Officials say it was probably caused by a soft raw milk cheese called Ouleout from Vulto Creamery in New York state.
The cheese was stocked by a Whole Foods shop in Fairfield, Connecticut, and may also have been available in specialised cheese shops.
The creamery recalled several soft cheeses on Tuesday.
Six cases of listeria have been recorded in Connecticut and Vermont, where the deaths occurred, as well as New York and Florida.
