Effects of tick control by acaricide self-treatment of white-tailed deer on host-seeking tick infection prevalence and entomologic risk for Ixodes scapularis-borne pathogens

We evaluated the effects of tick control by acaricide self-treatment of white-tailed deer on the infection prevalence and entomologic risk for three Ixodes scapularis-borne bacteria in host-seeking ticks. Ticks were collected from vegetation in areas treated with the 4-Poster device and from control areas over a 6-year period in five geographically diverse study locations in the Northeastern United States and tested for infection with two known agents of human disease, Borrelia burgdorferi and Anaplasma phagocytophilum, and for a novel relapsing fever-group spirochete related to Borrelia miyamotoi. Overall, 38.2% of adults and 12.5% of nymphs were infected with B. burgdorferi; 8.5% of adults and 4.2% of nymphs were infected with A. phagocytophilum; and 1.9% of adults and 0.8% of nymphs were infected with B. miyamotoi. In most cases, treatment with the 4-Poster device was not associated with changes in the prevalence of infection with any of these three microorganisms among nymphal or adult ticks. However, the density of nymphs infected with B. burgdorferi, and consequently the entomologic risk for Lyme disease, was reduced overall by 68% in treated areas compared to control areas among the five study sites at the end of the study. The frequency of bacterial coinfections in ticks was generally equal to the product of the proportion of ticks infected with a single bacterium, indicating that enzootic maintenance of these pathogens is independent. We conclude that controlling ticks on deer by self-application of acaricide results in an overall decrease in the human risk for exposure to these three bacterial agents, which is due solely to a reduction in tick density. © Copyright 2009, Mary Ann Liebert, Inc

ITMS CAPABILITIES IN ISOMER ANALYSIS .3. CHARACTERIZATION OF METHYL AND DIMETHYL DERIVATIVES OF 8-DESMETHYLSESELINE, POTENTIAL ANTIPROLIFERATIVE AGENTS, BY TANDEM MASS-SPECTROMETRY

Two sets of isomeric pyranocoumarins and pyranochromones have been studied by both electron impact and collision-induced dissociation. The daughter spectra were obtained by ion trap mass spectrometry experiments. Characteristic fragments were obtained in electron impact that allowed differentiation between the chromone and the coumarin systems. Distinction between isomers in each set was achieved by collision-induced daughter spectra of selected parent ions

Larval and nymphal tick burdens on <i>Peromyscus leucopus</i> expressed as mean tick count per mouse.

<p>Tick burdens are presented as best fit curves to field derived data from Block Island, RI (top) and Connecticut (bottom) sampled populations (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115494#pone.0115494.s002" target="_blank">S2 Fig</a>.).</p

Threshold curves for <i>Babesia microti</i> survival at different locations and mouse infection prevalences with <i>Borrelia burgdorferi</i> strain BL206.

<p>This figure shows differences in threshold curves, representing where <i>R</i>₀ = 1, and associated 95% confidence intervals (dotted curves), that separate regions of <i>s_N</i> and <i>c</i> where <i>B. microti</i> is expected to emerge and regions where it is expected to fade out. Threshold curves are contour curves where <i>R</i>₀ is plotted as a function of two variables: the proportion of fed infected larvae that survive to become infectious feeding nymphs, <i>s_N</i>, and the proportion of ticks feeding on <i>Peromyscus leucopus</i>, <i>c.</i> Plots indicate effects of location specific (Block Island and Connecticut) timing of tick activity as well as <i>B. burgdorferi</i> strain BL206 strain prevalence in mice (low  = 0.3 and high  = 0.8) on <i>R</i>₀. Coinfection significantly enhances the likelihood of <i>B. microti</i> establishment in Connecticut and on Block Island when <i>B. burgdorferi</i> prevalence among <i>P. leucopus</i> is high (0.80) (confidence bounds do not overlap). Differences in threshold curves for <i>B. burgdorferi</i> strain B348 are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115494#pone.0115494.s003" target="_blank">S3 Fig</a>.</p

Effect of coinfection on larval acquisition of <i>Babesia microti</i>.

<p>The results show the prevalence of <i>B. microti</i> in xenodiagnostic ticks that fed on mice infected with <i>B. microti</i> alone compared to mice coinfected with <i>B. microti</i> and <i>Borrelia burgdorferi</i> strain BL206 (A) or <i>B. burgdorferi</i> strain B348 (B). <i>B. microti</i> parasitemia in mice infected with <i>B. microti</i> alone or <i>B. microti</i> and <i>B. burgdorferi</i> strain B348 are shown in inset above B. The error bars indicate 95% confidence intervals.</p

Laboratory study design.

<p><i>Peromyscus leucopus</i> mice were infected with <i>Babesia microti</i> alone (Group 1 [8 mice]) or coinfected with <i>B. microti</i> and one of two strains of <i>Borrelia burgdorferi:</i> BL206 (Group 2 [3 mice]) or B348 (Group 3 [8 mice]). Xenodiagnosis was performed at 7, 14, 21, 28, 42 days. <i>B. microti</i> infection was determined in ticks at 7, 14, 21, 28, 42 days by qPCR. <i>B. microti</i> infection was determined in mouse blood at weeks 7, 14, 28, 42 days by flow cytometry.</p

Inefficient co-feeding transmission of Borrelia afzelii in two common European songbirds

The spirochete bacterium Borrelia afzelii is the most common cause of Lyme borreliosis in Europe. This tick-borne pathogen can establish systemic infections in rodents but not in birds. However, several field studies have recovered larval Ixodes ricinus ticks infected with B. afzelii from songbirds suggesting successful transmission of B. afzelii. We reviewed the literature to determine which songbird species were the most frequent carriers of B. afzelii-infected I. ricinus larvae and nymphs. We tested experimentally whether B. afzelii is capable of co-feeding transmission on two common European bird species, the blackbird (Turdus merula) and the great tit (Parus major). For each bird species, four naïve individuals were infested with B. afzelii-infected I. ricinus nymphal ticks and pathogen-free larval ticks. None of the co-feeding larvae tested positive for B. afzelii in blackbirds, but a low percentage of infected larvae (3.33%) was observed in great tits. Transstadial transmission of B. afzelii DNA from the engorged nymphs to the adult ticks was observed in both bird species. However, BSK culture found that these spirochetes were not viable. Our study suggests that co-feeding transmission of B. afzelii is not efficient in these two songbird species