Background:
While total numbers of pertussis cases this season are not higher compared to prior years, a greater proportion of infants are affected. After 8 confirmed cases in October and 19 confirmed cases in November 2007, December has more than 30 confirmed cases with a number still under investigation. Twelve (34%) of the 35 probable or confirmed cases reported in December were in infants under 12 months of age, compared to 23% for all of 2006 and 16% for 2005. Of these twelve infant cases, five also had a positive test for respiratory syncytial virus (RSV).
Health care providers should use droplet precautions (including a surgical mask) when within 3 feet of persons with suspected pertussis during patient encounters. Pertussis testing is available at the Public Health – Seattle & King County Laboratory (206 731-8950) as well as local reference laboratories. A negative pertussis culture or PCR test does not rule-out pertussis when the clinical picture is suggestive. In certain high-risk cases and contacts, initiating treatment after 3 weeks of paroxysmal cough and chemoprophylaxis for contacts should be considered. High-risk cases and contacts include infants aged <1 year and individuals with pertussis or suspected pertussis who may expose persons at high-risk of severe disease (health care workers; labor and delivery, neonatal, pediatric and post-partum staff; pediatricians; midwives, labor coaches, pregnant women; and other persons who may expose an infant).
A single dose of Tdap is recommended for adults 19-64 years of age to replace the next booster dose of Td, particularly adults who have close contact with infants <12 months of age. An interval as short as 2 years from the last Td is suggested; shorter intervals can be used. When possible, women should receive Tdap before becoming pregnant. Women who have not previously received Tdap should receive a dose of Tdap in the immediate postpartum period before being discharged home. Health-care personnel who work in hospitals or ambulatory care settings and have direct patient contact should receive a single dose of Tdap as soon as feasible if they have not previously received Tdap. Pertussis is notifiable immediately upon suspicion to Public Health at (206) 296-4774.
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