Bites and stings from larger animals
Do not attempt to pet, handle, or feed any animal, with the exception of domestic animals known to be free of any infectious disease. Most animal injuries are directly related to a person's attempt to touch or feed the animal.
Any bite or scratch by a mammal, including bats, should be promptly and thoroughly cleaned with large amounts of soap and water, followed by application of an antiseptic such as iodine or alcohol. The local health authorities should be contacted immediately for possible post-exposure rabies treatment, whether or not the person has been immunized against rabies. It may also be advisable to start an antibiotic, since wounds caused by animal bites and scratches frequently become infected. One of the newer quinolones, such as levofloxacin (Levaquin), which many travelers carry in case of diarrhea, would be an appropriate choice. A tetanus shot should be given if not administered within the last five years.
In the event of a venomous snake bite, move the victim a safe distance from the snake and place him or her at rest, with the affected extremity immobilized and kept below the level of the heart. Remove constrictive clothing and jewelry. Apply a pressure bandage which does not impede blood flow. Avoid tourniquets, which are no longer recommended. Bring the victim immediately to the nearest medical facility for administration of antivenom and supportive care. To reduce the risk of snake bites, wear boots and long pants and avoid perfumes and cologne.
If stung by a coelenterate, such as a jellyfish or Portuguese man-of-war, apply dilute vinegar or baking soda. Remove tentacles carefully, not with bare hands. If stung by a stinging fish, such as a weever, scorpionfish, stonefish, or stingray, immerse the limb in water at about 45 degrees C.
If bitten by a scorpion, apply ice, immobilize the affected body part, and seek immediate medical help. Scorpion bites are painful but generally not dangerous, except in infants. To prevent scorpion bites, sleep under mosquito nets, wear gloves and protective clothing when working around piles of wood or leaves, and be sure to inspect and shake out clothing, shoes, and sleeping bags before use.
From the World Health Organization
Animals and insects (in chapter "Environmental Health Risks")
Bites and stings due to terrestrial and aquatic animals in Europe (PDF)
From the Centers for Disease Control (CDC)
From "Health Information for Overseas Travel" (U.K.)
Dangerous bites and stings
From the New England Journal of Medicine
Bites of Venomous Snakes. Barry S. Gold, Richard C. Dart, Robert A. Barish. NEJM 2002; 347(5): 347-356