Health Alert
PERTUSSIS CLUSTER IN KENT COUNTY DELAWARE

The Delaware Division of Public Health (DPH) is issuing this health alert to inform the medical community of a cluster of pertussis (whooping cough) cases in western Kent County, Delaware.

Summary

DPH is investigating both confirmed and suspected cases of pertussis in western Kent County, particularly among persons in the Amish community. DPH is asking physicians and other health care providers to consider pertussis when evaluating a patient with an acute cough illness characterized by cough or cough with paroxysms, “whoop,” or post-tussive gagging/vomiting. Diagnosis of suspect pertussis should be verified with laboratory testing following the guidelines in the “Recommendations” section below. This will allow appropriate DPH follow-up of patients and the initiation of interventions to prevent further spread of the disease.

Pertussis is rapidly reportable in Delaware under the Regulations for Control of Communicable and other Disease Conditions. Report known or suspected cases of pertussis promptly to the DPH Office of Infectious Disease Epidemiology at 1-888-295-5156 or fax to (302) 223-1540.

Background

Pertussis, or whooping cough, is a highly communicable infectious disease caused by the bacterium, Bordetella Pertussis.Pertussis is characterized by coughing paroxysms that are often followed by a characteristic “whoop” sound and/or post-tussive vomiting. The incubation period is about 7-10 days (with a possible range of 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 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.

In 2004-2005, Delaware experienced a significant pertussis outbreak. While at this point, it does not appear that this outbreak is of the same magnitude, this situation can change rapidly and it is important that appropriate steps are taken to prevent further dissemination. A summary of the 2004/05 outbreak is available at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5530a1.htm

Recommendations/Reporting

• Report suspect pertussis cases to DPH at 1-888-295-5156 or fax to (302) 223-1540.
• 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 Delaware Public Health Laboratory (DPHL) for PCR or to commercial laboratories (i.e. Mayo, LabCorp, Quest) for PCR and culture. Follow the lab’s respective guidelines for collection and transport of the specimens.
• Testing performed at DPHL must be coordinated through the Office of Infectious Disease Epidemiology. Call 1-888-295-5156 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.
• Because protective efficacy of pertussis immunization wanes over time, the great majority of teenagers and adults are susceptible to pertussis even if immunized in early childhood. Immunization should be considered for household or close contacts, especially for those who have not been or are under-immunized.
• Refer to CDC’s pertussis pages for guidance regarding who to provide prophylaxis to as well as drug dosages and duration of treatment http://www.cdc.gov/pertussis/

For Additional Information

• DPH, Office of Infectious Disease Epidemiology at 1-888-295-5156. An epidemiologist is available 24/7.
• CDC - Pertussis: http://www.cdc.gov/pertussis/
• http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5530a1.htm

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