Increasing Prevalence of<i>Borrelia burgdorferi</i>sensu stricto–Infected Blacklegged Ticks in Tennessee Valley, Tennessee, USA

Hickling, Graham J.; Kelly, Janetta Renea; Auckland, Lisa D.; Hamer, Sarah A.

doi:10.3201/eid2409.180343

Cited by 21 publications

(13 citation statements)

References 14 publications

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“…However, the situation is complicated by the history of I. scapularis in North America, which has been characterized by range expansions from refugia in the northeastern coastal states and northern midwestern sites [41]. Indeed, recent studies have identified expansion of northern-type ticks south along the Appalachian Mountains of southwestern Virginia [42] and possibly in river valleys in northeastern Tennessee [43]. These ticks might act like northern ticks, resulting in an initial increase in the incidence of Lyme disease in the south.…”

Section: Plos Biologymentioning

confidence: 99%

Why Lyme disease is common in the northern US, but rare in the south: The roles of host choice, host-seeking behavior, and tick density

et al. 2021

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Lyme disease is common in the northeastern United States, but rare in the southeast, even though the tick vector is found in both regions. Infection prevalence of Lyme spirochetes in host-seeking ticks, an important component to the risk of Lyme disease, is also high in the northeast and northern midwest, but declines sharply in the south. As ticks must acquire Lyme spirochetes from infected vertebrate hosts, the role of wildlife species composition on Lyme disease risk has been a topic of lively academic discussion. We compared tick–vertebrate host interactions using standardized sampling methods among 8 sites scattered throughout the eastern US. Geographical trends in diversity of tick hosts are gradual and do not match the sharp decline in prevalence at southern sites, but tick–host associations show a clear shift from mammals in the north to reptiles in the south. Tick infection prevalence declines north to south largely because of high tick infestation of efficient spirochete reservoir hosts (rodents and shrews) in the north but not in the south. Minimal infestation of small mammals in the south results from strong selective attachment to lizards such as skinks (which are inefficient reservoirs for Lyme spirochetes) in the southern states. Selective host choice, along with latitudinal differences in tick host-seeking behavior and variations in tick densities, explains the geographic pattern of Lyme disease in the eastern US.

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Section: Plos Biologymentioning

confidence: 99%

Why Lyme disease is common in the northern US, but rare in the south: The roles of host choice, host-seeking behavior, and tick density

et al. 2021

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“…The cause of this disparity is not entirely understood; however, it is suspected that differences in host ecology and/or tick questing or feeding behavior may play a role 27,28 . Recently, however, there have been increased/first detections of B. burgdorferi -infected I. scapularis in some southeastern states (i.e., Kentucky and Tennessee) so continued surveillance is warranted 29,30 .…”

Section: Discussionmentioning

confidence: 99%

Frequent Prescribed Fires Can Reduce Risk of Tick-borne Diseases

Gleim

Zemtsova

Berghaus

et al. 2019

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Recently, a two-year study found that long-term prescribed fire significantly reduced tick abundance at sites with varying burn regimes (burned surrounded by burned areas [BB], burned surrounded by unburned areas [BUB], and unburned surrounded by burned areas [UBB]). In the current study, these ticks were tested for pathogens to more directly investigate the impacts of long-term prescribed burning on human disease risk. A total of 5,103 ticks (4,607 Amblyomma americanum , 76 Amblyomma maculatum , 383 Ixodes scapularis , two Ixodes brunneus , and 35 Dermacentor variabilis ) were tested for Borrelia spp., Rickettsia spp., Ehrlichia spp., and Anaplasma phagocytophilum . Long-term prescribed fire did not significantly impact pathogen prevalence except that A. americanum from burned habitats had significantly lower prevalence of Rickettsia (8.7% and 4.6% for BUB and UBB sites, respectively) compared to ticks from control sites (unburned, surrounded by unburned [UBUB])(14.6%). However, during the warm season (spring/summer), encounter rates with ticks infected with pathogenic bacteria was significantly lower (98%) at burned sites than at UBUB sites. Thus, despite there being no differences in pathogen prevalence between burned and UBUB sites, risk of pathogen transmission is lower at sites subjected to long-term burning due to lower encounter rates with infected ticks.

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“…Our analysis of canine serologic data confirmed increasing trends in seroprevalence of Bb and Anaplasma spp. in several areas, including northern New England, upstate New York, and western Pennsylvania, as well as in some southern states where the I. scapularis-pathogen-reservoir host maintenance cycles necessary to maintain these agents have apparently only recently become established [26,27]. Interestingly, the data in the present study also documented for the first time decreasing trends in canine seroprevalence for these tick-borne agents in some regions, including in several Mid-Atlantic States and in the Midwest where autochthonous transmission of Bb and Ap has long been recognized.…”

Section: Discussionmentioning

confidence: 99%

Trends in canine seroprevalence to Borrelia burgdorferi and Anaplasma spp. in the eastern USA, 2010–2017

et al. 2019

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Background Borrelia burgdorferi and Anaplasma phagocytophilum are tick-borne infections transmitted by Ixodes scapularis in the eastern USA; both agents cause disease in dogs and people. To characterize changes in seroprevalence over time, Cochran Armitage trend tests were used to evaluate percent positive test results for antibodies to B. burgdorferi and Anaplasma spp. in approximately 20 million canine tests from 2010–2017 in 25 states and 905 counties in the eastern USA. Results A significant decreasing trend in seroprevalence to B. burgdorferi was evident in eight states along the mid-Atlantic coast from Virginia to New Hampshire, and in Wisconsin. In contrast, a continued increasing trend was evident in five northeastern and Midwestern states where Lyme borreliosis is endemic or emerging, as well as in three southern states where endemicity has not yet been widely established. Similarly, seroprevalence to Anaplasma spp. showed a significant, although smaller, decreasing trend in five states along the mid-Atlantic coast from Virginia to Connecticut and Rhode Island, as well as in Minnesota and Wisconsin in the Midwest; despite the fact that those trends were significant they were weak. However, a strong increasing trend was evident in Massachusetts and three states in northern New England as well as in Pennsylvania. Conclusions As expected, seroprevalence continued to increase in regions where Lyme borreliosis and anaplasmosis are more newly endemic. However, the declining seroprevalence evident in other areas was not anticipated. Although the reasons for the decreasing trends are not clear, our finding may reflect shifting ecologic factors that have resulted in decreased infection risk or the combined positive influence of canine vaccination, tick control, and routine testing of dogs in regions where these infections have long been endemic. Analysis of trends in canine test results for tick-borne infections continues to be a valuable tool to understand relative geographical and temporal risk for these zoonotic agents.

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Increasing Prevalence ofBorrelia burgdorferisensu stricto–Infected Blacklegged Ticks in Tennessee Valley, Tennessee, USA

Cited by 21 publications

References 14 publications

Why Lyme disease is common in the northern US, but rare in the south: The roles of host choice, host-seeking behavior, and tick density

Why Lyme disease is common in the northern US, but rare in the south: The roles of host choice, host-seeking behavior, and tick density

Frequent Prescribed Fires Can Reduce Risk of Tick-borne Diseases

Trends in canine seroprevalence to Borrelia burgdorferi and Anaplasma spp. in the eastern USA, 2010–2017

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