Health Update
PERTUSSIS OUTBREAK CONTINUES AMONG KENT COUNTY RESIDENTS

The Delaware Division of Public Health (DPH) is alerting the Delaware medical community about additional cases of Bordetella pertussis (whooping cough) identified among residents of Kent County Delaware.

Background:

Since October, we have received widespread reports of Pertussis in the Amish community, primarily in Western Kent County. DPH continues to receive reports of suspect Pertussis among the Amish community. To date, there are 19 laboratory confirmed cases and a large number of clinical cases.

Clinical Description:

The symptoms can be divided into three stages:

• The first stage, the catarrhal stage, is characterized by the insidious onset of coryza, sneezing, low -grade fever, and a mild, occasional cough, similar to the common cold. The cough gradually becomes more severe, and after 1-2 weeks, the second stage, begins.
• The second stage, the paroxysmal stage, the patient has bursts, or paroxysms of numerous, rapid coughs. At the end of the paroxysm, a long inspiratory effort is usually accompanied by a characteristic high-pitched whoop. During such an attack, the patient may become cyanotic. Vomiting and exhaustion commonly follow the episode. The paroxysmal stage usually lasts 1 to 6 weeks, but may persist for up to 10 weeks.
• In the third stage, the convalescent stage, recovery is gradual. The cough becomes less paroxysmal and disappears over 2 to 3 weeks.

Milder cases have occurred predominantly among vaccinated and previously infected individuals. Persons with mild cases lack a characteristic whoop and other classic symptoms. These mild cases often only exhibit a cough for >7 days duration. However, they are still considered infectious to others.

Incubation Period:

The incubation period is between 4 to 21 days, usually 7 to 10 days.

Mode of Transmission:

Primarily by direct contact with discharges from respiratory mucous membranes of infected persons by the airborne route, probably by droplets. The disease is frequently brought home by an older sibling and sometimes by a parent.

Period of Communicability:

The communicable stage extends from the early catarrhal stage to 3 weeks after onset of typical paroxysms in patients not treated with antibiotics. When treated with erythromycin, the period of infectiousness usually is 5 days or less after onset of therapy.

Diagnosis:

The diagnosis of pertussis is usually based upon a characteristic history and physical examination. However, laboratory diagnosis may be useful in young infants, atypical cases, and cases modified by vaccine:

There are a variety of diagnostic tests available for Pertussis. However, due to the rapid turnaround time of PCR testing, DPH is encouraging physicians that wish to test for Pertussis to collect nasopharyngeal swabs and send them to the Delaware Public Health Laboratory (DPHL) in Smyrna for PCR testing. Polymerase chain reaction (PCR) testing of nasopharyngeal swabs or aspirates has been found to be a rapid, sensitive and specific method for diagnosing pertussis.

Please call (302) 653-2870 to arrange for such testing.

Control of Patients, Contacts and the Immediate Environment:

Families are to call their physician to obtain treatment. Physicians are required by regulation to report confirmed or suspected pertussis to the DPH at 1-888-295-5156. In the event that cases and contacts do not have a primary care physician, please call 1-888-295-5156 for further information.

Isolation and Quarantine:

Respiratory isolation is required for known cases. Suspected cases should be removed from the presence of young children and infants, especially nonimmunized infants, until the patients have received at least 5 days of a minimum 14-day course of antibiotics. Suspected cases who do not receive antibiotics, should be isolated for 3 weeks. Suspect cases that develop symptoms during the 3 week isolation period should seek medical attention.

Inadequately immunized household contacts less than 7 years of age should be excluded from schools, daycare centers and public gatherings for 21 days after the last exposure, or until the cases and contacts have received 5 days of a minimum 14-day course of appropriate antibiotics.

Protection of Contacts:

Close contacts under 7 years of age who have not received 4 DtaP/DTP doses or have not received a DtaP/DTP dose within 3 years should be given a dose as soon after exposure as possible. However, this is not always possible within the Amish community.

A 14-day course of Erythromycin for household and other close contacts, is highly recommended, regardless of immunization status and age.

Treatment, Prophylaxis and Prevention:

Vaccination with DTP/DTaP remains the best method of prevention of Pertussis. All household and close contacts of persons with Pertussis should be prophylaxed with antibiotics regardless of age or immunization status as mentioned above.

Antibiotic Dosing for Treatment and Prevention:

DRUGS OF CHOICE:

• Erythromycin (drug of choice):
  • Child: 40 mg/kg/day PO divided into 4 doses/day for 10-14 days (maximum of 2 grams/day)
  • Adult: 500 mg PO 4 times/day for 10-14 days
• Erythromycin Ethylsuccinate (EES):
  • Child: <10 lbs 15-25mg/kg/q12h (10-14days)
  • Child: 10-15 lbs 100mg bid (10-14 days)
  • Child: 16-25 lbs 200mg bid (10-14 days)
  • Child: 26-50 lbs 400mg bid (10-14 days)
  • Child: 51-100 lbs 600mg bid (10-14 days)
  • Adult: >100 lbs 800mg bid (10-14 days)

ALTERNATIVE DRUGS:

• Trimethoprim-Sulfamethoxazole:
  • Child: 8mg TMP/ 40mg SMX/kg/day PO q12 hours for 10-14 days
    (Not recommended for use in pediatric patients less than 2 months of age.)
  • Adult: 160 mg TMP/ 800 mg SMX PO q12 hours for 10-14 days
• Azithromycin (alternate choice for erythromycin intolerant patients):
  • Child: >6 months 10 mg/kg/day single dose for 5-7 day
    (Not to exceed 500 mg/day)
  • Adult: >88lbs 500mg single dose/day for 5-7 days

For Further Information:

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

You can obtain additional information about Pertussis on the Centers for Disease Control and Prevention website at: www.cdc.gov/doc.do/id/0900f3ec80228696