Thirty plus Years of Mushroom Poisoning

A Summary of the Approximately 2,000 Reports in the NAMA Case Registry
By Michael W. Beug, Marilyn Shaw, and Kenneth W. Cochran

Dr.. Trestrail compares numbers of mushroom toxic exposures reported to NAMA to reports to the Poison Control Centers compiled through the Toxic Exposure Surveillance System of the American Association of Poison Control Centers. From this data we can infer that mushrooms account for about 0.4 to 0.5% of total toxic exposures. NAMA is receiving reports totaling about 1% of mush- room poisoning cases that are reported to Poison Control Centers each year. While about 90% of mushrooms in the Toxic Exposure Surveillance System are unidentified, NAMA involvement drops the % unidentified mushrooms into the range of 10 to 30%. Also, since approximately 80% of the reports to PCCs involve asymtomatic events, we conclude that NAMA reports get filed for about 10% of the symptomatic poisoning cases (and probably well over 50% of the cases involving a fatality).

The NAMA database that is maintained of all of the poisoning case reports that have been received by the toxicology committee is not readily accessible when questions arise. This paper summarizes all reports in the database where the mushroom could be reasonably well identified. We cover all material through December 2005. Unlike the annual reports, we will not delve into treatments or why the person may have consumed the mushroom (e.g. for food, for recreation, mistaken identification, etc.). The only age determination we make is for adults (and here we treat teenagers as adults) versus children. However, bear in mind that symptoms can be most severe in individuals whose health is previously compromised (due to age, alcohol or chronic disease) and in children whose digestive and immune systems are not yet fully developed. There are unusual cases where the death is not directly due to mushroom toxins. These include a previously severely ill elderly man who ate several successive huge meals of a Gyromitra species but the symptoms related to his death did not match any known mushroom symptoms. A quadriplegic consumed purchased Psilocybe cubensis (of uncertain quality), went into anaphylactic shock and died. One woman of a group of five ate what was probably Laetiporus sulphureus suffered severe GI symptoms, dermatitis, and died in 19 hours while no one else in the group was even sick. After passing out unconscious from a large meal of Amanita muscaria, a man froze to death in his tent in Michigan. On the other side of the coin, we have not entered numerous cases where someone consumed an Amanita in the “Destroying Angel” group and had no ill effects or consumed a plateful of Chlorophyllum molybdites or some Amanita muscaria, etc. without getting sick. We have also not reported on the huge number of cases (roughly 33% of the total) where the cause of the poisoning is unclear due to the ingestion of several species at a time or due to the failure to preserve or produce any of the mushrooms for later identification. In some regions (the Rocky Mountain region and the Pacific Northwest) the reporting is quite extensive (though undoubtedly not complete).

In other regions the reporting is very spotty because at times during the past 23 years there have been few active experts in the area. Sometimes one can be quite certain about what mushroom was consumed but at other times it is just an educated guess based on mushrooms gathered near where the suspect mushrooms were picked or from pictures that the victim pointed out in a book. We have generally not attempted to use the most current name but have followed the names used in the reports. The approach has also been that of a “lumper.” For example Armillaria mellea and Laetiporus sulphureus, are now recognized as complexes of several species, but there has often been no way to figure out what the actual culprit was, though by looking at the location one can sometimes make a good guess. A confounding factor here is that mushrooms can be contaminated by bacteria and molds and the symptoms from bacterial and mold contamination are extremely similar to most mushroom poisoning symptoms. Some of the cases certainly do appear to have been a result of consumption of spoiled mushrooms that were old before consumption or had been frozen raw (which allows the bacteria to keep growing).

Also for mushrooms growing in lawns, flower beds, along roads and on golf courses there is the question of contamination by insecticides or heavy metals. In a few cases there was specific recollection of a recent Malathion or other insecticide spray. We have a Table of poisonings where alcohol is implicated because there were individuals who said that they could eat the mushrooms if they did not drink alcohol. We are certain that several additional GI cases were also alcohol related. We have tabulated all of the reported dermatitis cases because that information has remained scattered. Where the case involved both dermatitis and GI symptoms, the event was tabulated in both tables. We were surprised at some of the things that we found (or did not find). In over 2,000 reports, there were only three cases total involving a Cortinarius species, even though that is a huge genus with many large fleshy fungi. We did not find a single mention of a poisoning that matched the symptoms of orellanine poisonings. So far orellanine has been found in only one small brown Cortinarius species in North America. A further check of other available sources also failed to come up with any orellanine cases anywhere in North America.

While we have often seen 50% quoted as a death rate for consumption of mushrooms containing amatoxins, we calculated an 11% death rate for reported cases of people who became ill. The overall rate of death from amatoxins is well under 10% when you count the people who showed no symptoms. Furthermore, we only found record of 5 liver transplants for a transplant rate of 3.5% in amatoxin cases. From other sources, we know that Galerina autumnalis can be fatal, but none of those reports have made their way into the database. Similarly, many cases of Galerina autumnalis ingestion that did not lead to death did not make this report. The one death reported from mushrooms causing GI symptoms with unknown toxins/irritants was from Boletus pulcherrimus. To our surprise, there were no reported deaths from the mushrooms noted for causing kidney failure, Amanita smithiana and Paxillus involutus. Though Amanita smithiana was at one time thought to contain orellanine, orellanine is not present. The toxin in Amainta smithiana is allenic norleucine that is probably bound to a sugar in the mushroom. A second compound, chlorocrotylglycine, may also be toxic. The toxins in Paxillus involutus are unknown. We found cases where mothers became ill from a mushroom ingestion and nursing infants (and nursing puppies) became ill (the puppy died) from toxins in the milk. Though many people still eat Gyromitra esculenta, the large number of cases found where there was liver and/or kidney damage will hopefully lead individuals to cease this practice.

In examining animal poisoning cases, we were struck by how frequently dogs (and even cats) consume either Amanita muscaria or Amanita pantherina. Neither of these species is deadly in humans, but both can be lethal to cats and dogs. Similarly there were deaths of dogs from both Inocybe species and Scleroderma species, though we have no record of human deaths from these same species. We looked for mushroom poisonings of horses or cows. There were no poisonings recorded for these animals, though there were two poisonings recorded for a pig, including one death. We tried to answer a question for a woman from Oregon whose prize horse was healthy one day and dead the next. Her pasture was full of mushrooms. Her vet said that similar deaths of horses are not all that unusual. We hope that someone who reads this will become curious and some day have an answer of whether or not mushrooms are involved in these mysterious horse deaths.

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