After a brief spike in December, flu transmission in Delaware is back down to minimal levels. The Delaware Division of Public Health reported just 10 laboratory-confirmed cases of the flu for the week of Jan. 30-Feb. 5 — the most recent available data. There have been a total of 626 confirmed cases in Delaware this season from 432 New Castle County residents, 84 from Kent County and 110 in Sussex County. “That is quite remarkable,” said DPH director Dr. Karyl Rattay last week of the low rate of flu transmission.