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Clinical Toxicology, 44:185–188, 2006
Copyright © Taylor & Francis Group, LLC
ISSN: 0731-3810 print / 1097-9875 online
DOI: 10.1080/15563650500514590
185
LCLT
CASE REPORT
Hallucinatory Fish Poisoning (Ichthyoallyeinotoxism):
Two Case Reports From the Western Mediterranean
and Literature Review
Hallucinatory Fish Poisoning
Luc de Haro and Philip Pommier
Centre Antipoison, Hôpital Salvator, Marseille, France
Ichthyoallyeinotoxism is a rare kind of food poisoning con-
tracted following the ingestion of fish. The responsible toxins are
unknown, and the clinical feature is characterized by the develop-
ment of CNS disturbances, especially hallucinations and night-
mares. As the implicated fish species may be also related to
ciguatera poisoning, there may be possible confusion between the
two fish-borne intoxications. In order to clarify this, the literature
pertaining to “dreamfish” was reviewed and two cases are pre-
sented. A 40-year-old man experienced mild digestive troubles
and terrifying visual and auditory hallucinations after eating a
specimen of Sarpa salpa in a restaurant. As he had severe behav-
iour troubles, he was managed in the hospital and recovered 36 h
after the meal. He was unable to recall the hallucinatory period.
Another man, 90-years-old and previously healthy, had auditory
hallucinations 2 h after eating a specimen of Sarpa salpa. The two
following nights, he had numerous nightmares and recovered
spontaneously after a period of 3 days.
Keywords Ichthyoallyeinotoxism; Ichthyosarcotoxism; Hallucina-
tory Fish Poisoning; Dreamfish
INTRODUCTION
Ichthyosarcotoxism is a type of food poisoning caused via
the ingestion of fish. The most common and widely investi-
gated form of ichthyosarcotoxism is ciguatera poisoning that
affects the peripheral nervous system. It is due to contamina-
tion of fish flesh by various toxins produced by the benthic
dinoflagellate Gambierdiscus toxicus. A less common form is
ichthyoallyeinotoxism, characterized by development of cen-
tral nervous system disturbances, especially hallucinations and
nightmares. Ichthyoallyeinotoxism has been reported in many
locations around the world (1,2). The purpose of this article is
to describe two new cases of ichthyoallyeinotoxism that
occurred in the Western Mediterranean after ingestion of Sarpa
salpa, and to review the literature concerning this rare poisoning.
CASE 1
April 1994
A previously healthy 40-year-old executive began feeling
weak and tired within 2 h after eating freshly caught baked sea
bream (Sarpa salpa) for dinner while on vacation in Cannes on
the French Riviera. Nausea and vomiting developed quickly
during the night. The next day symptoms persisted and were
accompanied by marked muscle weakness. He decided to
shorten his vacation and drive home. At that point, he began to
experience blurring of vision and hallucinations involving
aggressive and screaming animals. Agitation and disorientation
led him to seek medical assistance (he was not able to drive
anymore as he was seeing giant arthropods around his car).
Physical examination upon arrival at the hospital emergency
room demonstrated no notable abnormalities: no fever, no sign
of focalization or sensory-motor deficit, and normal hemody-
namic status except for sinusal tachycardia linked directly to
the mental disturbances. During hospitalization, the patient
recovered rapidly with complete resolution of symptoms
within 36 h post ingestion. He was unable to recall the halluci-
natory period.
CASE 2
March 2002
A previously healthy 90-year-old retiree began experiencing
auditory hallucinations 2 h after ingesting a sea bream (Sarpa
salpa) that he had purchased from a professional fisherman in
Saint Tropez on the French Riviera. He was used to eating this
kind of fish, and had cleaned the fish after he had purchased it.
Hallucinations were of a particularly terrifying nature (human
screams and bird squealing), and he had numerous nightmares
for the next two nights. Fearing that these symptoms might
Received 15 March 2005; accepted 24 March 2005.
