Envenomation and consumption of poisonous seafood

• poisons
• natural toxins
• tropical medicine

Exposure to natural toxins is becoming more commonplace because of greater worldwide travel, increasing captivity of exotic animals in private and institutional collections, and an expansion in the trade in tropical seafood. Although the effects of natural toxins are often trivial, some may result in neurological emergencies. A good understanding of the origin and management of neurotoxic poisoning is therefore important for the neurologist interested in tropical medicine. The true incidence of neurotoxic poisonings is impossible to ascertain because of underreporting. It has been suggested that each year there may be up to 1000 deaths in the Maharashtra state of India 1 and 600 deaths in Sri Lanka resulting from snake bites, and 1000 to 2000 deaths in Mexico after scorpion stings. Tick paralysis has been estimated to cause the death of 10 000 calves each year.2 There are thought to be around 50 000 human victims of ciguatera poisoning each year.3

This editorial briefly outlines some of the effects of naturally occurring toxins on the human nervous system. We suggest that a general awareness of the circumstances in which exposure to natural toxins may occur and of the expression of poisoning in the form of clinical features will improve the prevention, detection, and management of these potentially fatal conditions. Three recent texts discussing some of these issues are available to the interested reader.4–6