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Venomous snakes are undoubtedly the most significant cause of both major morbidity and mortality amongst all terrestrial venomous and poisonous animals. Though poisoning by marine animals may affect large numbers of people, mortality is comparatively rare, thus venomous snakes are the leading cause of death from venomous and poisonous animals in all environments. In some parts of the rural tropics snakebite is in the top 10 to 15 most important health problems, but in temperate “western” countries, snakebite is often considered of negligible significance, a designation not necessarily in tune with reality.

Types of Venomous Snakes

There are approximately 3,000 species of snakes globally, but only about 600 species are venomous and most of these are found in just three snake Families: Lamprophiidae (subfamily Atractaspidinae), Elapidae (includes sea snakes, subfamily Hydrophiinae) and Viperidae. In addition, there are a number of snakes known collectively as Non-front-fanged Colubroid (NFFC) snakes (formerly inaccurately grouped in an artificial family, the Colubridae) that are capable of inflicting envenomation, but only a few species are considered to venomous.

These four groups of venomous snakes are covered in separate pages:

Lamprophiidae (subfamily Atractaspidinae)




Medically important non-venomous snakes

Compared to the human toll from venomous species, non-venomous snakes cause few problems, but it should not be forgotten that a few large non-venomous species, notably the pythons and boas (Family Boidae) can cause significant bites and rarely may even kill, more rarely still, actually eat humans.

FIGURE: Python skull showing numerous long recurved teeth.

Pythons and boas have many long sharp recurved teeth capable of penetrating deeply, even to bone in some areas, such as the hand. These teeth, in addition to a mechanical injury, may be expected to be coated with bacteria and so may cause significant local infection. In addition to the effects of the bite, large pythons and boas can potentially wrap around a human torso or neck and may cause crush injuries. These may include significant internal organ damage, in addition to the lethal effects of constriction of the cardiovascular and respiratory systems.