Colleen Chun

Incidence of herpes zoster, 1997-2002.

We estimated age-specific herpes zoster (HZ) incidence rates in the Kaiser Permanente Northwest Health Plan (KPNW) during 1997-2002 and tested for secular trends and differences between residents of two states with different varicella vaccine coverage rates. The cumulative proportions of 2-year-olds vaccinated increased from 35% in 1997 to 85% in 2002 in Oregon, and from 25% in 1997 to 82% in 2002 in Washington. Age-specific HZ incidence rates in KPNW during 1997-2002 were compared with published rates in the Harvard Community Health Plan (HCHP) during 1990-1992. The overall HZ incidence rate in KPNW during 1997-2002 (369/100,000 person-years) was slightly higher than HCHPs 1990-1992 rate when adjusted for age differences. For children 6-14 years old, KPNWs rates (182 for females, 123 for males) were more than three times HCHPs rates (54 for females, 39 for males). This increase appears to be associated with increased exposure of children to oral corticosteroids. The percentage of KPNW children exposed to oral corticosteroids increased from 2.2% in 1991 to 3.6% in 2002. Oregon residents had slightly higher steroid exposure rates during 1997-2002 than Washington residents. There were significant increases in HZ incidence rates in Oregon and Washington during 1997-2002 among children aged 10-17 years, associated with increased exposure to oral steroids.

Laboratory Diagnosis and Characteristics of Breakthrough Varicella in Children

The atypical features of varicella in vaccinated persons (breakthrough varicella [BTV]) present diagnostic challenges. We examined varicella-zoster virus (VZV) polymerase chain reaction (PCR) and immunoglobulin (Ig) M and IgG serologic test results for confirming BTV cases. Among 33 vaccinated children with varicella-like rash, we identified wild-type VZV in 58% overall and in 76% of those with adequate tissue specimens; no vaccine-type virus was found. Of the 12 subjects with PCR-confirmed BTV and acute-phase serum samples, 9 had detectable IgM, and all had highly elevated acute-phase IgG titers. Six subjects with negative PCR results had lower IgG titers and negative IgM results. Although PCR is the preferred method for laboratory confirmation of BTV, a positive serum varicella IgM test result should also be considered to be diagnostic in a suspected BTV case; however, a negative IgM test result cannot be used to rule out the diagnosis. The value of highly elevated IgG titers needs further evaluation. Larger studies are needed to confirm these results.

Laboratory characteristics of suspected herpes zoster in vaccinated children.

Varicella vaccination of children has decreased varicella disease incidence, but introduced the occurrence of herpes zoster (HZ) from vaccine-type virus. We identified 14 vaccinated children with suspected HZ and confirmed varicella virus by polymerase chain reaction in 6 cases. Two cases were due to vaccine-type virus. Serum varicella IgM and IgG were not useful for diagnosis of HZ among vaccinated children.

Passive Cigarette Smoke Exposure and Other Risk Factors for Invasive Pneumococcal Disease in Children: A Case-Control Study

OBJECTIVE To investigate whether passive cigarette smoke exposure increases the risk of invasive pneumococcal disease in children. METHODS In a population-based case-control study, 171 children aged 0 to 12 years with culture-confirmed invasive pneumococcal disease during the years 1994 to 2004 were identified. Two controls were matched to each case on age and patterns of Health Plan membership. We reviewed medical records of subjects and family members for information on household cigarette smoke exposure within 2 years of the diagnosis of invasive pneumococcal disease. We collected information on sex, race, pneumococcal vaccination, selected medical conditions, and medications in the 3 months before the diagnosis. RESULTS Similar proportions of cases (25%) and controls (30%) had definite or probable passive smoke exposure (odds ratio [OR] = 0.76, 95% confidence interval [CI] = 0.47-1.2). Cases of invasive pneumococcal disease were more likely to be nonwhite than controls (OR = 4.4, 95% CI = 2.3-8.2). Elevated risk of invasive pneumococcal disease was found in subjects with recent pulmonary diagnoses (OR = 2.2, 95% CI = 1.2-4.0) and recent antibiotic use (OR = 1.6, 95% CI = 1.1-2.3). CONCLUSIONS Passive cigarette smoke exposure was not associated with invasive pneumococcal disease in this pediatric population. Invasive pneumococcal disease was associated with recent pulmonary diagnoses and recent antibiotic use.

