Operational Considerations for Using Deer-Targeted 4-Poster Tick Control Devices in a Tick-borne Disease Endemic Community.

CONTEXT: In the northeastern United States, recommendations to prevent diseases spread by black-legged ticks ( Ixodes scapularis ) and lone star ticks ( Amblyomma americanum ) often rely on individuals to use personal protection or yard-based strategies. The 4-Poster deer treatment stations (4-Posters) suppress tick populations by treating deer hosts with acaricide, potentially offering a community-wide approach for reducing tick-borne diseases in endemic areas. The 4-Poster deployment logistics in mainland community settings are not well documented but are needed for future public health tick control efforts. PROGRAM: As part of a public health research effort to design a population-based 4-Poster effectiveness study aimed at reducing tick-borne disease incidence, TickNET researchers partnered with the Town of Ridgefield (Connecticut) to understand the feasibility and operational logistics of deploying 4-Posters on public land within a residential community to inform future public health interventions by municipalities or vector control agencies. IMPLEMENTATION: We deployed three 4-Posters on a municipal property from July to December 2020 and used motion-activated cameras to record wildlife activity nearby. We documented per-device operational details, costs, materials consumed, and animal activity. EVALUATION: Operation of 4-Posters was feasible, and device challenges were easily remedied. Deer visitation and heavy nontarget animal use were documented at all devices. Unexpectedly, monthly corn consumption was not correlated with monthly deer-view days. The monthly cost per device was US $1279 or US $305 per hectare with an average 21 minutes of weekly service time. DISCUSSION: Use of 4-Posters by communities, public health agencies, or vector control programs may be a practicable addition to tick management programs in tick-borne disease endemic areas in the Northeast. Such programs should carefully consider local and state regulations, follow manufacturer and pesticide label guidelines, and include wildlife monitoring. High labor costs incurred in this project could be mitigated by training vector control agency or municipality staff to service 4-Posters.

Acceptability of 4-poster deer treatment devices for community-wide tick control among residents of high Lyme disease incidence counties in Connecticut and New York, USA.

The 4-Poster Tick Control Deer Feeder (4-poster) device applies acaricide to white-tailed deer (Odocoileus virginianus) and can reduce populations of the blacklegged tick (Ixodes scapularis), which transmits the agents of Lyme disease, anaplasmosis, babesiosis, and Powassan virus disease in the Northeastern United States. While 4-poster devices have the potential to provide community-wide management of blacklegged ticks in Lyme disease endemic areas, no recent study has assessed their acceptability among residents. We conducted a survey of residents from 16 counties with high annual average Lyme disease incidence (≥ 10 cases per 100,000 persons between 2013 and 2017) in Connecticut and New York to understand perceptions and experiences related to tickborne diseases, support or concerns for placement of 4-poster devices in their community, and opinions on which entities should be responsible for tick control on private properties. Overall, 37% of 1652 respondents (5.5% response rate) would support placement of a 4-poster device on their own property, 71% would support placement on other private land in their community, and 90% would support placement on public land. Respondents who were male, rented their property, resided on larger properties, or were very or extremely concerned about encountering ticks on their property were each more likely to support placement of 4-poster devices on their own property. The primary reason for not supporting placement of a 4-poster device on one's own property was the need for weekly service visits from pest control professionals, whereas the top reason for not supporting placement on other land (private or public) was safety concerns. Most respondents (61%) felt property owners should be responsible for tick control on private properties. Communities considering 4-poster devices as part of a tick management strategy should consider targeting owners of larger properties and placing devices on public lands.

Changes in the microbiology, epidemiology, and outcomes of candidemia in Connecticut: A comparison between two periods using statewide surveillance.

Using statewide surveillance, we describe candidemia in Connecticut during 1998-2000 and 2019. In 2019, candidemia was more frequently associated with community-onset and non-albicans Candida species and less frequently associated with central vascular catheters, recent surgery, and in-hospital mortality. Understanding changes in candidemia can optimize clinical management and prevention strategies.

Economic Burden of Reported Lyme Disease in High-Incidence Areas, United States, 2014-2016.

