Does Lyme disease occur in the south?: a survey of emerging tick-borne infections in the region

Survey of veterinarians' perceptions of borreliosis in North Carolina

OBJECTIVE--To evaluate the practices and perceptions of veterinarians in North Carolina regarding borreliosis in dogs in various geographic regions of the state. DESIGN--Cross-sectional survey. SAMPLE--Data from 208 completed surveys. PROCEDURES--Surveys were distributed to veterinary clinics throughout North Carolina. Descriptive statistics were used to summarize perceptions pertaining to borreliosis among dogs in North Carolina. RESULts--A significantly higher proportion of responding veterinarians believed that borreliosis was endemic in the coastal (67.2%) and Piedmont (60.9%) areas of North Carolina, compared with more western regions (37.5%). The 3 variables found to be significantly different between the northern and southern regions of the state were the estimated number of borreliosis cases diagnosed by each responding veterinary clinic during the past year, the perception of borreliosis endemicity, and the perceptions related to the likelihood of a dog acquiring borreliosis in the state. CONCLUSIONS AND CLINICAL RELEVANCE--Veterinarians' perception of the risk of borreliosis in North Carolina was consistent with recent scientific reports pertaining to geographic expansion of borreliosis in the state. As knowledge of the epidemiological features of borreliosis in North Carolina continues to evolve, veterinarians should promote routine screening of dogs for Borrelia burgdorferi exposure as a simple, inexpensive form of surveillance that can be used to better educate their clients on the threat of transmission of borreliosis in this transitional geographic region.

The dog as a sentinel for human infection: prevalence of Borrelia burgdorferi C6 antibodies in dogs from southeastern and mid-Atlantic States

Lyme disease is the most frequently reported human vector-associated disease in the United States. Infection occurs after the bite of an Ixodid tick that is infected with Borrelia burgdorferi. Dogs have often been reported to serve as effective sentinel animals to assess the risk of human B. burgdorferi infection. Based on published data of human Lyme disease case numbers and our clinical impressions, we hypothesized that canine exposure to B. burgdorferi would be lower in North Carolina when compared to the exposure in Virginia, Maryland, and Pennsylvania. To address this hypothesis, we evaluated B. burgdorferi exposure status utilizing a specific and sensitive C6 peptide-based enzyme-linked immunosorbent assay. Our convenience sample included 1,666 canine serum samples submitted to the Vector-Borne Disease Diagnostic Laboratory from North Carolina (n = 987), Virginia (n = 472), Maryland (n = 167), and Pennsylvania (n = 40). Comparisons among states were made using the Chisquare test or the Fisher's exact test; p-values were adjusted for multiple comparisons using the Bonferroni correction. A Chi-square test for trend was used to determine if there was an increase in the frequency of seroreactors associated with the geographical origin of the samples. The proportion of seroreactive dogs in North Carolina was markedly lower (p < 0.008) than that observed in dogs from Virginia, Maryland, and Pennsylvania. These results support the hypothesis that B. burgdorferi transmission seems to occur infrequently in North Carolina dogs as compared to dogs residing in other southeastern and mid-Atlantic states. Furthermore, they support the utility of dogs as a sentinel to characterize the risk of B. burgdorferi transmission to humans in a defined geographical location.

Rapid Detection Methods and Prevalence Estimation forBorrelia lonestari glpQinAmblyomma americanum(Acari: Ixodidae) Pools of Unequal Size

DNA was extracted from pools of Amblyomma americanum ticks collected from vegetation at two sites in Fort Leonard Wood, Missouri and tested for the presence of Borrelia spp. Two new methods were developed to detect Borrelia lonestari DNA by targeting the glycerophosphodiester phosphodiesterase (glpQ) gene. The first method detected B. lonestari DNA using a SYBR green I melting curve analysis of the PCR product obtained with glpQ gene primers. The second method, a glpQ TaqMan assay, detected and confirmed the presence of B. lonestari glpQ-specific sequences. Twenty-two of 95 tick pools collected at site A148 contained B. lonestari DNA. None of 19 pools from site A241 contained B. lonestari DNA. No B. burgdorferi sensu lato DNA was detected using a SYBR green I melting curve analysis of the PCR product obtained with outer surface protein A (ospA) primers. The overall B. lonestari infection prevalence (with 95% confidence interval) at site A148 was estimated using two algorithms: minimum infection rate 4.14% (2.45, 5.84) and maximum likelihood with correction 4.82% (3.11, 7.16). The merits of each are discussed. Sequencing of the entire B. lonestari glpQ and partial 16S rRNA genes revealed two genetic variants circulating in this population of A. americanum from Missouri.

