According to popular beliefs, worms are hidden in the human body, causing various diseases and ailments. These parasites turn out to be easily vulnerable only on the fifth day of the fifth month of the lunar calendar, therefore, according to tradition, every year on this day the Vietnamese celebrate the holiday of That Doan Ngo (T≥t Đoan ng ⁇ ).
Early in the morning, instead of breakfast on this day, they eat a special dish ryownep —, a homemade dish of fermented boiled glutinous rice of a special variety of black or light yellow, as well as fruits.
Bunches of wormwood are hung in houses, which traditional medicine uses to treat colds, low temperatures and pain. And although the therapeutic effectiveness of this herb has not been proven by scientific methods, such treatment is widely practiced among the people.
Thet Doan Ngo is also called the Mid-Year Festival, as it occurs close to the summer solstice, when the sun is closest to the ground.