Approximately 476,000 cases of Lyme disease are diagnosed in the United States annually, yet comprehensive economic evaluations are lacking. In a prospective study among reported cases in Lyme disease-endemic states, we estimated the total patient cost and total societal cost of the disease. In addition, we evaluated disease and demographic factors associated with total societal cost. Participants had a mean patient cost of ≈$1,200 (median $240) and a mean societal cost of ≈$2,000 (median $700). Patients with confirmed disseminated disease or probable disease had approximately double the societal cost of those with confirmed localized disease. The annual, aggregate cost of diagnosed Lyme disease could be $345-968 million (2016 US dollars) to US society. Our findings emphasize the importance of effective prevention and early diagnosis to reduce illness and associated costs. These results can be used in cost-effectiveness analyses of current and future prevention methods, such as a vaccine.

Designing an Intervention Trial of Human-Tick Encounters and Tick-Borne Diseases in Residential Settings Using 4-Poster Devices to Control Ixodes scapularis (Acari: Ixodidae): Challenges for Site Selection and Device Placement.

Blacklegged ticks, Ixodes scapularis Say, transmit Lyme disease spirochetes and other human pathogens in the eastern United States. White-tailed deer (Odocoileus virginianus) are key reproductive hosts for I. scapularis adults, and therefore control methods targeting deer have the potential for landscape-wide tick suppression. A topical acaricide product, containing 10% permethrin, is self-applied by deer to kill parasitizing ticks when they visit 4-Poster Tick Control Deer Feeders (hereafter, 4-Posters) Previous 4-Poster intervention studies, including in residential settings, demonstrated suppression of I. scapularis populations but did not include human-based outcomes. To prepare for a proposed 4-Poster intervention trial in residential areas of Connecticut and New York that would include human-tick encounters and tick-borne diseases as outcomes, we sought to identify areas (study clusters) in the 80-100 ha size range and specific locations within these areas where 4-Poster devices could be deployed at adequate density (1 device per 20-25 ha) and in accordance with regulatory requirements. Geographic Information System-based data were used to identify prospective study clusters, based on minimum thresholds for Lyme disease incidence, population density, and forest cover. Ground truthing of potential 4-Poster placement locations was done to confirm the suitability of selected clusters. Based on these efforts, we failed to identify more than a few residential areas fulfilling all criteria for a treatment cluster. We, therefore, reconsidered pursuing the intervention trial, which required inclusion of >30 treatment clusters to achieve adequate statistical power. The 4-Poster methodology may be more readily evaluated in natural or public areas than in residential settings in NY or CT.

Hospital-acquired influenza in the United States, FluSurv-NET, 2011-2012 through 2018-2019.

OBJECTIVE: To estimate population-based rates and to describe clinical characteristics of hospital-acquired (HA) influenza. DESIGN: Cross-sectional study. SETTING: US Influenza Hospitalization Surveillance Network (FluSurv-NET) during 2011-2012 through 2018-2019 seasons. METHODS: Patients were identified through provider-initiated or facility-based testing. HA influenza was defined as a positive influenza test date and respiratory symptom onset >3 days after admission. Patients with positive test date >3 days after admission but missing respiratory symptom onset date were classified as possible HA influenza. RESULTS: Among 94,158 influenza-associated hospitalizations, 353 (0.4%) had HA influenza. The overall adjusted rate of HA influenza was 0.4 per 100,000 persons. Among HA influenza cases, 50.7% were 65 years of age or older, and 52.0% of children and 95.7% of adults had underlying conditions; 44.9% overall had received influenza vaccine prior to hospitalization. Overall, 34.5% of HA cases received ICU care during hospitalization, 19.8% required mechanical ventilation, and 6.7% died. After including possible HA cases, prevalence among all influenza-associated hospitalizations increased to 1.3% and the adjusted rate increased to 1.5 per 100,000 persons. CONCLUSIONS: Over 8 seasons, rates of HA influenza were low but were likely underestimated because testing was not systematic. A high proportion of patients with HA influenza were unvaccinated and had severe outcomes. Annual influenza vaccination and implementation of robust hospital infection control measures may help to prevent HA influenza and its impacts on patient outcomes and the healthcare system.

Evaluating public acceptability of a potential Lyme disease vaccine using a population-based, cross-sectional survey in high incidence areas of the United States.

