California health officials have raised concern over the whooping cough outbreak in the state, which so far has claimed as many as 10 lives of infants.

The tenth baby who lost to the disease was just 6 weeks old and was born prematurely. The baby died last week after undergoing treatment at Rady Children's Hospital in San Diego.

So far this year, over 5,270 cases of whooping cough have already been reported in California. The previous record was set in the year 1955, when as many as 4,949 cases of this highly-contagious disease were reported.

As per the health officials, all the infants who have died were too young and their immune system was not that strong to fight the disease.

In the year 2005, around 3,182 cases were reported in California, which included 574 hospitalisations and seven deaths.

Health officials also warn that children by the time they reach middle school are once again susceptible to this disease.

Dr. Jennifer Ashton told CBS News that children between the age group of 11 and 18 and those who remain in close contact with babies should receive the booster dose of the vaccine.

Dr. Ashton further said, "The vaccines you and I got really only cover us for five years. Again, if you or I get sick, not a big deal. If we pass it to a newborn, it could be deadly".