While there are multiple diseases that animals transmit to humans, this article deals with some of the most common ones – from rabies to toxoplasmosis, leptospirosis, and more.
Intro: Statistically speaking, the number of diseases crossing from animals to humans has decreased in the past decades, yet zoonotic infections still pose a threat to human health. From Lyme disease to Salmonellosis, we’re looking at some of the most common animal-transmitted illnesses out there.
1. Rabies
Veterinarians worldwide implemented vaccination plans allowing for rabies to become a far less common occurrence. Wild animals still transmit it, and the most dangerous species range from foxes and raccoons to bats. However, if you are a responsible pet owner and you make sure to take your dog or cat in for their yearly vaccine, it’s likely that your vet already immunized them against rabies.
As a result, even if your pet catches the virus from one of these wild animals or they come in contact with infected saliva in the forest or on a sidewalk, they will not develop the clinical illness itself. Rabies is not treatable at the moment. It is one of (if not the most) dangerous zoonotic diseases for both you and your pet.
This viral disease affects the central nervous system. It causes a variety of behavioral changes over a period of up to two weeks or more. If you get bitten by an animal, you should contact your emergency hospital right away. It is even more important to do so when you suspect that this animal didn’t receive a vaccine against rabies.
2. Lyme Disease
Animals are merely the vectors for this disease as it is primarily transmitted by ticks. Ticks carry a bacterium called Borellia burgdorferi, which causes the illness. If you share the same living space with a dog, for example, and you haven’t taken them to the vet clinic to get their external parasites removed in a long time, you do have a chance of becoming a victim of Lyme disease.
You should take Lyme disease seriously. There have been cases of people ending up in a coma from how severely the pathogen affected their bodies. Lyme disease causes a wide range of symptoms, from fatigue and slow thinking to severe cardiovascular complications, pain in the joints, and chronic general malaise. In the United States, the CDC estimates that doctors diagnose approximately 400,000 people with this disease on an annual basis.
3. Salmonellosis
Salmonellosis is a disease caused by a bacterium. You can easily get this illness not just from pets, but also from farm animals like chickens and ducks and their eggs. Reptilians are notorious for carrying the pathogen on their skin, and so are amphibians. It’s not uncommon for cats and dogs to be carriers as well, but this bacterial condition is much less common in them by comparison.
Given the living conditions of some of these animal species, their feces can end up in the water and contaminate it, leading to Salmonella infecting a whole animal group. The most common symptoms of an infection in people are diarrhea, nausea, and fever. Some individuals may experience vomiting, muscle aches, as well as bloody stools.
4. Toxoplasmosis
Toxoplasma gondii is one of the most notorious parasites that some cats carry and transmit to their owners. It is particularly dangerous for pregnant women as it can cause fetal developmental issues. Some people contract it when they’re young and healthy but show no symptoms whatsoever. A dirty litter box or cleaning it without using gloves when pregnant is a sure way of contracting Toxoplasma.
For immunocompromised individuals, this zoonotic disease is a real problem. Flu-like clinical signs are most common in this social category. Some people experience enlarged lymph nodes, poor vision, and other complications. If you are a cat owner, you can easily get your pet tested at the veterinary hospital to find out if your friend is a Toxoplasma carrier. We recommend testing both if you are and are not planning to become a parent in the near future.
5. Psittacosis (Parrot Fever)
A bacterium going by the name of Chlamydia psittaci causes this zoonotic disease. The bird species that most commonly transmit the illness to humans are pet birds like parrots and cockatoos, farm birds like chickens and geese, and wild birds such as pigeons. In birds, the infection causes symptoms ranging from diarrhea to runny eyes.
However, the health complications of Psittacosis are a bit more severe in humans. People affected by the illness often experience fever, headaches, respiratory distress, diarrhea, nausea, vomiting, and dehydration, as well as generalized body pain. Individuals with fully functioning immune systems shouldn’t experience the more severe forms of this disease. Nevertheless, children, seniors, pregnant women, as well as immunocompromised individuals can develop pneumonia, hepatitis, and heart inflammation (endo- and myocarditis).
6. Leptospirosis
Multiple animal species can transmit this bacterial disease to humans, but they’re not the only culprit. Generally, if this pathogen ends up in drinking water, lakes, or any other body of water than humans might come in contact with, it can easily cause an epidemic. In people, clinical signs of leptospirosis range from fever and muscle pain to gastrointestinal issues and skin rashes.
The more severely affected individuals can end up with long-term damage to some of their organs, such as their liver and kidneys. Similarly to one other disease mentioned in this article (Toxoplasmosis), Leptospira crosses the placental barrier and infects not just the pregnant mother, but also the fetus. Even in cases where the mother doesn’t even experience any symptoms, the fetus could still be affected by renal and liver damage and internal bleeding. Developmental issues are not uncommon at all.
7. Cat Scratch Disease
While it is known as Cat Scratch Disease, the truth is that this illness is transmitted by fleas, not cats themselves. So, if you’re not doing a great job treating your pet with flea killers on a regular basis (especially in the hot season), you might put yourself at risk of contracting this bacterial disease.
In cats, Bartonellosis (CSD) causes mild skin rashes. Even though it can have the same effect on humans, it often involves extra complications, such as the inflammation of lymph nodes, fever, loss of appetite, and more. The vast majority of patients recover without receiving any treatment. Blood tests detect this disease with ease.
8. Brucellosis
This disease is yet again caused by a bacterium, this time going by the name of Brucella spp. Its name changes depending on the strain affecting a particular species. Farm animals most commonly pass the infection to people, including cows, sheep, goats, pigs, and more exotic animals.
Although now completely treatable with antibiotics, people respond differently to a Brucella infection. Some might experience mild symptoms like headaches or joint pains. Others could develop fever and general malaise. Thankfully, due to many medical advances in both human and veterinary medicine, Brucellosis is becoming rarer by the day.
9. Giardiasis
Giardia is a parasite that causes havoc in people’s (and animals’) gastrointestinal health. In some parts of the world, the infection is endemic. It is so widespread by way of drinking contaminated water that many individuals develop natural immunity against this parasite in their childhood. Although infected, some people express no symptoms whatsoever. Others are not as lucky. They can get diarrhea, stomach pains, vomiting, as well as severe dehydration.
Drinking contaminated water is the primary cause of Giardiasis, but it can pass from pets to humans, as well. If your pet has gastrointestinal issues including diarrhea and you clean up after them, one good way of contracting Giardia is by not washing your hands properly. You’ll be relieved to know while this is one parasite that affect dogs, it is completely treatable.
10. Ringworm
As common as it is among wild and domestic animals, ringworm is also the least severe zoonotic infection on this list. Despite its name, ringworm is a fungal disease which causes skin rashes and itchiness. Pet owners often bring their infected pets to the veterinary clinic, where a diagnosis is performed using a skin scraping technique.
Because it can be transmitted from animals to humans and from humans to other humans so quickly, vets recommend getting treatment for ringworm even if you don’t think you have it. If your pet does, there’s a high chance you do, too. Plenty of over-the-counter medications against this pathogen are now readily available across the world.