BACKGROUND: Lyme disease incidence is increasing, despite current prevention options. New Lyme disease vaccine candidates are in development, however, investigation of the acceptability of a Lyme disease vaccine among potential consumers is needed prior to any vaccine coming to market. We conducted a population-based, cross-sectional study to estimate willingness to receive a potential Lyme disease vaccine and factors associated with willingness. METHODS: The web-based survey was administered to a random sample of Connecticut, Maryland, Minnesota, and New York residents June-July 2018. Survey-weighted descriptive statistics were conducted to estimate the proportion willing to receive a potential Lyme disease vaccine. Multivariable multinomial logistic regression models were used to quantify the association of sociodemographic characteristics and Lyme disease vaccine attitudes with willingness to be vaccinated. RESULTS: Surveys were completed by 3313 respondents (6% response rate). We estimated that 64% of residents were willing to receive a Lyme disease vaccine, while 30% were uncertain and 7% were unwilling. Compared to those who were willing, those who were uncertain were more likely to be parents, adults 45-65 years old, non-White, have less than a bachelor's degree, or have safety concerns about a potential Lyme disease vaccine. Those who were unwilling were also more likely to be non-White, have less than a bachelor's degree, or have safety concerns about a potential Lyme disease vaccine. In addition, the unwilling had low confidence in vaccines in general, had low perceived risk of contracting Lyme disease, and said they would not be influenced by a positive recommendation from a healthcare provider. DISCUSSION: Overall, willingness to receive a Lyme disease vaccine was high. Effective communication by clinicians regarding safety and other vaccine parameters to those groups who are uncertain will be critical for increasing vaccine uptake and reducing Lyme disease incidence.

Prevention of Lyme and other tickborne diseases using a rodent-targeted approach: A randomized controlled trial in Connecticut.

Tickborne diseases are an increasing public health problem in the northeastern USA. Bait boxes that apply acaricide to rodents have been shown in small field studies to significantly reduce abundance of Ixodes scapularis ticks as well as their pathogen infection rates in treated areas. The effectiveness of this intervention for preventing human tickborne diseases (TBDs) has not been demonstrated. During 2012-2016, TickNET collaborators conducted a randomized, blinded, placebo-controlled trial among 622 Connecticut households. Each household received active (containing fipronil wick) or placebo (empty) bait boxes in their yards over two consecutive years. Information on tick encounters and TBDs among household members was collected through biannual surveys. Nymphal ticks were collected from a subset of 100 properties during spring at baseline, during treatment, and in the year post-intervention. Demographic and property characteristics did not differ between treatment groups. There were no significant differences post-intervention between treatment groups with respect to tick density or pathogen infection rates, nor for tick encounters or TBDs among household members. We found no evidence that rodent-targeted bait boxes disrupt pathogen transmission cycles or significantly reduce household risk of tick exposure or TBDs. The effectiveness of this intervention may depend on scale of use or local enzootic cycles.

Human-tick encounters as a measure of tickborne disease risk in lyme disease endemic areas.

Entomological measures have long served as proxies for human risk of Lyme disease (LD) and other tickborne diseases (TBDs) in endemic areas of the United States, despite conflicting results regarding the correlation between these measures and human disease outcomes. Using data from a previous TBD intervention study in Connecticut, Maryland and New York, we evaluated whether human-tick encounters can serve as an accurate proxy for risk of TBDs in areas where LD and other Ixodes scapularis-transmitted infections are common. Among 2,590 households consisting of 4,210 individuals, experiencing a tick encounter was associated with an increased risk of both self-reported (RR = 3.17, 95% CI: 2.05, 4.91) and verified TBD (RR = 2.60, 95% CI: 1.39, 4.84) at the household level. Household characteristics associated with experiencing any tick encounter were residence in Connecticut (aOR = 1.86, 95% CI: 1.38, 2.51) or New York (aOR = 1.66, 95% CI: 1.25, 2.22), head of household having a graduate level education (aOR = 1.46, 95% CI: 1.04, 2.08), owning a pet (aOR = 1.80, 95% CI: 1.46, 2.23) and a property size of 2 acres or larger (aOR = 2.30, 95% CI: 1.42, 3.70). Results for individual characteristics were similar to those for households. Future prevention studies in LD endemic areas should consider using human-tick encounters as a robust proxy for TBD risk.

Declines in Human Papillomavirus (HPV)-Associated High-Grade Cervical Lesions After Introduction of HPV Vaccines in Connecticut, United States, 2008-2015.

