Infectious Disease Epidemiology

ADHS receives about 200-300 reports of pertussis per year. In 2005 Arizona had a state-wide outbreak of the disease, with 928 cases reported for the year. The state-wide outbreak was declared over on October 11, 2005; Pima and Coconino Counties remained in outbreak status into 2006.

What is pertussis?

Pertussis is a highly contagious bacterial infection that is vaccine-preventable. Coughing is the primary symptom of pertussis; fever is not present or is minimal throughout the course of illness. The cough of a patient with pertussis may begin as a mild cough and progress to attacks (paroxysms) of coughing, accompanied by gagging and/or vomiting. Some persons with pertussis make a "whoop" sound when they breath in after coughing.

Who can get pertussis?

Pertussis may affect anyone regardless of their age and vaccination status. It is most common in unimmunized or inadequately immunized persons (who typically experience more severe disease) and persons with waning immunity (protection from the vaccine lasts 5-10 years from the last dose).

How is pertussis spread?

Pertussis is spread through close contact with droplets from the mouth and nose of an infected person. Spread can happen when the infected person coughs, sneezes, or talks.

What are they symptoms of pertussis?

The initial symptoms of pertussis are similar to a mild cold and include runny nose and mild cough. The illness then progresses to episodes of severe coughing spasms. These episodes may ultimately last for several months duration and tend to be worse at night. Vomiting may occur after coughing episodes. The person with pertussis may look and feel healthy between coughing episodes. Immunized children, adolescents, and adults may have milder symptoms than unimmunized persons.

How soon after infection do symptoms appear?

Symptoms may appear between 7 - 10 days after exposure to an infected person (range 4-21 days). Rarely, this period may be as long as 42 days.

How long can someone spread pertussis?

A person with pertussis is considered infectious for 21 days after the onset of cough. Treatment with an appropriate antibiotic will shorten the infectious period to 5 days after the initiation of treatment if started early in the course of illness.

Can you catch pertussis more than once?

Immunity acquired from past infection may wane over time. However, some experts believe that immunity acquired from natural pertussis disease is lifelong.

What are the complications associated with pertussis?

Complications of pertussis include pneumonia, seizures, middle ear infection, dehydration, encephalopathy/brain damage, and death.

Infants are at highest risk of complications due to pertussis. Serious complications are less likely in older children, adolescents and adults but may occur.

Is there a vaccine for pertussis?

There are two vaccines for pertussis, one given as part of the childhood immunization schedule (DTaP [PDF 43K]) and one recently licensed for use in adolescents and adults (Tdap [PDF 59K]). Both of these pertussis vaccines are given in combination with diphtheria and tetanus.

What can be done to prevent the spread of pertussis?

The cornerstone of pertussis prevention is immunization. Before age 7 and preferably at school entry, children should have received 5 doses of DTaP vaccine. Adolescents and adults in need of Td should receive TdaP in its place, and any adults who have close contact with an infant less than one year of age should receive Tdap.

Persons with pertussis should stay home and avoid close contact with others until completion of 5 days of a prescribed course of antibiotic treatment.

Persons with any coughing illness (or other contagious illness) should avoid contact with infants and expectant mothers.

Handwashing may prevent the spread of all infectious diseases, including pertussis.

Caretakers of infants should take measures to limit the spread of contagious diseases, including pertussis, to infants in their care.

References:

CDC's Guidelines for Control of Pertussis Outbreaks
Pertussis Fact Sheet, Seattle/King County
Pertussis Fact Sheet, WA DOH
Pediatric Red Book
Chin's Control of Communicable Diseases

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