The effect of feeding duration on pathogen transmission was studied for individual ticks infected with either laboratory or field strains of the Lyme disease spirochete Borrelia burgdorferi and field strains of Ehrlichia phagocytophila, an agent of human granulocytic ehrlichiosis. Infected nymphal Ixodes scapularis were allowed to feed individually on mice, and equal numbers were removed at 24-h intervals for < or =96 h. Mice were assayed for infection by culture, serologic testing, and polymerase chain reaction (PCR) analysis. Fed ticks were assayed by culture or PCR analysis. Transmission of B. burgdorferi did not occur during the first 24 h among 66 attempts, with maximum transmission occurring between 48 and 72 h. A model estimating the probability of infection from individual ticks removed by patients in a Lyme disease-endemic area yielded an overall probability of 4.6%. Infected I. scapularis nymphs transmitted E. phagocytophila within 24 h in 2 of 3 attempts, which indicates that daily tick removal may not be adequate to prevent human infection with this agent.

Peyronie’s disease (PD) is a connective tissue disorder which can result in penile deformity. The prevalence of diagnosed PD in the United States (US) has been estimated to be 0.5% in adult males, but there is limited additional information comparing definitive and probable PD cases. We conducted a population-based survey to assess PD prevalence using a convenience-sample of adult men participating in the ResearchNow general population panel. Respondents were categorized according to PD status (definitive, probable, no PD) and segmented by US geographic region, education, and income levels. Of the 7,711 respondents, 57 (0.7%) had definitive PD while 850 (11.0%) had probable PD. Using univariate logistic regression modeling, older age (18–24 vs 24+) (OR = 0.721; 95% CI = 0.570,0.913), Midwest/Northeast/West geographic region (South vs Midwest/Northeast/West) (OR = 0.747; 95% CI = 0.646,0.864), and higher income level (<25K vs 25K+) (OR = 0.820; 95% CI = 0.673,0.997) were each significantly associated with reduced odds of having a definitive/probable PD diagnosis compared with no PD diagnosis. When all three variables were entered in a stepwise multivariable logistic regression, only age (OR = 0.642; 95% CI = 0.497, 0.828) and region (OR = 0.752; 95% CI = 0.647, 0.872) remained significant. This study is the first to report PD prevalence by geographic region and income, and it advocates that the prevalence of PD in the US may be higher than previously cited. Further, given the large discrepancy between definitive PD cases diagnosed by a physician and probable cases not diagnosed by a physician, much more needs to be done to raise awareness of this disease.

Ixodes scapularis Say nymphs collected from a natural focus of human granulocytic ehrlichiosis (HGE) in Westchester County, New York, transmitted the HGE agent to uninfected mice in the laboratory. Infection was demonstrated in 3 of 8 mice by polymerase chain reaction analysis of whole blood and microscopic examination of blood smears for morulae. Two of these mice were also positive by xenodiagnosis. Positive xenodiagnostic larvae maintained infection through molting and transferred infection to 1 of 3 mice. Naturally infected I. scapularis ticks transmit the agent of human granulocytic ehrlichiosis to mice, but both acquisition and transmission of this agent by I. scapularis appear to be less efficient than would be expected for Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, the agent of Lyme disease.

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Vector competence of Ixodes scapularis Say and Dermacentor variabilis Say for the agent of human granulocytic ehrlichiosis (HGE) was compared. Five white-footed mice, Peromyscus leucopus RaÞnesque, were inoculated intra-peritoneally with blood from a mouse infected with the agent of HGE. Approximately 100 I. scapularis and D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Fed larvae were collected, separated according to species and allowed to molt to nymphs. Twenty-six per cent of I. scapularis (34/131) and 11% of D. variabilis (11/96) tested positive for the agent of HGE by polymerase chain reaction (PCR) after molting to nymphs. Positive I. scapularis nymphs transmitted the agent of HGE to P. leucopus mice in 5 of 5 trials. In contrast, the positive D. variabilis nymphs did not transmit the agent of HGE in any of 6 trials. In a 2nd experiment, 3 P. leucopus mice were infested with I. scapularis nymphs that were infected with the agent of HGE. All 3 mice became infected with the agent of HGE and Ϸ300 D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Larvae were collected and allowed to molt to nymphs as before. Approximately 8% (5/60) of the nymphs became positive for the agent of HGE as determined by PCR. Twenty-Þve of these nymphs were then placed on each of 9 P. leucopus mice and allowed to feed to repletion. Evidence of transmission was not observed in any of 9 mice exposed to D. variabilis nymphs. These results demonstrate that although I. scapularis is a competent vector of the agent of the HGE, D. variabilis is not.