Decipher the mysterious death of 400 Chinese people

During the past three decades, every year during the peak season of the rainy season, many rural people in Yunnan Province, China, have suddenly died of heart failure.

Epidemiologist Robert Fontaine of the US Centers for Disease Control and Prevention talks about Little Bach mushroom in a seminar on Yunnan sudden death syndrome in Beijing, China on July 13.Photo: AP.

AP said that because of deaths every year, people call this phenomenon "Van Nam sudden death syndrome". No one knows the cause of this syndrome, although it has robbed the lives of about 400 people in three decades.

The BBC quoted Zhang Shu, a heart doctor from the Chinese Center for Disease Control and Prevention, saying that people were rumored to have many strange stories. For example, some people suddenly die while talking. Many people experience nausea, dizziness, heart palpitations, convulsions and exhaustion several hours before death.

The Chinese Center for Disease Control and Prevention established an expert team to investigate the case. After the investigation process lasted for 5 years, the expert team believed they had found the culprit. It is a fungus called Tieu Bach. They belong to the Trogia group and contain three toxic amino acids.

Robert Fontaine, an epidemiologist from the US Centers for Disease Control and Prevention, is one of the participants in the investigation process. He said experts went to remote villages on highlands in Yunnan province. "These are villages where many people die in a very short time in the summer," Fontaine said.

Mushroom hotpot dish in a restaurant in Yunnan province.Photo: flickr.com.

Health officials in Yunnan province discovered sudden death syndrome many years ago and called on the government for help in 2004.

The investigation team faces numerous obstacles. Many people communicate in the local language, making it difficult for experts to understand what they say. Villages are scattered in remote areas. The practice of burying the dead soon made the investigation team unable to examine the body. Heavy rains and landslides make moving difficult.

But even in the first year of the investigation process, experts narrowed down the list of causes. They found that most of the victims used to drink groundwater, neurological disorders and eating mushrooms.

The team focused on fungi because deaths often occurred during the mushroom harvest season. More than 90% of sudden death occurred in July and August. At the end of 2005, experts began to warn some villages not to eat strange mushrooms.

However, most people do not follow the warning. Yunnan is famous for its variety of delicious mushrooms, many of which are exported abroad at very high prices. So people in the villages often find mushrooms in the summer months.

By 2008, the investigation team found that in the homes of sudden deaths, there was a strange fungus that they called Little Bach. This mushroom is not sold in the market because it is too small and turns brown very quickly since people picked it. Perhaps because they could not sell, the people ate the mushroom Bai Bach.

'We constantly found them in all the places we went to , ' Fontaine said.

A frantic media campaign about the dangers of exotic mushrooms significantly reduces the number of deaths. In the past few years there were only a few deaths, and this year officials have not recorded any cases.

Even so, it seems that the veil of mystery has not been fully removed. Analysis results show that Xiaotang mushrooms contain some toxins, but their virulence is not strong enough to cause death. So scientists have to separate each substance and check what substances can cause heart failure.

Some experts believe there may be another agent, because many victims have very high levels of barium (Ba) in the body. Three are heavy metals in the soil and enter the fungus.

'The work is not over. We still have to do research in the laboratory , 'Fontaine admitted.

Cases of diseases and deaths from fungi are quite common in Asia. This is the statement of Mr. Diderik De Vleeschauwer, spokesperson of the United Nations Food and Agriculture Organization office in Thailand.