State health authorities say the number of whooping cough cases in California has jumped by more than 400 in two weeks.
California Department of Public Health spokesman Ken August says as of June 30, there have been 1,337 reported cases of whooping cough in California. About 700 more cases are being investigated by local health departments.
Whooping cough was declared an epidemic in California after 910 cases of the highly contagious disease were reported as of June 15.
August says the new numbers don't necessarily represent a surge in infection because the increase includes cases that are months old.
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Five California babies under 3 months of age have died of the illness, including a 4-week-old infant that died in Stanislaus County in early May. Unimmunized or incompletely immunized babies are particularly vulnerable.
Stanislaus County has an eightfold increase in confirmed cases, from 18 in the first six months of 2009 to 55 cases this year. County health officials are investigating other reports of potential whooping cough.
The caseload is expected to rise because the disease usually peaks in the second half of the year, said Dr. John Walker, county public health officer.
San Joaquin County Public Health Services has reported 19 suspected or confirmed cases since Jan. 1, compared with two cases last year.
Walker said the disease in Stanislaus County has sickened everyone from newborns to adults up to 68 years old. The county's infection rate for infants is 75 per 100,000, almost five times higher than the rate for children age 1 to 6, who are usually shielded by immunizations.
"Clearly it is a significant risk to newborns, and especially children who are less than 6 months old," Walker said.
His office continues to alert health care providers to watch for signs of whooping couch, and is urging hospitals to emphasize booster shots for post-partum women and their spouses, so they don't contract the illness and give it to their newborns.
Pertussis vaccinations do not protect babies until they are 6 months old, and the immunity wears thin by age 11 or 12.
Posters in the county vital records office, where parents pick up birth certificates, are directing them to the county immunization clinic. The county also has a campaign to alert Latino families about whooping cough. All of the deaths in California were Latino infants.
The county hopes to roll out a vaccination effort next week for parents of newborns and caregivers. The booster shots will be allocated to parents and caregivers who can't afford to get the shots from their doctors.
If it's not available from health care providers, south San Joaquin County residents can get recommended pertussis vaccinations at the Manteca Health Center, 124 Sycamore Ave., on Mondays from 8 to 11 a.m. and 1 to 4 p.m., and on Wednesdays from 10 a.m. to 1 p.m. and 3 to 6 p.m. The fee is $15, but no one is turned away because of inability to pay. Call 823-7104.