Ciguatera poisoning is characterized by the wide diversity of its symptoms, which are generally grouped into 5 main categories: gastrointestinal, neurological, cardiovascular, rheumatological and general symptoms. More than 175 different symptoms have been reported in the literature.
Organs and systems affected by ciguatoxins
Symptoms potentially observed in ciguatera cases
Currently, the diagnosis of CP is based solely on the history of intoxication; the species consumed and the nature and evolution of the symtpoms. Only the research for CTXs in leftover meals can confirm the exposure to CTXs. Certain symptoms such as paraesthesia (itching, burning, numbness) of the extremities, face, mouth and pain on contact with cold objects or liquids, as well as the worsening of symptoms after the consumption of certain foods, can be considered characteristic of ciguatera.
Usually, ciguatera has a low mortality rate (<0.1%) and so far has not been associated with the onset of critical illness (cancer, neurodegenerative pathologies,…). Rare fatal cases occur within the firts 48h after the poisoning and are usually due to a cardiovascular failure worsened by a severe dehydration caused by intense diarrhea and vomiting.
No fatalities directy related to CP were observed during the chronic phase.
Despite that this illness may prove to be particularly debilitating for a long period, up to a decade in rare cases, the symptoms subside spontaneously.
Finally, in rare cases, ciguatera may cause premature births and miscarriages in case of poisoning during pregnancy.
CHONOLOGY OF SYMPTOMS
Usually, the CP ”incubation period”, i.e. the period between the consumption of toxic meal and the onset of symptoms, ranges from 6h to 12h, in most cases.
Gastrointestinal symptoms, such as abdominal cramps, nausea, diarrhea and vomiting occur first, and usually resolve within 24h-48h, spontaneously or in response to treatment.
Some neurological symptoms (itching, headaches, parasthesia, dysesthesia…) can also appear in the first few hours.
Cardiovascular symptoms, such as hypotension, bradycardia, T wave abnormalities and rarely tachycardia, may occur within the first 24-48h. These disorders are generally indicative of an exposure to high amount of toxins. Without a rapid and appropriate medical support, those may lead to the patient’s death.
Fever is not encoutered in ciguatera. On the contrary, within the first 24h-48h, the subject may experience mild hypothermia and chills.
A “state phase”, marked by the onset of pronounced rheumatological, general and neurological symptoms, such as parasthesia (tingling in extremities and the orofacial region) accompanied by dysesthesia and/or cold allodynia (causing burning sensations in contact with cold objects or liquid) is observed.
Unlike gastrointestinal symptoms, neurological symptoms may last for several weeks, months or even years.
Pruritis, dizziness, parasthesia, dysesthesia, ataxia, generalized weakness and mood disorders (i.e. depression…) are known to last for a longer period.
In addition to the main symptoms listed above, a generalized weakness evoking the Chronic Fatigue Syndrome (CFS) is also commonly reported in endemic ciguatera areas. This persistent weakness, is proposed as an explanation for the depressive tendencies observed in some patients, without excluding the possibility of a direct action of ciguatoxins on the central nervous system.
CIGUATERA SYMPTOMATIC TRESHOLD
It may happen that, after sharing the same meal, only some persons develop the symptoms of the poisoning. This phenomenon can be illustrated with the theory of “the straw that broke the camel’s back”:
Frequent reef fish consumers of ciguatera endemic region, accumulate in their body trace amounts of ciguatoxins throughout their lives without necessarily developping the symptoms.
Depending on one’s diet, the amount of toxins stored in the body may vary from an individual to another. It is only when the “symptomatic threshold” is reached that the symptoms appear. Note , that the individual susceptibility also afects the level of this treshold, estimated around 0.1 ng of toxins per g. of flesh.