World Zoonoses Day 2022:
World Zoonoses Day is observed each year on July 6 commemorating the first vaccination administered against a zoonotic disease. It was on this day in 1885 that Louis Pasteur administered the first rabies vaccine to a human. The patient was a nine-year-old shepherd boy — Joseph Meister — who had been bitten by a rabid dog.
What are zoonotic diseases and how can they spread?
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Zoonotic diseases are any diseases that spread from animals to humans and vice versa. Some common examples are influenza, ebola and West Nile virus. Such diseases are very common, with 2 out of every 3 infectious diseases in people originally coming from animals. According to the CDC, 60 per cent of all existing infectious diseases are zoonotic, at least 70 per cent of emerging infectious diseases originate in animals, and 80 per cent of potential bioterror agents are zoonotic.
The diseases are caused by harmful pathogens like viruses, bacteria, parasites and fungi that can spread to humans and cause illnesses. Depending on the type of zoonotic disease, animals can be carrying the germs in them while appearing to be healthy, which can eventually make the people around them sick.
Because of the close interaction between animals and humans, zoonotic diseases can be spread quite easily, making it important to be aware of the different means of transfer.
Direct contact by petting or touching animals and through their bites and scratches can be a way for someone to be infected. Another way is to come into contact with the areas where the animals have lived, such as aquarium tank water or chicken coops. Foodborne and waterborne problems can also trigger an infection.
Zoonotic diseases over the years
Zoonotic influenza, or the animal influenza viruses that spread from animals to infect humans are also known for their contagiousness. Avian influenza virus subtypes and swine influenza virus subtypes circulating in animals can cause infection in people. This disease can also be spread from horses and dogs, who have their own varieties of influenza viruses. Typically, these human infections of zoonotic influenza don’t spread quickly between humans, but if they built the capacity to do so, then that could be the start of another pandemic because humans will have developed little immunity to battle the virus.
The most well-known case of a zoonotic disease is the plague or the Black Death that ravaged Europe between 1347 and 1351. It was responsible for taking more lives than any other known epidemic or war during that time period. The disease was thought to have been spread from rodents to humans by the bite of infected fleas.
Another recent and surging viral zoonotic disease is monkeypox. It’s transmitted to humans through close contact with an infected person or animal or with material contaminated by the virus. While the first monkeypox case in humans was identified in 1970 in the Democratic Republic of Congo, since then cases have appeared in some other African countries. But in May 2022, several cases were reported in non-endemic countries, which soon became the cause for alarm. Monkeypox is avoidable by restricting contact with infected people or animals, disinfecting frequently touched surfaces, wearing a mask covering the nose and mouth around others and through other hygiene methods. While the WHO labels a monkeypox outbreak poses “moderate risk” to the world, one death in Nigeria has been reported, and hence, the severity of the disease can’t be counted out.
Rabies is another well-known and well-feared zoonotic disease. If someone presents clinical symptoms of it, rabies is almost 100% fatal. In most cases, domestic dogs are responsible for rabies virus transmission to humans. It can be spread through bites or scratches, usually via saliva. Rabies is present on all continents except Antarctica. However, globally rabies deaths are rarely reported because of the vaccine designed by Louis Pasteur.
To find a solution to the dreaded and horrible disease, Pasteur conducted experiments using rabbits and transferred the infectious agent from animal to animal. He desiccated the spinal cords of the infected animals to reduce the impact of the invisible agents but later realized that instead of lessening the agent’s impact, his treatment had, in fact, neutralized it. Thus, rather unknowingly, Pasteur created a vaccine that would save the lives of so many.
Malaria is another example of a zoonotic disease caused by the biting of infected female Anopheles mosquitoes. According to the latest World malaria report, there were 241 million cases of malaria reported in 2020 compared to 227 million cases in 2019. 627,000 people died due to malaria in 2020. Four African countries accounted for nearly half of all malaria deaths worldwide. These included Nigeria, the Democratic Republic of Congo, the United Republic of Tanzania and Mozambique. But the global burden of this disease can be reduced. In 2021, the World Health Organization (WHO) recommended the use of the RTS, S/AS01 (RTS, S) malaria vaccine in children living in places with moderate to high malaria transmission.
The most recent Covid-19 pandemic is also reportedly thought to be a zoonotic disease. No animal reservoir has been found yet, which is why this classification is premature. While scientists debate whether Covid-19 is zoonotic or not, it’s important to remember that as of July 2022, Covid-19 has claimed the lives of 6,364566 people worldwide and that taking the vaccine and ensuring proper hygiene steps can prevent the spread of Covid.
How can we control the spread of zoonotic diseases?
There are some simple steps that can be taken to prevent zoonotic diseases. Some include washing hands right after being with and around animals. Even if someone hasn’t touched the animals, washing hands ensures that germs can’t be spread.
Preventing bites from mosquitoes, ticks and fleas can prove to be helpful, as well. Making sure that one consumes clean, drinking water and handles food bought from outside safely can curb the spread of zoonotic diseases, too.