Tick bite and Lyme disease-related emergency department encounters in New Hampshire, 2010-2014

Tick-Borne Diseases

Ticks are responsible for the vast majority of vector-borne illnesses in the United States. The number of reported tick-borne disease (TBD) cases has more than doubled in the past 20 years. The majority of TBD cases occur in warm weather months in individuals with recent outdoor activities in wooded areas. The risk of contracting a TBD is also highly dependent on geographic location. Between 24 and 48 hours of tick attachment is required for most disease transmission to occur. Only 50% to 70% of patients with a TBD will recall being bitten by a tick, and TBDs are often initially misdiagnosed as a viral illness. Most TBDs are easily treated when diagnosed early in their course.

Emergency Department Syndromic Surveillance to Monitor Tick-Borne Diseases: A 6-Year Small-Area Analysis in Northeastern Italy

Tick-borne diseases (TBD) are endemic in Europe. However, surveillance is currently incomplete. Alternative strategies need to be considered. The aim of this study was to test an Emergency Department Syndromic Surveillance (EDSyS) system as a complementary data source to describe the impact of tick bites and TBD using a small-area analysis approach and to monitor the risk of TBD to target prevention. ED databases in the Local Health Authority 8 District (Veneto, Italy) were queried for tick-bite and TBD-related visits between January 2017 and December 2022. Hospitalisations were also collected. Events involving the resident population were used to calculate incidence rates. A total of 4187 ED visits for tick-bite and 143 for TBD were recorded; in addition, 62 TBD-related hospitalisations (of which 72.6% in over 50 s and 22.6% in over 65 s). ED visits peaked in spring and in autumn, followed by a 4-week lag in the increase in hospital admissions. The small-area analysis identified two areas at higher risk of bites and TBD. The use of a EDSyS system allowed two natural foci to be identified. This approach proved useful in predicting temporal and geographic risk of TBD and in identifying local endemic areas, thus enabling an effective multidisciplinary prevention strategy.

Emergency Department Visits for Tick Bites - United States, January 2017-December 2019

The incidence of tickborne diseases in the United States is increasing; reported cases more than doubled from >22,000 in 2004 to >48,000 in 2016 (1). Ticks are responsible for approximately 95% of all locally acquired vectorborne diseases reported by states and the District of Columbia, with Lyme disease accounting for >80% of those cases (2). After a tick bite, persons might seek care at an emergency department (ED) for tick removal and to receive postexposure prophylaxis, which has been shown to effectively prevent Lyme disease when taken within 72 hours of a high-risk bite (3). Using data from CDC's National Syndromic Surveillance Program (NSSP), investigators examined ED tick bite visits during January 2017-December 2019 by sex, age group, U.S. region, and seasonality. During this 36-month period, 149,364 ED tick bite visits were identified. Mean cumulative incidence was 49 ED tick bite visits per 100,000 ED visits overall; incidence was highest in the Northeast (110 per 100,000 ED visits). The seasonal distribution of ED tick bite visits was bimodal: the larger peak occurred during the spring and early summer, and the smaller peak occurred in the fall. This pattern aligns with the seasonality of a known and abundant human-biter, the blacklegged tick, Ixodes scapularis (4). Compared with other age groups, pediatric patients aged 0-9 years accounted for the highest number and incidence of ED tick bite visits; incidence was higher among male patients than among females. Tick bites are not monitored by current surveillance systems because a tick bite is an event that in and of itself is not a reportable condition to health departments. Syndromic surveillance of ED tick bite visits can provide timely information that might predict temporal and geographic risk for exposure to tickborne diseases and guide actionable public health messaging such as avoiding tick habitats, wearing repellent consistently when outdoors, and performing regular tick checks during times of increased tick bite risk.

Assessing Public Tick Identification Ability and Tick Bite Riskiness Using Passive Photograph-Based Crowdsourced Tick Surveillance

Tick identification is critical for assessing disease risk from a tick bite and for determining requisite treatment. Data from the University of Rhode Island's TickEncounter Resource Center's photo-based surveillance system, TickSpotters, indicate that users incorrectly identified their submitted specimen 83% of the time. Of the top four most commonly submitted tick species, western blacklegged ticks (Ixodes pacificus Cooley & Kohls [Ixodida: Ixodidae]) had the largest proportion of unidentified or misidentified submissions (87.7% incorrectly identified to species), followed by lone star ticks (Amblyomma americanum Linneaus [Ixodida: Ixodidae]; 86.8% incorrect), American dog ticks (Dermacentor variabilis Say [Ixodida: Ixodidae]; 80.7% incorrect), and blacklegged ticks (Ixodes scapularis Say [Ixodida: Ixodidae]; 77.1% incorrect). More than one quarter of participants (26.3%) submitted photographs of ticks that had been feeding for at least 2.5 d, suggesting heightened risk. Logistic regression generalized linear models suggested that participants were significantly more likely to misidentify nymph-stage ticks than adult ticks (odds ratio [OR] = 0.40, 95% confidence interval [CI]: 0.23, 0.68, P < 0.001). Ticks reported on pets were more likely to be identified correctly than those found on humans (OR = 1.07, 95% CI: 1.01-2.04, P < 0.001), and ticks feeding for 2.5 d or longer were more likely to be misidentified than those having fed for one day or less (OR = 0.43, 95% CI: 0.29-0.65, P < 0.001). State and region of residence and season of submission did not contribute significantly to the optimal model. These findings provide targets for future educational efforts and underscore the value of photograph-based tick surveillance to elucidate these knowledge gaps.

Incidence of Lyme Disease Diagnosis in a Maryland Medicaid Population, 2004-2011

The epidemiology of Lyme disease has been examined utilizing insurance claims from privately insured individuals; however, it is unknown whether reported patterns vary among the publicly insured. We examined trends in incidence rates of first Lyme disease diagnosis among 384,652 Maryland Medicaid recipients enrolled from July 2004 to June 2011. Age-, sex-, county-, season-, and year-specific incidence rates were calculated, and mixed-effects multiple logistic regression models were used to study the relationship between Lyme disease diagnosis and these variables. The incidence rate in our sample was 97.65 cases per 100,000 person-years (95% confidence interval (CI): 91.53, 104.06), and there was a 13% average annual increase in the odds of a Lyme disease diagnosis (odds ratio = 1.13, 95% CI: 1.09, 1.17; P < 0.001). Incidence rates for males and females were not significantly different, though males were significantly more likely to be diagnosed during high-season months (relative risk (RR) = 1.24, 95% CI: 1.06, 1.44) and less likely to be diagnosed during low-season months (RR = 0.63, 95% CI: 0.46, 0.87) than females. Additionally, adults were significantly more likely than children to be diagnosed during low-season months (RR = 1.59, 95% CI: 1.19, 2.12). While relatively rare in this study sample, Lyme disease diagnoses do occur in a Medicaid population in a Lyme-endemic state.