“Can my dog make me sick?” I get this question at dinner parties more often than you’d think, and my answer is always the same: yes, occasionally — and knowing how is far more useful than worrying that he might. Illnesses that pass from animals to people are called zoonotic diseases, and according to the,[1] roughly 6 in 10 known infectious diseases in people can be spread from animals. But here’s the context that matters: your healthy, well-cared-for pet is one of the lowest-risk animal relationships in your life. With about two-thirds of households sharing their homes with pets, the overwhelming majority never catch anything from them. The families who do run into trouble are almost always missing one of a small handful of simple habits. So let me give you the honest map.
The Four Infections I Most Often See Cross the Species Line
Out of the long list of,[2] these are the four that actually show up in family homes — and none of them should send anyone into a panic.
Ringworm: A Fungus, Despite the Name
Last spring, the Ortiz family adopted Biscuit, a 10-week-old tabby from a shelter. Two weeks later, both kids had circular, scaly, itchy patches on their arms — and a week after that, Dad’s forearm “lit up like a target,” as his wife put it. That’s ringworm, or dermatophytosis — a fungal infection, not a worm. The most common species, Microsporum canis, spreads by direct contact and by shared bedding, brushes, and couches. Kittens from shelters and catteries are classic carriers, often with no symptoms at all or just patchy hair loss.
“I honestly thought it was eczema,” Mrs. Ortiz told me. “Then everyone started matching.”
Ringworm is annoying and contagious but very treatable. The pet needs a vet visit (topical or oral antifungals — your vet will tailor treatment), the humans need their doctor, and the household needs hot-water laundry and no shared grooming tools. It’s inconvenient, not dangerous, for most people.
Cat Scratch Disease: When a Kitten Scratch Lingers
A pediatrician once called me about a 14-year-old boy with a lump under his arm the size of a golf ball. Three weeks earlier, the family’s new kitten had scratched his hand. Classic cat scratch disease, caused by the bacterium Bartonella henselae — an estimated 12,000 outpatient cases a year in the US, with around 500 hospitalizations. Fleas spread it between cats, and kittens under a year old are far more likely than adults to carry it.
In people, it typically means swollen lymph nodes near the scratch, low-grade fever, and fatigue, and it usually resolves on its own. Serious complications are rare and occur almost exclusively in people with weakened immune systems. Prevention comes down to two things: year-round flea control, and washing any scratch immediately with soap and water.
Toxoplasmosis: The Most Misunderstood of the Bunch
One of my clients, twelve weeks pregnant, called me in tears. Her aunt had told her the cat had to go.
“So I have to rehome Duchess? Tell me the truth.”
The truth: no. More than 40 million Americans carry Toxoplasma gondii, but here’s what almost nobody knows — a cat only sheds the parasite in her feces for about one to two weeks, usually once in her entire life, after her first exposure. And those eggs need one to five days outside the cat before they can infect anyone. Scoop the litter box daily and the risk drops dramatically. Even better: most human infections actually come from undercooked meat, unwashed produce, and garden soil — not from cats. An indoor cat eating commercial food is about as low-risk as it gets. Keep the cat; delegate litter duty if you can, or wear gloves and wash your hands if you can’t.
Intestinal Parasites: The Sandbox Problem
Roundworm eggs can survive in soil for years, and uncovered sandboxes are a favorite playground for them — including for neighborhood cats using them as litter boxes. Roughly 5% of the US population has antibodies to Toxocara, and while serious outcomes are rare, the CDC estimates around 70 people — mostly children — lose vision each year when a larva migrates to the eye. Hookworm larvae in contaminated soil can burrow into bare skin, causing “creeping eruption,” a winding, intensely itchy rash. Giardia and Cryptosporidium, shed in pet feces, cause stomach upset.
The defenses: year-round parasite prevention, regular fecal exams (several for puppies and kittens, then as your vet recommends), picking up pet waste promptly, keeping sandboxes covered, and washing hands after gardening and sandbox play.
The Hygiene Habits That Do the Heavy Lifting
A widely cited [3] makes a point I stand behind: pet ownership brings measurable health benefits — fewer allergies in kids, better cardiovascular and emotional health — and a short list of consistent habits keeps the infection risk minimal.
- Wash your hands with soap and water after petting, cleaning up waste, or handling pet food.
- Skip the face kisses — for both directions — and never let pets lick open wounds, babies’ faces, or a pacifier that hit the floor. (Yes, I’ve seen the dog-bowl pacifier. Wash it, don’t rinse it.)
- Supervise children under five, whose hands live in their mouths, and teach the rhythm early: pet, then wash.
- Scoop the litter box daily; pregnant family members should delegate or glove up.
- Pick up feces promptly in the yard and on walks, and keep sandboxes covered.
- Keep flea control going year-round — it’s the backbone of preventing both cat scratch disease and tapeworms.
- Wash every bite and scratch immediately, and call your doctor if you see spreading redness or swelling.
- Keep vet visits routine. Fecal exams, deworming, and vaccines protect your whole household. Worth asking your vet about: leptospirosis, spread through the urine of wildlife and contaminated water, is on the rise in urban and suburban dogs, and many vets now recommend broader vaccination.
Extra Care for Pregnancy, Toddlers, and Weakened Immune Systems
If You’re Pregnant
Keep the cat, with the litter precautions above. Honestly, the bigger toxoplasmosis risks are in your kitchen and garden: cook meat thoroughly, wash produce, and wear gloves while gardening.
If Someone Is Immunocompromised
I’ll admit I’ve changed my mind here. Early in my career, I’d hedge when a client undergoing chemotherapy or living with HIV asked whether they should give up their pet. Today my answer is a firm no — with adjustments — because we’ve learned that losing a beloved companion often costs more, in real health terms, than the manageable infection risk. The adjustments: choose calm adult pets over kittens (kittens are the classic carriers of ringworm and Bartonella), skip reptiles, amphibians, and young poultry, which commonly carry Salmonella, and have someone else handle litter boxes and waste cleanup. And loop in both your physician and your veterinarian — we talk to each other more than people realize.
If You Have Toddlers
Children under five are the group I worry about most, purely because of the hand-to-mouth reflex. Reptiles and amphibians shouldn’t live in homes with preschoolers at all — in the US, selling turtles under four inches has been banned since 1975 precisely because of Salmonella outbreaks in children, and the small turtles still sold informally keep causing them.
The Raw Diet Question I Get Every Week
I understand the impulse behind raw feeding — everyone wants to do the best for their animal. But the evidence here is one-sided: the FDA, CDC, and major veterinary associations advise against raw diets because commercial raw foods are regularly contaminated with Salmonella, Listeria, and E. coli — and raw-fed pets shed those bacteria in their saliva and feces, right where kids and immunocompromised family members live. In 2024, H5N1 avian influenza killed cats that had consumed contaminated raw milk and raw food, including one in Oregon, prompting a recall of a frozen raw cat food in January 2025. Cooked, balanced diets deliver the same nutrition without the dice-roll.
Here’s my takeaway after two decades of this work: about 3 in 4 new or emerging infectious diseases in people originate in animals — mostly wildlife, not the dog asleep on your couch. Our health and our pets’ health are one system, and that’s exactly why a dewormed, vaccinated, flea-free pet is one of the safest animal relationships your family will ever have. The goal isn’t distance from the animals we love. It’s good veterinary care, a little soap and water, and informed caution instead of fear.
Sources
- CDC — cdc.gov
- zoonotic diseases from pets — wesvet.com
- review on reducing pet-associated infections — pmc.ncbi.nlm.nih.gov