However, in severe cases the neurological symptoms are known to persist from weeks to months. In a few isolated cases neurological symptoms have persisted for several years, and in other cases recovered patients have experienced recurrence of neurological symptoms months to years after recovery. Such relapses are most often associated with changes in dietary habits or with consumption of alcohol. There is a low incidence of death resulting from respiratory and cardiovascular failure. Clinical testing procedures are not presently available for the diagnosis of ciguatera in humans.
Diagnosis is based entirely on symptomology and recent dietary history.
Many other species of warm-water fishes harbor ciguatera toxins. The occurrence of toxic fish is sporadic, and not all fish of a given species or from a given locality will be toxic. The relative frequency of ciguatera fish poisoning in the United States is not known. However, the increasing per capita consumption of fishery products coupled with an increase in interregional transportation of seafood products has expanded the geographic range of human poisonings. The ciguatera toxins can be recovered from toxic fish through tedious extraction and purification procedures.