The dog as a sentinel for human infection: prevalence of Borrelia burgdorferi C6 antibodies in dogs from southeastern and mid-Atlantic states

Lyme disease is the most frequently reported human vector-associated disease in the United States. Infection occurs after the bite of an Ixodid tick that is infected with Borrelia burgdorferi. Dogs have often been reported to serve as effective sentinel animals to assess the risk of human B. burgdorferi infection. Based on published data of human Lyme disease case numbers and our clinical impressions, we hypothesized that canine exposure to B. burgdorferi would be lower in North Carolina when compared to the exposure in Virginia, Maryland, and Pennsylvania. To address this hypothesis, we evaluated B. burgdorferi exposure status utilizing a specific and sensitive C6 peptide-based enzyme-linked immunosorbent assay. Our convenience sample included 1,666 canine serum samples submitted to the Vector Borne Disease Diagnostic Laboratory from North Carolina (n = 987), Virginia (n = 472), Maryland (n = 167), and Pennsylvania (n = 40). Comparisons among states were made using the Chi-square test or the Fisher's exact test; p-values were adjusted for multiple comparisons using the Bonferroni correction. A Chi-square test for trend was used to determine if there was an increase in the frequency of seroreactors associated with the geographical origin of the samples. The proportion of seroreactive dogs in North Carolina was markedly lower (p < 0.008) than that observed in dogs from Virginia, Maryland, and Pennsylvania. These results support the hypothesis that B. burgdorferi transmission seems to occur infrequently in North Carolina dogs as compared to dogs residing in other southeastern and mid-Atlantic states. Furthermore, they support the utility of dogs as a sentinel to characterize the risk of B. burgdorferi transmission to humans in a defined geographical location.

Emerging tick-borne infections: rediscovered and better characterized, or truly ‘new’?

The emergence of Lyme borreliosis as a public health burden within the last two decades has stimulated renewed interest in tick-borne infections. This attention towards ticks, coupled with advances in detection technologies, has promoted the recognition of diverse emergent or potentially emerging infections, such as monocytic and granulocytic ehrlichiosis, local variants of spotted fever group rickettsioses, WA-1 babesiosis, or a Lyme disease mimic (Masters' Disease). The distribution of pathogens associated with well-described tick-borne zoonoses such as human babesiosis due toBabesia microtiorB.divergensseems wider than previously thought. Bartonellae, previously known to be maintained by fleas, lice or sandflies, have been detected within ticks. Purported ‘new’ agents, mainly identified by sequencing of PCR products and comparison with those sequences present in GenBank, are being increasingly reported from ticks. We briefly review the diversity of these infectious agents, identify aetiological enigmas that remain to be solved, and provide a reminder about ‘old friends’ that should not be forgotten in our pursuit of novelty. We suggest that newly recognised agents or tick/pathogen associations receive careful scrutiny before being declared as potential public health burdens.

Glycerophosphodiester phosphodiesterase gene (glpQ) of Borrelia lonestari identified as a target for differentiating Borrelia species associated with hard ticks (Acari:Ixodidae)

A glpQ ortholog was identified in DNA from Borrelia lonestari-positive Amblyomma americanum, providing further evidence that B. lonestari is more closely related to the relapsing fever group spirochetes than to borreliae that cause Lyme disease. This finding provides a basis for developing diagnostic assays to differentiate species of borrelia transmitted by hard ticks.

DNA evidence of Borrelia lonestari in Amblyomma americanum (Acari: Ixodidae) in southeast Missouri

Amblyomma americanum collected near Lake Wappapello, Missouri, tested positive for Borrelia lonestari using polymerase chain reaction and sequence analyses of B. lonestari 16S rRNA and flagellin (flaB) genes. Twelve pools containing a total of 214 nymph or adult ticks contained evidence of infection with B. lonestari (minimum prevalence 5.6%). These data suggest that persons in southeast Missouri are at risk for exposure to B. lonestari after A. americanum tick bite, a possible cause of erythema migrans-like rash illness in this region. Derivation of the complete coding sequence for B. lonestari flaB is also reported.