Address correspondence to Luc de Haro, Toxicovigilance, Centre
Antipoison, Hôpital Salvator, 249 boulevard Sainte Marguerite,
13009 Marseille, France. E-mail: luc.deharo@ap-hm.fr
186
TABLE 1
Fish species described as hallucinogenic in the Literature
Fish Families Species
Geographical
distribution Common names
Feeding
behaviour
Described as
hallucinogenic in
Acanthuridae Acanthurus triostegus Indo-Pacific Ocean Convict surgeonfsh, Tang (USA),
Manini (Hawaii)
Herbivorous Hawaii (8)
Kyphosidae Kyphosus cinerascens
Kyphosus vaigiensis
Kyphosus fuscus
3 species in
Indo-Pacific Ocean
Sea chub (USA), Nenue, Manaloa
(Hawaii), Dreamfish (Norfolk)
Herbivorous K. cinerascens and K. vaigiensis
in Hawaii (8); K. fuscus in
Norfolk Island (9)
Mugilidae Mugil cephalus
Neomyxus chaptalli
Cosmopolitan
Indo-Pacific Ocean
Common mullet (USA), Ama (Hawaii),
Haarder, flathead mullet (South Africa)
Omnivorous Hawaii (3)
Mullidae Mulloidichthys
samoensis
Upeneus arge
Both species in
Indo-Pacific Ocean
Surmullet, goatfish (USA), Weke’a’a,
Weke-ula (Hawaii for M. samoensis),
Weke pueo (Hawaii for U. arge), Jome
(Marshall Islands), Tebaweina
(Gilbert Islands), Afolu i’a sina (Samoa)
Omnivorous Both species in
Hawaii (3,14,18).
Pomacentridae Abudefduf
septemfasciatus
Indo-Pacific Ocean Damselfish (USA), Maomao (Hawaii),
Ulavapua, Alala saga, Mutu (Samoa),
Bakej (Marshall Islands), Tebukibuki
(Gilbert Islands), Palata (Philippines),
Sergent-Major (French Polynesia)
Herbivorous Gilbert Islands (10)
Serranidae Epinephelus
corallicola
Tropical Indo-Pacific
Ocean
Coral Grouper (USA), Gatala (Samoa),
Rero (Polynesia), Baraka, Kugtung
(Philippines), Coral Rockcod
(Australia), Vieille (Seychelles,
Mauritius, French)
Carnivorous Gilbert Islands (10)
Siganidae Siganus argenteus
Siganus corallinus
Siganus luridus
Siganus rivulatus
Siganus spinus
5 species in Indo-Pacific
Ocean, S. luridus and
S.rivulatus settled in
Mediterranean and
Red sea
Rabbitfish (English), Poisson Lapin,
Cordonnier (Mauritius, Réunion,
French), Aras (Israel)
Herbivorous S. argenteus and S. corallinus in
Mauritius (19).
S. luridus in Israel (7, 16).
S. rivulatus in Mauritius (19)
and suspected in Israel (5).
Siganus spinus in Réunion
island (12)
Sparidae Sarpa salpa Mediterranean sea Saupe (English & French), Salema
(Spain & Israel)
Herbivorous Tunisia (4), France (11) and
Israel (5,6).
HALLUCINATORY FISH POISONING 187
signal the beginning of a major mental illness, he did not tell
his friends or attending physician. The manifestations abated
three days after he had eaten the fish. Later, he recalled a warn-
ing that he had heard at the fish market concerning the halluci-
nogenic potential of sea bream and decided to contact the
Poison Control Center in Marseille.
DISCUSSION
Clinical symptoms of ichthyoallyeinotoxism occur within a
few minutes to 2 h after ingestion of toxic fish. The first symp-
toms resemble inebriety with loss of balance and coordination
and generalized malaise (1–3). Sore throat and heartburn have
also been reported in the initial phase. Within a few hours, spe-
cific signs of poisoning occur including delirium, visual and/or
auditory hallucinations (often involving animals), depression,
feelings of impending death with reactive tachycardia and
hyperventilation, and disturbed behavior. If they are able to
sleep, patients classically report terrifying nightmares (3). Gas-
trointestinal symptoms including nausea, abdominal pain, and
diarrhea have been described in a few cases, but are usually
low-grade (3). No specific treatment or antidote treatment is
available. Appropriate management of transient behavioral
disturbances (e.g., using benzodiazepine or neuroleptics), is
important to prevent self-inflicted or other injury. Symptomatic
treatment for gastrointestinal manifestation can enhance
patient comfort. Symptoms generally abate within 24 to 36 h,
but weakness may persist for several days (1–3).
