Local Health Department Costs Associated with Response to a School-Based Pertussis Outbreak --- Omaha, Nebraska, September--November 2008

Pertussis is a highly infectious, vaccine-preventable respiratory illness. With the advent of a vaccine, case numbers fell in the United States from a high of 265,269 in 1934 (1) to a low of 1,010 cases in 1976, but then resurged to 25,827 in 2004. During 2004--2008, the average was 18,161 cases per year (2,3). Close contacts of persons with pertussis are at increased risk for developing infection and are recommended to receive preventive antibiotics (4) for two reasons: 1) the illness can be debilitating, with cough lasting several weeks and sometimes being severe enough to cause urinary incontinence, rib fracture, or other complications; and 2) the illness can be fatal in infants; it caused an average of 17 deaths each year during 2002--2006 (3). During pertussis outbreaks, the resources needed to identify and treat contacts can strain local public health resources (5). The Douglas County Health Department (DCHD) in Omaha, Nebraska, responded to a school-based pertussis outbreak with 26 cases occurring in late 2008. To assess the costs incurred by a local health department responding to such an outbreak, DCHD and CDC evaluated the total resources used by DCHD. This report describes the results of that analysis, which indicated that 1) staff members reported 1,032 person-hours spent responding to the outbreak, and 2) the total cost of outbreak response, including overhead, labor, travel, and other costs, was $52,131 (measured in 2008 U.S. dollars). The majority of costs (59%) occurred during an intensive 10-day period, when most of the contact tracing and prophylaxis recommendations were made. The elevated incidence of pertussis and the burden of response placed on health departments warrants exploring the impact of alternative response and chemoprophylaxis strategies.

On September 26, 2008, DCHD was notified of a student, aged 5 years, with a diagnosis of pertussis. The student attended a private school with approximately 600 other students in kindergarten through 12th grade. DCHD followed pertussis response protocols in which close contacts were identified and contacted. In keeping with CDC pertussis response guidelines, DCHD recommended chemoprophylaxis for close contacts, defined as persons who had direct face-to-face contact with an ill person, or shared a confined space with an ill person for more than 1 hour, or had direct contact with respiratory, oral, or nasal secretions from a symptomatic person (4). DCHD also recommended that the school exclude persons with a cough from school until they were evaluated by a doctor. After four additional cases were reported in the school on October 28, DCHD further recommended that students with cough be excluded from school until evaluated by a physician and either treated or determined not to have pertussis.

On November 17, CDC investigators were deployed at the request of DCHD to assist with the response and data analysis and assess the cost to the health department for its response. Cost data were obtained in a three-step process. First, DCHD management personnel were interviewed to determine the temporal course of the outbreak and response, the number of staff members involved in the response, and the health department's operating costs, including labor and overhead. Second, a survey instrument was created and distributed to DCHD personnel to assess time spent performing various activities during the outbreak response. The survey was voluntary and de-identified. Each survey was confidentially matched with the corresponding salary and fringe benefit rate obtained from accounting staff. Third, cost figures were calculated by multiplying hours worked by salary plus the fringe benefit rate, then adding travel and overhead expenses.* Cost was summed by operating division and compared with the division budget to determine the proportion of the total operating budget required for this outbreak response.

To assess the cost to DCHD during different phases of the response, data were split into three periods: 1) the initial period, from the first case notification to the declaration of the outbreak (September 26--October 26); 2) the outbreak period, when most of the cases were reported and DCHD worked to update control measures (October 27--November 5); and 3) the follow-up and reporting period, when DCHD implemented new control measures and observed reduced incidence of disease (November 6--21). Also, cost was separated by four DCHD divisions involved in the outbreak: Administration, Epidemiology, Data, and Media Relations.† Finally, labor cost was calculated by period and division as a percentage of the total DCHD labor budget. Labor cost as a proportion of labor budget was used to determine how many personnel in each division worked on the outbreak during that period. For example, a percentage of 100% would mean that the division spent all available personnel resources on the outbreak.

To classify staff time, the survey captured several time categories, including investigation, communication, decisions and implementation, and "other." The categories were derived from interviews with health department staff members before conducting the survey. Investigation included all activities related to identifying contacts (contact tracing), following up with potential close contacts, analysis of epidemiologic data, other investigation, and record keeping. Communication time was divided among physicians, parents, school, and the media. Decisions and implementation were activities related to coordination of control measures during the outbreak. Specifically, these involved meetings to discuss how to identify close contacts, whether or not to exclude anyone with a cough from school, and "other." The "other" category included meetings with parents of school children and travel time.

