Whooping cough is making a comeback. The Centers for Disease Control and Prevention reported 41,000 cases last year in the United States, the highest level in decades. One reason for these numbers could be that immunity from the vaccine diminishes each year after the fifth dose is given to children around four to six years of age, according to a recent study.
Other factors in this increase include a true increase in whooping cough, increased recognition and reporting by physicians, and improved lab tests to identify the disease.
We asked blog contributor Stephen C. Aronoff, M.D., M.B.A., from Temple University Hospital and a specialist in pediatric infectious diseases, to tell us more about whooping cough and the best ways to protect our children from it.
What is whooping cough?
Whooping cough is a respiratory disease caused by a bacteria called Bordetella pertussis. After infancy, individuals infected with B. pertussis develop a cold-like illness without fever and a cough that can last from weeks to months. Unlike a typical upper respiratory infection, patients with pertussis develop extended sudden attacks of a cough characterized by a loud, inspiratory whoop at the conclusion of the coughing jag.
Pertussis is a serious disease among infants less than six months of age who are not fully immunized and particularly among premature infants. In these children, the disease can be complicated by periods when breathing stops (apnea), pneumonia, seizures, and behavior changes. Death can occur in very rare cases. The
CDC reported 18 pertussis-related deaths during 2012 with the majority of deaths occurring in infants younger than three months of age.
Is there a treatment for whooping cough?
Not really. Outside of infancy, the disease runs its natural course and any complications that may occur, such as rib fractures or pneumonia, are treated as they occur. Young infants who are infected are usually evaluated and monitored in the hospital. Close monitoring and respiratory support are used as needed.
Azithromycin, an antibiotic, is often given to patients with whooping cough. Unfortunately, this drug does not affect the duration or the intensity of the disease. Azithromycin eliminates the bacteria from respiratory secretions, decreasing the risk of spread of the disease by cough. This is important in families and situations where infected individuals may come in contact with infants under six months of age who are not fully immunized.
Can whooping cough be prevented?
Yes. Vaccination for whooping cough is part of the recommended vaccination package for infants. The initial series consists of 3 vaccinations given at 2, 4, and 6 months of age; boosters are given at 18 months of age, between 4 and 6 years of age, between 11 and 12 years of age and every 10 years thereafter. The vaccine is very effective at preventing the disease.
If there is an effective vaccine then why has there been such a large increase in pertussis cases?
Before effective vaccination, large outbreaks of pertussis occurred every three to five years and average case numbers ranged from 175,000 to 250,000 cases per year during epidemics. The original vaccine, introduced in the late 1940’s, consisted of bacteria that were grown in culture and then killed. This whole cell vaccine, in use until the early 1990’s, reduced the annual number of cases of whooping cough to less than 15,000. Unfortunately, this vaccine was associated with a number of side effects, which were ultimately disproven, and acceptance of the vaccine by parents decreased in the 1980’s and 1990’s.
To address this issue, an acellular vaccine was developed, introduced in the mid 1990’s, and remains in current use. Unlike the original vaccine, the acellular vaccine only contains proteins that have been inactivated in much the same way that the proteins in tetanus and diphtheria vaccine are no longer active. Studies with this vaccine have shown that vaccinated infants develop a level of protection similar to the whole cell vaccine, but without all of the side effects.
In 2010, a large outbreak of pertussis began in California. As part of the investigation of this outbreak, the immune status of 277 children between four and 12 years of age was compared to similarly aged children without pertussis. The investigators found that immunity after the fifth booster, usually given between four and six years of age, waned quickly over the next five years. These findings were confirmed in a second study of children in Minnesota and Oregon and suggest that a significant number of children lose protection prior to the acellular vaccine booster given between 11 and 12 years of age.
So what can I do to ensure my child is protected against pertussis?
The best protection against pertussis remains vaccination. Your child’s primary healthcare provider is familiar with the updated vaccination recommendations of the American Academy of Pediatrics and the Advisory Committee on Immunization Practices of the CDC. While the number of cases associated with pertussis outbreaks has increased, the overall rate of disease is still 10 fold less than the reported rates from the prevaccine era.
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