Pet owners intrigued by the exotic are getting something extra with their imported iguanas -- exotic forms of Salmonella bacteria that can cause life-threatening illness in humans, Cornell University veterinary researchers are finding.

An influx of cases at the Veterinary Diagnostic Laboratory in Cornell's College of Veterinary Medicine prompts diagnosticians here to issue a warning: Wash your hands after handling iguanas and other reptiles and anything they may have contacted.

"There is no question that iguanas are appealing pets. They are inexpensive 'mini-dinosaurs' that fit in apartments, classrooms and daycare centers. And iguanas look clean, but what you don't see is the bacteria," said Patrick L. McDonough, Ph.D., assistant director of bacteriology in the Veterinary Diagnostic Laboratory.

Like most other reptiles, iguanas carry Salmonella in their intestinal tracts, McDonough noted. 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. Adults with fully functional immune systems usually suffer little more than uncomplicated gastroenteritis (with vomiting, fever, diarrhea and cramps), McDonough said. But for high-risk individuals -- such as immunosuppressed persons, those taking antibiotics, pregnant women, the very old and children under age 5 -- salmonellosis can have serious consequences, including septicemia, meningitis and abortion.

"Iguanas are part of the 'dinomania' phenomenon that really took off after Jurassic Park," McDonough said. "They are now the most popular reptile in the more than 7 million-plus pet reptiles in the United States, and another 900,000 are coming into the country every year."

Most iguanas sold in pet stores are captured in the wild or hatched at "reptile ranches" in Central and South America, and the bacteria they carry are just as exotic, McDonough said. At least 20 different types of Salmonella have been identified in iguanas.

In one recent, tragic case that prompted the New York State Department of Health to issue an alert, a pregnant woman with fever and diarrhea went into preterm labor in Syracuse. When the baby died in 12 hours, blood tests from the mother and child identified the same, uncommon strain of bacteria, Salmonella poona, that was subsequently found in the family's pet iguana.

At the Cornell Veterinary Diagnostic Laboratory, the state's center for animal-related disease tests from county health departments, zoos and veterinarians, a record number of reptile salmonella cases were referred last year. "This could be the turtle problem revisited," McDonough said, recalling the 1970s when thousands of cases of salmonellosis were traced to Salmonella in baby turtles. The outbreak led the U.S. Food and Drug Administration to ban the sale of turtles under 4 inches long, and many states enacted similar laws.

In retrospect, some public-health authorities now believe that education of people would have been more effective than regulation of turtles. And some experts, including Cornell's McDonough, think the iguana-salmonella problem can be handled with public education.

Herpetological organizations and pet-industry trade groups are taking that approach, McDonough said, and the New York State Department of Health now asks all 1,300 pet stores in the state to distribute a bulletin: "Attention! Health Alert for Reptile Owners." There is also an Internet site, "Reptile-associated Salmonellosis" on the World Wide Web at .

Antibiotics for iguanas are not the answer, McDonough said. Antibiotic-resistant bacteria would survive, posing an even greater threat to humans. Sanitation is the solution, the diagnostician said.

"Wash you hands with warm soapy water immediately after handling iguanas or their cage litter and before touching food or anyone else. Keep iguanas away from at-risk people," he said. "And keep iguanas out of the kitchen."