At least 30 people have contracted a rare skin infection after buying seafood at markets in Chinese neighborhoods across New York City, prompting health officials to issue a warning to consumers and market workers to take precautions when handling raw or live fish. The source of the outbreak was unclear, but health officials said that all of the people who were infected had bought fish at markets in Sunset Park, Brooklyn; Flushing, Queens; or Chinatown, in Manhattan. There was no evidence that eating fish from any of those markets could cause illness, officials said. “People are encouraged to wear waterproof...