More than 21,000 in U.S. caught whooping cough in 2010

According to U.S. health officials, over 21,000 people in the United States were infected with whooping cough in 2010, which represents the highest number of cases since 2005.

Most of the cases of infection were in children and teens, Third Age reports.

Health officials are confused by the increase in cases, especially since the whooping cough vaccine appears to be highly effective in children, according to Third Age.

Whooping cough, also known as pertussis, starts out with cold-like symptoms but leads to intense coughing fits that can occur sporadically for weeks. Whooping cough led to at least 26 deaths in the United States last year.
Contagious adolescents can be a threat to vulnerable infants, because while 95 percent of children have had at least three shots against whooping cough, whooping cough vaccines for adults and adolescents were not licensed until 2005. As a result, vaccination rates for these groups are much lower - one study even had adults pegged as low as a six percent immunization rate against pertussis, Third Age reports.

It is recommended that all adults who are around infants receive the whooping cough vaccine.

Worldwide, there are 30 to 50 million cases of pertussis with around 300,000 deaths every year, the Centers for Disease Control reports. The disease can be life-threatening for infants. Over 50 percent of infants under one year of age who get the disease must be hospitalized.