Though many people simply grab a bag of mushrooms from their local store, others prefer to forage. But incorrectly identifying wild mushrooms can lead to more than an upset stomach, it could prove fatal. Researchers from the USDA's Agricultural Research Service have developed a portable test to help.
Expert foragers can identify different types of mushrooms by sight, but others may mistake similar-looking safe varieties for toxic ones. For example, Amanita phalloides (commonly known as the Death Cap) has a similar look to the safe-to-eat Amanita velosa (Springtime Amanita). But you wouldn't want to mix the two up.
The research team says that consuming toxic mushrooms causes more than a hundred deaths around the world every year, but also sees many more seeking urgent medical attention. The most serious cases are said to be caused by a class of toxins called amanitins – collectively known as amatoxins. Fatal concentrations of these toxins can be as small as 0.1 mg/kg of body weight.
The researchers point out that there are only a few laboratories capable of testing biological specimens for amatoxins, and even then the results may take a while to appear, perhaps not soon enough to help a patient. The new test can identify the presence of amanitins in minutes.
"This test can provide more information about a wild mushroom beyond physical appearance and characteristics, and detect something we cannot even see – the presence of amanitins," said Candace Bever, who worked on the project.
The lateral flow immunoassay (LFIA) test relies on a specific reactive monoclonal antibody and is sensitive to 10 parts per billion, and comprises a sample pad, a conjugate pad, nitrocellulose membrane, and a wicking pad. The team says that a mushroom sample the size of a grain of rice can be used, but the test can also identify toxins in the urine of those who have already consumed suspect fungi.
Results from lab tests were compared with tests undertaken using liquid chromatography-mass spectrometry methods, with diagnostic efficiency of samples described as outstanding. And since dogs out on walks may also consume toxic mushrooms, tests using dog urine confirmed that the LFIA test also worked for pooches.
At the moment, the project would need to find a commercial partner before it's available for us to buy. And even then, it currently only detects the presence or absence of amatoxins, it doesn't identify the presence of other toxins or hallucinogens so can't determine if a mushroom can be safely eaten.
"Our hope is that doctors and veterinarians will be able to quickly and confidently identify amatoxin poisoning rather than having to clinically eliminate other suspected gastrointestinal diseases first," Bever added. "We also hope that will give patients a better chance at recovery, even though there are no clearly effective, specific treatments right now."
A paper on the research has been published in the journal Toxins.
Source: Agricultural Research Service