As of Wednesday, there were 40 confirmed cases of whooping cough in the Contra Costa County so far this year, compared to only 18 confirmed cases in all of 2009, according to the health services department.
In the Bay Area, there were six times as many cases of the illness between January and May compared to the same period last year, according to Contra Costa Public Health Nurse Susan Farley.
Farley said the disease, which is extremely contagious, is particularly dangerous for infants, who often have to be hospitalized and monitored.
Although there haven't been any fatalities in Contra Costa County from the disease in several years, statewide there has been an average of three whooping cough-related deaths per year. So far this year, however, there have already been five deaths in California caused by the disease, Farley said.
The germ that causes whooping cough, also known as pertussis, is spread when an infected person coughs or sneezes. Symptoms of the disease begin as ordinary cold-like symptoms such as a runny nose and watery eyes. As it progresses, a cough often develops, which can continue for weeks or even months.
Infants under 4 months old sometimes don't develop a cough, but the illness can cause them to stop breathing, Farley said. In slightly older babies and children, coughing fits cause them to exhale for such a long time that when they finally take a breath, they are gasping for air and often make a whooping sound that gives the disease its name.
Although whooping cough is often thought of as a childhood disease, nearly all infants who get it are infected by their parents, according to Contra Costa Health Services Immunization Coordinator Erika Jenssen.
Health officials do not know exactly what is causing the increase in cases, but Farley said it is probably due to an accumulation of people who have not been vaccinated or received booster shots. The disease tends to peak every three to five years, she said.
In an effort to stop the epidemic before the disease's normal annual peak month in August, Contra Costa Health Services is urging everyone to get vaccinated, especially people who come into contact with infants, Farley said.
On June 25, the health services department will be offering free vaccinations to anyone under 65 years old at its Women, Infants and Children clinic in Richmond from 9 a.m. to 3 p.m. The clinic is located at 100 38th St.
County residents can also obtain coupons for free booster shots from the health services website at www.cchealth.org.
Anyone who thinks they may have the illness should contact their health care provider.