Lyme Disease, Virginia, USA, 2000–2011

Brinkerhoff, R. Jory; Gilliam, Will F.; Gaines, David N.

doi:10.3201/eid2010.130782

Cited by 39 publications

(39 citation statements)

References 32 publications

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“…Given the lack of systematic surveillance for I. scapularis , one might ask if the range expansion suggested by our data is real or merely an artifact of enhanced tick surveillance and research activities in some areas. A true range expansion of I. scapularis in northern states, as described in this report, is supported by the largely concordant changes in the distribution of human Lyme disease cases captured through mandatory reporting of the disease since 1991 (Rand et al 2007, Raizman et al 2012, Lee et al 2013, Serra et al 2013, Brinkerhoff et al 2014, Robinson et al 2014, Wang et al 2014, Kugeler et al 2015, Mead 2015). Moreover, as detailed later in the text, true range expansions of I. scapularis have been documented in some areas where tick surveillance was conducted routinely during the period of emergence, or where extensive surveys were conducted at discrete time-points spanning periods from when the tick was absent through invasion and establishment.…”

Section: Discussionsupporting

confidence: 66%

“…Review of Lyme disease and I. scapularis surveillance reports (see references in Table 2) suggests that the tick is expanding westward across the state, with highly Lyme disease endemic counties still focused in the eastern panhandle. Similarly, in Virginia, I. scapularis was considered established primarily in eastern coastal counties previously (Dennis et al 1998), but the current survey shows the tick to now be established throughout most of Virginia, with the highest densities of openly host-seeking ticks occurring in higher elevation sites (Brinkerhoff et al 2014, Kelly et al 2014). The spread of openly host-seeking I. scapularis appears to have proceeded in a southwesterly direction in Virginia, concordant with the expanding geographic distribution of Lyme disease cases and increasing incidence in Virginia (Brinkerhoff et al 2014, Lantos et al 2015).…”

Section: Discussionmentioning

confidence: 79%

“…Rising case counts and geographical expansion of Lyme disease endemic areas have been attributed to range expansion of I. scapularis in the eastern United States (Bacon et al 2008, Rydzewski et al 2012, Lee et al 2013, Brinkerhoff et al 2014, Robinson et al 2014, Wang et al 2014, Khatchikian et al 2015, Kugeler et al 2015, Stone et al 2015). However, because of a lack of systematic surveillance of I. scapularis and I. pacificus , national trends in the geographic distribution of these medically important ticks are difficult to document.…”

mentioning

confidence: 99%

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County-Scale Distribution ofIxodes scapularisandIxodes pacificus(Acari: Ixodidae) in the Continental United States

2016

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The blacklegged tick, Ixodes scapularis Say, is the primary vector to humans in the eastern United States of the Lyme disease spirochete Borrelia burgdorferi, as well as causative agents of anaplasmosis and babesiosis. Its close relative in the far western United States, the western blacklegged tick Ixodes pacificus Cooley and Kohls, is the primary vector to humans in that region of the Lyme disease and anaplasmosis agents. Since 1991, when standardized surveillance and reporting began, Lyme disease case counts have increased steadily in number and in geographical distribution in the eastern United States. Similar trends have been observed for anaplasmosis and babesiosis. To better understand the changing landscape of risk of human exposure to disease agents transmitted by I. scapularis and I. pacificus, and to document changes in their recorded distribution over the past two decades, we updated the distribution of these species from a map published in 1998. The presence of I. scapularis has now been documented from 1,420 (45.7%) of the 3,110 continental United States counties, as compared with 111 (3.6%) counties for I. pacificus. Combined, these vectors of B. burgdorferi and other disease agents now have been identified in a total of 1,531 (49.2%) counties spread across 43 states. This marks a 44.7% increase in the number of counties that have recorded the presence of these ticks since the previous map was presented in 1998, when 1,058 counties in 41 states reported the ticks to be present. Notably, the number of counties in which I. scapularis is considered established (six or more individuals or one or more life stages identified in a single year) has more than doubled since the previous national distribution map was published nearly two decades ago. The majority of county status changes occurred in the North-Central and Northeastern states, whereas the distribution in the South remained fairly stable. Two previously distinct foci for I. scapularis in the Northeast and North-Central states appear to be merging in the Ohio River Valley to form a single contiguous focus. Here we document a shifting landscape of risk for human exposure to medically important ticks and point to areas of re-emergence where enhanced vector surveillance and control may be warranted.