Use of Fc-binding proteins to identify cell surface and secreted antigens associated with group B streptococci

Publisher Summary This chapter discusses the use of Fc-binding proteins to identify cell surface and secreted antigens associated with group B streptococci. Binding proteins that interact specifically with the Fc region of immunoglobulin molecules have been isolated from a variety of staphylococcal and streptococcal species. These bacterial proteins bind specifically and with high affinity to the Fc regions of various immunoglobulin species, primarily of the IgG class. The range of reactivities of bacterial Fc-binding proteins is expanding as additional interactions of bacterial products with immunoglobulins. The two-stage radioimmunoassay (RIA) is used to identify type-specific antigens expressed isolates of group B streptococci. This assay utilizes the ability of radiolabeled, bacterial immunoglobulin Fc-binding proteins to bind with high affinity to the Fc region of type-specific rabbit antibodies, which have been previously reacted with intact bacteria. The two-stage RIA and all of its adaptations utilize small quantities of intact bacteria, require less type-specific antisera than conventional precipitin testing, and are rapid, semi quantitative, and objective. The use of intact bacteria enables the detection of acid-labile antigens in their native, unmodified form.

Family Characteristics Associated with Likelihood of Varicella Vaccination.

CONTEXT The introduction of the varicella vaccine as a routine pediatric immunization in the US, in 1995, provided an opportunity to assess factors associated with uptake of new vaccines in the member population of the Kaiser Permanente Northwest (KPNW) Health Plan. OBJECTIVE Identify factors associated with varicella vaccination in the KPNW population in the first five years after varicella vaccine was introduced. DESIGN A retrospective cohort of children under age 13 years between June 1995 and December 1999, without a history of varicella disease was identified using KPNW automated data. Membership records were linked to vaccine databases. Cox regression was used to estimate likelihood of varicella vaccination during the study period in relation to age, sex, primary clinicians specialty, and Medicaid eligibility. For a subset whose parents answered a behavioral health survey, additional demographic and behavioral characteristics were evaluated. MAIN OUTCOME MEASURE Varicella vaccination. RESULTS We identified 88,646 children under age 13 years without a history of varicella; 22% were vaccinated during the study period. Varicella vaccination was more likely among children who were born after 1995, were not Medicaid recipients, or had pediatricians as primary clinicians. In the survey-linked cohort, positively associated family characteristics included smaller family size; higher socioeconomic status; and parents who were older, were college graduates, reported excellent health, and received influenza vaccination. CONCLUSION Understanding predictors of early varicella vaccine-era vaccine acceptance may help in planning for introduction of new vaccines to routine schedules.

Positive Predictive Value of ICD-9 Code for Herpes Zoster Among Children During the Varicella Vaccine Era.

We examined the positive predictive value of the herpes zoster ICD-9 diagnosis code 053 in the Kaiser Permanente Northwest integrated health plan. Among children 0-17 years old, the positive predictive value was 87.1% (95% confidence interval: 84.2-89.6) and 96.8% (95% confidence interval: 95.0-98.1) during the years 1997-2002 and 2005-2009, respectively, using chart review of the medical record as the diagnostic standard.

A Ten-Year Case-Control Study of Passive Smoke Exposure as a Risk Factor for Pertussis in Children

The authors conducted a matched case-control study of laboratory-confirmed pertussis cases, occurring from 1/1/1996 to 12/31/2005, in children up to 12 years of age who were members of a large managed care organization. Sixty-five laboratoryconfirmed cases of pertussis were identified. Using multivariable conditional logistic regression analysis, the authors did not detect a statistically significant association between pertussis and household passive exposure to cigarette smoking.

PS1-17: Herpes Zoster in Children

Background and Aims: Vaccine-strain herpes zoster (HZ) is a potential adverse outcome of varicella vaccination. Data are needed on the incidence of and risk factors for vaccine-strain HZ among children <18 years of age. The Centers for Disease Control and Prevention (CDC) funded a study at Kaiser Permanente Northwest (KPNW) to determine the number and proportion of pediatric HZ cases caused by varicella vaccine, assess positive predictive value (PPV) of physician diagnosis of HZ, and compute incidence of vaccine and wild-type HZ in the KPNW population. Methods: We used electronic data to identify all pediatric medical office visits with a HZ diagnosis. During the visit, the provider collected a lesion specimen and completed a questionnaire. The study nurse called to interview the parent and, if no specimen was previously collected, schedule a home visit to obtain it. A follow-up questionnaire on severity and duration of HZ was returned four weeks after rash onset. Specimens were sent to the National Varicella-Zoster Virus (VZV) Laboratory at the CDC for PCR analysis to confirm presence of the virus and classify it as wild-type or vaccine-type. Results: From 5/2005 to 3/2009, we enrolled 308 subjects in the study. Two-hundred eighty-one (96%) had adequate lesion specimens for PCR analysis. We found VZV in 75% of adequate specimens; 69% were wild-type, while 9% were vaccine-type and 1% (2) were vaccine:wild-type recombination. Among vaccinated subjects, 69% had wild-type HZ. The PPV for provider diagnosis of ‘definite HZ’ was 83%: 85% for unvaccinated subjects and 76% for vaccinated subjects. Incidence rates for vaccine-strain and wild-type VZV in plan children age 0–17 will be presented. Conclusions: Vaccine-strain VZV was found in a minority of HZ cases in this age group. We observed recombination of vaccine-strain and wild-type viruses in two subjects. Provider diagnosis of HZ was good overall.