Newborns are at greatest risk for becoming infected with the bacterium that has sickened nearly 2,200 people in Texas this year, and the count continues to rise. These are just the confirmed cases. Some estimates are that for every laboratory-confirmed case, 5 to 10 additional cases exist.
Two Texas infants have died from pertussis so far this year. While the death toll may seem small, the opposite can be said for hospitalizations of infected babies. Officials from the Texas Department of State Health Services say the current whooping cough outbreak is on track to be the worst in more than 50 years in that state. Likewise, in 2012, the CDC reported pertussis cases nationwide were the highest in 50 years.
Certain diseases have herd immunity. Chicken pox, for example is now uncommon because children have immunity through vaccination; older adults have immunity because they had the disease. But when vaccination rates wane or when immunity from vaccination dwindles, herd immunity breaks down.
Pertussis does not have herd immunity. It is just so common, said Allen County Commissioner of Health Dr. Deborah McMahan.
In Texas, some of the blame for the outbreak could be due to the state's lax rules on childhood immunizations. Texas parents need only state for personal reasons they don't want their children vaccinated. Their babies, children and adolescents can freely go to daycare, preschool and school unimmunized.
But immunization rules aside, multiple studies show adult family members are the most common source of spread of whooping cough to infants, who do not receive their first pertussis vaccination in the 5-shot series until 2 months of age.
Even for the infant who has started the series but who hasn't completed it, they are especially at risk, McMahan said. According to the CDC, 90 percent of pertussis deaths occur among infants 1 and under, with parents the No. 1 source of infection.
Researchers at the University of North Carolina-Chapel Hill's School of Public Health studied primary sources of infection among children with pertussis from four countries, including the United States. Parents were the source in 55 percent of cases, siblings the source in 16 percent of cases, aunts or uncles in 10 percent, grandparents in 6 percent, and cousins, close family friends and non-family caregivers the source in the remainder.
As adults we may not even realize we have whooping cough, which has been coined the 100-day cough. The hallmark whooping sound is not evident. The nagging cough is often chalked up to on-going bronchitis or chronic allergies.
Alarmingly, you spread it before you get the cough. You don't feel bad when you're in the incubation period, McMahan said.
Pertussis vaccine is given in a combination shot with diphtheria and tetanus vaccine. Infants and young children should receive the DTaP at 2 months, 4 months, 6 months, between 15 and 18 months of age, and then again between ages 4 and 6. Children ages 11 to 18 who have completed the early childhood series should get a booster. The vaccines contain inactivated forms of the bacteria toxins.
Inactivated means the substance no longer produces disease but does trigger the body to create antibodies that give it immunity against the toxins.
The CDC's Advisory Committee on Immunization Practices (ACIP) recommends all adults, ages 19 to 64, have one booster vaccination of Tdap, the combo vaccine used in older children and adults. Adults 65 and older who have or anticipate close contact with infants under age 1 should also receive a single dose of Tdap. ACIP updates note the vaccine is safe for any adult of any age.
The newest recommendations from ACIP are that pregnant women get a Tdap booster between 27 and 36 weeks gestation, though it can be given at any time during the pregnancy. The Tdap booster should be repeated during every pregnancy.
By giving the pregnant mother the vaccine, she will generate antibodies and pass the antibodies on to the baby, McMahan explained. This passive antibody transfer will help protect the baby during those vulnerable early months of life before the initial series of shots is completed.
Allen County pertussis cases have declined in recent years, from 35 in 2009 to 2012, with no pertussis deaths in those years. That's the good news. But Franklin County in neighboring Ohio had a major outbreak in 2011. Prevention is easy. Have all infants and children immunized and every adult get a booster shoot. None of us has an excuse for putting a vulnerable infant or any child or adult at risk.
To learn moreFor more information on pertussis and vaccination recommendations, visit:
U.S. pertussis cases
Vaccine to prevent pertussis first became available in the mid- to late 1940s. Prior to that time, between 100,000 and 300,000 U.S. cases of pertussis, or whooping cough, were reported each year.
*2012 data is preliminary.