As the number of reported whooping cough cases surpasses 18,000, U.S. health officials are bracing themselves for the worst outbreak of the disease in half a century.
Washington and Wisconsin have already declared a whooping cough epidemic, with each state reporting more than 3,000 cases of the highly contagious upper respiratory infection, also known as pertussis.
The Centers for Disease Control and Prevention have already received double the number of reports of cases from this time last year. Nine people have died after contracting pertussis in the last few years, a result of these increased outbreaks.
Health experts blame a growing trend in parents refusing vaccinations against pertussis and other contagious diseases such as measles, mumps, meningitis, hepatitis and chicken pox. The increased number of vaccinated tweens who are coming down with whooping cough point to the need for whooping cough boosters.
The U.S. groups of 10-, 13- and 14-year-olds who are experiencing a high illness rate had DTaP vaccinations, which were introduced in 1997 at the same time that the prior DTP vaccine was discontinued.
The earlier vaccine used whole cell parts made of killed pertussis bacteria, while DTaP uses only small acellular bacteria pieces, not the whole bacteria cell, said Donn Moyer, Washington state Health Department spokesman.
Whooping cough is particularly dangerous for infants under the age of one year, so the CDC is encouraging all adults, including pregnant women, to get a DTaP booster.
Initial symptoms of pertussis look like an especially harsh cold: fever, runny nose, sneezing, occasional cough. The second stage of the infection involves a fast, severe and mucus-y cough accompanied by the characteristic high-pitched whoop sound typically escalating at night.