Can J Microbiol. 2012 Feb 17;
Chaconas G

Lyme borreliosis, also known as Lyme disease, is now the most common vector transmitted disease in the northern hemisphere. It is caused by the spirochete Borrelia burgdorferi and related species. In addition to their clinical importance, these organisms are fascinating to study because of the wide variety of unusual features they possess. Ongoing work in the laboratory in several areas will be described. (1) The segmented genomes contain up to two dozen genetic elements, the majority of which are linear with covalently closed hairpin ends. These linear DNAs also display a very high degree of ongoing genetic rearrangement. Mechanisms for these processes will be described. (2) Persistent infection by Borrelia species requires antigenic variation through a complex DNA rearrangement process at the vlsE locus on the linear plasmid lp28-1. Novel features of this recombination process will be presented. (3) Evidence for a new global regulatory pathway of B. burgdorferi gene expression that is required for pathogenicity will be described. The DEAH box RNA helicase HrpA is involved in this pathway, which may be relevant in other bacteria. (4) The mechanism of B. burgdorferi to effectively disseminate throughout its host is being studied in real time by high resolution intravital imaging in live mice. Recent work will be presented.

Parasitology. 2012 Feb 16; 1-17
Randolph SE, Dobson AD

SUMMARYThe twin concepts of zooprophylaxis and the dilution effect originated with vector-borne diseases (malaria), were driven forward by studies on Lyme borreliosis and have now developed into the mantra "biodiversity protects against disease". The basic idea is that by diluting the assemblage of transmission-competent hosts with non-competent hosts, the probability of vectors feeding on transmission-competent hosts is reduced and so the abundance of infected vectors is lowered. The same principle has recently been applied to other infectious disease systems - tick-borne, insect-borne, indirectly transmitted via intermediate hosts, directly transmitted. It is claimed that the presence of extra species of various sorts, acting through a variety of distinct mechanisms, causes the prevalence of infectious agents to decrease. Examination of the theoretical and empirical evidence for this hypothesis reveals that it applies only in certain circumstances even amongst tick-borne diseases, and even less often if considering the correct metric - abundance rather than prevalence of infected vectors. Whether dilution or amplification occurs depends more on specific community composition than on biodiversity per se. We warn against raising a straw man, an untenable argument easily dismantled and dismissed. The intrinsic value of protecting biodiversity and ecosystem function outweighs this questionable utilitarian justification.

Clin Vaccine Immunol. 2012 Feb 15;
Wagner B, Freer H, Rollins A, Garcia-Tapia D, Erb HN, Earnhart C, Marconi R, Meeus P

Lyme disease in the USA is caused by Borrelia burgdorferi sensu stricto which is transmitted to mammals by infected ticks. Borrelia spirochetes differentially express immunogenic outer surface proteins (Osp). Our aim was to evaluate antibody responses to Osp antigens to aid the diagnosis of early infection and the management of Lyme disease. We analyzed antibody responses during the first 3 months after experimental infection of dogs using a novel multiplex assay. Results were compared to those obtained with two commercial assays detecting C6 antigen. Multiplex analysis identified antibodies to OspC and C6 as early as 3 weeks and those to OspF by 5 weeks post infection (p.i.). Antibodies to C6 and OspF increased throughout the study, while antibodies to OspC peaked between 7-11 weeks p.i. and declined thereafter. A short-term antibody response to OspA was observed in 3/8 experimentally infected dogs on day 21 p.i.. Quant® C6 ELISA results matched multiplex results during the first 7 weeks p.i., however antibody levels subsequently declined by up to 29%. Immune responses were then analyzed in sera from 125 client owned dogs and revealed high agreement between antibodies to OspF and C6 as robust markers for infection. Results from canine patient sera supported that OspC is an early infection marker and antibodies to OspC decline over time. Onset and decline of antibody responses to B. burgdorferi Osp antigens and C6 reflect their differential expression during infection. They provide valuable tools to determine the stage of infection, treatment outcomes and vaccination status in dogs.

Proc Natl Acad Sci U S A. 2012 Feb 6;
Harman MW, Dunham-Ems SM, Caimano MJ, Belperron AA, Bockenstedt LK, Fu HC, Radolf JD, Wolgemuth CW

The Lyme disease spirochete Borrelia burgdorferi exists in nature in an enzootic cycle that involves the arthropod vector Ixodes scapularis and mammalian reservoirs. To disseminate within and between these hosts, spirochetes must migrate through complex, polymeric environments such as the basement membrane of the tick midgut and the dermis of the mammal. To date, most research on the motility of B. burgdorferi has been done in media that do not resemble the tissue milieus that B. burgdorferi encounter in vivo. Here we show that the motility of Borrelia in gelatin matrices in vitro resembles the pathogen's movements in the chronically infected mouse dermis imaged by intravital microscopy. More specifically, B. burgdorferi motility in mouse dermis and gelatin is heterogeneous, with the bacteria transitioning between at least three different motility states that depend on transient adhesions to the matrix. We also show that B. burgdorferi is able to penetrate matrices with pore sizes much smaller than the diameter of the bacterium. We find a complex relationship between the swimming behavior of B. burgdorferi and the rheological properties of the gelatin, which cannot be accounted for by recent theoretical predictions for microorganism swimming in gels. Our results also emphasize the importance of considering borrelial adhesion as a dynamic rather than a static process.

