Whooping cough could reach its highest level in more than 50 years.
As of July, nearly 18,000 cases have been reported, more than twice as many as at this time last year, the Centers for Disease Control and Prevention reports. At this pace, the number of whooping cough cases will surpass every year since 1959.
Public health officials are concerned that the surge might be due in part to a switch in vaccines 15 years ago. The change was based in part on now-discredited concerns about the dangers of the older vaccine.
"We may need to go back to 1959 to find as many cases reported" halfway through the year, said Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases.
Whooping cough, called pertussis by doctors, is a highly contagious bacterial disease and very dangerous to infants and young children. Half of babies who get it are hospitalized, Schuchat said.
The disease leads to severe coughing that causes children to make a distinctive whooping sound as they gasp for breath. In rare cases, it can be fatal. Nine children have died this year.
Before the introduction of a vaccine in the 1940s, whooping cough sickened as many as 200,000 people a year in the USA, killing up to 10,000. Cases, which tend to come in waves and peak every three to five years, declined to a historic low of 1,010 in 1976.
Though 95% of toddlers are vaccinated, only 8.2% of adults are, and they are the ones most likely to infect babies, Schuchat said.
The highest rates of infection are in babies younger than 12 months old, and half of the cases are in those younger than 3 months.
Babies are too young to be protected by the first vaccination, usually given at 2 months, so vaccinating their mothers and the people around them is key to protecting them.
Washington state is in the midst of a major whooping cough outbreak. "As of the end of last week, we've had more than 3,000 cases," said Mary Selecky, secretary of the state Department of Health. "My biggest concern is for the babies."
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