Look But Don’t Touch: Zoonotic Diseases and Where They Come From

Look But Don’t Touch: Zoonotic Diseases and Where They Come From

<p>Animals are your friends, or at least some of them are anyway. Zoonotic diseases refer to infections that transmit from animals to humans, and the first thing that springs to mind for everyone of course is COVID. </p> <p>World Zoonoses Day, observed every year on July 6th, commemorates the historic achievement of Louis Pasteur, who administered the first successful rabies vaccine to a human on this day in 1885. This day is used as a critical reminder of how interwoven the health of both humans and animals is and why we need to be vigilant and proactive to manage zoonotic diseases.</p> <h2>Zoonoses in a nutshell</h2> <p>Zoonoses are infectious diseases that are transmitted from animals to humans, and they can be caused by various pathogens, including bacteria, viruses, parasites, and fungi. Zoonosis can spread through direct contact with animals, through the consumption of contaminated food or water, or via vectors such as mosquitoes and ticks.</p> <figure><img src="https://cdn.storymd.com/optimized/Nq4yK8LH7A/thumbnail.jpg" alt="Zoonotic Infections Are a One Health Issue | Source: CDC" /> <figcaption>Zoonotic Infections. <em>Source: CDC</em></figcaption> </figure> <h3>Effect on public health</h3> <p>Zoonotic diseases are responsible for some of the most widespread and devastating outbreaks in human history. We all know about the famous Black Death (caused by the bacterium <em>Yersinia pestis)</em>, which decimated Europe's population in the 14th century. More recent outbreaks like the Ebola virus and COVID underscore the ongoing threat posed by zoonotic pathogens.</p> <h2>Superstars of the zoonotic disease realm</h2> <p>Some well-known zoonotic diseases include:</p> <h3>Rabies</h3> <p>Bites from a rabid animal require prompt treatment because cases are almost always fatal once clinical symptoms start showing. The rabies virus is present in saliva and is introduced to the body via the wound of a bite. </p> <p>Rabies targets the central nervous system, causing severe brain damage and death. Post-exposure prophylaxis (PEP) treatment is nearly 100% effective if administered promptly, and around 60,000 Americans receive PEP treatment every year following potential exposure to rabies. Raccoons, skunks, and foxes are common carriers of rabies.</p> <figure><img src="https://cdn.storymd.com/optimized/JA05NrcOo9/thumbnail.jpg" alt="Rabies symptoms in humans | Source: Global Alliance for Rabies Control (https://rabiesalliance.org)" /> <figcaption>Rabies Symptoms in Humans. <em>Source: Global Alliance for Rabies Control</em></figcaption> </figure> <h3>Influenza</h3> <p>Certain strains of influenza have animal origins and can cause widespread illness among people. You’ve almost certainly heard of bird flu (H5N1) and swine flu (H1N1), and the former is a major concern for public health experts right now. </p> <p>Bird flu is spreading in American dairy farms as the disease transmits from birds to cows, but it does not appear to jump so easily to humans — so far. There have only been a handful of human cases until now, and the situation is being monitored closely to see if there is a spike in transmission to or among humans. </p> <figure><img src="https://cdn.storymd.com/optimized/kqrRJvSZqn/thumbnail.jpg" alt="How Infected Backyard Poultry Could Spread Bird Flu to People | Source: CDC" /> <figcaption>How Infected Backyard Poultry Could Spread Bird Flu to People. <em>Source: CDC</em></figcaption> </figure> <h3>Lyme disease</h3> <p>We are now in prime tick season, and fans of the great outdoors need to take proper precautions. Lyme disease, caused by the bacterium <em>Borrelia burgdorferi</em>, is transmitted through the bite of infected ticks. </p> <h3>Malaria, chikungunya, and Dengue fever</h3> <p>These three are all mosquito-borne diseases that are more common in places like the Caribbean and sub-Saharan Africa. Symptoms include vomiting, fever, and headaches.