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10 Not-So-Loveable Pet-to-People Illnesses

6 min read

By Emily Lockhart

You might love your cute-as-can-be kitten or your dear doggy to the ends of the earth, but did you know that pets carry diseases that can be transferred to humans? That’s right, while Hammy hamster, Polly the parrot, and Sibyl the snake may provide good companionship and unconditional love on one hand—they can also be the harbingers of several infectious viruses, bacteria, and fungi that can endanger their owners.

Beware of these eight not-so-loveable pet-to-people illnesses…

1. Toxoplasmosis from Cats

No one likes a dirty, clumpy cat litter box—including fluffy! But more importantly, parasites, or toxoplasma gondii, can linger in the feces of an infected feline’s litter box. This is why it’s so important to clean your cat’s litter daily and wash your hands thoroughly afterwards. Also, toxoplasmosis can cause birth defects in unborn child, which is why pregnant women shouldn’t clean kitty’s litter.

Toxoplasma parasites will cause infected humans to experience flu-like symptoms—including headache, muscles stiffness, swollen glands, fatigue, low-grade fever, and in severe cases, blurred vision (or ocular toxoplasmosis). If you have a healthy immune system, illness will usually pass in 2 weeks without treatment. However, if your immune system is compromised, you should seek immediate medical attention to be treated for this infectious disease.

2. Roundworms from Dogs

The majority of cute little puppies and kittens are born with roundworms, but vegetarians will test and treat them during their first check-up. Problems arise when a vet doesn’t examine newborn animals and roundworm eggs transfer to humans—usually when humans handle infected soil or dirt (if your pet does his or her business outside).

When roundworm eggs are accidentally ingested by humans, a low-grade fever, persistent dry cough, or shortness of breath may occur. The majority of healthy people may not experience any symptoms whatsoever. However, those with compromised immunity can suffer from vision and breathing difficulties, and neurological issues, and may need a round of anti-parasitic drugs to banish roundworm parasites for good.

3. Salmonellosis from Reptiles

I sympathize with those who live in small spaces and opt for a lizard, turtle, iguana, or snake instead of a dog or cat. However, the Centers for Disease Control caution that your reptile may carry salmonellosis, a type of salmonella bacteria that resides without issue in reptiles, but makes humans quite ill.

The CDC warns that handling your pet (or petting zoo reptiles), cleaning their habitat, or feeding them on shared surfaces can result in the transfer of salmonellosis. Feeding your reptile vegetables infected with salmonella bacteria (i.e., kale, broccoli, or other greens) can also cause salmonella. This is why thorough washing your hands after any contact is imperative. The disease will cause flu-like muscle stiffness, abdominal cramps, diarrhea, and fever in infected humans for roughly a week.

4. Leptospirosis from Dogs, Mice, and Rats

Leptospira is a bacterial infection that lives in the infected urine of dogs, mice and rats. Humans typically pick it up if they have indirect contact with contaminated soil, where it can linger for months. They may also pick it up after contact with animal cage contents or via an animal’s paws.

Leptospirosis in humans may cause chills, fever, abdominal cramps, skin rash, and vomiting. However, a prescribed antibiotic (i.e., penicillin) will clear up symptoms quickly. If left untreated, leptospirosis infection can result in kidney failure. It’s best avoided by vaccinating your dog and washing thoroughly after handling pet rodents.

5. Cat-Scratch Fever from Cats

Cat-scratch fever is a catchy song, but cat scratch illness, from a type of bacteria known as Bartonella henselae, won’t have you tapping your feet and singing along. This illness is transferred from cat to person when a feline has fleas to scratch at then scratches you and breaks the skin.

If a skin infection occurs the bacteria can enter your bloodstream and cause uncomfortable flu-like symptoms—such as swollen glands, fever, and general malaise. To avoid a case of cat scratch illness, wash the area thoroughly if you are bitten or clawed by a frisky feline, and also make sure your cat takes flea medication.

6. Rabies from Dogs

One of the better known pet to human shared diseases is rabies—thanks to the movie Cujo (that dog still terrifies me to this day). However, rabies is more prone to wile animals, such as foxes, bats, and raccoon rather than domesticated dogs.

However, if your dog doesn’t get his rabies vaccination, he or she could become infected via the bite (saliva) of an infected wild animal. Rabies is a fatal illness, causing symptoms of delirium, hallucinations, and achy flu-like feelings, and a need for a series of painful rabies shots. The Centers for Disease Control considers rabies almost always fatal in humans and pets, which is why pet rabies vaccinations are vital.

7. Avian Tuberculosis from Birds

Avian TB (or Mycobacterium avium complex) is actually a form of tuberculosis that attacks the lungs. It’s often transmitted from unregistered birds (or illegally traded birds from Central America and Mexico) to unknowing human owners. The infection in airborne and often severely resistant to antibiotics, which means treatment is tricky.

According to doctors from New York’s North Shore University Hospital, Emergency wing, infection with Avian TB is rare and typically only strikes those with low immunity. However, if you own a pet bird, or visit an aviary, hand washing is imperative after contact to prevent infection.

8. Tapeworms in Dogs

Tapeworms can be something out or a horror movie, if you’ve ever had a look at one. Pets often become infected if they have fleas and swallow a contaminated insect. Your pet can infect you if you have contact with their rear end (anus) through cleaning or stool pick up, however, pet to human infection is considered rather rare.

Tapeworms in humans cause severe gastrointestinal discomfort—such as cramps, poor digestion, and weight loss without explanation. The treatment for tapeworms is an oral medication. The best prevention against tapeworms is flea and tick prevention, which means medication for your pet, regular vet examinations for worms, and safe disposal of dog feces.

9. Lymphocytic Choriomeningitis from Hamsters and Guinea Pigs

Hammy hamster is a jolly sort, running on his wheel and scurrying around your shoulders, but he’s also a prime host of lymphocytic choriomeningitis (LCM), a viral disease caused by the lymphocytic choriomeningitis virus (or LCMV), transmitted via that infected animal bedding, urine, and droppings of rodents.

The CDC considers LCM particularly dangerous for pregnant women and unborn babies, as the illness can develop into encephalitis and birth defect, and even require immediate hospitalization. mean a trip to the hospital. LCM symptoms mimic the flu—with general achy muscles, swollen glands, and fever. To prevent LCM, wash your hands thoroughly when you handle pet rodents.

10. Psittacosis from Birds

Polly might want a cracker, but your beautiful pet macaw, parrot, or parakeet can give you something quite nasty back in return—psittacosis, a type of infected caused by the Chlamydophila psittaci bacteria.

Psittacosis is often transferred from bird to human during cage cleanings—as the bacteria live in dried bird secretions. So even if your bird appears in full form, you can become ill with a dry cough, chills, fever, any achy muscles. Treatment is typically a round of antibiotics (i.e., tetracycline). To prevent illness, clean bird cages in a well-ventilated area and wear a mask and gloves to handle bird droppings.

Emily Lockhart


Emily Lockhart is a certified yoga instructor and personal trainer. She believes that being healthy is a lifestyle choice, not a punishment or temporary fix to attain a desired fitness or body image goal. Anna helps her clients take responsibility for their own health and wellness through her classes and articles on ActiveBeat.

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