BACKGROUND: Trends in human papillomavirus (HPV)-associated cervical lesions can provide an indication of vaccine impact. Our purpose was to measure trends in cervical lesions during 2008-2015 and to consider possible explanations including vaccination coverage, changes in screening for cervical cancer, and risk behaviors for acquiring HPV. METHODS: Connecticut (CT) implemented mandatory reporting of cervical intraepithelial neoplasia grades 2/3 and adenocarcinoma in situ (cervical intraepithelial neoplasia grade 2 or higher [CIN2+]) in 2008. Trends by age and birth cohort were modeled using negative binomial regression and change-point methods. To evaluate possible explanations for changes, these trends were compared to changes in HPV vaccination coverage, cervical cancer screening, an antecedent event to detection of a high-grade lesion, and changes in sexual behaviors and Chlamydia trachomatis, an infection with similar epidemiology to and shared risk factors for HPV. RESULTS: A significant decline in CIN2+ was first evident among women aged 21 years in 2010, followed by successive declines in women aged 22-26 years during 2011-2012. During 2008-2015, the rates of CIN2+ declined by 30%-74% among women aged 21-26 years, with greater declines observed in the younger women. Birth cohorts between 1985 and 1994 all experienced significant declines during the surveillance period, ranging from 25% to 82%. Ecological comparisons revealed substantial increases in HPV vaccination during this time period, and more modest reductions in cervical cancer screening and sexual risk behaviors. CONCLUSIONS: The age and cohort patterns in our data suggest that declines in CIN2+ during 2008-2015 are more likely driven by HPV vaccination, introduced in 2006, than by changes in screening or risk behavior.

Respiratory Viral Testing and Influenza Antiviral Prescriptions During Hospitalization for Acute Respiratory Illnesses.

We examined respiratory viral testing and influenza antiviral prescriptions at a US tertiary care hospital. During the 2010-11 to 2012-13 influenza seasons, antiviral prescriptions among acute respiratory illness (ARI) hospitalizations were associated with viral testing (rate ratio = 15.0), and empiric prescriptions were rare (<1% of ARI hospitalizations).

Burden of Nursing Home-Onset Clostridium difficile Infection in the United States: Estimates of Incidence and Patient Outcomes.

Background. Approximately 4 million Americans receive nursing home (NH) care annually. Nursing home residents commonly have risk factors for Clostridium difficile infection (CDI), including advanced age and antibiotic exposures. We estimated national incidence of NH-onset (NHO) CDI and patient outcomes. Methods. We identified NHO-CDI cases from population-based surveillance of 10 geographic areas in the United States. Cases were defined by C difficile-positive stool collected in an NH (or from NH residents in outpatient settings or ≤3 days after hospital admission) without a positive stool in the prior 8 weeks. Medical records were reviewed on a sample of cases. Incidence was estimated using regression models accounting for age and laboratory testing method; sampling weights were applied to estimate hospitalizations, recurrences, and deaths. Results. A total of 3503 NHO-CDI cases were identified. Among 262 sampled cases, median age was 82 years, 76% received antibiotics in the 12 weeks prior to the C difficile-positive specimen, and 57% were discharged from a hospital in the month before specimen collection. After adjusting for age and testing method, the 2012 national estimate for NHO-CDI incidence was 112 800 cases (95% confidence interval [CI], 93 400-131 800); 31 400 (28%) were hospitalized within 7 days after a positive specimen (95% CI, 25 500-37 300), 20 900 (19%) recurred within 14-60 days (95% CI, 14 600-27 100), and 8700 (8%) died within 30 days (95% CI, 6600-10 700). Conclusions. Nursing home onset CDI is associated with substantial morbidity and mortality. Strategies focused on infection prevention in NHs and appropriate antibiotic use in both NHs and acute care settings may decrease the burden of NHO CDI.

Effectiveness of Residential Acaricides to Prevent Lyme and Other Tick-borne Diseases in Humans.

BACKGROUND: In the northeastern United States, tick-borne diseases are a major public health concern. In controlled studies, a single springtime application of acaricide has been shown to kill 68%-100% of ticks. Although public health authorities recommend use of acaricides to control tick populations in yards, the effectiveness of these pesticides to prevent tick bites or human tick-borne diseases is unknown. METHODS: We conducted a 2-year, randomized, double-blinded, placebo-controlled trial among 2727 households in 3 northeastern states. Households received a single springtime barrier application of bifenthrin or water according to recommended practices. Tick drags were conducted 3-4 weeks after treatment on 10% of properties. Information on human-tick encounters and tick-borne diseases was collected through monthly surveys; reports of illness were validated by medical record review. RESULTS: Although the abundance of questing ticks was significantly lower (63%) on acaricide-treated properties, there was no difference between treatment groups in human-tick encounters, self-reported tick-borne diseases, or medical-record-validated tick-borne diseases. CONCLUSIONS: Used as recommended, acaricide barrier sprays do not significantly reduce the household risk of tick exposure or incidence of tick-borne disease. Measures for preventing tick-borne diseases should be evaluated against human outcomes to confirm effectiveness.

