Evidence for a High Attack Rate and Efficacy of Erythromycin Prophylaxis in a Pertussis Outbreak in a Facility for the Developmentally Disabled

Abstract

During an outbreak of pertussis in residents and staff of a facility for the developmentally disabled, 149 persons had laboratory evidence of Bordetella pertussis infection; 130 (87%) reported respiratory illness. Infection rates (IR) in affected wards ranged from 6% to 91%. Most residents were adolescents and adults and had received a full course of diphtheria-tetanus toxoids-pertussis (DTP) vaccine; IRs increased with increasing time after the last DTP dose in fully vaccinated residents. The IR was lower in residents on wards where erythromycin treatment/prophylaxis was started two or fewer weeks after the onset of illness in the first case on the ward (IR, 16%), compared with four or more weeks after onset (IR, 75%; P less than 10(-6)). Respiratory symptoms were milder in ill residents treated within seven days of onset of illness. Although B. pertussis transmission was substantial, erythromycin treatment of patients and prophylaxis of exposed persons was effective in decreasing transmission and disease severity. Carbamazepine toxicity occurred in seven (19%) of 37 residents when carbamazepine was administered with erythromycin.

Laboratory Diagnosis of Pertussis

“…Since both the sensitivity and specificity of this assay are low (31), DFA diagnosis should always be supported by culture, PCR, or serology.…”

“…In studies in which IgM, IgA, and IgG antibodies were measured in sera from patients with well-documented pertussis and with various ages and vaccination histories, the common finding was that the IgG parameters were most sensitive (31,180,182,191,193,194). Likewise, in studies in which IgG and IgA antibodies were measured, IgG parameters were more sensitive than IgA parameters, and combinations of IgG and IgA parameters (with "and/or" interpretation) did not enhance or only slightly enhanced the sensitivity (186,187,(195)(196)(197)(198).…”

“…Cutoff points for significant increases of antibody in paired sera used in various studies included 1.5-fold (17, 187), 2-fold (31,198,201,209,225,228,(235)(236)(237)(238), 3-fold (193,194,208), and 4-fold (9,182). Because of the limited accuracy of ELISA (high CVs) at low values (222), a criterion for the minimal level to be reached in the second serum is included in most definitions for significant dynamics, i.e., minimally 4 times the detection level or, specifically for IgG-Ptx ELISA, minimally 20 CBER EU/ml or 20 WHO IU/ml.…”

The Challenges of Pertussis Outbreaks in Healthcare Facilities: Is There A Light at the End of the Tunnel?

“…Infected HCWs can then serve as vectors of infection to other susceptible contacts, including patients, other employees, and even their own children. 10 Nosocomial exposure to B. pertussis results in substantial disruptions and costs to the healthcare system, to HCWs, and to individual contacts. Costs include, but are not limited to, person-hours spent by infection control and occupational health staff investigating the contacts of an index patient and of exposed persons, laboratory evaluation of symptomatic contacts, antimicrobial prophylaxis for exposed individuals, efforts to alert communities of pertussis outbreaks, uncompensated medical costs borne by contacts, and loss of productivity and wages from HCWs who are ill and/or furloughed.…”

Pertussis: A Continuing Hazard for Healthcare Facilities

“…79 Therapy of infected patients and chemoprophylaxis of exposed HCWs has been successful in terminating outbreaks in healthcare institutions. 27 ' 80 The potential epidemiological flaws in clinical trials of erythromycin prophylaxis have been reviewed. 81 Erythromycin-resistant clinical isolates oiB pertussis have been reported, raising concern about the use of macrolides for therapy or prophylaxis 82,83 ; however, recent surveys of B pertussis strains demonstrate that macrolide resistance is uncommon.…”