not be the last pandemic.
In 2016, the United Nations Program for Environment (Unep) warned about the rising global epidemic zoonotic. He noted that 75 percent of all emerging infectious diseases in humans are of animal origin and are closely related to the health of ecosystems.
According to the report “Frontiers 2016” Unep, zoonoses are opportunistic and thrive when there are changes in the environment, in the host animals or human, or on the same pathogens.
In the past century, the combination of population growth and the reduction of ecosystems and biodiversity resulted in opportunities that facilitated the transfer of pathogens from animals to people. On average, a new infectious disease emerges in humans every four months, according to the report.
Human activities have caused major alterations in the environment, because when you change the use of land for urban settlements, agriculture, logging, or industries and their associated infrastructure, has fragmented or invaded the habitat of the animal.
We have destroyed natural areas buffer, which typically separate humans from wildlife, and with this, he created bridges for which the pathogens pass from animals to people.
This situation has been exacerbated by the climate crisis, caused by the unprecedented increase of the emissions of greenhouse gases in the atmosphere. Changes in temperature, moisture, and seasonality, affect the survival of microbes in the environment, and the evidence suggests that the epidemics will be more frequent as the climate continued its transformation.
The consequences of climate change disproportionately affect those with fewer resources, which increases their vulnerability, and expands the possibilities of spread of zoonotic diseases.
CHANGES IN THE GUESTS
Human activity can also transform to the populations that serve as hosts of certain pathogens, in particular migration, urbanisation, dietary preferences, the demands of business and travel.
In many developing countries, the economic growth and the transition from rural to urban areas have stimulated the demand for meat and dairy products, which has led to the expansion of crop lands and livestock more intensive, near and around the cities, resulting in an increase of the exposure to disease.
The livestock is, often, a bridge epidemiological between wildlife and humans, such as in the case of influenzas such as avian and swine. The pathogen is first circulated from infected wild birds to poultry, and then moved on to humans. The same in the case of pigs.
The proximity to different species in the so-called markets wet or the consumption of wild animals may also facilitate the transmission from animal to human. The first cases of SARS were associated to contact with civets caged in a market, and it is believed that some cases of ebola in Central Africa were transferred to animal hosts to humans when consumed gorilla meat infected.
The incubation, which is the time between the human infection and the time in which the person has symptoms, can last for days or weeks, but every day millions of people travel from one country to another in hours. A disease originating in one country can quickly spread to others, regardless of the distances, which is particularly visible in the rapid spread of the COVID-19, which affected almost all the nations of the world during the three months of the first reported case.