The stomach flu, or gastroenteritis, can be caused by a number of different viruses that attack your gastrointestinal system. These viruses can be contracted from food that was inadequately prepared or in conditions with poor hygiene.
The Rothschild family remains the wealthiest family in human history and, according to The Richest, it still possesses roughly US$350 billion in assets throughout the world. The same publication mentioned that the secrecy which surrounds the Rothschild family and the scale of their operations have prevented anyone from estimating exactly how much this family is worth.
The Forbes World's Billionaires list is the definitive list of the world's wealthiest people, profiling and ranking billionaires from 70 countries by their estimated net worth. Now, to the original remark - Rothschilds are not $500 trillion USD rich.