No abstract

Lyme disease (LD) is the most common vector-borne disease in Maryland and the United States. Surveillance for LD is valuable for understanding the burden of the disease, particularly to assess whether the disease is spreading and to appreciate who is affected. However, not all cases of LD in Maryland are reported, and surveillance practices vary across each of Maryland's 24 local health departments (LHDs). To better understand this variability and to systematically characterize the surveillance process, we surveyed Maryland's LHDs regarding LD surveillance. The Maryland Local Health Department Lyme Disease Surveillance Survey has been administered annually since 2011. Questions asked each year included whether all LD reports are investigated or only a subset, and how many reports are not entered into the surveillance database. Since 2011, Maryland has lost surveillance personnel for LD. Each year from 2009 to 2012, a median 3598 (range 2462 to 5722) reports were not entered into the surveillance database and hence not investigated. These reports represent 43-55% of all reports received for the year. Over time, more LHDs chose to streamline their LD investigation approach by investigating only those reports that met the criteria for laboratory evidence of infection: in 2008, 5 (21%) LHDs investigated only a subset of LD reports; by 2013, this increased to 15 (63%). There is wide variability across LHDs in how LD investigations are conducted. Maryland LHDs have experienced a loss of LD surveillance personnel with a concomitant increase in the number of LHDs adopting a streamlined approach to investigating cases. These findings underscore the tremendous burden of LD on the public health agencies and highlight the need for alternative approaches that can both reduce burden and preserve surveillance data quality.

L yme disease is a bacterial illness caused primarily by infection with Borrelia burgdorferi, transmitted by the bite of infected Ixodes scapularis and I. pacificus ticks in the United States. Early symptoms can include a rash known as erythema migrans and influenza-like symptoms (1). Disseminated infection can cause neurologic, musculoskeletal, and cardiac complications; in rare cases, cardiac involvement can be fatal (1-4). Most patients will experience a full recovery after antibiotic treatment, although a minority may continue to experience symptoms related to disease sequelae (1).Lyme disease case numbers consistently rank in the top 10 among all nationally notifiable conditions, and it is the most commonly reported vector-borne disease in the United States (4,5). Annually, >30,000 cases are reported to the Centers for Disease Control and Prevention (4), but recent studies have demonstrated that the annual number of diagnosed cases is ≈476,000 (6). This figure represents a substantial disease burden, but the total economic cost to US society is unknown (7).Economic evaluations for Lyme disease have limitations (7). Most studies report direct medical costs but lack data on nonmedical costs and losses in productivity (8)(9)(10)(11). Several studies were conducted >2 decades ago in a few Maryland counties where Lyme disease was emerging (9,11,12); however, this limited scope prevents generalizability to other areas in which the disease is endemic, and results might not be representative of today's costs because of changes in disease management and healthcare structures. More recent studies have used diagnosis codes (e.g., International Classification of Diseases, 9th Revision, Clinical Modification) to identify Lyme disease patients from insurance claims databases. However, the low sensitivity and specificity of these codes in identifying actual cases (13,14) might lead to incorrect estimates of direct medical costs attributable to the disease. The few studies that provide more comprehensive cost estimates of Lyme disease were conducted in Europe under healthcare systems with financing structures different from those of the United States (15-17). As such, updated estimates of the total

In Maryland, Lyme disease (LD) is a reportable disease and all laboratories and healthcare providers are required to report to the local health department. Given the volume of LD reports and effort required for investigation, surveillance for LD is burdensome and subject to underreporting. We explored the utility of International Classification of Diseases, 9th Revision, Clinical Modification (administrative) codes for use with LD surveillance. We aimed to collect the administrative codes for a 10% sample of 2009 LD reports (n = 474) from 292 facilities stratified by case classification (confirmed, probable, suspected and not a case). Sixty-three per cent (n = 184) of facilities responded to the survey, and 341 different administrative codes were obtained for 91% (n = 430) of sampled reports. The administrative code for Lyme disease (088.81) was the most commonly reported code (133/430 patients) among sampled reports; while it was used for 62 of 151 (41%) confirmed cases, it was also used for 48 of 192 (25%) not a case reports (sensitivity 41% and specificity 73%). A combination of nine codes was developed with sensitivity of 74% and specificity of 37% when compared to not a case reports. We conclude that the administrative code for LD alone has low ability to identify LD cases in Maryland. Grouping certain codes improved sensitivity, but our results indicate that administrative codes alone are not a viable surveillance alternative for a disease with complex manifestations such as LD.

