Poisonous mushrooms were the most common cause of outbreaks in China during a 14-year period, according to a study.

Researchers looked at data reported to the National Foodborne Disease Outbreak Surveillance System from 2003 to 2017 and published findings in the journal Food Control.

A total of 19,517 outbreaks, which resulted in 235,754 illnesses, 107,470 hospitalizations, and 1,457 deaths, were recorded during the period.

Stats on mushroom outbreaks
Of the 13,307 outbreaks with known etiology, almost a third were caused by poisonous mushrooms, followed by Vibrio parahaemolyticus at 11 percent while the percentage linked to saponin, Salmonella, nitrite, pesticides, Staphylococcus aureus and Bacillus cereus were all in single figures.

Of 13,305 outbreaks associated with a single food category, fungi – mainly poisonous mushrooms – were most commonly implicated, followed by meats, vegetables, aquatic animals, condiments, poisonous plants such as saponin, tung oil or seed and aconite, as well as grains such as rice and noodles.

Among almost 19,000 outbreaks with reported settings, nearly half were associated with food prepared in a household, followed by less than a quarter with food made in a restaurant, and less than a fifth prepared in a canteen.

“Analysis of foodborne disease outbreaks can provide insight into the most important causative agents and sources of foodborne disease, and assist public health agencies determine the high-risk etiology and food pairs, specific points of contamination and settings to reduce foodborne disease illnesses,” said researchers.

Wild mushroom poisoning incident
Another study, published in China CDC Weekly, described 10 cases of wild mushroom poisoning in a city of Zhejiang Province this past year.

From late June to mid-July, 2019, three suspected food poisoning events occurred in Shaoxing City, Zhejiang Province. Ten patients with different degrees of liver damage were found and one person died. Poisonings were caused by ingestion of a wild mushroom (Amanita rimosa) containing amanitin toxins.

The Xinchang County CDC of Shaoxing City, received a report from a local hospital that six patients in a family went to a doctor with suspected food poisoning in late June. Patients had gastrointestinal irritation symptoms including nausea, vomiting, and diarrhea in the early stages.

They then developed different degrees of liver function damage. One person died of acute liver failure but the other patients improved after medical treatment and were discharged one week later. On July 11, the Shaoxing City CDC got a report from the local hospital of another two patients with similar symptoms.

Until July 25, 10 patients meeting the case definition were found, including six in Xinchang County and two each in Keqiao District and Zhuji County. Before 2019, there were one to two cases of wild mushroom containing amanitin toxins poisoning each year in Zhejiang Province.

All patients came from three families in Shaoxing City, who lived tens of kilometers apart. The families did not know each other, nor did they have any other common exposure factors. All patients became sick 10 to 22 hours after family dinners. Wild mushrooms were collected on mountains near the residences and were one of the main foods with noodles or as a soup. Amanitin toxins were found in eight patients’ plasma samples and two people’s urine samples.

CDCs in Shaoxing city carried out publicity and education about wild mushroom poisonings and prohibited residents from picking and eating them. No similar incidents occurred until mid-August 2019. In China, about 20 species of mushrooms can cause death, and most people are not able to identify which types are edible.

The rainy season in Zhejiang Province is from the middle of June to mid-July and with the average temperature, combined to make suitable growing conditions for wild mushrooms. Local CDCs decided to set up warning signs prohibiting the picking and eating of wild mushrooms in mountain areas to prevent such incidents.