Protocol stems spread of nosocomial pertussis

Exposed, asymptomatic workers can be contagious

Nosocomial pertussis infections appear to be making a resurgence. Multiple outbreaks of the highly contagious disease have been widely reported, including a 1993 episode at a pediatric hospital during which 87 employees contracted pertussis.

Increased spread of the disease, say experts, has been facilitated by several factors, including waning immunity among vaccinated adults and adolescents; failure of hospital employees to recognize the early symptoms of pertussis, especially in adults (which may not include coughing); and delays in treating and isolating infected individuals and employees or patients who have been exposed to the disease.

Though the disease does not pose a serious threat to adults, it can be life-threatening to infants and young children. The World Health Organiza tion estimates that in 1994 there were 40 million cases of pertussis worldwide, and 360,000 children died of the disease.¹

"Many physicians are not familiar with the manifestations of pertussis, especially in adults. Hence, the diagnosis frequently is missed, leading to failure to institute proper isolation and therapy," according to one expert.²

"In the U.S., reports of pertussis have increased since 1988, and we know that immunity is declining. But we don’t know how big the problem is," says Donna J. Haiduven, BSN, MSN, CIC, PhD-C, infection control supervisor at the Santa Clara Valley Medical Center in San Jose, CA, a 600-bed teaching facility affiliated with Stanford University Medical School. Adding to the threat of nosocomial transmission, Haiduven continues, are atypical presentation of the disease, infection from symptomatic adults with undiagnosed disease, diagnostic errors or delays, and poor compliance with childhood vaccination schedules.

At Santa Clara Valley, 49 pertussis exposures originating in the emergency department or the pediatric unit were recorded between July 1, 1989, and June 30, 1997. The facility responded by establishing guidelines to manage pertussis exposures among patients and employees. "Our goal was to create a standardized, practical protocol to protect visitors, patients, and employees," Haiduven says. "We believe the protocol has been effective." Haiduven says she believes that every time the pertussis protocol was used at Santa Clara Valley, no secondary transmission occurred.

The protocol defines an exposure as an unmasked direct contact with respiratory secretions or large aerosol droplet inhalation from infected persons. When an exposure is suspected, the hospital infection control department guides its response by a standardized checklist, which lists the following sequence of steps, according to Haiduven:

1. Verify the diagnosis.

2. Isolate the patient and send the exposed employee home.

3. Restrict infected visitors from the hospital.

4. Determine the length of the potential contagious period.

5. Interview infected staff members and/or conduct a chart review of the infected patient.

6. Determine which other departments or patients are at risk for exposure.

7. Notify the Employee Health Service, the Emergency Department, the laboratory, and the public health department of the exposure.

8. Prepare and distribute appropriate memoranda.

9. Arrange isolation guidelines and dates for the index case and any exposed patients.

10. Collect information from Employee Health Services and the Emergency Department on treated employees and/or those who refuse treatment.

11. Check the census daily for discharged exposed patients during the potentially contagious period.

12. Complete an exposure summary.

Patients who have a suspected or diagnosed case of pertussis are placed on droplet precautions until a diagnosis is either confirmed or ruled out or until they have been on effective drug therapy for five days. Patients who receive no drug therapy are isolated for 21 days after the onset of illness if they are still in the hospital, according to Haiduven.

Once an employee exposure to a patient with a diagnosed or suspected case of pertussis has been verified, the department manager where the exposure occurred posts a contact list to be signed by all employees who have had direct contact with an infected patient or exposed employee. All employees on the list must report to Employee Health Services. A chart review is also conducted to determine if personnel from other departments might have been in contact with the infected patient. (See CDC guidelines for employee exposures to pertussis, p. 107.)

Exposed, asymptomatic employees who wish to continue their duties can choose from two options. One requires the employee to complete five full days of effective chemoprophylaxis. If all five days of chemoprophylaxis are completed before the first possible communicable day (namely, seven days after the first day of exposure to a case of pertussis), then no further action is required. Otherwise, the employee must wear a mask when caring for children under the age of four.

Under the second option, an asymptomatic exposed employee who wishes not to take prophylactic medications but who wants to continue working must wear a mask during the entire comnmunicable period of the disease — from seven days after the first possible date of exposure to 14 days after the last possible date. Haiduven explains that the mask must be worn at all times while in the hospital and changed at least every hour or when the mask becomes moist. With either option, if an employee becomes symptomatic, he or she is sent home.

There is a standardized form for each of the two courses of action. The exposed employee must sign the appropriate one, thereby agreeing to adhere to the required postexposure protocol.

The policy for asymptomatic exposed employees who choose not to receive chemoprophylaxis is more conservative than the guidelines promulgated by the Centers for Disease Control and Prevention, which do not place any restrictions upon employees who have been exposed to pertussis but are asymptomatic. But Haiduven notes that asymptomatic exposed employees can be contagious when the catarrhal phase of the disease begins, before coughing starts.

"A lot of people may not attribute catarrhal symptoms to pertussis. If those employees continue to practice [without precautions], they might be spreading the illness before they even get a cough," she says. "We handle all employees as if they might develop pertussis, and we don’t rely on employees to notice possible early pertussis symptoms in themselves."

This conservative approach, Haiduven says, has greater potential to prevent additional exposures. "Some people may not agree with it, but we feel it cuts down on the number of exposures before coughing starts. It’s an additional protection for an employee receiving prophylactic treatment."

In the event of a pertussis outbreak, the existing protocol would stand and possibly be augmented by mandating widespread masking of employees until the threat of disease transmission has passed.

Erythromycin is the only FDA-approved drug for postexposure pertussis prophylaxis, though the newer macrolide-class drugs clarithromycin and azithromycin are often better-tolerated by recipients, according to Haiduven. For people who are allergic to macrolides, an alternative is the drug trimethoprim-sulfamethoxazole.

The hospital also has a protocol that covers visiting children. Children visiting the hospital must be screened for communicable diseases, including pertussis. If they display certain symptoms or haven’t had all necessary vaccinations (varicella, measles, pertussis, rubella); if they have been exposed to any other child with a communicable disease within the past three weeks; or if they have had disease symptoms within the last 48 hours, such as any evidence of ear drainage, rash, red runny eyes, or a runny nose, they are denied visitation rights.

References

1. Ivanoff B, Roberson SE. Pertussis: A worldwide problem. Dev Biol Stand 1997; 89:3-13.

2. Weber DJ, Rutala WA. Pertussis: An underappreciated risk for nosocomial outbreaks. Infect Control Hosp Epidemiol 1998; 19:Editorial.