Ichthyoallyeinotoxism is widespread in tropical and temper-
ate areas of the Indian and Pacific Oceans as well as in the
Mediterranean Sea. Toxic fish species belong to the 8 families
detailed in Table 1. Most are herbivores or scavengers living in
coastal areas. It should be noted that toxicity in all species var-
ies according to fishing location, season, and way of preparing
the fish (3). In the Mediterranean, most poisonings involving
Sarpa salpa (eaten in Tunisia, France and Israel but considered
as inedible in Italy and Spain), have been reported in spring
and summer (4–7). A classically reported exacerbating factor is
consumption of fish cooked without removing the head, and/or
not immediately gutted after being caught (8). Although the
toxic agents are still unknown, some authors have implicated
toxic macroalgaes (caulerpaceae family) that are ingested and
contaminate the flesh of fish (3,4). These toxins are probably
heat stable since case reports have been described after inges-
tion of fried, boiled, steamed or raw fish (3,7). Most cases have
been described anecdotally as unexpected, sporadic accidental
food poisonings, usually occurring in endemic areas after con-
sumption of fish considered as safe. However some cases of
intentional consumption of “dreamfish” have been reported (8–
10). Consumption of Sarpa salpa was reported for recreational
purposes in the Mediterranean during the Roman Empire (11),
and for ceremonial purposes particularly in Polynesian popula-
tions (8–10). The traditional names given to hallucinogenic
species reflect their potentially toxic effect. Sarpa salpa is
called “the fish that makes dreams” in Arab; Siganus spinus is
called “the fish that inebriates” in Mascareignes (southwest
coast of Reunion Island) (12,13); and Mulloidichthys samoen-
sis is called “the chief of ghosts” in the Hawaiian Islands of
Molokai, Kauai, and Oahu (8, 14,15).
It should be emphasized that tropical fish species that cause
ichthyoallyeinotoxism are also implicated in cases of ciguatera
poisoning. In this regard, there has been some confusion con-
cerning these two forms of ichthyosarcotoxism. Some cases of
ichthyoallyeinotoxism reported in the western (11) and eastern
Mediterranean (5–7,16) after ingestion of Sarpa salpa or Siga-
nus luridus, have been described as ciguatera despite typical
clinical signs of ichthyoallyeinotoxism, (i.e., hallucinations
and nightmares lasting for a few hours). In this regard, it
should be noted that the presence of Gambierdiscus toxicus,
the dinoflagellate solely responsible for ciguatera, has not been
formally documented in the Mediterranean. It should be
emphasized that there are differences in clinical expression:
ichthyoallyeinotoxism is characterized by central nervous sys-
tem involvement, whereas ciguatera features peripheral ner-
vous system involvement. The two diseases are also different
with regard to potential severity and duration. Most patients
with ichthyoallyeinotoxism recover within 36 h (1–3), while
many patients with ciguatera die or present prolonged symp-
tomatology for several months (17).
CONCLUSION
Ichthyoallyeinotoxism is a rare, poorly understood fish-
borne intoxication. Its incidence is probably underestimated for
several reasons. The first is that symptoms often occur at night
and are short-lived. As a result, patients do not always seek
medical advice, as was the case for our second patient. Another
reason is that the disease occurs in remote geographical areas
(islands and isolated archipelagoes), where there are few medi-
cal facilities able to document cases. Finally, voluntary inges-
tion by its very nature seldom leads to medical intervention.
Great care is necessary to avoid confusing ichthyoallyeinotox-
ism and ciguatera that involve the same species in overlapping
endemic areas.
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