In total, 26 laboratory-confirmed pertussis cases occurred (in 24 students and two staff members) (Figure). Two of the 26 cases were identified after the survey was conducted, and the costs associated with them were not included in the analysis. DCHD recommended chemoprophylaxis for 148 close contacts. DCHD staff members contributed 1,031 person-hours to control the outbreak during the period observed (Table 1). Outbreak cost totaled $52,131, or approximately $2,172 per case, which was nearly 1% of DCHD's annual program budget, excluding grants and external funding sources. Each case of pertussis required nearly 42 regular person-hours and approximately 1 hour of overtime. The time spent investigating a pertussis case included tracing of all close contacts, and each pertussis case led to an average of 21 telephone calls and chemoprophylaxis recommendations for six close contacts (range: zero to 70). DCHD did not pay for antibiotics or laboratory testing.

Of the total cost, the largest components were investigations (37.2%) and decisions and implementation (22.9%). Resource use was most intensive during the outbreak period for all divisions (Table 2). The most heavily affected divisions were Epidemiology (156% of budgeted hours), Administration (46%), and Media Relations (41%).§ The Epidemiology Division's 156% resource use reflected overtime and compensation hours worked during the outbreak period. In total, staff members reported 28 hours of overtime with the largest component of overtime allocated to investigation-related activities.

Reported by

AM Pour, PhD, CD Allensworth, MPH, Douglas County Health Dept, Omaha, Nebraska. TA Clark, MD, JL Liang, DVM, P Cullison Bonner, MD, Div of Bacterial Diseases, ML Messonnier, PhD, GR Beeler Asay, PhD, Prevention Effectiveness Fellow, Immunization Svcs Div, National Center for Immunization and Respiratory Diseases, CDC.

Editorial Note

This pertussis outbreak in Omaha in 2008 was resource-intensive and expensive for the local health department, with total costs estimated at $52,000 and 1,000 hours of staff time committed to the outbreak. Beyond the direct costs measured by the survey, the outbreak affected other projects and public health priorities of DCHD. Many staff members stopped working on their previous projects to work on the outbreak; although most staff members were able to return and complete their projects, DCHD staff members reported a total delay of 83 days on those projects. Staff members reported greater than usual stress resulting from balancing or delaying competing priorities. For example, staff members worked extra hours to respond to a tuberculosis case identified during the outbreak. Had the pertussis outbreak not occurred, staff members would have handled the tuberculosis case during regular working hours.

Such evaluations of public response costs to disease are rare in the literature. One other report evaluated the cost to a state health department responding to a measles outbreak in 2004 (6). Using a similar cost evaluation method, the authors found a very high cost of response (approximately $60,000 for one case).

When responding to the outbreak, the major costs to this health department were investigation of cases and decisions and implementation of updated chemoprophylaxis guidelines. Within these two components, data analysis, tracing contacts, and determining the appropriate close contact definition required the most time of health department personnel. Other health departments have employed guidelines that target tracing and chemoprophylaxis of contacts (7). Adoption of such targeted chemoprophylaxis strategies might streamline notification procedures and result in more efficient and complete notification of contacts at risk for severe or fatal disease, including infants (7). However, the effectiveness of targeted versus wider chemoprophylaxis remains to be determined.

The findings in this report are subject to at least three limitations. First, this report focused on the direct public cost incurred by a local health department in response to a pertussis outbreak. The private costs of pertussis, including those costs borne by patients, persons recommended chemoprophylaxis, health-care providers, or institutions, were not analyzed in this study. However, private costs of pertussis are well studied elsewhere and can be substantial (8,9). Second, although this report measured the total delay in projects resulting from the outbreak, it did not measure the type or number of projects delayed. Future cost analyses also should measure the "opportunity cost" of outbreaks in more detail. Finally, although these data offer a picture of public health cost when responding to an outbreak, they only reflect the resource use of one health department and might differ for other health departments. For example, health departments that pay for laboratory testing and antibiotic courses for patients would incur additional costs.

Costs of response to pertussis outbreaks can be substantial. Investigations and developing recommendations were the most resource-intensive aspects of this outbreak for the local health department. The elevated incidence of pertussis and the burden of response placed on health departments warrants exploring the impact of alternative response and chemoprophylaxis strategies.

Acknowledgments

This report is based, in part, on contributions by T Kelso and other staff members of the Douglas County Health Dept, Omaha, Nebraska; J Liko, MD, and P Cieslak, MD, Oregon Public Health Dept; and C Thomas, DVM, and H Wu, MD, Div of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, CDC.

References

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