Two of the three fatalities are from the coastal villages of San Vicente and San Agustin, and the third from Barangay IV.
Dr. Eduardo Posadas, city health officer, however, said the 818 recorded gastroenteritis cases were lesser than those during the same period last year.
Posadas said his office, with the help of barangay health workers, have conducted massive disinfection of water sources and household containers to contain the spread of gastroenteritis.
He advised residents to continue cleaning their surroundings and properly boil their drinking water.
Gastroenteritis is a water-borne disease that affects mostly children with weak resistance. It can be acquired from drinking contaminated water.