Pertussis (Whooping Cough)

Pertussis is a highly contagious infection of the respiratory tract. It is caused by the bacterium Bordetella pertussis ( a gram-negative coccobacillus). Whooping cough gets its name from the whooping sound the child makes when trying to draw a breath after a coughing spell. The incubation period is thought to be 7-10 days (range 4-21 days). Pertussis is transmitted from person to person via aerosolized droplets produced from a cough or sneeze or by direct contact with secretions from the respiratory tract of infectious individuals. Individuals with pertussis are most infectious (contagious) during the catarrhal period when the person has symptoms similar to a head cold, and the first two weeks after the onset of the cough (i.e. approximately 21 days total). Some individuals, such as infants who remain culture-positive for several weeks, may be infectious for a longer period.

Children who are too young to be fully vaccinated and those who have not completed the primary vaccination series are at the highest risk for severe illness. Adolescents and adults become susceptible when immunity wanes. Compared with un-immunized children, adolescents and adults with pertussis are more likely to have a milder illness, i.e an illness that resembles an upper respiratory infection or an acute cough illness without paroxysms, whoop, or post-tussive vomiting.

Although pertussis is preventable, the incidence (new cases) has increased steadily since the 1980s. In the United States, 5,000-7,000 cases are reported each year. In 1996 there were 7,796 cases reported. Each year 5-10 children die from pertussis in the United States. Epidemics occur in the United States every 3-5 years. The most recent epidemic occurred in 1996.

There are three stages of illness. The first stage is catarrhal stage lasts for up to two weeks. The second stage is the paroxysmal stage and lasts for up to six weeks. The final stage is the convalescent stage and lasts for up to six to twelve weeks.

Employee and Family Information Sheet 


The onset of the illness is insidious, with symptoms similar to those of a minor upper respiratory infection or head cold. During the first two weeks a runny nose with an intermittent non-productive cough is common. This period is followed by episodes of paroxysmal coughing (severe coughing spells), whooping, and post-tussive vomiting. The paroxysmal coughing episodes frequently last for several weeks.

The disease peaks in severity after one or more weeks of paroxysmal coughing and begins to taper off with a convalescent period of 2-6 weeks that may last up to 3 months in some cases.

Major complications are most common among infants and young children. They include hypoxia, apnea, pneumonia, seizures, encephalopathy, and malnutrition. Most deaths occur among unvaccinated children or children too young to be vaccinated.


Infection Control is to be notified for both suspected and confirmed cases of pertussis at UC Davis Health. The patient will be put in isolation and on droplet precautions per health system policies and procedures. Patients are usually in isolation for the first 5 days of their antibiotic course. If it is suspected that an individual has pertussis, a nasopharayngeal swab or aspirate is collected and sent for culture. If pertussis is highly suspected, close and high risk contacts are identified and treated. If suspicion of pertussis is low (i.e. sporadic case, no epidemiological linkage to a confirmed pertussis case, no paroxysms, etc.) treatment may start after it is determined by the lab that the individual has a positive culture for pertussis.

The usual treatment for both cases and exposed individuals is a 14 day course of erythromycin. Other drugs are available if the person is allergic to erythromycin. Initiating treatment three or more weeks after the onset of cough has limited benefit to both the patient and contacts. However, treatment is recommended for up to six weeks after the onset of cough in late pregnancy.

Health care workers should be considered exposed and regarded as close contacts only if the source is a confirmed case or if the source is a suspected case during an outbreak. Close contact includes activities such as performing a physical examination, suctioning, intubation, bronchoscopy, feeding, bathing, or other procedures with close or prolonged interaction.

Work status

Health care workers with symptoms of pertussis will be excluded from working until they have had 5-7 days of antimicrobial treatment. Asymptomatic health care workers who have had close contact with a pertussis case will be given antibiotic prophylaxis; their work status shall be determined by Employee Health Services. Health care workers with symptoms of pertussis who cannot take or refuse to take antimicrobial therapy will be excluded from work for 21 days from the onset of cough.

If the employee is either exposed to pertussis at work, or becomes ill from a pertussis exposure at work he/she will be evaluated and treated by employee health. If the employee is exposed outside of work, his/her personal physician is responsible for evaluating and treating the employee; his/her work status will be determined by employee health.

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