Pet Reptiles Pose Risk of Salmonella Infection for Their Ownersby Carol Lewis
A 6-week-old boy in Ohio was hospitalized with diarrhea, stiff neck, and fever. He was treated and released from the hospital after 56 days.
Vomiting, bloody diarrhea, and fever put a 3-week-old Pennsylvania girl in the hospital. She was treated with penicillin and discharged 11 days later.
A 5-month-old girl in New Jersey was hospitalized because of vomiting, lethargy and fever. She was treated and allowed to return home after 10 days.
Besides some of their symptoms, what did all three infants have in common? Each tested positive for salmonella bacteria, and all had exposure to a reptile.
Approximately 3 percent of American households own an estimated 7.3 million reptiles, according to the Pet Industry Joint Advisory Council. Because the most popular species will not breed if closely confined, most reptiles are captured in the wild or hatched at reptile ranches and imported. The number of reptiles imported into the United States has increased dramatically from 27,806 in 1986 to 798,405 in 1993, as reported by the U.S. Fish and Wildlife Service, and the majority are iguanas.
But what many animal lovers don't know is that with these imported pets come exotic forms of salmonella bacteria that can cause life-threatening illness in humans.
"Many parents do not know that owning an iguana puts their children at risk for salmonella infection," say researchers from the national Centers for Disease Control and Prevention in Atlanta. Even in homes where young children and infants are not permitted to touch or come in contact with the animals, they may still become infected, according to a study published in the March 1997 issue of the Journal of Pediatrics.
What Is Salmonella?
Salmonella is the genus name of a number of bacteria commonly associated with food poisoning from contaminated or undercooked foods, and salmonellosis is the disease the bacteria can cause. In food-related cases, most people suffer from gastroenteritis, often experiencing vomiting, fever, diarrhea, and cramps. For high-risk individuals, such as those with weakened immune systems, those taking antibiotics, pregnant women, the elderly, and children under 5, salmonellosis may be even more devastating, leading to blood infections, meningitis, abortion, and death.
In a case reported by the New York Health Department in 1995, a pregnant woman with fever and diarrhea went into preterm labor and delivered a baby who died 12 hours later. Follow-up blood samples of mother and child, in conjunction with samples from the family's pet iguana, tested positive for the salmonella strain associated with reptiles.
"Like most other reptiles, iguanas carry salmonella in their intestinal tracts," says Patrick L. McDonough, Ph.D., assistant director of bacteriology at Cornell University's College of Veterinary Medicine in New York. "The bacteria are 'shed' periodically in the animals' feces, and that's how the bacteria gets on the animals' skin, their cages, and other materials they touch."
An influx of cases at Cornell University since 1993 has prompted officials to warn owners that good hygiene is essential to prevent the spread of salmonella.
"Wash your hands with warm, soapy water immediately after handling iguanas or their cage litter, and before touching food or anyone else," McDonough says. He adds that while researchers once believed salmonellosis was transmitted primarily through direct contact with reptiles, it is now known that the bacteria need only be present on surfaces or on the hands of others to infect individuals indirectly.
In one such case, 20 patients were diagnosed with the disease within eight days of visiting a Komodo dragon exhibit at a Colorado zoo. According to Joseph Madden, Ph.D., strategic manager for microbiology at FDA's Center for Food Safety and Applied Nutrition, zoo officials believe that the dragons had, while being moved to their cages, licked several handrails at the zoo, and those areas were then touched by zoo visitors who subsequently ate lunch without washing their hands.
An Outbreak Revisited
In the early 1970s, FDA banned the distribution and sale of baby turtles with shells 4 inches in length or less after a quarter million infants and small children were diagnosed with having turtle-associated salmonellosis. The agency believed that turtles larger than 4 inches did not pose the same threat since youngsters would not likely try to fit them into their mouths. CDC estimated that in 1973, pet turtles accounted for 14 percent of the salmonella-caused illnesses in the United States.
But the FDA-imposed ban allows for some exceptions. Turtles still can be exported to other countries and sold to experts for bona fide scientific, educational and exhibition purposes. Selling turtles to pet stores is not considered a bona fide purpose.
Janet McDonald, a public affairs specialist with FDA's San Francisco district office, believes that since the turtle issue is so old, people have forgotten that they are still illegal in the United States.