Testing practices and volume of non-Lyme tickborne diseases in the United States.

Large commercial laboratories in the United States were surveyed regarding the number of specimens tested for eight tickborne diseases in 2008. Seven large commercial laboratories reported testing a total of 2,927,881 specimens nationally (including Lyme disease). Of these, 495,585 specimens (17%) were tested for tickborne diseases other than Lyme disease. In addition to large commercial laboratories, another 1051 smaller commercial, hospital, and government laboratories in four states (CT, MD, MN, and NY) were surveyed regarding tickborne disease testing frequency, practices, and results. Ninety-two of these reported testing a total of 10,091 specimens for four tickborne diseases other than Lyme disease. We estimate the cost of laboratory diagnostic testing for non-Lyme disease tickborne diseases in 2008 to be $9.6 million. These data provide a baseline to evaluate trends in tickborne disease test utilization and insight into the burden of these diseases.

Emerging Infections Program--State Health Department Perspective.

The Emerging Infections Program (EIP) is a collaboration between the Centers for Disease Control and Prevention and 10 state health departments working with academic partners to conduct active population-based surveillance and special studies for several emerging infectious disease issues determined to need special attention. The Centers for Disease Control and Prevention funds the 10 EIP sites through cooperative agreements. Our objective was to highlight 1) what being an EIP site has meant for participating health departments and associated academic centers, including accomplishments and challenges, and 2) the synergy between the state and federal levels that has resulted from the collaborative relationship. Sharing these experiences should provide constructive insight to other public health programs and other countries contemplating a collaborative federal-local approach to collective public health challenges.

Training in Infectious Disease Epidemiology through the Emerging Infections Program Sites.

One objective of the Emerging Infections Program (EIP) of the US Centers for Disease Control and Prevention is to provide training opportunities in infectious disease epidemiology. To determine the extent of training performed since the program's inception in 1995, we reviewed training efforts at the 10 EIP sites. By 2015, all sites hosted trainees (most were graduate public health students and physicians) who worked on a variety of infectious disease surveillance and epidemiologic projects. Trainee projects at all sites were used for graduate student theses or practicums. Numerous projects resulted in conference presentations and publications in peer-reviewed journals. Local public health and health care partners have also benefitted from EIP presentations and training. Consideration should be given to standardizing and documenting EIP training and to sharing useful training initiatives with other state and local health departments and academic institutions.

Burden of Clostridium difficile infection in the United States.

BACKGROUND: The magnitude and scope of Clostridium difficile infection in the United States continue to evolve. METHODS: In 2011, we performed active population- and laboratory-based surveillance across 10 geographic areas in the United States to identify cases of C. difficile infection (stool specimens positive for C. difficile on either toxin or molecular assay in residents ≥ 1 year of age). Cases were classified as community-associated or health care-associated. In a sample of cases of C. difficile infection, specimens were cultured and isolates underwent molecular typing. We used regression models to calculate estimates of national incidence and total number of infections, first recurrences, and deaths within 30 days after the diagnosis of C. difficile infection. RESULTS: A total of 15,461 cases of C. difficile infection were identified in the 10 geographic areas; 65.8% were health care-associated, but only 24.2% had onset during hospitalization. After adjustment for predictors of disease incidence, the estimated number of incident C. difficile infections in the United States was 453,000 (95% confidence interval [CI], 397,100 to 508,500). The incidence was estimated to be higher among females (rate ratio, 1.26; 95% CI, 1.25 to 1.27), whites (rate ratio, 1.72; 95% CI, 1.56 to 2.0), and persons 65 years of age or older (rate ratio, 8.65; 95% CI, 8.16 to 9.31). The estimated number of first recurrences of C. difficile infection was 83,000 (95% CI, 57,000 to 108,900), and the estimated number of deaths was 29,300 (95% CI, 16,500 to 42,100). The North American pulsed-field gel electrophoresis type 1 (NAP1) strain was more prevalent among health care-associated infections than among community-associated infections (30.7% vs. 18.8%, P<0.001). CONCLUSIONS: C. difficile was responsible for almost half a million infections and was associated with approximately 29,000 deaths in 2011. (Funded by the Centers for Disease Control and Prevention.).

Lyme disease testing by large commercial laboratories in the United States.

