Two cases of pertussis, including one 6-year-old Ashland child, have been confirmed in Jackson County and three other youngsters have symptoms that strongly indicate they have been infected.




State public health officials announced Thursday that a case of pertussis (commonly known as whooping cough) has also been confirmed in Marion County, and they encouraged parents to make sure to have their children immunized against what can be a fatal disease for infants.




The first Jackson County case was confirmed in a Jacksonville-area toddler on Jan. 3. A second case was confirmed in a 6-year-old Ashland child on Jan. 10, said Viki Brown, Jackson County director of public health services.




Public health officials are always concerned when pertussis occurs in Ashland because a large percentage of Ashland parents have chosen not to immunize their children, expressing doubts about the safety of immunizations. In 2005, public health officials estimated as many as 10 percent of Ashland children weren't immunized against potentially deadly diseases such as pertussis.




All of the five Jackson County cases are children and none of them were currently immunized, Brown said. She said none of the five had contact with each other, but they may have had contact with some other person, as yet unknown, who could have infected them.




Brown said confirming a case of whooping cough can be difficult because the bacterium that causes it, Bordetella pertussis, is hard to collect.




"You have to go way back through the nose into the upper throat (to get samples)," she said.




Without a positive culture, a case can't be officially confirmed, but health workers often identify "presumptive" cases on the basis of other symptoms, such as the deep, rasping, persistent cough that persists for weeks or even months after the original cold-like symptoms have faded.




Pertussis is most contagious during its cold-like early phase. Most otherwise-healthy adults can eventually overcome the bacterium, but they can spread it to others. This "adult reservoir" of bacteria is often the source of new cases among youngsters.




Pertussis vaccine is typically administered to children at 2 , 4 and 6 months and again at 15 to 18 months. The vaccine seems to lose its efficacy over time, because pertussis has been seen to develop in adolescents who were vaccinated.




Public health officials recommend adults and children over age 7 get immunized with the new Tdap (for tetanus, diphtheria and pertussis) vaccine, which is now routinely given for people who need a regular tetanus booster.




Oregon last had a major pertussis outbreak in 2004, when cases reached an all-time high of 14.9 per 100,000, or twice the national average. Four infants in Oregon have died of pertussis during the past seven years. Jackson County had a serious outbreak in 2003, when 135 cases were recorded, but that number fell to just six cases in 2004.




A Klamath County baby died of pertussis during the 2003 outbreak.