The ciguatoxins are a class of poison

Poison

In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....

ous organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s found in some fish that causes ciguatera

Ciguatera

Ciguatera is a foodborne illness caused by eating certain reef fishes whose flesh is contaminated with toxins originally produced by dinoflagellates such as Gambierdiscus toxicus which lives in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are...

.

There are several different chemicals in this class. "CTX" is often used as an abbreviation in their names. - Ciguatoxin 1 - Ciguatoxin 2 - Ciguatoxin 3 - Ciguatoxin 4B (also called Gambiertoxin 4b)

Toxic Effect

Ciguatoxin lowers the threshold for opening voltage-gated sodium channels in synapses of the nervous system

Nervous system

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...

. Opening a sodium channel causes depolarization

Depolarization

In biology, depolarization is a change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential...

, which could sequentially cause paralysis, heart contraction, and changing the senses of hearing and cold.

Because they do not cross the blood brain barrier (BBB), ciguatoxins solely affect the peripheral nervous system

Peripheral nervous system

The peripheral nervous system consists of the nerves and ganglia outside of the brain and spinal cord. The main function of the PNS is to connect the central nervous system to the limbs and organs. Unlike the CNS, the PNS is not protected by the bone of spine and skull, or by the blood–brain...

 (PNS).

The major symptoms will develop within a few hours of toxin ingestion: vomiting, diarrhea, numbness of extremities, mouth and lips, reversal of hot and cold sensation, muscle and joint aches. The symptoms may last from days to weeks or even months depending on each individual situation. There is no antidote for ciguatoxin poisoning.

Bioaccumulation route

Ciguatoxin is produced by Gambierdiscus toxicus, a type of dinoflagellate

Dinoflagellate

The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...

, which are eaten by big coral reef fish, such as grouper

Grouper

Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes.Not all serranids are called groupers; the family also includes the sea basses. The common name grouper is usually given to fish in one of two large genera: Epinephelus...

, wrasse

Wrasse

The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 82 genera, which are divided into nine subgroups or tribes....

, triggerfish

Triggerfish

Triggerfishes are about 40 species of often brightly colored fishes of the family Balistidae. Often marked by lines and spots, they inhabit tropical and subtropical oceans throughout the world, with the greatest species richness in the Indo-Pacific...

, lionfish

Lionfish

Lionfish may refer to:* genus Pterois, collectively known as the lionfish* Red Lionfish , a significant invasive species off the East Coast of North America and in the Caribbean-Fish:...

, and amberjack

Amberjack

Amberjack refers to 3 species of Atlantic fish of the Carangidae family , which includes the jacks and the pompanos.Greater amberjacks, Seriola dumerili, are the largest of the jacks. They usually have dark stripes extending from nose to in front of their dorsal fins...

.
Ciguatoxin usually accumulates in skin, head, viscera, and roe of the fish.

Ciguatoxin cannot be destroyed by cooking. Rapid testing for this toxin in fish marketed as food is not standard.