Whooping cough is an infectious respiratory illness caused by the Bordetella pertussis bacteria. The infection is spread through contact with contaminated respiratory droplets. Initially, symptoms are vague and may be mistaken as a cold or respiratory illness. Signs include low-grade fever, weakness, runny nose, eye tearing and cough. After one to two weeks, patients develop severe bouts of coughing followed by a characteristic "whooping" sound when inhaling. This stage of the disease lasts up to six weeks. During the final phase, symptoms slowly subside. However, the cough often persists for weeks.

In some cases, pertussis can be a serious infection. Patients may experience pneumonia, dehydration, weight loss, sleep problems, seizures, brain damage or death. Young infants who contract pertussis are especially at risk for secondary bacterial pneumonia, which can be fatal.

Today, children are vaccinated against pertussis as part of their routine immunizations. However, research shows immunity wears off after about 5 to 10 years. Health experts say about 50 percent of American adults have no immunity to pertussis. Thus, the number of infections is rising. According to the National Foundation for Infectious Diseases, more than 20,000 cases of pertussis were reported in the U.S. in 2005. But experts believe a majority of cases go unrecognized or unreported and the true incidence may be as high as one million cases a year.

In response to the problem, the FDA has approved two new vaccines for pertussis to be given as booster doses. BOOSTRIX® is approved as a booster for children 10 to 18. ADACEL™ is approved as a booster for people 11-64. Both are combination vaccines that are similar to the DTaP (diphtheria/tetanus/acellular pertussis) vaccine given to infants. However, the booster vaccines contain lower doses of the diphtheria and pertussis components. The National Foundation for Infectious Diseases has a campaign, called Wipe Out the Whoop, to educate the public on the importance of getting all family members properly vaccinated from pertussis.

Protecting Health Care Workers

Health care personnel who are directly involved in the care of sick children are at high risk for contracting pertussis. Early signs of infection are vague and may be dismissed as a respiratory illness. By the time a child develops the characteristic "whooping" cough sound, he/she may have already passed on the infection to caregivers.

Tom Talbot, M.D., M.P.H., an Assistant Professor of Medicine at Vanderbilt University Medical Center, says the standard intervention is to provide antibiotics to all healthcare workers who have been directly involved in the child's care. But the antibiotics are potent and can cause gastrointestinal illness themselves. Health care experts also worry that overuse of antibiotics could lead to the development of strains of diseases that are resistant to treatment.

The Centers for Disease Control and Prevention and the National Foundation for Infectious Diseases currently recommend all healthcare workers receive a pertussis booster in place of the traditional tetanus-booster. But doctors aren't sure if people who have been vaccinated still need to get antibiotics.

Researchers at Vanderbilt want to find out if vaccinated workers really need antibiotics after exposure to pertussis. Roughly 1,000 healthcare workers will receive the pertussis booster. The workers will be closely followed. Those that are exposed to pertussis will be randomly divided into two groups. Only one group will get antibiotics. Investigators will then study the rates of infection among the two groups.

For general information on whooping cough (pertussis):

Centers for Disease Control and Prevention, National Immunization Program

National Foundation for Infectious Diseases