DOI: 10.6084/m9.figshare.30053164
title: A narrative review of toxicity after exposure to true morel (<i>Morchella</i> genus) and false morel (<i>Gyromitra</i> genus) mushroom ingestions

description: The clinical presentations associated with <i>Morchella</i> spp. (true morel) and <i>Gyromitra</i> spp. (false morel) mushroom ingestions are incompletely characterized. The objective of this review is to describe the clinical presentations reported after <i>Morchella</i> spp. and <i>Gyromitra</i> spp. ingestions. This is a narrative review to identify studies reporting toxicity in humans from <i>Morchella</i> spp. and <i>Gyromitra</i> spp. The literature search was performed in two stages. First, a search of Medline, Embase, PubMed, Scopus, and Agricultural & Environmental Science electronic databases was performed. The search strategy employed a combination of controlled vocabulary terms and free-text terms. Terms such as “morel,” “true morel,” “false morel,” “morchella,” “gyromitra,” and “lorchel” were utilized in conjunction with keywords related to toxicity. Duplicate articles were removed. Second, a manual search of the references for the included articles was performed. Inclusion criteria were peer-reviewed human reports of mushroom ingestion in all languages up to 31 December 2024, with sufficient description of three components: acute ingestions to <i>Morchella</i> spp. or <i>Gyromitra</i> spp., clinical manifestations, and medical outcome. There were 84 articles that met the inclusion criteria. The articles described 201 and 52 individual <i>Gyromitra</i> spp. and <i>Morchella</i> spp. ingestions, respectively. The mortality rate in these articles was 28.9% for <i>Gyromitra</i> spp. and 7.7% for <i>Morchella</i> spp. The clinical presentation after <i>Morchella</i> spp. ingestion was primarily neurologic (65.4%), most commonly dizziness and/or unsteadiness/ataxia (51.9%), without any reported seizures, with a median onset of 12 h (IQR: 9–12 h). Gastrointestinal (50.0%) effects were less common and often early, with a median onset of 2.3 h (IQR: 1.1–9 h). Hepatic effects were uncommon (17.3%) and only present when other organ systems were involved. No fatalities from <i>Morchella</i> spp. ingestion were reported until 2024. However, three articles published in 2024 report multiple cases of critical illness and fatality after <i>Morchella</i> spp. ingestion. The clinical presentation of <i>Gyromitra</i> spp. ingestions was primarily gastrointestinal (88.1%) and often delayed with a median onset of 9 h (IQR: 6–12 h). Hepatic (53.7%) and neurologic (51.7%) effects were also commonly reported. Seizures were only reported in 13.9% of <i>Gyromitra</i> spp. ingestions and mostly in fatal cases (82.1%) later in the disease course. Hemolysis was reported in only a minority of <i>Gyromitra</i> spp. (2.5%) ingestions. <i>Morchella</i> spp. ingestions were most frequently associated with a constellation of neurologic symptoms, including dizziness, unsteadiness, and ataxia. Approximately half of the patients displayed gastrointestinal symptoms, typically within the first 6 h. The absence of gastrointestinal symptoms did not preclude the involvement of other organ systems. However, the recent critical and fatal cases of <i>Morchella</i> spp. ingestion display a pattern of severe, early vomiting and diarrhea, sometimes with shock, hemorrhagic gastrointestinal complications, and multi-system organ failure. <i>Gyromitra</i> spp. ingestions commonly displayed delayed gastrointestinal, hepatic, and/or neurologic effects. However, seizures were uncommon other than in the late stages of fatal cases with coma. This review has limitations, including reporting and publication biases. However, having a better understanding of what has been reported in the literature provides better insight into these rare toxicologic presentations. The clinical presentations following the ingestion of <i>Morchella</i> spp. and <i>Gyromitra</i> spp. mushrooms reported in the literature follow distinct patterns that differ from what is commonly reported in reference texts. <i>Morchella</i> spp. ingestions were associated with a constellation of neurological symptoms, including dizziness, unsteadiness, and ataxia, and many patients developed gastrointestinal symptoms, which typically occurred within 6 h. Several reports in 2024 described cases of critical illness, including early gastrointestinal symptoms, sometimes with shock, hemorrhagic gastrointestinal complications, and multi-system organ failure. Toxicity after <i>Gyromitra</i> spp. ingestion typically results in delayed gastrointestinal symptoms followed by hepatic and neurologic effects. Seizures were mostly reported as late findings in fatal cases after the onset of coma and multi-organ injury.