You’ve probably heard about bird flu in the news or seen warnings about avoiding contact with certain animals. Or you’ve probably still remembered how COVID-19 hit the world; it all started from an animal.
But what exactly is bird flu, or how exactly does the COVID-19 wave start? And why are experts concerned about diseases that come from animals? It’s part of Zoonotic Disease, and let’s talk about it.
What Is a Zoonotic Disease?
A zoonotic disease, or zoonosis, is an illness caused by viruses, bacteria, parasites, or fungi that spread between animals and people. According to the World Health Organization (WHO), there are three classes of Zoonotic diseases.
First, endemic zoonoses are present in many places and affect many people and animals. Second, epidemic zoonoses, which are sporadic in temporal and spatial distribution, and emerging and re-emerging zoonoses, which are newly appearing in a population or have existed previously but are rapidly increasing in incidence or geographical range.
These diseases are becoming more frequent due to increasing human-animal interactions, climate change, wildlife crime, and changes in land use.
Some common examples of zoonotic diseases include bird flu (avian influenza), COVID-19, Rabies, Swine flu, Salmonella, and Ebola—the list is still going on.
Each of these diseases started in animals and ‘transferred’ to people, often with serious consequences. Bird flu is among the most well-known zoonotic diseases, also known as avian influenza.
Bird flu spreads when people come into contact with infected poultry or surfaces contaminated with secretions from infected birds. Outbreaks are more likely to happen in places where people live close to animals, such as poultry farms or live bird markets.
When bird flu infects humans, it can cause symptoms like fever, cough or sore throat, muscle aches, difficulty breathing, and eye infections (conjunctivitis). In severe cases, it can lead to pneumonia, multi-organ failure, and even death.
How scary is Zoonotic Disease?
As we saw with the 1918 influenza and COVID-19 pandemics, new zoonotic diseases—or new strains of them—take tremendous resources and time before we find effective treatments and prevention.
In the meantime, they can kill or debilitate countless individuals, overwhelm health services, and devastate agriculture and other livelihoods, making zoonotic diseases a serious threat not only to public health but also to economies and food security.
Rabies is one of the viral zoonotic diseases that causes progressive and fatal inflammation of the brain and spinal cord. According to the WHO, Rabies is estimated to cause 59,000 human deaths annually in over 150 countries, with 95% of cases occurring in Africa and Asia.
List of zoonotic diseases
Several pathogens, including viruses, bacteria, parasites, fungi, and prions, can cause zoonotic diseases.
Here are some of the most well-known Zoonotic diseases, according to the International Fund for Animal Welfare:
- Widespread diseases: HIV, COVID-19, the 1918 influenza (Spanish flu), rabies, avian influenza (bird flu), Ebola, Mpox (monkey pox), West Nile virus, Nipah virus, Zika virus, SARS, MERS, yellow fever
- Parasitic: toxoplasmosis, Giardiasis, scabies
- Bacterial: Lyme disease, cat scratch disease, anthrax, salmonellosis, zoonotic tuberculosis, Bubonic plague
- Fungal: ringworm, sporotrichosis (rose handler’s disease)
- Prionic: bovine spongiform encephalopathy (BSE, or mad cow disease), chronic wasting disease (zombie deer disease)
Many of those names may sound familiar, such as Lyme disease, monkey pox, and rabies.
The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) stated that more than 60 percent of known infectious diseases in humans could be zoonotic in origin.
They also report that approximately 75% of new or emerging infectious diseases in people come from animals.
Insects like fleas and mosquitoes often act as vectors, transferring a pathogen from an animal to a human. Sometimes zoonotic diseases mutate within humans, creating a human-only strain.
So, How Do Zoonotic Diseases Spread?
Want to protect yourself from zoonotic diseases? Learn how to reduce risks when interacting with animals and stay updated on emerging outbreaks.
Here’s the list:
- Direct contact with animals, their saliva, blood, urine, or feces
- Indirect contact by touching surfaces contaminated by animals
- Foodborne transmission occurs when eating undercooked or contaminated meat, eggs, or dairy
- Vector-borne transmission happens when a mosquito, flea, or tick carrying a pathogen bites a human
- Airborne transmission occurs in droplets or dust particles that contain the pathogen.
Also, the ways we exploit wildlife and their ecosystems have led to deadly disease spillover both directly and indirectly, because the diseases we get from domesticated animals often have their origins in wildlife.
