While most lizards are harmless, some species can present dangers due to their size, defensive behaviors, or the pathogens they carry. Understanding these interactions is important for safety and appreciating these diverse reptiles.
Lizard Behavior and Defense
Lizards exhibit defensive rather than aggressive behaviors when encountering humans. Their primary instinct is to flee from perceived threats. Many are timid and will attempt to escape by running away or finding cover if approached.
Biting is a last resort for a lizard that feels cornered, threatened, or unable to escape. Their bites are a warning or a means to deter an aggressor, rather than an attempt to cause serious harm.
Recognizing Dangerous Species
While most lizards are harmless, certain species can pose a physical threat due to their venom, powerful bites, or defensive capabilities. The most well-known venomous lizards are the Gila monster and the Mexican beaded lizard, both found in the Southwestern United States, Mexico, and Guatemala. These lizards possess venom glands in their lower jaws and deliver venom through grooved teeth, often by chewing to allow the venom to seep into the wound. Their bites can cause excruciating pain, swelling, and a drop in blood pressure, though fatalities in healthy adults are rare.
Beyond venom, some large lizard species can inflict significant injury with their powerful jaws, sharp teeth, or strong tails. Komodo dragons, the largest lizards, possess venom and bacteria in their saliva, which can lead to severe infection and blood clotting issues. While rare, their bites can be fatal to humans if not treated promptly. Monitor lizards, such as Nile monitors and Asian water monitors, can grow quite large and have strong jaws, sharp teeth, and muscular, whip-like tails. A bite from a large monitor can cause deep lacerations and significant bleeding, and their tails can deliver a forceful blow used for defense.
Health Considerations from Lizards
Lizards, even seemingly healthy ones, can carry bacteria that pose health risks to humans, primarily Salmonella. This bacterium naturally resides in the intestinal tract of many reptiles and is shed through their feces. Humans can contract salmonellosis through direct contact with a lizard, its feces, or contaminated surfaces, particularly if hands are not washed before touching the mouth or preparing food.
Symptoms of salmonellosis include diarrhea, abdominal cramps, fever, and sometimes vomiting, appearing 12 to 72 hours after exposure. While most people recover without medical intervention, the infection can be more severe in vulnerable populations such as infants, young children, the elderly, and individuals with weakened immune systems, potentially leading to hospitalization or, in rare cases, life-threatening complications. Reptiles carrying Salmonella show no signs of illness themselves.
Safe Encounters and Pet Ownership
Interacting safely with lizards, whether in the wild or as pets, involves adopting cautious and hygienic practices. When encountering lizards in their natural habitat, it is best to observe them from a distance. Attempting to catch, handle, or provoke any wild lizard should be avoided, as this increases the risk of a defensive bite. If a lizard enters a human dwelling, allowing it to exit on its own or contacting animal control for safe removal is the best approach, rather than trying to handle it directly.
For those who own lizards as pets, responsible care and hygiene are important to minimizing health risks. Always wash hands thoroughly with soap and water immediately after handling a lizard, its enclosure, or any related equipment and food. Keep reptiles out of areas where food is prepared, served, or stored, such as kitchens, and use dedicated containers for cleaning their habitats. Young children, pregnant women, and individuals with compromised immune systems are at a higher risk for severe infections and should limit or avoid direct contact with pet reptiles.