Zoonosis is a disease that can be transmitted to humans from animals. Transmission occurs when an animal infected with bacteria, viruses, parasites, and fungi comes into contact with humans.
Over 200 diseases are currently classified as zoonoses. Common examples include tick-borne illnesses such as Lyme disease, wildlife-transmitted illnesses such as rabies, farm animal-transmitted diseases such as bovine tuberculosis from cattle, and mosquito-transmitted diseases such as the West Nile virus, malaria, and yellow fever.
What are Zoonoses?
Zoonotic diseases can be global, or they can be inherent to a specific region of the world. The pandemic of the coronavirus disease 2019 (COVID-19) which s caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been classified as a zoonotic disease, however, no animal reservoir has yet to be confirmed.
The number of zoonotic diseases may increase as rates of worldwide travel, globalization of markets, and the human destruction of animal habitats continue to rise.
Human-animal contact
Humans can come into contact with animals in a number of ways. People have been keeping domesticated animals for companionship and protection. Many humans have also raised farm animals for food for thousands of years.
Humans can also be exposed to animals during nature hikes, trips to the park or beach, at farms, zoos, or state fairs, or in their own gardens. Certain occupations such as farm workers, wildlife biologists, veterinarians, or even construction workers building homes on newly cleared land are particularly susceptible.
In addition, increased rates of globalization and worldwide travel enable zoonotic diseases that may have once been limited to specific geographical locations to now appear all across the globe. For example, two healthcare workers in the United States were exposed to the Ebola virus while caring for sick travelers from Africa, even though the bats that are thought to host the virus are not native to the U.S.
Transmission
There are numerous modes of zoonotic disease transmission. Humans can become infected through a tick or mosquito bite, handling or eating undercooked or raw meat, or coming into contact with the blood, urine, or feces of an infected animal.
Children under the age of 5, pregnant women, adults over the age of 65, as well as people with compromised immune systems are particularly susceptible to zoonotic diseases. Although there are animals all around us, there are a number of precautions that a person can take to protect themselves.
First, it is important to regularly use bug repellent containing 20% N,N-Diethyl-meta-toluamide (DEET) to prevent mosquitoes and ticks from biting. It is also crucial to check for ticks on the skin after spending time outside.
Second, thorough washing of the hands and vegetables both during and after meal preparation, as well as the complete cooking of foods, can limit food-borne illnesses. Lastly, it is recommended to always thoroughly wash hands after visiting a farm, zoo, state fair, or any facility where a person may touch animals.
Zoonoses and public health
Zoonotic diseases are a worldwide public health risk. In developing countries, diseases such as malaria can greatly burden the public healthcare system and affect local economies. In addition, as food markets continue to globalize, food-borne zoonotic diseases can limit agriculture, food production, and international trade agreements.
The World Health Organization (WHO) has implemented several initiatives to help reduce the transmission of zoonoses. These include surveillance, tracking, and reporting activities, as well as the development of preparedness and response plans in the event of an epidemic infection. Public and professional education can also reduce the transmission of zoonotic diseases.
Locally, veterinarians are required to report the incidence of some zoonotic diseases in order to limit or confine outbreaks.
References
Further Reading
Halting pandemics at the source: The call for a proactive 'One Health' approach