</p> <figure><img src="https://cdn.storymd.com/optimized/RdawnVFXAl/thumbnail.jpg" alt="What are the signs and symptoms of malaria? | Source: Medical gallery of Mikael Haggstrom 2014" /> <figcaption>Symptoms of Malaria. <em>Source: Medical gallery of Mikael Haggstrom 2014</em></figcaption> </figure> <h3>COVID</h3> <p>Famously, COVID is thought to have originated in bats and then transmitted to humans through an intermediary host.</p> <h2>How do zoonotic diseases spread to humans?</h2> <p>The emergence and spread of zoonotic diseases, especially ones that envelop the world like COVID, are dependent on numerous factors lining up in their favor. For example:</p> <ul> <li><strong>Urbanization and habitat encroachment.</strong> The more we dig into new environments and encroach on wildlife habitats, the greater the chances we have of interactions with animals and creating new ways for pathogens to pass between species. <br /><br /></li> <li><strong>Global travel and trade.</strong> Ours is a heavily interconnected world, and the rapid movement of people, animals, and goods across the globe makes it almost inevitable that highly infectious diseases would jump from one region to another.<br /><br /></li> <li><strong>Climate change.</strong> Messed-up ecosystems and weather patterns can affect the distribution and behavior of disease vectors like mosquitoes and ticks. These agents of disease are increasingly moving their habitats to previously inhospitable places, bringing them into closer contact with humans.<br /> <figure><img src="https://cdn.storymd.com/optimized/WdxDQ7ted2/thumbnail.png" alt="Impact of Climate Change on Human Health | Source: Centers for Disease Control and Prevention" /> <figcaption>Impact of Climate Change on Human Health. <em>Source: CDC</em></figcaption> </figure> </li> <li><strong>Agricultural practices.</strong> Our vast farming and livestock production capabilities create conditions that are conducive to the spread of diseases among animals and from animals to humans.<br /><br /></li> <li><strong>Wildlife trade.</strong> The unregulated trade of wild animals for food, pets, or traditional medicine can introduce new pathogens to human populations. Wildlife markets, where live animals are sold or slaughtered, often feature environments where various species in poor health are in proximity to humans.</li> </ul> <h2>How are we countering the spread of zoonotic diseases?</h2> <p>It doesn’t take a genius to know that controlling zoonotic diseases is complicated. A multifaceted approach that accounts for the health of humans, animals, and the environment alike is necessary to catch and contain these infectious agents before they get out of control. </p> <p>Key strategies include:</p> <ul> <li><strong>Surveillance and monitoring.</strong> We need robust systems to detect and respond to outbreaks early. This includes monitoring wildlife, livestock, and human health data.<br /><br /></li> <li><strong>Vaccination and treatment.</strong> The ability to rapidly develop and distribute vaccines and treatments for both humans and animals is essential. <br /><br /></li> <li><strong>Public education.</strong> Raising awareness about zoonotic diseases and promoting practices that reduce risk, such as proper handwashing and food safety.<br /><br /></li> <li><strong>Research and innovation.</strong> Investing in research to better understand zoonotic pathogens and develop new tools for diagnosis, prevention, and treatment.<br /><br /></li> <li><strong>Policy and regulation.</strong> Setting out laws and regulations to control wildlife trade, manage agricultural practices, and protect ecosystems.</li> </ul><h2>More on Zoonotic Diseases</h2><ul><li><a href="https://soulivity.storymd.com/journal/yj5dgpeinm-zoonotic-diseases" target="_blank">Zoonotic Diseases (Animal Diseases) and Your Health</a></li><li><a href="https://soulivity.storymd.com/journal/pwvvvxa07w-rabies" target="_blank">Rabies: Transmission, Symptoms, Prevention, Treatment</a></li><li><a href="https://soulivity.storymd.com/journal/9jkpz8r0bm-bird-flu" target="_blank">Bird Flu (Avian Influenza): Types, Transmission, Symptoms</a></li></ul>
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