COULD YOUR DOG MAKE YOU SICK?

Many of us love our dogs almost as though they were members of our families. Indeed, dogs serve valuable roles in our society – they can improve health by lowering blood pressure and cholesterol and triglyceride levels, they improve feelings of loneliness, they increase opportunities for exercise and they can help to teach children vital lessons in responsibility. However, these same furried friends can pass on diseases that are usually simply unpleasant but can on rare occasions be fatal.

There are approximately 45 million dog owners and 63 million pet dogs in the United States. A zoonotic disease is a disease passed from animals to people. Dog-related zoonotic diseases may be transmitted via parasites, fungi, bacteria or viruses.

The most common parasitic diseases are roundworm (Toxocariasis) and hookworm (Ancylostoma). Puppies are likely to be born with both roundworm and hookworm contracted from their mothers. They can pass eggs in their stool. The eggs can hatch into larvae (immature worms) and both eggs and larvae can be found in dog stool or in dirt where animals have been. Infection with roundworm or hookworm can occur after accidentally eating or direct contact with contaminated dirt. Because young children often play in dirt, they are the most likely to become infected with roundworm and hookworm. Most of these infections do not have any symptoms at all but may occasionally cause serious disease. Systemic toxocariasis – caused by roundworm – usually affects about 10,000 small children per year and is caused by migration of the parasite to the liver or lungs leading to cough, fever, enlarged liver and sometimes behavior disorders. Rarely, some roundworms can lodge in the eye and lead to blindness. Cutaneous larva migrans is caused by hookworm and is characterized by the invasion of the larva under the skin where a red snake-like track develops as the larva travels in the skin.

Ringworm is not a worm at all but is a fungus that can affect the skin of dogs or people. People may contract it by petting an affected dog that may not show any signs of disease. People with ringworm may have a ring-shaped rash that is red and itchy. It may also affect the scalp and produce bald patches. It can also spread to the groin where it causes “jock itch” or to the feet where it causes “athlete’s foot.”

A number of bacterial infections are also transmitted from dogs to humans via dog stool. Campylobacter and Salmonella are probably the most common dog-related zoonotic diseases and cause gastroenteritis – fever, nausea, vomiting, and diarrhea. Many kinds of pets – including cats, dogs and reptiles – are Campylobacter carriers, and it is estimated that transmission between pets and humans cause more than 200,000 cases of gastroenteritis.

Dogs bite more than 4.7 million people a year, accounting for almost 400,000 emergency room visits. However, only about five percent of these bites actually lead to any kind of infection. Perhaps the most frightening dog-related zoonotic disease is rabies, which is caused by a virus. In the United States, because of high vaccination rates, rabies is rare – with only 47 cases reported between 1990 and 2005 – and is found mostly in wild animals. Most dog-related cases that do occur are found along the United States-Mexico border. After a bite from an affected dog, it may take 1 to 3 months to develop symptoms that include fever, headache and nervous system signs such as confusion or agitation.

Dog-related zoonotic diseases can largely be prevented by taking the following steps:

• Always wash your hands thoroughly after contact with animals and their stool.

• Avoid rough play with dogs to prevent scratches and bites.

• Treat your dogs to prevent worm disease.

• Small children should avoid contact with puppies that have a higher infection rate of roundworm and hookworm.

• Keep vaccinations current for all dogs and do not allow your dogs to have contact with wild animals.

Dr. Kelly McMahon, a graduate of Yale College and the University of Pittsburgh School of Medicine, is board certified in Internal Medicine. She is a member of the American College of Physicians and the Allegheny County and Pennsylvania Medical Societies. She is in solo practice in the North Hills.