Ticks Tick Borne Dis. 2012 Feb; 3(1): 18-26
McNally KL, Mitzel DN, Anderson JM, Ribeiro JM, Valenzuela JG, Myers TG, Godinez A, Wolfinbarger JB, Best SM, Bloom ME

Ixodid ticks are vectors of human diseases such as Lyme disease, babesiosis, anaplasmosis, and tick-borne encephalitis. These diseases cause significant morbidity and mortality worldwide and are transmitted to humans during tick feeding. The tick-host-pathogen interface is a complex environment where host responses are modulated by the molecules in tick saliva to enable the acquisition of a blood meal. Disruption of host responses at the site of the tick bite may also provide an advantage for pathogens to survive and replicate. Thus, the molecules in tick saliva not only aid the tick in securing a nutrient-rich blood meal, but can also enhance the transmission and acquisition of pathogens. To investigate the effect of feeding and flavivirus infection on the salivary gland transcript expression profile in ticks, a first-generation microarray was developed using ESTs from a cDNA library derived from Ixodes scapularis salivary glands. When the salivary gland transcript profile in ticks feeding over the course of 3 days was compared to that in unfed ticks, a dramatic increase in transcripts related to metabolism was observed. Specifically, 578 transcripts were up-regulated compared to 151 down-regulated transcripts in response to feeding. When specific time points post attachment were analyzed, a temporal pattern of gene expression was observed. When Langat virus-infected ticks were compared to mock-infected ticks, transcript expression changes were observed at all 3 days of feeding. Differentially regulated transcripts include putative secreted proteins, lipocalins, Kunitz domain-containing proteins, anti-microbial peptides, and transcripts of unknown function. These studies identify salivary gland transcripts that are differentially regulated during feeding or in the context of flavivirus infection in Ixodes scapularis nymphs, a medically important disease vector. Further analysis of these transcripts may identify salivary factors that affect the transmission or replication of tick-borne flaviviruses.

Ticks Tick Borne Dis. 2012 Feb; 3(1): 1-7
Probst C, Ott A, Scheper T, Meyer W, Stöcker W, Komorowski L

OspC is the main target for IgM in early-stage Lyme disease. As such it is employed as its native or recombinant form in routine immunoassays for the determination of Borrelia-specific antibodies. However, recombinant OspC has so far not shown the antigenicity of the native protein. The latter contains an intrinsic signal sequence and an adjacent cysteine residue, the attachment site of the lipid membrane anchor which has been discussed to have an adjuvant effect on the immune reaction. In expression experiments, we have found a recombinant variant, an OspC covalently homodimerized via an N-terminal disulfide bridge, that shows a remarkably enhanced antigenicity without lipid attachment. Three such OspCs derived from different Borrelia strains were subsequently expressed in E. coli and purified under non-reducing conditions. In non-reducing SDS-PAGE, OspC(Δ1-18) exhibited a 48-kDa band of dimeric OspC. When incubated with IgM-OspC-positive human sera, the reaction at 48kDa was always stronger than at 24kDa of monomeric OspC(Δ1-18, C19G). A lineblot with OspC(Δ1-18) also showed a higher diagnostic accuracy than that obtained with OspC(Δ1-18, C19G) based on a higher affinity of IgM for the dimeric form. When used for the immunization of mice, dimeric OspC(Δ1-18) induced consistent high-titre antibodies against OspC, whereas OspC(Δ1-18, C19G) failed to provoke significant titres in some animals. We conclude that the disulfide-bridging of 2 OspC molecules via their N termini forms a complex that is more suitable for the determination of IgM-OspC and is a promising candidate for a monovalent vaccine.

J Med Entomol. 2012 Jan; 49(1): 11-22
Eisen RJ, Piesman J, Zielinski-Gutierrez E, Eisen L

Lyme disease is the most commonly reported vector-borne disease in the United States, with the majority of cases occurring in the Northeast. It has now been three decades since the etiological agent of the disease in North America, the spirochete Borrelia burgdorferi, and its primary North American vectors, the ticks Ixodes scapularis Say and I. pacificus Cooley & Kohls, were identified. Great strides have been made in our understanding of the ecology of the vectors and disease agent, and this knowledge has been used to design a wide range of prevention and control strategies. However, despite these advances, the number of Lyme disease cases have steadily increased. In this article, we assess potential reasons for the continued lack of success in prevention and control of Lyme disease in the northeastern United States, and identify conceptual areas where additional knowledge could be used to improve Lyme disease prevention and control strategies. Some of these areas include: 1) identifying critical host infestation rates required to maintain enzootic transmission of B. burgdorferi, 2) understanding how habitat diversity and forest fragmentation impacts acarological risk of exposure to B. burgdorferi and the ability of interventions to reduce risk, 3) quantifying the epidemiological outcomes of interventions focusing on ticks or vertebrate reservoirs, and 4) refining knowledge of how human behavior influences Lyme disease risk and identifying barriers to the adoption of personal protective measures and environmental tick management.

