Bring 2 cups juice to a boil in a small saucepan over high heat. Meanwhile, pour water into a large heatproof bowl. Sprinkle gelatin over the water; let stand for 3 minutes. Add the juice and stir to completely dissolve the gelatin, 2 to 3 minutes. Add sugar and stir for 1 minute to dissolve.
Gastroenteritis (often referred to as the stomach flu , however, it is not related to the influenza virus. Gastroenteritis is a nonspecific term for various inflammatory problems in the gastrointestinal tract with the most common symptoms and signs being diarrhea, nausea, vomiting, and abdominal pains.s previously mentioned, although it is not caused by influenza viruses, gastroenteritis is commonly referred to as the stomach flu because most people have acute symptoms that last a day or so, and then begin to resolve, like the symptoms of more benign flu strains.
Stomach Flu Symptoms. For people with stomach flu, symptoms may include watery diarrhea, vomiting, and body aches. Other symptoms include  fever, chills, and a general sense of tiredness. In most cases, symptoms of stomach flu last anywhere from one to ten days, depending on which virus is responsible for the illness. An Introduction to Stomach Flu Signs and Symptoms When a person becomes infected with a stomach flu virus (see Types of Stomach Flu Viruses), it begins to multiply within the small intestine. After approximately one to ten days, stomach flu signs and symptoms can appear. This period between stomach flu transmission and the start of symptoms is the stomach flu incubation period.