Health Alert
PERTUSSIS OUTBREAK IN KENT COUNTY, DELAWARE

SUMMARY

DPH is investigating an outbreak of pertussis in the Amish population in Kent County, Delaware. As of June 20, 2018, three laboratory confirmed cases of pertussis, and several more cases epidemiologically linked to the lab-confirmed cases, have been identified.

DPH is asking physicians and other health care providers to consider pertussis when evaluating a patient with a new onset cough illness characterized by cough or cough with paroxysms, “whoop” sound, or post-tussive gagging/vomiting. Persons with a clinical picture compatible with pertussis should have samples sent for laboratory testing (see laboratory testing below).

Pertussis is a reportable disease in Delaware. Confirmed and suspected cases of pertussis should be reported to DPH. This will allow for appropriate DPH follow-up with patients, and the initiation of interventions to prevent further spread of the disease in the community.

Report known or suspected cases of pertussis promptly to the DPH Office of Infectious Disease Epidemiology at 302-744-4990, fax to (302) 223-1540, or email to reportdisease@delaware.gov.

BACKGROUND

Pertussis, or whooping cough, is a highly contagious communicable disease caused by the bacterium, Bordetella Pertussis. Pertussis is transmitted through air-borne droplets (coughing, sneezing) or direct contact with fluids or respiratory secretions of infected persons.

Pertussis is characterized by coughing paroxysms that are often followed by a characteristic “whoop” sound and/or post-tussive vomiting. Its incubation period is about 4 to 21 days (average 7 to 10 days). Illness onset is insidious with symptoms similar to those of a minor upper respiratory infection (catarrhal period). During the first 1 to 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 of any age, including teens and adults who were vaccinated only at a young age, although infants aged less than one year have the highest rates of complications.

The last outbreak of pertussis in Delaware occurred in early 2014, also among Kent County’s Amish population. More than 200 people were affected.

At this point, the outbreak does not yet appear to be widespread; however, the situation can change rapidly, and it is important that appropriate steps are taken to prevent further spread of the disease.

REPORTING

• Report suspect pertussis cases to DPH at 302-744-4990, fax to (302) 223-1540, or reportdisease@delaware.gov.

LABORATORY TESTING

• All suspected 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 should be obtained using a Dacron (not cotton) swab inserted slowly through the nostril to the posterior pharynx. Gently rotate swab for 10 seconds before withdrawing.
• Samples may be sent to the Delaware Public Health Laboratory (DPHL) for PCR or to commercial laboratories (i.e. Mayo, LabCorp, Quest) for PCR and culture.
• Detailed guidance on sample collection and transport of specimens is available at https://www.cdc.gov/pertussis/clinical/diagnostic-testing/index.html
• Testing performed at DPHL must be coordinated through the Office of Infectious Disease Epidemiology. Call 302-744-4990 or send report (email: reportdisease@delaware.gov or fax: 302-223-1540) prior to submitting samples to DPHL.
• Note that serology is not beneficial as a diagnostic tool for pertussis.
• Macrolide antibiotics (azithromycin, erythromycin) are the drugs of choice for treatment for persons with pertussis as well as for chemoprophylaxis for exposed persons.
• Exposure is defined as face-to-face contact, direct contact with respiratory, oral, or nasal secretions, or being in the same room or ward with a coughing pertussis patient.

For Additional Information

• CDC - Pertussis: http://www.cdc.gov/pertussis/
• Pertussis Diagnostic Testing: https://www.cdc.gov/pertussis/clinical/diagnostic-testing/index.html
• Pertussis Vaccination: https://www.cdc.gov/pertussis/vaccines.html
• Pertussis Frequently Asked Questions: https://www.cdc.gov/pertussis/about/faqs.html
• Postexposure Antimicrobial Prophylaxis: https://www.cdc.gov/pertussis/outbreaks/pep.html

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