"We're still seeing sales of baby turtles and iguanas at flea markets and street fairs, and owners need to be aware that these pets can transmit disease, particularly to very young children because of their hand-to-mouth activity," she said. "The sale of reptiles is definitely on the rise."
Darrell Lee, an FDA computer expert who works with McDonald, saw firsthand that the sale of baby turtles is "a very brisk business" on a recent visit to Oakland's Chinatown. According to Lee, youngsters were peddling turtles and their cages at a rate of five every 15 minutes.
"It was like a street corner sale generating a huge profit," Lee recalled. "Here they were, young children selling them to other kids with no adults around."
But some public officials and responsible members of the scientific profession now believe that educating people rather than regulating reptiles would be more effective in controlling the spread of salmonella infection. According to several state health departments, there has been considerable effort to educate pediatricians, hospitals, clinics, and pet shop owners.
Robert and Lisa Wenner of Brunswick, Md., couldn't agree more about educating the public. The couple, with the help of their two young sons, operate an iguana rescue mission from their home and won't even consider adopting out these animals until they are convinced that prospective pet owners know and understand the risks associated with owning one.
"I recommend people buy a book about iguanas which tells all about the risk from exposure to salmonella," Robert says. And that's after he subjects them to a rigorous question-and-answer session to determine if indeed they do have a thorough understanding of the hazards involved. In the two years since the Wenners have owned their seven iguanas as personal pets, they say they have experienced no disease-related problems, which they attribute to the meticulous hygiene they insist their family members practice.
"We bathe our iguanas every day and disinfect our tub afterward each and every time," Robert says. And a trip to the sink to wash up with an antibacterial soap by all family members after each handling goes without saying. As to the three 4-foot-tall cages that house their pets, Lisa adds, "You have to commit yourself to cleaning them every single day."
But not all experts agree that bathing iguanas everyday is good practice. Victoria Hampshire, V.M.D., a veterinarian in the carnivore and ungulate unit at the National Institutes of Health, cautions against daily, harsh scrubbing of the animals because of the likelihood of dry skin and fungal infections. She believes that washing the iguana everyday should not be necessary if the animal has clean water and an adequate UV light source. A safe compromise, she says, would be to squirt down or mist the iguana daily.
A kennel technician for the Frederick County Animal Control, Lisa Wenner is all too aware of the hazards associated with animals and contracted diseases in general. However, not one case of reptile-associated salmonellosis has been reported since she began working there over six years ago. Wenner believes that the staunch efforts made by local veterinarians and health department officials to inform the public through literature and public forums are key to preventing the spread of the disease.
"What we've learned from the vets is that as long as you keep the reptiles clean and you clean up yourself and your surroundings after handling, you will minimize the risk of infection with salmonella," she says. Additionally, in the one and a half years since the Wenners have adopted out 15 iguanas through their rescue mission, no cases of the infection have been reported.
Salmonellosis, from any source, is not a disease to be taken lightly. The bottom line in deciding whether an iguana or other reptile is right for your family, suggests veterinarian Douglas R. Mader of Long Beach, Calif., in his 1993 report on reptile medicine, is first to consider the ages and overall health of your loved ones. Then, if you decide to go ahead, consistently practice meticulous hygiene. Because young children are at increased risk for reptile-associated salmonellosis and severe complications, reptiles may not be appropriate pets in households where family members are younger than 5 years, or are at increased risk for infection.
To put the problem of salmonella infection in perspective, Mader says that if good hygiene is practiced, veterinarians, veterinary staff, and reptile owners are at a greater risk of contracting salmonellosis from uncooked chicken than they are from handling reptiles.
Carol Lewis is a writer with FDA's Office of Consumer Affairs.
Never eat or put anything in your mouth during or after handling your animals.
Never clean cages in the kitchen or anywhere you prepare food for human consumption.
Always wash your hands with a disinfectant soap after handling your animals. Washing with water alone is not effective in eliminating salmonella.
Do not permit unsupervised handling of reptiles by children under 12.
Do not handle reptiles with open cuts or sores unless they are well covered with dressings. Rubber gloves are strongly recommended.
Do not use kitchen sinks, bathtubs, or shower stalls for cleaning reptiles or their cages unless you thoroughly disinfect afterwards with a bleach-containing product.
Reptiles are not a good choice for day-care centers.
Seek the care of a reputable exotics veterinarian to obtain regular fecal examinations and diet recommendations.
FDA Consumer magazine (November-December 1997)