Cases of pertussis, a potentially deadly disease also known as whooping cough, are on the rise in Napa County this year, Napa County's top health official said.
Napa County Public Health Officer Dr. Karen Smith said 17 cases have been reported so far this year, nine of them in the last two weeks.
There were 13 pertussis cases in Napa County in all of 2013. All but three of this year's 17 reported cases have been in children of middle or high school age, Smith said.
Whooping cough usually only causes a severe cough in older children and adults, but it is a potentially deadly infection in infants under six months old who are more likely to require hospitalization and may die if they become infected, health officials said.
Smith urged women in their third trimester of pregnancy to get vaccinated for pertussis to provide protection of the infant through transfer of antibodies from the mother before birth and by preventing the mother from passing a pertussis infection to the young infant after birth.
Family members and childcare providers who have contact with the infant also should be vaccinated, health officials said.
Pertussis is cyclical and peaks every three to five years, health officials said. The last epidemic in California was in 2010 when there were 9,100 cases statewide and 10 infant deaths.
All of Napa County's neighboring counties also are experiencing a high rate of pertussis, public health officials said.
Symptoms of pertussis are an acute cough usually preceded by cold-like symptoms. Usually a fever is absent, health officials said.
Infants under six months old may have no apparent cough, and the infant's face may turn red or purple.