An Attack by a Teiidae Lizard (Tegu) on a Human: Is There a Pattern of the Injuries?

To the Editor:

Tegus, or teiús, are South American large lizards that can reach up to 6.5 feet (2 m) in length. The tegus are part of the Tupinambis genus (Squamata order/Teiidae family), and the most distributed species is the Tupinambis merianae (Duméril and Bibron, 1839).^1,2 The tegus are strong lizards that have a black body with yellow stripes, with strong jaws, and a long and muscular tail (Figure 1). They are animals that live in cerrados (savannah-like environments), especially in Brazil. In nature, these lizards feed on fruits, eggs, larvae, worms, insects, and carrion. The tegus also can feed on domestic animals, invading fowl runs to eat eggs and chicks.^1,2

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Figure 1

Tupinambis merianea, the teiú, or tegu, lizard. This great reptile has teeth (inset) that can destroy soft tissue and bone of the victims.

When threatened, the lizard usually tries to escape. If that is impossible, it can strike severe blows with the tail. It may also bite, causing significant lacerations. The teeth are not great, but have a solid base and are driven by the crushing force of the bite, which can destroy soft tissue and bone. ³ Human injuries from Teiidae lizards are rare, however, and reliable descriptions of attacks are even rarer. ⁴

A Teiidae lizard of the Tupinambis merianea species bit a 64-year-old urban resident who was visiting a rural area. He was at his farm located next to Botucatu town, in the Southeast region of Brazil. The man cornered the lizard when it was eating eggs in the chicken coop. The reptile was very aggressive because the victim’s dog was barking and trying to attack it through the screen of the pen. The man was filming the lizard through an opening on the screen, and when the camera was placed at a height of about 2.6 feet (0.8 m) above the ground, he was bitten on the end of the middle finger of his right hand. The bite caused loss of soft tissue of the distal phalanx (Figure 2). After the bite, the patient had intense bleeding and persistent pain. He cleaned the wound with soap and water, pressed it, and went to the emergency care unit. The lizard was captured, and measured approximately 5 feet (1.5 m) in length.

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Figure 2

(Left) The lizard bite on the end of the middle finger of the victim’s right hand. (Right) Note the loss of soft tissue of the distal phalanx.

At the hospital, the bite area was extensively irrigated, and antisepsis was performed with chlorhexidine and povidone-iodine solution. The nail was removed, and a compressive dressing was applied. The patient received analgesics and tetanus immunization. Fractures were not seen on radiograph (Figure 3). Amoxicillin/clavulanate 500 mg/125 mg orally three times a day was prescribed for 10 days (a first dose of amoxicillin/clavulanate 1000 mg/200 mg intravenous was administered in the hospital to aid the prevention of soft tissue infection and osteomyelitis), and dressings containing an ointment with collagenase (0.6 U/g) and chloramphenicol (0.01 g/g) were applied until the wound was completely healed. A skin graft was proposed for the site of the bite but the patient decided for second intention healing of the wound. The wound healed completely without infection after 2 months.

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Figure 3

The radiologic examination shows important destruction of the soft tissues of the extremity of the right middle finger, but no bone lesions.

The description of this case is very similar to another reported by one of the authors in Wilderness & Environmental Medicine. ⁴ It is especially interesting to emphasize the lizard fight with the dog. The injury also is very similar to the cited report (distal phalanx). We think that there is a pattern of Teiidae attacks on humans and their injuries. These seem to be related to common living areas, provoked attacks (the lizard defended itself in the two reported cases), pet intervention, and highly destructive bites on the hands of the victims who tried to get close to the reptile.

If the interface with humans is inevitable, animals like the tegus should be respected. Otherwise, serious injury may happen to people who do not understand them.