Dogs and puppies can pass germs, diseases and worms on to people, but it does not occur often. There are certain precautions that you can take to help prevent this from happening. First and foremost, make sure that the dog or puppy you are playing with looks healthy. Do not touch or contact an obviously sick dog. Make sure that your personal dog has regular check ups and is checked for worms by your veterinarian. Look for obvious signs of disease such as spots missing fur on your dog. Hot spots or places that your dog keeps chewing or biting at can be another sign of infection.

One of the best lines of defense from getting sick from contact with a dog is to wash your hands well, especially with anti-bacterial soap. After dog or puppy contact, keep your hands away from your face, especially your mouth. Do not eat finger foods after dog contact until you can wash. Do not let your dog lick you on your face. Try not to have contact with dog saliva, urine or dog feces.

Dogs and puppies can carry a fair variety of bacteria, parasites, fungus and worms. Some of these are fairly common in dogs and others are quite rare. Some people are more likely than others to catch these diseases. Some of the factors associated with catching the diseases depend upon the persons age and status of their health. People who are more likely to get diseases from dogs include infants, children younger than 5 years old, organ transplant patients, people with HIV/AIDS, and people being treated for cancer.

The following diseases may be carried by dogs:

Brucella canis Infection (brucellosis): A bacterial disease rarely associated with dogs.

Campylobacter Infection (campylobacteriosis): A bacterial disease associated with dogs, cats, and farm animals. If your dog has diarrhea, you may want to consult with your veterinarian, as this disease may be the culprit and it is passable to humans. If you develop symptoms, including diarrhea, vomiting, abdominal cramps, and/or nausea, contact your physician. Be sure to inform him or her of your pet and if it is ill.

Cryptosporidium (cryptosporidiosis): A parasitic disease associated with dogs, especially puppies, cats, and farm animals. Animals can carry this parasite in their feces and pass it to people. Animals do not have to be ill to pass Cryptosporidium to humans, they may just carry the disease. This disease usually causes a mild to severe infection of the gastrointestinal system, including watery diarrhea, fever, abdominal cramps, nausea, and vomiting.

Dipylidium Infection (tapeworm): A parasitic disease associated with dogs, cats and fleas. Fleas carry the tapeworm and the dog must swallow the flea (which may easily happen during grooming) to allow the tapeworms to hatch and grown in the dog. For a person to become infected with Dipylidium, or tapeworm, he or she must accidentally swallow an infected flea. Most reported cases involve children. The risk of infection with this tapeworm in humans is low.

Giardia Infection (giardiasis): A parasitic disease associated with various animals, including dogs and their environment (including water). The Giardia parasite lives in the intestine of infected humans or animals. Millions of germs can be released in a bowel movement from an infected human or animal. Giardia is found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals.

Hookworm Infection: A parasitic disease associated with dogs and cats and their environment. Puppies and kittens are especially likely to have hookworm infections. Animals that are infected pass hookworm eggs in their stools. The eggs can hatch into larvae, and both eggs and larvae may be found in dirt where animals have been. Eggs or larvae can get into your body when you accidentally eat or have direct contact with contaminated dirt. For example, this can happen if a child is walking barefoot or playing in an area where dogs or cats have been.

Leishmania Infection (leishaniasis): A parasitic disease associated with dogs and sand flies outside the United States.

Leptospira Infection (leptospirosis): A bacterial disease associated with wild and domestic animals, including dogs. In people, the symptoms are often like the flu, but sometimes leptospirosis can develop into a more severe, life-threatening illness with infections in the kidney, liver, brain, lung, and heart.

Lyme Disease: A bacterial disease that can affect dogs and ticks. People get Lyme disease when they are bitten by ticks carrying B. burgdorferi, and this is in certain parts of the country.

Q Fever (Coxiella burnettii): A bacterial disease occasionally associated with dogs, but more often associated with sheep, cattle and goats, especially their birth products.

Rabies: A viral disease associated with various animals, including dogs. This is fairly rare in the US.

Ringworm: A fungal disease associated with dogs. Ringworm is transmitted from direct contact with an infected animal's skin or hair. Dogs and cats, especially kittens or puppies, can have ringworm that can be passed to people.