Pets provide us with abundant amusement and unconditional companionship. What's more, studies show that they can even benefit our overall health. Research from the University of Buffalo suggests that pets can help reduce their owners' blood pressure and regulate their heart rate in times of stress. Another study found that elderly subjects who observed fish swimming in an aquarium experienced a decrease in pulse rate and a reduction in muscle tension.


But pets are animals, and as such, they can unknowingly transmit dangerous microorganisms to their owners. The best thing you can do to protect yourself and your family is to educate yourself before getting a pet. And if you do become a pet owner, be sure to keep your critter clean and schedule regular veterinarian visits. Here, a list of some common (and not-so-common) pets and the health hazards they could potentially pose:


Iguanas and turtles. A report released in 2002 estimated that 90 percent of reptiles, particularly green iguanas, carry salmonella in their intestines, which can then affect owners who come in contact with their excrement while cleaning their tanks. In 1976, the Food and Drug Administration (FDA) banned the sale of turtles with a shell of less than four inches to stop a salmonella outbreak that had occurred during a baby turtle craze. The measure produced a 77 percent decrease in reptile-related salmonella illnesses, according to The Humane Society, but it has yet to bring a complete halt to the sale of baby turtles.


Ferrets. Whether these descendents of the European polecat present a credible threat to humans has been the subject of much debate lately. States such as California and cities such as Manhattan have banned the sale and possession of ferrets because they've been believed to be unpredictable and dangerous, prone to biting frenzies that are especially harmful to infants and children. Some are also known to carry and transmit rabies. However, archaeological and historical evidence shows that ferrets have been domesticated for at least 2,500 years, and a study published in the Journal of Veterinary Medicine estimates that dogs are 200 times more likely to bite humans than are ferrets.


Parrots and parakeets. Their songs may be soothing, but our fine-feathered friends can also pass along Chlamydia psittaci, a form of pneumonia. Humans acquire the bacteria through contact with dust from bird feathers, bird droppings, or from the bite of a bird carrying the bacteria. This pneumonia can last several weeks and can be especially dangerous to the elderly population. Thanks to antibiotic-laced feed and a quarantine period imposed on imported birds, incidences of this type of pneumonia have become extremely rare.


Prairie dogs. This bizarre pet trend was eventually put to a stop due to serious health risks. When an outbreak of monkeypox (a rare viral disease) linked to pet prairie dogs and Gambian pouched rats was confirmed in June 2003, the Centers for Disease Control (CDC) and the Department of Human Health and Safety (HSS) issued a joint order that banned the import of several African rodents and the transport, sale, or release of pet prairie dogs. Then, on November 4, 2003, the CDC and FDA issued a joint "Interim Final Rule" that made the previous order permanent and also added some new restrictions. The new order specifically bans the capture of wild prairie dogs and the trade of prairie dogs within states as well as between states.