Health Update
BORDETELLA PERTUSSIS: PUBLIC HEALTH SURVEILLANCE,
LABORATORY TESTING AND DIAGNOSIS

The Delaware Division of Public Health (DPH) is providing the following information to the medical community concerning Pertussis in Delaware.

Disease Description

Pertussis, or whooping cough, is a highly communicable infectious disease caused by the bacterium, Bordetella pertussis. Pertussis is characterized by coughing paroxysms that are continuous without inspiration until the end and are often followed by the characteristic whoop and/or post-tussive vomiting. The incubation period is about 7-10 days (range 4-21 days). Illness onset is insidious, with symptoms similar to those of a minor respiratory infection (catarrhal period). During the first 1-2 weeks of illness, coryza with an intermittent non-productive cough is common; this period is followed by episodes of paroxysmal coughing which frequently last for several weeks (paroxysmal period). Pertussis may occur among persons at any age regardless of vaccination status and may be relatively common among adolescents and adults, although infants aged less than one year have the highest rates of reported disease.

Public Health Surveillance

Pertussis is rapidly reportable in Delaware under the Regulations for Control of Communicable and other Disease Conditions. DPH receives reports from commercial and hospital laboratories, individual practitioners, hospitals, etc.

Due to the communicability of the organism, DPH, Bureau of Epidemiology investigates every case that is reported.

This investigation consists of:

  • Verifying diagnosis;
  • Establishing infection control mechanisms to prevent further transmission;
  • Documenting effective treatment; and
  • Enhancing surveillance in institutions, communities or families to identify additional cases.

The Bureau of Epidemiology is receiving an increasing amount of calls and reports for pertussis. Most of these reports are based on a clinical diagnosis without any laboratory confirmation or a diagnosis based upon laboratory serology only. When such reports are received, DPH is unable to properly or effectively investigate these cases without proper laboratory testing and subsequent diagnosis. This is of special concern when a hospitalized patient, healthcare worker, daycare or school are involved and infection control measures are not able to be implemented due to a lack of proper laboratory confirmation.

DPH is asking for your assistance in obtaining proper laboratory tests for suspect pertussis cases. Making a specific diagnosis of pertussis in patients with clinical evidence of infection is one of the many challenges presented by Bordetella pertussis.

Thus far in 2006, DPH has received reports of approximately 17 pertussis cases. Of those, DPH was only able to confirm and provide appropriate follow-up for 3 cases. The remaining 14 cases were diagnosed clinically or had only serology testing performed.

Laboratory Testing and Diagnosis

  • Culture is the "gold standard" for laboratory confirmation and must be collected before treatment is initiated.
  • Due to the length of time to grow a culture, polymerase chain reaction (PCR) can be performed simultaneously on the same biologic samples as cultures. This allows for a quicker turn around time while waiting for the culture to grow. PCR can also be performed in the absence of a culture as a confirmatory diagnostic tool.
  • Serology is not beneficial as a diagnostic tool for pertussis due to the necessity of collecting acute and convalescent specimens. Because of the insidious onset of pertussis, patients or their caregivers often delay seeking medical care and an acute serum cannot be obtained.
    • All suspect cases of pertussis should have a nasopharyngeal (NP) aspirate or swab obtained for culture and/or PCR from the posterior nasopharynx. (Throat and anterior nasal swabs have unacceptably low rates of recovery of B. pertussis)
    • NP specimens are obtained using a Dacron (not cotton) swab inserted slowly through the nostril to the posterior pharynx. Ideally, the swab is gently rotated for 10 seconds before withdrawing.
    • When planning to order a culture AND PCR, insert both swabs simultaneously. The PCR swab goes back into the sterile container and does not require any transport media. The culture swab is placed in Regan-Lowe transport media.
    • Commercial laboratories (i.e. Mayo, LabCorp, Quest) can perform PCR and culture. Please follow their respective guidelines for collection and transport of the specimens.
    • Delaware Public Health Laboratory (DPHL) can perform PCR. DPHL does not perform B. pertussis culture. Testing performed at DPHL must be coordinated through the Bureau of Epidemiology (302-744-4541 OR 888-295-5156).

For Additional Information

Please contact DPH, Bureau of Epidemiology at 302-744-4541 OR 1-888-295-5156. The number is available during normal business hours and during non-business hours for emergencies.

Further information from CDC regarding Pertussis can be found at: http://www.cdc.gov/ncidod/diseases/submenus/sub_pertussis.htm

Categories of Health Alert messages:

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  • Health Advisory: Provides important information for a specific incident or situation; may not require immediate action.
  • Health Update: Provides updated information regarding an incident or situation; unlikely to require immediate action.
  • Health Information: Provides general health information which is not considered to be of an emergent nature.

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