New York City health officials have identified an outbreak of a rare skin infection in at least 30 people who handled live or raw fish or seafood purchased in markets in the Manhattan, Brooklyn, and Queens Chinatowns. Mycobacterium marinum, the source of the infection, enters the skin through cuts or other injuries. Symptoms include red, tender swelling under the skin of the hands and arms, hand or arm pain, and difficulty moving fingers. Officials are warning customers to wear waterproof gloves in their home when preparing live or raw fish or seafood that came from a market in Chinatown, especially if they have cuts or abrasions. Employees of these seafood markets and the restaurants that purchase food from these markets also are urged to wear waterproof gloves when handling live or raw fish or seafood. Infected people need to take one or more antibiotics to treat the infection. Only a few specific antibiotics can cure this infection, the health department says, so treatment should begin quickly. If the infection isn’t treated correctly, it can worsen over weeks or months and may require surgery. There is no risk associated with consuming the food from these markets. Officials are urging anyone with symptoms of an M. marinum infection, or who believes they are at risk, to see a dermatologist or an infectious disease physician.