BACKGROUND: Laboratory testing is helpful when evaluating patients with suspected Lyme disease (LD). A 2-tiered antibody testing approach is recommended, but single-tier and nonvalidated tests are also used. We conducted a survey of large commercial laboratories in the United States to assess laboratory practices. We used these data to estimate the cost of testing and number of infections among patients from whom specimens were submitted. METHODS: Large commercial laboratories were asked to report the type and volume of testing conducted nationwide in 2008, as well as the percentage of positive tests for 4 LD-endemic states. The total direct cost of testing was calculated for each test type. These data and test-specific performance parameters available in published literature were used to estimate the number of infections among source patients. RESULTS: Seven participating laboratories performed approximately 3.4 million LD tests on approximately 2.4 million specimens nationwide at an estimated cost of $492 million. Two-tiered testing accounted for at least 62% of assays performed; alternative testing accounted for <3% of assays. The estimated frequency of infection among patients from whom specimens were submitted ranged from 10% to 18.5%. Applied to the total numbers of specimens, this yielded an estimated 240 000 to 444 000 infected source patients in 2008. DISCUSSION: LD testing is common and costly, with most testing in accordance with diagnostic recommendations. These results highlight the importance of considering clinical and exposure history when interpreting laboratory results for diagnostic and surveillance purposes.

Complications among adults hospitalized with influenza: a comparison of seasonal influenza and the 2009 H1N1 pandemic.

BACKGROUND: Persons with influenza can develop complications that result in hospitalization and death. These are most commonly respiratory related, but cardiovascular or neurologic complications or exacerbations of underlying chronic medical conditions may also occur. Patterns of complications observed during pandemics may differ from typical influenza seasons, and characterizing variations in influenza-related complications can provide a better understanding of the impact of pandemics and guide appropriate clinical management and planning for the future. METHODS: Using a population-based surveillance system, we compared clinical complications using International Classification of Diseases, Ninth Revision (ICD-9) discharge diagnosis codes in adults hospitalized with seasonal influenza (n = 5270) or 2009 pandemic influenza A(H1N1) (H1N1pdm09; n = 4962). RESULTS: Adults hospitalized with H1N1pdm09 were younger (median age, 47 years) than those with seasonal influenza (median age, 68 years; P < .01), and differed in the frequency of certain underlying medical conditions. Whereas there was similar risk for many influenza-associated complications, after controlling for age and type of underlying medical condition, adults hospitalized with H1N1pdm09 were more likely to have lower respiratory tract complications, shock/sepsis, and organ failure than those with seasonal influenza. They were also more likely to be admitted to the intensive care unit, require mechanical ventilation, or die. Young adults, in particular, had 2-4 times the risk of severe outcomes from H1N1pdm09 than persons of the same ages with seasonal influenza. CONCLUSIONS: Although H1N1pdm09 was thought of as a relatively mild pandemic, these data highlight the impact of the 2009 pandemic on the risk of severe influenza, especially among younger adults, and the impact this virus may continue to have.

Clostridium difficile infection among children across diverse US geographic locations.

OBJECTIVE: Little is known about the epidemiology of Clostridium difficile infection (CDI) among children, particularly children ≤3 years of age in whom colonization is common but pathogenicity uncertain. We sought to describe pediatric CDI incidence, clinical presentation, and outcomes across age groups. METHODS: Data from an active population- and laboratory-based CDI surveillance in 10 US geographic areas during 2010-2011 were used to identify cases (ie, residents with C difficile-positive stool without a positive test in the previous 8 weeks). Community-associated (CA) cases had stool collected as outpatients or ≤3 days after hospital admission and no overnight health care facility stay in the previous 12 weeks. A convenience sample of CA cases were interviewed. Demographic, exposure, and clinical data for cases aged 1 to 17 years were compared across 4 age groups: 1 year, 2 to 3 years, 4 to 9 years, and 10 to 17 years. RESULTS: Of 944 pediatric CDI cases identified, 71% were CA. CDI incidence per 100,000 children was highest among 1-year-old (66.3) and white (23.9) cases. The proportion of cases with documented diarrhea (72%) or severe disease (8%) was similar across age groups; no cases died. Among the 84 cases interviewed who reported diarrhea on the day of stool collection, 73% received antibiotics during the previous 12 weeks. CONCLUSIONS: Similar disease severity across age groups suggests an etiologic role for C difficile in the high rates of CDI observed in younger children. Prevention efforts to reduce unnecessary antimicrobial use among young children in outpatient settings should be prioritized.