With the death of the nine infants due to whooping cough in California this year, it has been signaled that the disease has made its comeback in the state.

Around 600 babies are suffering from severe stages of whooping cough and more than 4,100 have been detected with the same in the region. As per the health officials, this time, the outbreak is the worst since 1955.

California especially is the most vulnerable to pertussis, as there is no compulsory vaccination there and parents can deny having one. Also, people have a notion that whooping cough vaccination aggravates autistic conditions, thus they are keeping their children without immunization. In 2009, 13% parents refused to get their children vaccinated.

Not taking vaccine is not the only cause of increasing menace of the disease, as thought by many health experts because it can also suppress the vaccines.

Thomas Clark, a leading pertussis tracker at the Centers for Disease Control and Prevention in Atlanta said, "There's no such thing as being fully vaccinated against pertussis. Your immunity is always waning over time".

The disease starts with a common cold and turns into a severe respiratory infection that causes a ‘whoop’ sound in the patients’ cough.

Whooping cough took life of 14 and infected 17,000 in 2009, as reported by the CDC. For the nation, the worst year was 2005, when 25, 000 cases were reported and 39 got died of pertussis.