Exposure to Borrelia burgdorferi and Other Tick-Borne Pathogens in Gettysburg National Military Park, South-Central Pennsylvania, 2009

Vector borne and zoonotic diseases (Larchmont, N.Y.) (Impact Factor: 2.3). 04/2014; 14(4). DOI: 10.1089/vbz.2013.1363
Source: PubMed


Abstract Since 1998, Lyme disease cases have increased in south-central Pennsylvania, which includes Gettysburg National Military Park (NMP). Limited information is available about tick populations or pathogens in this area, and no data regarding frequency of tick bites or prevention measures among Gettysburg NMP employees are available. To address these gaps, ticks were collected, classified, and replaced (to minimize disruptions to tick populations) at two sites within Gettysburg NMP during April-September, 2009, among eight nonremoval samplings. On two additional occasions during May and June, 2009, ticks were collected and removed from the two original sites plus 10 additional sites and tested for tick-borne pathogens by using PCR. A self-administered anonymous survey of Gettysburg NMP employees was conducted to determine knowledge, attitudes, and practices regarding tick-borne diseases. Peak Ixodes scapularis nymph populations were observed during May-July. Of 115 I. scapularis ticks tested, 21% were infected with Borrelia burgdorferi, including 18% of 74 nymphs and 27% of 41 adults; no other pathogen was identified. The entomologic risk index was calculated at 1.3 infected nymphs/hour. An adult and nymph Amblyomma americanum were also found, representing the first confirmed field collection of this tick in Pennsylvania, but no pathogens were detected. The survey revealed that most park employees believed Lyme disease was a problem at Gettysburg NMP and that they frequently found ticks on their skin and clothing. However, use of personal preventive measures was inconsistent, and 6% of respondents reported contracting Lyme disease while employed at Gettysburg NMP. These findings indicate a need to improve surveillance for tick bites among employees and enhance prevention programs for park staff and visitors.

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Available from: Ellen Stromdahl, Oct 13, 2014
    • "The 47.4% prevalence rate of B. burgdorferi in this study is consistent with the 42–52% rates found previously in Pennsylvania by Courtney et al. (2003) and Steiner et al. (2008) and the neighboring states of Maryland, New Jersey, and New York, where Lyme disease is hyperendemic (Amerasinghe and Scott 1993, Varde et al. 1998, Schulze et al. 2003, Steiner et al. 2008). However, it is higher than the 26.8% reported by Han et al. (2014) for southcentral Pennsylvania, 14.7% by Lord et al. (1992) for northwest Pennsylvania, and 4.3% by Cherepko et al. (2010) for northeast Pennsylvania. A recent study in Ohio, which borders Pennsylvania to the west and is not currently considered an endemic state, showed a much lower rate of 2.4% infection from questing adult ticks (Wang et al. 2014). "
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    ABSTRACT: The etiological agents responsible for Lyme disease (Borrelia burgdorferi), human granulocytic anaplasmosis (Anaplasma phagocytophilum), and babesiosis (Babesia microti) are primarily transmitted by the blacklegged tick, Ixodes scapularis Say. Despite Pennsylvania having in recent years reported the highest number of Lyme disease cases in the United States, relatively little is known regarding the geographic distribution of the vector and its pathogens in the state. Previous attempts at climate-based predictive modeling of I. scapularis occurrence have not coincided with the high human incidence rates in parts of the state. To elucidate the distribution and pathogen infection rates of I. scapularis, we collected and tested 1,855 adult ticks statewide from 2012 to 2014. The presence of I. scapularis and B. burgdorferi was confirmed from all 67 Pennsylvania counties. Analyses were performed on 1,363 ticks collected in the fall of 2013 to avoid temporal bias across years. Infection rates were highest for B. burgdorferi (47.4%), followed by Ba. microti (3.5%) and A. phagocytophilum (3.3%). Coinfections included B. burgdorferi + Ba. microti (2.0%), B. burgdorferi + A. phagocytophilum (1.5%) and one tick positive for A. phagocytophilum + Ba. microti. Infection rates for B. burgdorferi were lower in the western region of the state. Our findings substantiate that Lyme disease risk is high throughout Pennsylvania. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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