Int J Cardiol. 2012 Feb 1;
Wenger N, Pellaton C, Bruchez P, Schläpfer J

Emerg Infect Dis. 2012 Feb; 18(2): 242-7
Ertel SH, Nelson RS, Cartter ML

To determine the effect of changing public health surveillance methods on the reported epidemiology of Lyme disease, we analyzed Connecticut data for 1996-2007. Data were stratified by 4 surveillance methods and compared. A total of 87,174 reports were received that included 79,896 potential cases. Variations based on surveillance methods were seen. Cases reported through physician-based surveillance were significantly more likely to be classified as confirmed; such case-patients were significantly more likely to have symptoms of erythema migrans only and to have illness onset during summer months. Case-patients reported through laboratory-based surveillance were significantly more likely to have late manifestations only and to be older. Use of multiple surveillance methods provided a more complete clinical and demographic description of cases but lacked efficiency. When interpreting data, changes in surveillance method must be considered.

Rev Med Suisse. 2012 Jan 11; 8(323): 32-5
Baumgartner JD, Christin L

A study published in 1998 linking MMR vaccine and autism was recently retracted by the Lancet because the data were falsified. The impressive reduction of invasive pneumococcal diseases with the 7-valent pneumococcal conjugate vaccine is due to a more than 90% reduction in rates of infections due to vaccinal serotypes at the expense of a slight increase in non-vaccinal serotypes. Genes encoding resistance factors to several antibiotic classes were detected in 30000-year-old samples. New Delhi metallo-beta-lactamase 1 was frequently detected in street water in New Dehli. Azithromycin decreased COPD exacerbations in a select group of patients with COPD at the cost of more frequent small decrements in hearing. Cranberry juice did not prevent recurrent urinary tract infections. Some patients with persistent symptoms after Lyme disease had higher levels of anti-Borrelia antibodies than cured patients.

Am J Trop Med Hyg. 2012 Feb; 86(2): 320-327
Diuk-Wasser MA, Hoen AG, Cislo P, Brinkerhoff R, Hamer SA, Rowland M, Cortinas R, Vourc'h G, Melton F, Hickling GJ, Tsao JI, Bunikis J, Barbour AG, Kitron U, Piesman J, Fish D

Abstract. The geographic pattern of human risk for infection with Borrelia burgdorferi sensu stricto, the tick-borne pathogen that causes Lyme disease, was mapped for the eastern United States. The map is based on standardized field sampling in 304 sites of the density of Ixodes scapularis host-seeking nymphs infected with B. burgdorferi, which is closely associated with human infection risk. Risk factors for the presence and density of infected nymphs were used to model a continuous 8 km×8 km resolution predictive surface of human risk, including confidence intervals for each pixel. Discontinuous Lyme disease risk foci were identified in the Northeast and upper Midwest, with a transitional zone including sites with uninfected I. scapularis populations. Given frequent under- and over-diagnoses of Lyme disease, this map could act as a tool to guide surveillance, control, and prevention efforts and act as a baseline for studies tracking the spread of infection.

QJM. 2012 Feb 1;
Cottle LE, Mekonnen E, Beadsworth MB, Miller AR, Beeching NJ

BACKGROUND: Concerns about over-diagnosis and inappropriate management of Lyme disease (LD) are well documented in North America and supported by clinical data. There are few parallel data on the situation in the UK. AIM: To describe the patterns of referral, investigation, diagnosis and treatment of patients with suspected LD referred to an infectious disease unit in Liverpool, UK. Previous management by National Health Service (NHS) and non-NHS practitioners was reviewed. DESIGN: Descriptive study conducted by retrospective casenotes review. METHODS: Retrospective casenotes review of adults referred with possible LD to an infectious disease unit in Liverpool, UK, over 5 years (2006-2010). RESULTS: Of 115 patients, 27 (23%) were diagnosed with LD, 38 (33%) with chronic fatigue syndrome (CFS) and 13 (11%) with other medical conditions. No specific diagnosis could be made in 38 (33%). At least 53 unnecessary antibiotic courses had been given by non-NHS practitioners; 21 unnecessary courses had been prescribed by NHS practitioners. Among 38 patients, 17 (45%) with CFS had been misdiagnosed as having LD by non-NHS practitioners. CONCLUSION: A minority of referred patients had LD, while a third had CFS. LD is over-diagnosed by non-specialists, reflecting the complexities of clinical and/or laboratory diagnosis. Patients with CFS were susceptible to misdiagnosis in non-NHS settings, reinforcing concerns about missed opportunities for appropriate treatment for this group and about the use of inappropriate diagnostic modalities and anti-microbials in non-NHS settings.