Detection of Borrelia lonestari, putative agent of southern tick-associated rash illness, in white-tailed deer (Odocoileus virginianus) from the southeastern United States

To determine if white-tailed deer may serve as a reservoir host for Borrelia lonestari, we used a nested PCR for the Borrelia flagellin gene to evaluate blood samples collected from deer from eight southeastern states. Seven of 80 deer (8.7%) from 5 of 17 sites (29.4%) had sequence-confirmed evidence of a B. lonestari flagellin gene by PCR, indicating that deer are infected with B. lonestari or another closely related Borrelia species. Our findings expand the known geographic range of B. lonestari and provide the first evidence of this organism in a vertebrate other than humans.

Patterns of Lyme disease diagnosis and treatment by family physicians in a southeastern state

This study examined how often physicians in Georgia diagnose and treat Lyme disease as well as the criteria they use to reach a diagnosis of Lyme disease. A survey was sent to 1,331 family physicians in Georgia concerning how many cases of Lyme disease the physicians diagnosed, and the criteria used to make the diagnosis, during the preceding 12 months. Of 710 responses, 167 physicians treated 316 cases of Lyme disease without a firm diagnosis. In addition, 125 physicians diagnosed 262 cases of Lyme disease, 130 without serologic testing and 132 with serologic testing. Family Physicians in Georgia diagnose Lyme disease at a rate 40 times greater than the surveillance case rate reported in Georgia.

Lone star tick-infecting borreliae are most closely related to the agent of bovine borreliosis

Although Borrelia theileri, the agent of bovine borreliosis, was described at the turn of the century (in 1903), its relationship with borreliae causing Lyme disease or relapsing fever remains undescribed. We tested the previously published hypothesis that spirochetes infecting Lone Star ticks (Amblyomma americanum) may comprise B. theileri by analyzing the 16S ribosomal DNAs (rDNAs) and flagellin genes of these spirochetes. B. theileri, the Amblyomma agent, and B. miyamotoi formed a natural group or clade distinct from but most closely related to that of the relapsing fever spirochetes. B. theileri and the Amblyomma agent were 97 and 98% similar at the nucleotide level within the analyzed portions of the 16S rDNA and the flagellin gene respectively, suggesting a recent divergence. The agent of bovine borreliosis might be explored as a surrogate antigen for the as-yet-uncultivatable Amblyomma agent in studies designed to explore the etiology of a Lyme disease-like infection associated with Lone Star ticks.

Isolation, cultivation, and characterization of Borrelia burgdorferi from rodents and ticks in the Charleston area of South Carolina

Twenty-eight Borrelia burgdorferi isolates from the Charleston, S.C., area are described. This represents the first report and characterization of the Lyme disease spirochete from that state. The isolates were obtained from December 1994 through December 1995 from the tick Ixodes scapularis, collected from vegetation, and from the rodents Peromyscus gossypinus (cotton mouse), Neotoma floridana (eastern wood rat), and Sigmodon hispidus (cotton rat). All isolates were screened immunologically by indirect immunofluorescence with monoclonal antibodies to B. burgdorferi-specific outer surface protein A (OspA) (antibodies H5332 and H3TS) and B. burgdorferi-specific OspB (antibodies H6831 and H614), a Borrelia (genus)-specific antiflagellin antibody (H9724), Borrelia hermsii-specific antibodies (H9826 and H4825), and two polyclonal antibodies (one to Borrelia species and another to B. burgdorferi). Six of the isolates were analyzed by exposing Western blots to monoclonal antibodies H5332, H3TS, H6831, and H9724. All isolates were also analyzed by PCR with five pairs of primers known to amplify selected DNA target sequences specifically reported to be present in the reference strain, B. burgdorferi B-31. The protein profiles of six of the isolates (two from ticks, one from a cotton mouse, two from wood rats, and one from a cotton rat) also were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We conclude that the 28 Charleston isolates are B. burgdorferi sensu stricto based on their similarities to the B. burgdorferi B-31 reference strain.