Animals in general tend to avoid human beings, but they can attack, particularly if they are with young. In areas of endemic rabies, domestic dogs, cats, or other animals should not be petted. Wild animals should be avoided.

The bites, stings, and contact of some insects cause unpleasant reactions. Medical attention should be sought if an insect bite or sting causes redness, swelling, bruising, or persistent pain. Many insects also transmit communicable diseases. Some insects can bite and transmit disease without the person being aware of the bite, particularly when camping or staying in rustic or primitive accommodations. Insect repellents, protective clothing, and mosquito netting are advisable in many parts of the world (See p. 180, Protection Against Mosquitoes and Other Arthropod Vectors).

Poisonous snakes are hazards in many parts of the world, although deaths from snake bites are relatively rare. The Australian brown snake, Russell's viper and cobras in southern Asia, carpet vipers in the Middle East, and coral and rattlesnakes in the Americas are particularly dangerous. Most snakebites are the direct result of handling or harassing snakes, which bite as a defensive reaction. Attempts to kill snakes are dangerous, often leading to bites on the fingers. The venom of a small or immature snake may be even more concentrated than that of a larger individual, therefore all snakes should be left strictly alone.

Less than half of all snake bite wounds actually contain venom, but medical attention should be sought anytime a bite wound breaks the skin. A pressure bandage, ice (if available), and immobilization of the affected limb are recommended first aid measures while the victim is moved as quickly as possible to a medical facility. Specific therapy for snakebite is controversial, and should be left to the judgement of local emergency medical personnel. Snakes tend to be active at night and in warm weather. As a precaution, boots and long pants may be worn when walking outdoors at night in snake-infested regions. Bites from scorpions may be painful but seldom are dangerous except possibly in infants. In general, exposure to bites can be avoided by sleeping under mosquito nets and by shaking clothing and shoes before putting them on, particularly in the morning. Snakes and scorpions tend to rest in shoes and clothing.