Claudia Miller

Explaining Low Rates of Autism Among Hispanic Schoolchildren in Texas

In data from the Texas Educational Agency and the Health Resources and Services Administration, we found fewer autism diagnoses in school districts with higher percentages of Hispanic children. Our results are consistent with previous reports of autism rates 2 to 3 times as high among non-Hispanic Whites as among Hispanics. Socioeconomic factors failed to explain lower autism prevalence among Hispanic schoolchildren in Texas. These findings raise questions: Is autism underdiagnosed among Hispanics? Are there protective factors associated with Hispanic ethnicity?

An Outbreak of Measles in an Undervaccinated Community

Measles is readily spread to susceptible individuals, but is no longer endemic in the United States. In March 2011, measles was confirmed in a Minnesota child without travel abroad. This was the first identified case-patient of an outbreak. An investigation was initiated to determine the source, prevent transmission, and examine measles-mumps-rubella (MMR) vaccine coverage in the affected community. Investigation and response included case-patient follow-up, post-exposure prophylaxis, voluntary isolation and quarantine, and early MMR vaccine for non-immune shelter residents >6 months and <12 months of age. Vaccine coverage was assessed by using immunization information system records. Outreach to the affected community included education and support from public health, health care, and community and spiritual leaders. Twenty-one measles cases were identified. The median age was 12 months (range, 4 months to 51 years) and 14 (67%) were hospitalized (range of stay, 2–7 days). The source was a 30-month-old US-born child of Somali descent infected while visiting Kenya. Measles spread in several settings, and over 3000 individuals were exposed. Sixteen case-patients were unvaccinated; 9 of the 16 were age-eligible: 7 of the 9 had safety concerns and 6 were of Somali descent. MMR vaccine coverage among Somali children declined significantly from 2004 through 2010 starting at 91.1% in 2004 and reaching 54.0% in 2010 (χ2 for linear trend 553.79; P < .001). This was the largest measles outbreak in Minnesota in 20 years, and aggressive response likely prevented additional transmission. Measles outbreaks can occur if undervaccinated subpopulations exist. Misunderstandings about vaccine safety must be effectively addressed.

Self-reported sensitivity to chemical exposures in five clinical populations and healthy controls

Two hundred and twenty-five subjects, including normal volunteers and patients with previously documented seasonal affective disorder (SAD), chronic fatigue syndrome (CFS), Cushings syndrome, Addisons disease and obsessive-compulsive disorder (OCD), completed a self-rated inventory of reported sensitivity to various chemical exposures. Patients with CFS, Addisons disease and SAD self-reported more sensitivity to chemical exposures than normal controls. In addition, women reported more sensitivity than men. This report suggests that chemical sensitivity may be a relevant area to explore in certain medical and psychiatric populations. A possible relationship between reported chemical sensitivity and hypothalamic-pituitary-adrenal (HPA)-axis functioning is discussed.

Understanding Trends in Pertussis Incidence: An Agent-Based Model Approach

OBJECTIVESnWe examined the impact of undetected infections, adult immunity, and waning vaccine-acquired immunity on recent age-related trends in pertussis incidence.nnnMETHODSnWe developed an agent-based model of pertussis transmission in Dakota County, Minnesota using case data from the Minnesota Department of Health. For outbreaks in 2004, 2008, and 2012, we fit our model to incidence in 3 childrens age groups relative to adult incidence. We estimated parameters through model calibration.nnnRESULTSnThe duration of vaccine-acquired immunity after completion of the 5-dose vaccination series decreased from 6.6 years in the 2004 model to approximately 3.0 years in the 2008 and 2012 models. Tdap waned after 2.1 years in the 2012 model. A greater percentage of adults were immune in the 2008 model than in the 2004 and 2012 models. On average, only 1 in 10 adult infections was detected, whereas 8 in 10 child infections were detected.nnnCONCLUSIONSnThe observed trends in relative pertussis incidence in Dakota County can be attributed in part to fluctuations in adult immunity and waning vaccine-acquired immunity. No single factor accounts for current pertussis trends.

