A 2004 whooping cough outbreak at a Texas hospital has been traced back to a nurse who worked in the nursery at the time of the outbreak, according to the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report published June 6.

"The nurse lost her immunity," said Dr. Len Horovitz, an attending physician in the department of pulmonology at Lenox Hill Hospital in New York City. "It usually happens to adults over age 20 because they haven't had their booster in a while. Their last booster was probably in high school."

Health officials began investigating the outbreak after six infants were identified in the first half of June 2004 with symptoms consistent with whooping cough, also called pertussis, including cough, congestion, vomiting and shortness of breath.

Public health officials later found that a total of 11 infants, nine of whom had to be admitted to the hospital, had to be treated for whooping cough. Five infants ended up in intensive care units.

The infection was traced back to a nurse who was working in the newborn nursery at the time of the infants' births. She cared for 113 infants during this period. Both the nurse and her husband were diagnosed and treated for whooping cough.

The nurse had been vaccinated for pertussis as a youth. The CDC noted that because whooping cough is highly contagious all health-care workers and adults who work with children should be vaccinated as adults as well.

Fortunately, all of the infants recovered.

"If everyone gets their immunizations up to date... we can eliminate pertussis just like we’ve eliminated polio, diphtheria and tetanus," said Horovitz.

"Once you have your immunity back, you don't carry or get the disease," he concluded.

The Centers for Disease Control and Prevention (CDC) recommends a combined tetanus, diphtheria and pertussiss (Tdap) vaccine for adults 19 to 64 who were administered their last tetanus vaccine more than 10 years ago.

Click here to see the CDC report.