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Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 79%

mentioning

confidence: 99%

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County-Scale Distribution ofIxodes scapularisandIxodes pacificus(Acari: Ixodidae) in the Continental United States

2016

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“…First, ticks from Pearisburg, VA, had the highest burden of Borrelia, and the burden was higher than that of ticks from the Northeast, all of which were confirmed to harbor B. burgdorferi sensu stricto. Lyme disease is endemic in the Northeast but has only recently emerged in the part of Virginia where Pearisburg is located (45). Second, ticks from only 5 sites had light Rickettsia burdens (Ͻ20%), and ticks from 3 of these sites were heavily infected with members of the family Enterobacteriaceae.…”

Section: Discussionmentioning

confidence: 99%

Variation in the Microbiota of Ixodes Ticks with Regard to Geography, Species, and Sex

Treuren

Ponnusamy

Brinkerhoff

et al. 2015

Appl Environ Microbiol

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n Ixodes scapularis is the principal vector of Lyme disease on the East Coast and in the upper Midwest regions of the UnitedStates, yet the tick is also present in the Southeast, where Lyme disease is absent or rare. A closely related species, I. affinis, also carries the pathogen in the South but does not seem to transmit it to humans. In order to better understand the geographic diversity of the tick, we analyzed the microbiota of 104 adult I. scapularis and 13 adult I. affinis ticks captured in 19 locations in South Carolina, North Carolina, Virginia, Connecticut, and New York. Initially, ticks from 4 sites were analyzed by 454 pyrosequencing. Subsequently, ticks from these sites plus 15 others were analyzed by sequencing with an Illumina MiSeq machine. By both analyses, the microbiomes of female ticks were significantly less diverse than those of male ticks. The dissimilarity between tick microbiomes increased with distance between sites, and the state in which a tick was collected could be inferred from its microbiota. The genus Rickettsia was prominent in all locations. Borrelia was also present in most locations and was present at especially high levels in one site in western Virginia. In contrast, members of the family Enterobacteriaceae were very common in North Carolina I. scapularis ticks but uncommon in I. scapularis ticks from other sites and in North Carolina I. affinis ticks. These data suggest substantial variations in the Ixodes microbiota in association with geography, species, and sex.

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“…Further research could also explore other environmental variables such as humidity, temperature, and rainfall that could be important indicators for Lyme disease emergence. Brinkerhoff et al (2014) report that human Lyme disease is present at higher elevations in Virginia than anticipated, while Diuk-Wasser et al (2012) found that low elevations, low levels of vapor pressure deficits, and small extremes in minimum temperature were correlated with the presence of nymphs infected with B. burgdorferi in a study across the eastern United States. Estrada-Peña (2002) also reports on the importance of climate variability, particularly increased winter temperatures and higher rainfall, to the creation of suitable habitat for Ixodes scapularis.…”

Section: Future Researchmentioning

confidence: 97%

An Examination of the Demographic and Environmental Variables Correlated with Lyme Disease Emergence in Virginia

et al. 2015

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Lyme disease is the United States' most significant vector-borne illness. Virginia, on the southern edge of the disease's currently expanding range, has experienced an increase in Lyme disease both spatially and temporally, with steadily increasing rates over the past decade and disease spread from the northern to the southwestern part of the state. This study used a Geographic Information System and a spatial Poisson regression model to examine correlations between demographic and land cover variables, and human Lyme disease from 2006 to 2010 in Virginia. Analysis indicated that herbaceous land cover is positively correlated with Lyme disease incidence rates. Areas with greater interspersion between herbaceous and forested land were also positively correlated with incidence rates. In addition, income and age were positively correlated with incidence rates. Levels of development, interspersion of herbaceous and developed land, and population density were negatively correlated with incidence rates. Abundance of forest fragments less than 2 hectares in area was not significantly correlated. Our results support some findings of previous studies on ecological variables and Lyme disease in endemic areas, but other results have not been found in previous studies, highlighting the potential contribution of new variables as Lyme disease continues to emerge southward.

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Lyme Disease, Virginia, USA, 2000–2011

Abstract: Geographic expansion of Ixodes scapularis ticks has increased human exposure to Borrelia burgdorferi.

Cited by 39 publications

References 32 publications

County-Scale Distribution ofIxodes scapularisandIxodes pacificus(Acari: Ixodidae) in the Continental United States

County-Scale Distribution ofIxodes scapularisandIxodes pacificus(Acari: Ixodidae) in the Continental United States

Variation in the Microbiota of Ixodes Ticks with Regard to Geography, Species, and Sex

An Examination of the Demographic and Environmental Variables Correlated with Lyme Disease Emergence in Virginia

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