120: Mushrooms

INTRODUCTION

The diversity of mushroom species is evident in our grocery stores, our restaurant menus, and our environment. The enhanced interest in mushrooms has led to experimentation by young and old—old citizens and our newest immigrants and our young children reaching for what might become an innocuous or a serious ingestion. Rigor in analyzing the possible ingestion is indispensable for physicians treating a patient who has ingested a mushroom of concern. This chapter offers general information of the most consequential toxicologic groups of mushrooms and emphasizes clinical diagnosis over mushroom identification.

EPIDEMIOLOGY

Unintentional ingestions of mushrooms particularly in children represent a small but relatively constant percentage of consultations requested from poison centers (Chap. 136). A summary of a quarter century of American Association of Poison Control Centers (AAPCC) data reveals that mushrooms represent less than 0.25% of the reported human exposures. Combined data accumulated by the AAPCC and the Mushroom Poisoning Registry of the North American Mycological Association indicates that approximately 5 patient exposures to toxic mushrooms per 100,000 persons occur per year. Some variations result from geographic and climatic conditions and mycologic habitats.¹²¹ Although the methods of analysis of patients with mushroom exposure have changed over the past 30 years, cumulative AAPCC data consistently demonstrate the relative benignity of the vast majority of exposures. The inability of most health care providers to correctly identify the ingested mushroom and the rarity of lethal outcomes are demonstrated by the accumulated data. In 75% to 95% of cases, the exact species was unidentified¹²¹ (Chap. 136). More than 50% of exposed individuals had no symptoms. Most patients were treated at home and rarely had major toxicity. During the 30 years covered by the AAPCC data, fewer than 100 patients died of their mushroom ingestion. Of the mushrooms associated with death, most were Amanita spp and several were hallucinogens, Boletus spp, gyromitrin-containing mushrooms, while others remained unidentified. All reported deaths occurred in adults. Those containing either hallucinogens or gastrointestinal (GI) toxins were the most common reported exposures, yet they accounted for less than 10% of all mushroom exposures. All other presumed exposures represented less than 2% of the total number of identified. Because 75% to 95% of mushrooms involved in exposures are never identified, a strategy for making significant decisions with incomplete data is essential.

CLASSIFICATION AND MANAGEMENT

This chapter does not address molds, mildews, and yeasts, which in addition to mushrooms are all categorized as fungi. The unifying principle for fungi is the lack of the photosynthetic capacity to produce nutrition. Survival is achieved by the enyzymatic capacity of these organisms to integrate into living materials and digest them. Molds are ubiquitous and often associated with varied adverse health effects such as rhinitis, rashes, headaches, and asthma.²¹ Trichothecenes are mold-related mycotoxins that are discussed in Chap. 133 as potential biological weapons. All ...