Assessing the Impact of a Pertussis Active Surveillance Program on Provider Testing Behavior, Minnesota 2005–2009

OBJECTIVESnThe Minnesota Department of Health, in collaboration with the Centers for Disease Control and Prevention, implemented the Pertussis Active Surveillance Project to better understand pertussis epidemiology. We evaluated the programs impact.nnnMETHODSnClinics in 2 counties were offered free diagnostic testing and an educational presentation covering pertussis epidemiology. Clinics were identified as either active or intermittent, with active clinics testing 33% or more of the total number of months enrolled. We used generalized estimating equations to assess changes in provider testing behavior over the project period.nnnRESULTSnNinety-seven clinics enrolled, with 38% classified as active. Active clinics were more likely to use the state lab for diagnostic testing and had a larger staff. During the project period, a decline in days coughing at the time of visit occurred in both jurisdictions.nnnCONCLUSIONSnProviding clinics with free diagnostic testing influenced their participation levels. Among active clinics, results suggest changes in provider testing behavior over the course of the project. However, given the lack of robust participation, this resource-intensive strategy may not be a cost-effective approach to evaluating trends in pertussis epidemiology.

Risk Factors Associated with Bordetella pertussis among Infants Aged ≤4 Months in the pre-tdap Era — United States, 2002–2005

Background: In the United States, infants have the highest reported pertussis incidence and death rates. Improved understanding of infant risk factors is needed to optimize prevention strategies. Methods We prospectively enrolled infants ⩽4 months of age with incident-confirmed pertussis from 4 sites during 2002–2005 (preceding pertussis antigen-containing vaccination recommendations for adolescents/adults); each case-patient was age and site matched with 2 control subjects. Caregivers completed structured interviews. Infants and their contacts ≥11 years of age were offered serologic testing for IgG; being seropositive was defined as ≥94 antipertussis toxin IgG enzyme-linked immunosorbent assay units per milliliter. Results: Enrolled subjects (115 case-patients; 230 control subjects) had 4396 contacts during incubation periods; 83 (72%) case-patients had ≥1 contact with prolonged (≥5 days) new cough in primary or secondary households. In multivariable analysis, the odds for pertussis were higher for infants with primary/secondary household contacts who had a prolonged new cough, compared with infants who did not. These contacts included mother [adjusted matched odds ratio (aMOR), 43.8; 95% confidence interval (CI), 6.45–298.0] and ≥1 nonmother contact (aMOR, 20.1; 95% CI, 6.48–62.7). Infants receiving breast milk with 0–1 formula feedings daily had decreased pertussis odds (aMOR, 0.27; 95% CI, 0.08–0.89), compared with those receiving more formula. Of 41 tested case-patients, 37 (90%) were seropositive. Conclusions: Pertussis in infants was associated with prolonged new cough (≥5 days) in infants’ household contacts. Findings suggest that breastfeeding protects against pertussis and warrants recommendation with pertussis prevention strategies, which currently include pertussis vaccination of pregnant mothers and infants’ close contacts.

Chemical Sensitivity: An Emerging Public Health and Environmental Problem

Chemical exposures are endemic to our modem industrial society. People who believe they are chemically sensitive are caught up in an acrimonious crossfire among competing groups of physicians including traditional allergists and clinical ecologists. This acrimony is fueled by different medical/scientific paradigms of the definition and nature of disease or symptoms associated with exposure to low levels of chemicals in food and water, the outdoor environment, the work environment, indoor air, and consumer products. Much, but by no means all, of the early anecdotal evidence for chemical sensitivities has been reported by clinical ecologists-physician practitioners whose clinical practices have come under intense criticism. However, chemical sensitivity is by no means the exclusive property of clinical ecology. The fields of occupational and environmental medicine increasingly contain sufficient examples to suggest that a serious public health problem is emerging. Although a precise number for the magnitude of the problem is not available, evidence for significant and increasing chemical sensitivity is provided by (1) recent dramatic increases in synthetic organic chemical production and pesticide use, (2) decreased ventilation in buildings, especially those that are energy-tight, (3) increased outbreaks of sick-building illness, (4) increased reporting of symptoms in chemically contaminated communities, (5) increases in the numbers of physicians treating chemically sensitive patients, and (6) increases in the numbers of people reporting sensitivity. In this article we focus on the nature of chemical sensitivity.