The bacteria Bordetella pertussis causes pertussis, a respiratory illness lasting several weeks and characterized by severe episodes of cough.
What is going on in the body?
Pertussis is spread from person to person through respiratory secretions. The time from exposure to pertussis until symptoms begin is usually 1 to 2 weeks.
The disease begins with mild common cold-like symptoms, but can progress to severe episodes of coughing. In young children, the episodes of coughing may be followed by a characteristic whooping sound when breathing in. Patients will sometimes vomit after a coughing episode.
The disease is most severe in young infants. It can be associated with long periods without breathing (apnea), or respiratory arrest.
The main symptom in older children and adults is often a persistent, hacking cough that lasts a few weeks to months. Some call it the "One Hundred Day Cough."
The disease has become much less common with routine use of the pertussis vaccine over the past 60 years.
What are the causes and risks of the infection?
Bordetella pertussis causes pertussis. The disease is highly contagious by the inhalation of droplets and aerosols, especially from a person with a cough.
Though some immunity results from one episode of the disease, the protection wanes over time so that a person may become susceptible again. For the same reason, adults who were immunized as children are susceptible.
What can be done to prevent the infection?
The pertussis vaccine provides protection against pertussis illness for several years following vaccination. Immunization does not necessarily prevent a person from carrying the bacteria, however.
The pertussis vaccine is given in combination with diphtheria and tetanus toxoids in a shot called "DTaP" for children, or "Tdap" for adolescents and adults. Tdap was recently approved to replace next due the tetanus-diphtheria booster in adults under age 65.
Common side effects of the vaccine are fever and redness, swelling, and pain at the site of the injection. These side effects are less common with the current vaccine (made of specific bacterial parts) than with the older vaccine (made of whole killed bacteria.) Rare side effects include an allergic reaction and febrile seizures.
A person in close contact with an individual with pertussis should take antibiotics to prevent the disease. This is true even for persons who have been vaccinated, because the vaccine is not 100% effective.
How is the infection diagnosed?
Bordetella pertussis can be cultured from a sample of mucus taken with a thin swab from the back of the nasal cavity. It usually takes about 2 weeks to obtain a culture result. In addition, special antibody stains can be used to detect the organism in 1 to 2 days. Laboratory diagnosis is less reliable than that for most other respiratory diseases.
Long Term Effects
What are the long-term effects of the infection?
For several months following pertussis illness, even a mild upper respiratory infection, such as a cold, can cause prolonged coughing spells.
What are the risks to others?
Pertussis can be spread to those who have not been immunized, through respiratory secretions of an infected person. Those with cough illnesses should avoid contact with young infants.
Erythromycin may be prescribed for family members of a person with pertussis, particularly those under 2 years old.
It is especially important for adults who care for infants to receive the Tdap booster vaccine. Because the infants are too young to be vaccinated themselves, they can be protected by this "cocooning" strategy.
What are the treatments for the infection?
Erythromycin, an antibiotic, is given to treat the infection. Other antibiotics used for pertussis include azithromycin (i.e., Zithromax, Zmax) or clarithromycin (i.e., Biaxin). Penicillins and cephalosporins are not effective.
Antibiotics, if given very early in the course of the disease, may reduce the symptoms. If given later, it has no effect on the disease, but it will decrease the risk of spreading the infection to others.
What are the side effects of the treatments?
The most common side effects of erythromycin are abdominal cramping, nausea, vomiting, and diarrhea.
What happens after treatment for the infection?
As the person recovers from pertussis, the coughing and vomiting gradually subside.
How is the infection monitored?
Once pertussis has subsided, a person should no longer need monitoring. A person who has had pertussis may find him- or herself more susceptible to respiratory infections for a few months.