In Maryland, Lyme disease (LD) is the most widely reported tickborne disease. All laboratories and healthcare providers are required to report LD cases to the local health department. Given the large volume of LD reports, the nuances of diagnosing and reporting LD, and the effort required for investigations by local health department staff, surveillance for LD is burdensome and subject to underreporting. To determine the degree to which misclassification occurs in Maryland, we reviewed medical records for a sample of LD reports from 2009. We characterized what proportion of suspected and “not a case” reports could be reclassified as confirmed or probable once additional information was obtained from medical record review, explored the reasons for misclassification, and determined multipliers for a more accurate number of LD cases. We reviewed medical records for reports originally classified as suspected (n = 44) and “not a case” (n = 92). Of these 136 records, 31 (23%) suspected cases and “not a case” reports were reclassified. We calculated multipliers and applied them to the case counts from 2009, and estimate an additional 269 confirmed and probable cases, a 13.3% increase. Reasons for misclassification fell into three general categories: lack of clinical or diagnostic information from the provider; surveillance process errors; and incomplete information provided on laboratory reports. These multipliers can be used to calculate a better approximation of the true number of LD cases in Maryland, but these multipliers only account for underreporting due to misclassification, and do not account for cases that are not reported at all (e.g., LD diagnoses based on erythema migrans alone that are not reported) or for cases that are not investigated. Knowing that misclassification of cases occurs during the existing LD surveillance process underscores the complexities of LD surveillance, which further reinforces the need to find alternative approaches to LD surveillance.

Tick-borne diseases (TBDs) are increasing despite prevention recommendations. We explored whether cost is a barrier to prevention use in Connecticut and Maryland, using a cross-sectional survey. Respondents were queried regarding their willingness to pay for chemical, natural, and rodent-targeted yard pesticide treatments and permethrin-treated clothing. We evaluated associations between demographics, TBD knowledge and attitudes, and willingness to pay for prevention methods. Most respondents would pay for yard treatments (85%); 95% preferring natural pesticide, and 82% would pay for permethrin-treated clothing. Most did not want to pay more than $99 for any of the yard treatments. Having a household income of $100 000 was associated with willingness to pay $100 or more for chemical, natural, or rodent-targeted treatments and $25 or more for permethrin self-treated and pretreated clothing. Yard treatments, especially natural pesticides, were acceptable for TBD prevention; however, current pricing may be cost-prohibitive. Permethrin-treated clothing may be an affordable and acceptable prevention method.

We conducted a cross‐sectional study to evaluate associations between pet characteristics and behaviours and risk of tick encounters among pets and pet owners. We defined a tick encounter as ticks found crawling on or attached to a pet or pet owner. Information about pet characteristics, interactions between owners and pets, and tick encounters were captured through an online survey. Associations were evaluated using univariate and multivariable analyses. In univariate analysis, walking dogs only on pavement reduced risk of tick encounter among owners (prevalence ratio (PR) = 0.51, 95% confidence interval (CI): 0.30, 0.84). Having a dog or cat that hunted small animals increased risk of tick encounter among owners (PR = 1.66, 95% CI: 1.30, 2.13; PR = 1.57, 95% CI: 1.05, 2.34, respectively). No direct interactions between owners and pets (e.g., pets sleeping on owners' beds) were associated with increased risk of tick encounters among owners. In multivariable analysis among dog owners, having a pet with a tick encounter within the last six months was associated with increased risk of owner tick encounter (adjusted odds ratio (aOR) = 4.17, 95% CI: 2.94, 5.92); in addition, having a dog that hunts small animals was associated with increased risk of owner tick encounter (aOR = 1.97, 95% CI: 1.25, 3.11). These results suggest that the location of pet‐owner interactions may be more important than the type of interactions. Pet owners should avoid tick habitat with pets; when that is not possible, proper use of tick preventive products for pets, wearing repellents by owners and conducting tick checks for both pets and owners is critical for prevention of tick encounters and tick‐borne disease.

No abstract