Tetrodotoxin poisoning

Tetrodotoxin is another potent neurotoxin, is also known as anhydrotetrodotoxin 4-epitetrodotoxin, or tetrodonic acid, is a marine biotoxin associated with certain fish species, notably pufferfish.

Although the ingestion of livers from certain species of puffer fish is the most common cause of tetrodotoxin poisoning, tetrodotoxin also appears in trigger fishes, ocean sunfishes, globefishes, porcupine fishes, some parrot fishes, a goby, xanthid crabs, sea stars and angel fish, a horse crab, a number of marine snails, a flatworm, a South Atlantic sea squirt, ribbon worms and marine red algae.

Bacteria, omnipresent organism that commonly inhabit the aquatic system, are implicated as the primary source of tetrodotoxin.

There are several microbial sources of tetrodotoxin in including Pseudomonas, Vibrio, Listonella, and Alteromonas species. It has been suggested that the puffer fish accrue tetrodotoxin as a biological defense agent. There appears to be symbiotic association between tetrodotoxin-producing bacteria and higher organism, which offer distinct advantages to both partners.

The lethal dose of tetrodotoxin is only 5 mg/kg in the guinea pig. In humans, the lethal dose is 334 mg/kg by ingestion. Tetrodotoxin affects the nervous system by preventing the propagation of the nerve impulse.
Tetrodotoxin poisoning

Puffer fish poisoning

Puffer fish poisoning is results from ingestion of the flesh of certain species of fish belonging to the Tetraodontidae. These fish can be found in both fresh and salt water and can inflate their bodies to a nearly spheric shape using air or seawater.

The toxin involved is called tetrodotoxin and was originally believed to be a true ichthyosarcotoxin produced by the fish itself. Puffer fish, the most common source of tetrodotoxin, is eaten as the delicacy fugu in some Southeast Asian countries.

Although tetrodotoxin is concentrated in the fish’s skin and internal organs, all parts of the fish may contain it. Most poisonings occur in Japan, where sushi chefs must be licensed in the proper technique of preparing puffer fish owing to risk of death with improper preparation.

Tetrodotoxin blocks the action potentials in nerves by binding to the pores of the voltage-gated, fast sodium channels in nerve cell membrane.

The symptoms of puffer fish poisoning are similar to those described for paralytic shellfish poisoning, including initial tingling and numbness of lips, tongue and fingers leading to paralysis of the extremities; ataxia,; difficulty on speaking; and finally death buy asphyxiation due to respiratory paralysis. Nausea and vomiting are common early symptoms.
Puffer fish poisoning