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• Posted April 3, 2023

Iguana Bite Left Vacationing Toddler a Medical Issue Months Later

A family vacation to remember, but maybe not for the best reasons.

Doctors report on an unusual case where a hungry iguana bit a vacationing toddler's hand, passing on an infection with a germ called Mycobacterium marinum.

A 3-year-old girl named Lena Mars, of San Jose, Ca., was visiting Costa Rica with her family and eating cake while sitting on the beach. Suddenly an iguana ran up and bit the girl on the back of her left hand before snatching away the cake.

Lena was immediately taken to a local clinic for treatment. But it was what happened months later that shed light on this rare infection.

After the bite, the girl's superficial wound on the back bone of her middle finger healed quickly with no issues after it was disinfected. Lena was also given five days of the antibiotic amoxicillin for potential salmonella exposure, which is common after reptile bites, the researchers said.

Lena eventually developed a small bump on the back of her left hand, which her parents, Julian and Luisa, noted about five months after the bite. Over the next three months, it gradually became larger. Then, the skin in that area became red and mildly painful in the three months that followed.

A visit to the Stanford Children's Health Hospital in California included an ultrasound that revealed a mass consistent with a ganglion cyst, which is a fluid-filled lump. The location and symptoms, however, didn't make sense for this cyst.

An orthopedic surgeon removed the 2-centimeter thick-walled mass from Lena's hand. When he did, he saw pus oozing from the wound, a sign of infection.

After looking at the tissue under a microscope, the surgeon found extensive tissue death and necrotizing granulomatous inflammation, which is an area of inflammation where the tissue has died.

The team then did lab cultures, which found M. marinum, which is resistant to common antibiotics, including amoxicillin.

So, doctors gave the girl the antibiotics rifampin (Rifadin) and clarithromycin (Klaricid). Luckily Lena responded well to treatment.

The finding is to be presented at the European Congress of Clinical Microbiology & Infectious Diseases, being held from April 15 to 18 in Copenhagen, Denmark.

"Our daughter, Lena, just celebrated her 4^th birthday and is still recovering from the surgery in November," Lena's mom, Luisa Mars, said in a meeting news release. "The wound is just closing, and the whole healing process has taken more strength than the bite itself. Lena is the bravest child we can imagine, and she is handling the situation pretty well. She definitely remembers the bite and knows that the bacteria came from the iguana. She will probably never forget the experience, but we hope that someday we can all laugh about what happened."

Photo of Lena with her parents on vacation in Costa Rica

The study authors believe Lena's is the first reported case of M. marinum infection following an iguana bite.

M. marinum has been known to infect humans who have skin wounds exposed to contaminated fresh or salt water. It causes a tuberculosis-like illness in fish.

Other infections from iguana bites can include Serratia marcescens and Staphylococcus aureus, as well as Salmonella enterica. About 75% to 90% of both wild and captive reptiles are colonized with these bacteria.

"M. marinum prefers lower temperatures [86 degrees Fahrenheit] for optimal growth, and it's highly likely that the cold-blooded iguana, with body temperatures ranging from [71.6 degrees to 98.6 degrees F], may sustain these microbes as reservoirs,"explained lead author Dr. Jordan Mah, from Stanford University School of Medicine.

"The bite resulted in colonization by a bacterium rarely found in humans, and demonstrates that iguanas may be carriers of harmful bacteria capable of producing severe infections,"Mah said in a meeting news release. "This may help inform health care professionals of less commonly known bacterial infections following unusual zoonotic exposures."

Research presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

The Sepsis Alliance has more on animal bites.

SOURCE: European Congress of Clinical Microbiology & Infectious Diseases, news release, March 31, 2023